AQA Triple Science: Biology — Recall & Retrieval

4.1.1.1 Eukaryotes and Prokaryotes

1.

What type of cell is a bacterium?

Prokaryotic cell.

2.

Where is the genetic material found in a eukaryotic cell?

Inside the nucleus.

3.

State two structures found in bacterial cells.

Cell membrane and cell wall.

4.

What is the name of the small rings of DNA found in some bacterial cells?

Plasmids.

5.

State two differences between prokaryotic cells and eukaryotic cells.

No nucleus; no membrane-bound organelles.

6.

Explain why bacterial cells do not need a nucleus to contain their DNA.

The DNA is free in the cytoplasm as a single circular chromosome, so a nucleus is not needed.

4.1.1.2 Animal and Plant Cells

1.

What organelle contains the genetic material in animal cells?

Nucleus.

2.

What is the function of mitochondria?

Site of aerobic respiration; releases energy (ATP).

3.

Name two structures found in plant cells but not animal cells.

Cell wall and chloroplasts.

4.

What is the function of chloroplasts?

Contain chlorophyll to absorb light energy for photosynthesis.

5.

Explain the function of the permanent vacuole in plant cells.

Contains cell sap and maintains turgor pressure to keep the cell rigid.

6.

Compare the structures found in plant cells and animal cells.

Both have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cellulose cell wall, chloroplasts and a permanent vacuole.

Sub-cellular Structures and Their Functions

1.

What is the function of the nucleus?

Contains DNA and controls the activities of the cell.

2.

What is the function of ribosomes?

Site of protein synthesis.

3.

What is the function of the cell membrane?

Controls the movement of substances into and out of the cell.

4.

Why do muscle cells contain many mitochondria?

They need lots of energy for contraction, so they contain many mitochondria.

5.

Why do cells contain different numbers of organelles?

Different specialised cells have different functions and therefore different numbers of organelles.

6.

Match the following structures to their functions: nucleus, mitochondria, ribosomes, chloroplasts.

Nucleus – controls the cell and contains DNA; mitochondria – site of aerobic respiration; ribosomes – protein synthesis; chloroplasts – photosynthesis.

Required Practical 1: Using a Light Microscope

1.

What type of microscope is used to observe plant and animal cells in the required practical?

Light microscope.

2.

What is the purpose of using a stain when observing cells?

To increase contrast and make cell structures easier to see.

3.

What two things should be included when drawing a biological specimen?

A title and labels.

4.

What is the purpose of including a magnification scale on a microscope drawing?

To show the actual size of the specimen.

5.

Describe the correct order of steps when preparing a microscope slide.

Place the specimen on a slide, add water and stain if required, lower the coverslip carefully, then observe starting with the lowest magnification.

6.

Calculate the magnification of an image that is 20 mm long if the real cell size is 0.02 mm.

1000×.

Scale and Size of Cells

1.

What unit is commonly used to measure cells?

Micrometres (µm).

2.

What does the prefix micro- mean?

One millionth (10⁻⁶).

3.

Convert 1 mm into micrometres.

1000 µm.

4.

Convert 5000 µm into millimetres.

5 mm.

5.

Express 0.000005 m in standard form.

5 × 10⁻⁶ m.

6.

Explain why standard form is useful when measuring cells.

It makes very small numbers easier to write and compare.

4.1.1.3 Cell Specialisation

1.

What is a specialised cell?

A cell adapted to carry out a specific function.

2.

Name a specialised animal cell.

Sperm cell.

3.

Name a specialised plant cell.

Root hair cell.

4.

State one adaptation of a sperm cell.

Tail to swim to the egg.

5.

State one adaptation of a root hair cell.

Large surface area for absorbing water and mineral ions.

6.

Explain how the adaptations of specialised cells help them carry out their functions.

Their adaptations enable them to perform their specific functions efficiently.

4.1.1.4 Cell Differentiation

1.

What is differentiation?

The process by which a cell becomes specialised.

2.

Why do cells differentiate?

To carry out a specific function.

3.

What does a cell become after differentiation?

A specialised cell.

4.

When do most animal cells differentiate?

During early development.

5.

Why can many plant cells continue to differentiate throughout life?

Many plant cells retain the ability to divide and differentiate throughout life.

6.

Explain why differentiation is important in multicellular organisms.

It allows multicellular organisms to have specialised cells that perform different functions efficiently.

4.1.1.5 Microscopy

1.

What is magnification?

How many times larger the image is than the actual object.

2.

What is resolution?

The ability to distinguish two close points as separate.

3.

Which type of microscope generally has the highest magnification and resolution?

Electron microscope.

4.

What is the formula for calculating magnification?

Magnification = Image size ÷ Actual size.

5.

What magnification does a microscope have if the image is 1000 times larger than the actual object?

1000×.

6.

Why are electron microscopes able to show smaller structures than light microscopes?

They have much higher magnification and resolution, allowing smaller structures to be seen.

4.1.1.6 Culturing Microorganisms (Biology Only)

1.

How do bacteria reproduce?

By binary fission.

2.

What is binary fission?

A type of asexual reproduction where one bacterium divides into two identical cells.

3.

How quickly can bacteria divide when conditions are suitable?

Every 20 minutes.

4.

Name two conditions needed for bacterial growth.

Warm temperature and nutrients. (Also accept moisture.)

5.

Calculate the number of bacteria produced after two divisions from one bacterium.

4 bacteria.

6.

Why are bacteria grown on agar plates in laboratories?

To grow and study bacteria.

Aseptic Technique

1.

Why are Petri dishes sterilised before use?

To kill microorganisms and prevent contamination.

2.

Why are culture media sterilised before bacteria are added?

To prevent contamination by unwanted microorganisms.

3.

Why is an inoculating loop heated before transferring bacteria?

To sterilise it before transferring bacteria.

4.

Why are Petri dish lids taped after bacteria are added?

To reduce contamination while allowing oxygen to enter.

5.

Why are school cultures usually incubated at 25°C?

To reduce the risk of growing harmful pathogens.

6.

What is the purpose of aseptic technique?

To prevent contamination and ensure reliable results.

Required Practical 2: Antibiotics and Antiseptics

1.

What is measured to investigate the effect of antibiotics on bacteria?

The size of the zone of inhibition.

2.

What is a zone of inhibition?

The clear area around an antibiotic disc where bacteria have not grown.

3.

What does a larger zone of inhibition show?

The antibiotic is more effective against the bacteria.

4.

Why must the same volume of antibiotic be used on each agar plate?

To make it a fair test.

5.

Why are bacteria grown on agar before testing antibiotics?

To produce an even lawn of bacteria for reliable results.

6.

How is the area of a circular zone of inhibition calculated?

Area = πr²

4.1.2.1 Chromosomes

1.

Where are chromosomes found?

In the nucleus.

2.

What molecule are chromosomes made from?

DNA.

3.

What is a gene?

A section of DNA that codes for a protein.

4.

How many copies of each chromosome are normally found in body cells?

Two copies (one from each parent).

5.

Explain the relationship between DNA, genes and chromosomes.

DNA makes up genes, and genes are found on chromosomes.

6.

Why must chromosomes be copied before cell division?

So each new cell receives an identical set of chromosomes.

4.1.2.2 Mitosis and the Cell Cycle

1.

What type of cell division produces genetically identical cells?

Mitosis.

2.

What happens to DNA before a cell divides?

It is replicated.

3.

What are the two cells produced by mitosis like?

Genetically identical to each other and the parent cell.

4.

Name two situations where mitosis occurs.

Growth and tissue repair. (Also accept asexual reproduction in some organisms.)

5.

Put these stages of the cell cycle in order: cell growth, DNA replication, cell division.

Cell growth → DNA replication → Cell division (mitosis).

6.

Why is mitosis important for growth and repair?

It produces genetically identical cells for growth, repair and replacement.

4.1.2.3 Stem Cells

1.

What is a stem cell?

An unspecialised cell that can divide and differentiate.

2.

Where are embryonic stem cells found?

In embryos.

3.

What can stem cells differentiate into?

Many different specialised cell types.

4.

Where are adult stem cells found in humans?

Bone marrow.

5.

What are meristem cells found in plants able to produce?

Any type of plant cell.

6.

Give one medical use of stem cells.

Replacing damaged cells, e.g. treating leukaemia with bone marrow stem cells.

4.1.3.1 Diffusion

1.

What is diffusion?

The net movement of particles from a high concentration to a low concentration.

2.

In which direction do particles move during diffusion?

From high concentration to low concentration.

3.

Name one substance that moves by diffusion.

Oxygen. (Also accept carbon dioxide.)

4.

State three factors that affect the rate of diffusion.

Concentration gradient, temperature and surface area.

5.

Why does increasing surface area increase the rate of diffusion?

More particles can cross the membrane at the same time.

6.

Why do single-celled organisms have a high surface area to volume ratio?

It allows substances to diffuse quickly enough to meet the cell's needs.

Surface Area to Volume Ratio

1.

What does surface area to volume ratio compare?

The amount of surface area compared with the volume.

2.

What happens to surface area to volume ratio as a cell gets bigger?

It decreases.

3.

Calculate the surface area of a cube with sides of 2 cm.

24 cm².

4.

Calculate the volume of a cube with sides of 2 cm.

8 cm³.

5.

Explain why large organisms need exchange surfaces.

They have a low surface area to volume ratio and cannot rely on diffusion alone.

6.

Explain why cells remain small.

Small cells have a larger surface area to volume ratio, making diffusion more efficient.

Exchange Surfaces

1.

Name one exchange surface in humans.

Alveoli. (Also accept small intestine.)

2.

Name one exchange surface in plants.

Root hair cells. (Also accept leaves.)

3.

State one feature of an efficient exchange surface.

Large surface area.

4.

How are alveoli adapted for gas exchange?

Large surface area, thin walls and a good blood supply.

5.

How are fish gills adapted for gas exchange?

Large surface area, thin exchange surface and good blood flow.

6.

How are leaves adapted for gas exchange?

Large surface area, thin structure and stomata for gas exchange.

4.1.3.2 Osmosis

1.

What is osmosis?

The net movement of water molecules through a partially permeable membrane from a dilute solution to a concentrated solution.

2.

What substance moves during osmosis?

Water molecules.

3.

What type of membrane is needed for osmosis?

A partially permeable membrane.

4.

In which direction does water move during osmosis?

From a dilute solution to a concentrated solution.

5.

What happens to a plant cell placed in a dilute solution?

It becomes turgid.

6.

What happens to a plant cell placed in a concentrated solution?

It becomes plasmolysed.

Required Practical 3: Osmosis in Plant Tissue

1.

What type of plant tissue is commonly used in the osmosis required practical?

Potato cylinders.

2.

Why are potato cylinders placed into different concentrations of solution?

To investigate the effect of different concentrations on osmosis.

3.

Why is the mass of potato cylinders measured before and after the experiment?

To calculate the change in mass due to water movement.

4.

Calculate the percentage change in mass if a potato cylinder changes from 5 g to 6 g.

20%.

5.

Why should potato cylinders be the same size at the start?

To make it a fair test.

6.

Why are repeats carried out in the osmosis investigation?

To improve the reliability of the results.

4.1.3.3 Active Transport

1.

What is active transport?

The movement of substances from a low concentration to a high concentration against the concentration gradient.

2.

Does active transport require energy?

Yes.

3.

In which direction does active transport move substances?

From low concentration to high concentration.

4.

Where does the energy for active transport come from?

Respiration.

5.

Why do root hair cells use active transport?

To absorb mineral ions from dilute soil.

6.

Give one difference between diffusion and active transport.

Diffusion does not require energy and moves down a concentration gradient; active transport requires energy and moves against the concentration gradient.

Topic 1 Review

1.

What is the difference between a prokaryotic cell and a eukaryotic cell?

Prokaryotic cells have no nucleus or membrane-bound organelles; eukaryotic cells do.

2.

Name the organelle where aerobic respiration occurs.

Mitochondria.

3.

Explain why specialised cells have different structures.

They are adapted to carry out specific functions efficiently.

4.

State the three ways substances move across cell membranes.

Diffusion, osmosis and active transport.

5.

What type of cell division produces identical cells?

Mitosis.

6.

Explain why cells need transport systems.

As organisms become larger, diffusion alone is too slow, so transport systems move substances efficiently around the body.

4.2.1 Principles of Organisation

1.

What are the basic building blocks of all living organisms?

Cells.

2.

What is a tissue?

A group of similar cells working together to carry out a particular function.

3.

What is an organ?

A group of different tissues working together to perform a particular function.

4.

What is an organ system?

A group of organs working together to carry out a particular function.

5.

Put these levels of organisation in order: organ, cell, organism, tissue.

Cell → Tissue → Organ → Organ system → Organism.

6.

Explain how tissues work together to form an organ.

Different tissues perform different functions and work together to allow the organ to carry out its role.

4.2.2.1 The Human Digestive System

1.

What is the main function of the digestive system?

To break down food into small soluble molecules that can be absorbed into the blood.

2.

Where does digestion begin in the human body?

The mouth.

3.

Name the organ where most absorption of digested food occurs.

The small intestine.

4.

State the role of the small intestine in digestion and absorption.

Completes digestion and absorbs soluble products of digestion into the bloodstream.

5.

Explain why digestion produces small soluble molecules.

Small soluble molecules can pass through the walls of the small intestine into the blood.

6.

Explain how the digestive system and circulatory system work together.

The digestive system breaks food into soluble molecules, which the circulatory system transports to cells throughout the body.

Enzymes and Metabolism

1.

What type of biological molecule are enzymes?

Proteins.

2.

What is the function of enzymes?

To act as biological catalysts that speed up chemical reactions.

3.

What is the active site of an enzyme?

The part of the enzyme where the substrate binds.

4.

Explain why enzymes are specific to their substrates.

Each enzyme has an active site with a specific shape that only fits one substrate.

5.

Describe the lock and key model of enzyme action.

The substrate has a complementary shape to the enzyme's active site.

6.

Explain why changes in temperature can affect enzyme activity.

High temperatures change the shape of the active site (denature the enzyme), reducing or stopping enzyme activity.

Digestive Enzymes

1.

Which enzyme breaks down starch?

Amylase.

2.

Which enzyme breaks down proteins?

Protease.

3.

Which enzyme breaks down lipids?

Lipase.

4.

What are the products of protein digestion?

Amino acids.

5.

What are the products of lipid digestion?

Fatty acids and glycerol.

6.

Explain why the products of digestion can be absorbed into the bloodstream.

They are small and soluble, so they can pass through the wall of the small intestine into the bloodstream.

Bile

1.

Where is bile produced?

The liver.

2.

Where is bile stored?

The gall bladder.

3.

What is the role of bile in digestion?

Neutralises stomach acid and emulsifies fats.

4.

Why does bile neutralise stomach acid?

To provide the optimum alkaline pH for enzymes in the small intestine.

5.

Explain how bile increases the rate of fat digestion.

It breaks large fat droplets into smaller droplets, increasing the surface area for lipase.

6.

Explain why lipase works more effectively after bile has acted on fats.

Emulsification increases the surface area, allowing lipase to digest fats more quickly.

Required Practical 4: Testing for Biological Molecules

1.

Which food test is used to test for starch?

Iodine solution.

2.

Which food test is used to test for protein?

Biuret reagent.

3.

Which food test is used to test for sugars?

Benedict's solution.

4.

What colour change shows a positive Benedict's test result?

Blue to brick-red (after heating).

5.

Explain why different reagents are used to test different food molecules.

Each reagent reacts specifically with a different biological molecule.

6.

Describe how to test a food sample for starch, protein and sugar.

Add iodine for starch (blue-black if present); add Biuret reagent for protein (lilac if present); add Benedict's solution and heat for reducing sugars (blue to green/yellow/orange/brick-red).

Required Practical 5: Effect of pH on Amylase

1.

Which enzyme is investigated in the pH practical?

Amylase.

2.

Which substance is broken down by amylase?

Starch.

3.

Which reagent is used to test for starch?

Iodine solution.

4.

Explain why pH is controlled during an enzyme investigation.

pH affects enzyme activity, so it must be kept constant for a fair test.

5.

Explain why temperature must be controlled when investigating enzyme activity.

Temperature also affects enzyme activity and must be controlled.

6.

Explain how the time taken for starch to disappear can be used to measure enzyme activity.

The shorter the time taken for starch to disappear, the faster the enzyme is working.

4.2.2.2 The Heart and Blood Vessels

1.

What is the main function of the heart?

To pump blood around the body.

2.

What type of circulatory system do humans have?

A double circulatory system.

3.

Which side of the heart pumps blood to the lungs?

The right side.

4.

Which side of the heart pumps blood around the body?

The left side.

5.

Name the five main blood vessels associated with the heart.

Aorta, vena cava, pulmonary artery, pulmonary vein and coronary arteries.

6.

Explain why the heart is described as a double circulatory system.

Blood passes through the heart twice during one complete circulation of the body.

Structure of the Heart

1.

Which organ pumps blood around the body?

The heart.

2.

What is the function of the ventricles?

To pump blood out of the heart.

3.

What is the function of the atria?

To receive blood returning to the heart.

4.

Why is the left ventricle thicker than the right ventricle?

It pumps blood at higher pressure around the whole body.

5.

Explain why the heart muscle needs its own blood supply.

The heart muscle needs oxygen and glucose for aerobic respiration.

6.

Explain the role of the natural pacemaker and state where it is found.

It generates electrical impulses that control the heart rate and is found in the right atrium of the heart.

The Lungs and Gas Exchange

1.

What gas enters the blood in the lungs?

Oxygen.

2.

What gas leaves the blood in the lungs?

Carbon dioxide.

3.

What structure in the lungs is adapted for gas exchange?

Alveoli.

4.

Name the blood vessels surrounding alveoli.

Capillaries.

5.

Explain how alveoli are adapted for gas exchange.

Large surface area, moist surface, thin walls (one cell thick) and a good blood supply.

6.

Explain why a good blood supply increases the efficiency of gas exchange.

It maintains a steep concentration gradient for rapid diffusion.

Blood Vessels

1.

Name the three types of blood vessel.

Arteries, veins and capillaries.

2.

Which blood vessel carries blood away from the heart?

Arteries.

3.

Which blood vessel carries blood towards the heart?

Veins.

4.

Explain why arteries have thick muscular walls.

To withstand the high pressure of blood pumped from the heart.

5.

Explain why capillaries have thin walls.

To provide a short diffusion distance for substances.

6.

Compare the structures of arteries, veins and capillaries.

Arteries have thick muscular, elastic walls and a small lumen; veins have thinner walls, a large lumen and valves; capillaries have walls one cell thick for efficient exchange.

4.2.2.3 Blood

1.

What type of tissue is blood?

A connective tissue.

2.

What is the liquid part of blood called?

Plasma.

3.

Name the four main components of blood.

Plasma, red blood cells, white blood cells and platelets.

4.

What is the function of red blood cells?

To transport oxygen.

5.

What is the function of white blood cells?

To defend the body against pathogens.

6.

Explain how red blood cells are adapted to transport oxygen.

They contain haemoglobin, have no nucleus and are biconcave, giving a large surface area for oxygen transport.

4.2.2.4 Coronary Heart Disease: A Non-Communicable Disease

1.

What type of disease is coronary heart disease?

A non-communicable disease.

2.

What builds up inside coronary arteries during coronary heart disease?

Fatty deposits (plaques).

3.

What does the narrowing of coronary arteries reduce?

Blood flow to the heart muscle.

4.

What is the purpose of a stent?

To keep the coronary artery open.

5.

How do statins reduce the risk of coronary heart disease?

They reduce blood cholesterol levels.

6.

Explain why reduced oxygen supply damages heart muscle.

Less oxygen means less aerobic respiration, so less energy is released and heart muscle cells can die.

Treatments for Cardiovascular Disease

1.

What is a stent used for?

To keep narrowed coronary arteries open.

2.

What are statins used for?

To reduce blood cholesterol levels.

3.

What is a mechanical heart valve used to replace?

A damaged heart valve.

4.

What may a patient receive during heart failure?

A heart transplant or an artificial heart.

5.

State one artificial device used to support the heart.

An artificial heart or a ventricular assist device (VAD).

6.

Explain why different treatments have different risks and benefits.

Treatments vary in effectiveness, recovery time, side effects and risk of complications.

4.2.2.5 Health Issues

1.

What is meant by health?

The state of physical and mental well-being.

2.

Name two types of disease.

Communicable and non-communicable diseases.

3.

State one factor that can affect physical health.

Diet. (Also accept exercise, stress or life situation.)

4.

Explain how diseases can interact with each other.

One disease can increase the likelihood or severity of another.

5.

Explain how defects in the immune system can affect health.

They reduce the body's ability to fight infection.

6.

Explain how lifestyle factors can affect disease risk.

Smoking, poor diet, lack of exercise and alcohol can increase disease risk.

4.2.2.6 The Effect of Lifestyle on Some Non-Communicable Diseases

1.

What is a risk factor?

A factor that increases the chance of developing a disease.

2.

Name one lifestyle risk factor for disease.

Smoking. (Also accept poor diet, alcohol or lack of exercise.)

3.

How can smoking increase the risk of lung disease?

It damages the lungs and can cause diseases such as COPD and lung cancer.

4.

How can diet affect cardiovascular disease?

Diets high in saturated fat increase blood cholesterol and the risk of coronary heart disease.

5.

Explain why obesity increases the risk of Type 2 diabetes.

Obesity can reduce the body's response to insulin.

6.

Explain how alcohol can affect the liver and brain.

Alcohol can damage liver cells and affect brain function.

Risk Factors and Data

1.

What does correlation mean?

A relationship between two variables.

2.

What type of graph can show a correlation between two variables?

A scatter graph.

3.

What is a risk factor?

A factor that increases the chance of developing a disease.

4.

Explain why correlation does not always prove causation.

Other variables may be responsible for the relationship.

5.

Describe how scientists use data to investigate disease risk factors.

They analyse data to identify patterns and possible risk factors.

6.

Explain why large samples are useful when studying disease patterns.

They produce more reliable and representative results.

4.2.2.7 Cancer

1.

What is cancer?

Uncontrolled cell division.

2.

What is a tumour?

A mass of abnormal cells.

3.

What is the difference between benign and malignant tumours?

Benign tumours do not spread; malignant tumours invade other tissues and spread.

4.

Why are malignant tumours more dangerous than benign tumours?

They can spread to other parts of the body through the bloodstream or lymphatic system.

5.

State one lifestyle risk factor linked to cancer.

Smoking.

6.

Explain how cancer can spread to other parts of the body.

Cancer cells break away from the original tumour and form secondary tumours elsewhere in the body.

4.2.3.1 Plant Tissues

1.

What type of organ is a leaf?

An organ.

2.

Name the tissue where photosynthesis mainly occurs.

Palisade mesophyll tissue.

3.

What is the function of xylem tissue?

Transports water and mineral ions from the roots to the leaves.

4.

What is the function of phloem tissue?

Transports dissolved sugars (products of photosynthesis) around the plant.

5.

Explain how palisade mesophyll cells are adapted for photosynthesis.

They contain many chloroplasts near the upper surface of the leaf to absorb maximum light.

6.

Explain how different plant tissues allow the plant to survive.

Different tissues are specialised for functions such as photosynthesis, transport and protection, enabling the plant to survive.

Leaf Structure

1.

What tissue covers the outside of a leaf?

Epidermal tissue.

2.

What is the function of guard cells?

To open and close the stomata.

3.

What are stomata?

Pores in the leaf that allow gas exchange.

4.

Explain why leaves contain spongy mesophyll.

To allow gases to diffuse through the leaf.

5.

Explain how stomata control water loss.

Guard cells open and close the stomata to regulate water loss and gas exchange.

6.

Explain how the structure of a leaf allows efficient photosynthesis.

A large surface area, thin structure, palisade cells with many chloroplasts, air spaces in the spongy mesophyll and stomata all increase the efficiency of photosynthesis.

4.2.3.2 Plant Organ System

1.

Name the three main organs in a plant transport system.

Roots, stem and leaves.

2.

What substance does xylem transport?

Water and mineral ions.

3.

What substance does phloem transport?

Dissolved sugars.

4.

What process moves water through a plant?

Transpiration.

5.

Explain how root hair cells are adapted to absorb water and minerals.

They have a large surface area and thin walls, allowing efficient absorption of water by osmosis and mineral ions by active transport.

6.

Explain the difference between transpiration and translocation.

Transpiration is the loss of water from leaves; translocation is the movement of dissolved sugars in the phloem.

Root Hair Cells, Xylem and Phloem

1.

What process allows root hair cells to absorb water?

Osmosis.

2.

What process allows root hair cells to absorb mineral ions?

Active transport.

3.

What strengthens xylem vessels?

Lignin.

4.

What do phloem tubes transport?

Dissolved sugars.

5.

Explain why root hair cells have a large surface area.

It increases the rate of absorption of water and mineral ions.

6.

Explain how xylem structure is adapted for transporting water.

Xylem vessels are dead, hollow tubes strengthened with lignin, allowing water and mineral ions to move efficiently.

Transpiration and Stomata

1.

What is transpiration?

The loss of water vapour from the leaves.

2.

Through which structures does water leave a leaf?

Stomata.

3.

What is the function of guard cells?

To control the opening and closing of the stomata.

4.

Name four factors that affect transpiration rate.

Light intensity, temperature, humidity and air movement (wind).

5.

Explain how increased temperature affects transpiration.

Higher temperatures increase evaporation and diffusion, increasing transpiration.

6.

Explain how light intensity affects transpiration.

Higher light intensity opens the stomata for photosynthesis, increasing transpiration.

Measuring Transpiration

1.

What is measured when investigating transpiration rate?

Water uptake.

2.

What apparatus can be used to measure water uptake by a plant?

A potometer.

3.

Why are experiments repeated when measuring transpiration?

To improve the reliability of the results.

4.

Calculate the rate of water uptake if 10 cm³ of water is taken up in 5 hours.

2 cm³ per hour.

5.

Explain why environmental conditions must be controlled during a transpiration investigation.

To ensure a fair test.

6.

Explain why changing one factor at a time improves an investigation.

It ensures that any changes in water uptake are due only to the independent variable.

Topic 2 Review

1.

State the order of organisation from cell to organism.

Cell → Tissue → Organ → Organ system → Organism.

2.

Explain the role of enzymes in digestion.

Enzymes are biological catalysts that speed up the breakdown of large insoluble food molecules into small soluble molecules for absorption.

3.

Explain how the heart transports blood around the body.

The heart pumps deoxygenated blood to the lungs and oxygenated blood to the rest of the body in a double circulatory system.

4.

State the functions of the four components of blood.

Plasma – transports blood cells and dissolved substances; red blood cells – transport oxygen; white blood cells – defend against pathogens; platelets – help blood to clot.

5.

Explain how lifestyle factors increase disease risk.

Lifestyle factors such as smoking, poor diet, lack of exercise and excessive alcohol consumption increase the risk of non-communicable diseases.

6.

Explain how plant tissues are adapted for transport and photosynthesis.

Xylem transports water and mineral ions, phloem transports dissolved sugars, root hair cells absorb water and mineral ions efficiently, and leaves are adapted for photosynthesis with many chloroplasts and a large surface area.

4.3.1.1 Communicable (Infectious) Diseases

1.

What is a pathogen?

A microorganism that causes disease.

2.

Name the four types of pathogen.

Bacteria, viruses, fungi and protists.

3.

What is an infectious disease?

A disease caused by pathogens that can be spread between organisms.

4.

State three ways pathogens can be spread.

Air, water and direct contact. (Also accept contaminated food.)

5.

Explain why viruses can cause damage to body cells.

They reproduce inside body cells, damaging or destroying them.

6.

Explain why bacteria can make humans feel ill.

They produce toxins that damage tissues and make people feel ill.

4.3.1.2 Viral Diseases

1.

What type of pathogen causes measles?

A virus.

2.

How is measles spread?

By droplets from coughs and sneezes.

3.

State one symptom of measles.

Red skin rash. (Also accept fever.)

4.

How does HIV affect the immune system?

It attacks white blood cells of the immune system.

5.

How is HIV transmitted between people?

Through sexual contact or exchange of body fluids (e.g. blood).

6.

Explain how Tobacco Mosaic Virus affects plant growth.

It causes discolouration of leaves, reducing chlorophyll and photosynthesis.

Measles

1.

What type of microorganism causes measles?

A virus.

2.

How is the measles virus spread?

By droplets from coughs and sneezes.

3.

State two symptoms of measles.

Red skin rash and fever.

4.

Why are most young children vaccinated against measles?

To provide immunity and prevent the disease spreading.

5.

Explain why measles can sometimes be fatal.

It can lead to serious complications such as pneumonia or encephalitis.

6.

Explain how vaccination reduces the spread of measles.

Vaccinated people are immune, reducing the spread of the virus through the population.

HIV

1.

What type of pathogen causes HIV?

A virus.

2.

What does HIV attack in the human body?

White blood cells.

3.

State one way HIV can be transmitted.

Unprotected sexual contact. (Also accept blood-to-blood contact or shared needles.)

4.

What condition can develop when HIV damages the immune system severely?

AIDS.

5.

Why can people with AIDS become ill from other infections?

Their immune system is weakened and cannot fight off infections effectively.

6.

How can antiretroviral drugs help people with HIV?

They stop the virus reproducing, slowing damage to the immune system.

Tobacco Mosaic Virus (TMV)

1.

What type of pathogen causes TMV?

A virus.

2.

Which type of organism is affected by TMV?

Plants.

3.

What appearance does TMV cause on plant leaves?

A mosaic pattern of discoloured patches on the leaves.

4.

Why does TMV reduce plant growth?

It reduces photosynthesis.

5.

Explain how TMV affects photosynthesis.

Less chlorophyll is available to absorb light for photosynthesis.

6.

Explain why a plant infected with TMV may produce a lower yield.

Less photosynthesis means less glucose is produced for growth, reducing crop yield.

4.3.1.3 Bacterial Diseases

1.

What type of pathogen causes Salmonella food poisoning?

Bacteria.

2.

How is Salmonella usually spread?

By eating contaminated food, especially poultry.

3.

State two symptoms of Salmonella infection.

Fever and stomach cramps. (Also accept vomiting or diarrhoea.)

4.

Why do bacteria produce toxins?

They damage body cells and tissues.

5.

How is gonorrhoea spread?

Through sexual contact.

6.

Why are some strains of gonorrhoea difficult to treat?

Some strains have become resistant to antibiotics.

Salmonella

1.

What type of pathogen causes Salmonella food poisoning?

Bacteria.

2.

How can Salmonella bacteria enter the human body?

By eating contaminated food.

3.

State two symptoms caused by Salmonella.

Fever and diarrhoea. (Also accept stomach cramps or vomiting.)

4.

How can Salmonella in poultry be controlled?

Vaccinating poultry.

5.

Explain why good hygiene reduces the spread of Salmonella.

It reduces the spread of bacteria and contamination of food.

6.

Explain how bacterial toxins cause illness.

Toxins produced by the bacteria damage cells and tissues, causing illness.

Gonorrhoea

1.

What type of pathogen causes gonorrhoea?

Bacteria.

2.

How is gonorrhoea transmitted?

Through sexual contact.

3.

State one symptom of gonorrhoea.

Pain when urinating. (Also accept thick yellow or green discharge.)

4.

Which antibiotic was previously used to treat gonorrhoea?

Penicillin.

5.

Why have some strains of gonorrhoea become resistant to antibiotics?

Overuse of antibiotics has led to antibiotic-resistant strains.

6.

State two ways the spread of gonorrhoea can be reduced.

Using barrier contraception (e.g. condoms) and treating infected people with appropriate antibiotics.

4.3.1.4 Fungal Diseases

1.

What type of pathogen causes rose black spot?

Rose black spot.

2.

Which organism is affected by rose black spot?

Rose plants.

3.

State one symptom of rose black spot.

Purple or black spots on leaves.

4.

How is rose black spot spread?

By water or wind.

5.

Why does rose black spot reduce plant growth?

It reduces photosynthesis because leaves are damaged or lost.

6.

State two methods used to control rose black spot.

Use fungicides and remove or burn infected leaves.

4.3.1.5 Protist Diseases

1.

What type of pathogen causes malaria?

A protist.

2.

Which organism acts as the vector for malaria?

Female mosquito.

3.

What disease is caused by the malarial protist?

Malaria.

4.

State one symptom of malaria.

Recurrent fever. (Also accept chills or flu-like symptoms.)

5.

Explain why mosquitoes are important in the spread of malaria.

Mosquitoes transmit the protist between humans.

6.

State two ways the spread of malaria can be reduced.

Destroy mosquito breeding sites and use insecticide-treated bed nets.

4.3.1.6 Human Defence Systems

1.

What is the first barrier against pathogens entering the body?

The skin.

2.

What substance in the stomach destroys many pathogens?

Hydrochloric acid.

3.

How do hairs and mucus in the nose help defend the body?

They trap pathogens and prevent them entering the lungs.

4.

What is the role of white blood cells?

To defend the body against pathogens.

5.

Name the three ways white blood cells defend against pathogens.

Phagocytosis, producing antibodies and producing antitoxins.

6.

Explain how phagocytosis helps remove pathogens.

White blood cells engulf and digest pathogens.

White Blood Cells

1.

What type of cell helps defend the body against pathogens?

White blood cell.

2.

What process involves white blood cells engulfing pathogens?

Phagocytosis.

3.

What do antibodies bind to on pathogens?

Antigens.

4.

What do antitoxins neutralise?

Toxins produced by bacteria.

5.

Explain why antibodies are specific to particular pathogens.

Each antibody has a complementary shape to a specific antigen.

6.

Explain how white blood cells help the body recover from infection.

They engulf pathogens, produce antibodies to destroy them and produce antitoxins to neutralise bacterial toxins.

4.3.1.7 Vaccination

1.

What is introduced into the body during vaccination?

Dead or inactive pathogens, or parts of pathogens (antigens).

2.

Are the pathogens used in vaccines usually alive or dead/inactive?

Dead or inactive.

3.

Which cells produce antibodies after vaccination?

White blood cells (lymphocytes).

4.

What happens if the same pathogen enters the body again?

They produce antibodies rapidly, destroying the pathogen before symptoms develop.

5.

Explain why vaccination prevents illness.

It stimulates the immune system to produce memory cells without causing disease.

6.

Explain how high vaccination rates reduce the spread of disease.

Fewer people can become infected, reducing the spread of the disease (herd immunity).

4.3.1.8 Antibiotics and Painkillers

1.

What type of pathogen can antibiotics kill?

Bacteria.

2.

Name one antibiotic.

Penicillin.

3.

Why do antibiotics not kill viruses?

Viruses reproduce inside body cells, so antibiotics cannot target them.

4.

What is the purpose of painkillers?

To relieve pain but not kill pathogens.

5.

Why are antibiotics becoming less effective?

Because antibiotic-resistant bacteria are developing.

6.

Explain how antibiotic resistance develops in bacteria.

Random mutations make some bacteria resistant; these survive treatment, reproduce and pass on the resistance allele.

4.3.1.9 Discovery and Development of Drugs

1.

Where did the drug digitalis originally come from?

The foxglove plant.

2.

Which plant does aspirin originate from?

Willow.

3.

Who discovered penicillin?

Alexander Fleming.

4.

What is the purpose of preclinical testing?

To test toxicity, efficacy and dosage using cells, tissues and live animals.

5.

What is tested during clinical trials?

Toxicity, efficacy and optimum dose in healthy volunteers and patients.

6.

Explain why new medicines must be tested before use.

To ensure they are safe, effective and the correct dose before being licensed.

Drug Testing

1.

What does toxicity testing investigate?

Whether the drug is harmful.

2.

What does efficacy testing investigate?

Whether the drug works.

3.

What is meant by the optimum dose?

The most effective dose with the fewest side effects.

4.

Why are very low doses used at the start of clinical trials?

To reduce the risk of harmful side effects.

5.

What is a placebo?

A dummy treatment with no active drug.

6.

Why are double blind trials used?

To prevent bias and produce valid, reliable results.

4.3.2.1 Producing Monoclonal Antibodies

1.

What are monoclonal antibodies?

Antibodies produced from a single clone of cells that are identical and specific to one antigen.

2.

What cells produce antibodies?

Lymphocytes.

3.

What type of cell is produced when lymphocytes are combined with tumour cells?

A hybridoma cell.

4.

What is a hybridoma cell able to do?

Divide repeatedly and produce identical antibodies.

5.

Why are hybridoma cells cloned?

To produce large quantities of identical monoclonal antibodies.

6.

Explain why monoclonal antibodies are specific.

They bind to one specific antigen because they are all identical.

4.3.2.2 Uses of Monoclonal Antibodies

1.

Give one use of monoclonal antibodies.

Pregnancy tests. (Also accept treating cancer or identifying pathogens.)

2.

How can monoclonal antibodies be used in pregnancy tests?

They bind to the hormone hCG, producing a coloured line if it is present.

3.

How can monoclonal antibodies identify pathogens?

They bind to specific antigens on pathogens.

4.

How can monoclonal antibodies be used to locate molecules in cells?

They are attached to fluorescent dyes that bind to target molecules.

5.

How can monoclonal antibodies target cancer cells?

They carry drugs or radioactive substances directly to cancer cells.

6.

Explain why monoclonal antibodies can be useful in medical treatments.

They target specific cells, reducing damage to healthy cells.

4.3.3.1 Detection and Identification of Plant Diseases

1.

State one sign that a plant may be diseased.

Stunted growth. (Also accept spots on leaves, areas of decay, malformed stems or discolouration.)

2.

Name one type of pathogen that can infect plants.

Virus. (Also accept bacteria, fungi or protists.)

3.

What does stunted growth suggest about a plant?

The plant may be diseased or have a mineral ion deficiency.

4.

How can plant diseases be identified using testing kits?

By using testing kits containing monoclonal antibodies.

5.

What nutrient deficiency causes chlorosis?

Magnesium ion deficiency.

6.

Why are magnesium ions needed by plants?

Magnesium ions are needed to make chlorophyll for photosynthesis.

Plant Ion Deficiencies

1.

Which ion is needed to make chlorophyll?

Magnesium ions.

2.

Which ion is needed for protein synthesis?

Nitrate ions.

3.

What symptom is caused by nitrate deficiency?

Stunted growth.

4.

What symptom is caused by magnesium deficiency?

Chlorosis (yellow leaves).

5.

Explain why nitrate deficiency affects plant growth.

Nitrate ions are needed to make amino acids and proteins for growth.

6.

Explain why magnesium deficiency reduces photosynthesis.

Magnesium is needed to make chlorophyll, so less photosynthesis occurs.

4.3.3.2 Plant Defence Responses

1.

State one physical defence response in plants.

Cellulose cell walls. (Also accept waxy cuticle.)

2.

What substance are plant cell walls made from?

Cellulose.

3.

What is the function of the waxy cuticle on leaves?

It forms a barrier to prevent pathogens entering the plant.

4.

State one chemical defence response in plants.

Antibacterial chemicals. (Also accept poisons.)

5.

State one mechanical defence response in plants.

Thorns or hairs.

6.

Explain how plant defence responses reduce infection or damage.

They prevent pathogens entering the plant or discourage animals from damaging it.

Topic 3 Review

1.

Name the four types of pathogen.

Bacteria, viruses, fungi and protists.

2.

State how viruses reproduce inside the body.

They reproduce inside living cells.

3.

Explain how vaccines protect against disease.

They stimulate the immune system to produce memory cells, providing immunity.

4.

Explain why antibiotics do not work against viruses.

Viruses reproduce inside body cells, so antibiotics cannot destroy them.

5.

State the function of antibodies.

To bind to specific antigens on pathogens.

6.

Explain how plants defend themselves against pathogens.

Plants use physical, chemical and mechanical defences to reduce infection and damage.

4.4.1.1 Photosynthetic Reaction

1.

What process do plants use to make glucose?

Photosynthesis.

2.

What two substances are needed for photosynthesis?

Carbon dioxide and water.

3.

What gas is produced during photosynthesis?

Oxygen.

4.

Write the word equation for photosynthesis.

Carbon dioxide + water → glucose + oxygen.

5.

State the chemical formula for carbon dioxide, water, oxygen and glucose.

CO₂, H₂O, O₂, C₆H₁₂O₆.

6.

Explain why photosynthesis is described as an endothermic reaction.

Light energy is absorbed to drive the reaction.

Photosynthesis and Chloroplasts

1.

Where in a plant cell does photosynthesis occur?

Chloroplasts.

2.

What pigment absorbs light energy for photosynthesis?

Chlorophyll.

3.

What organelle contains chlorophyll?

Chloroplast.

4.

Explain why chloroplasts are important for photosynthesis.

They contain chlorophyll, which absorbs light energy for photosynthesis.

5.

Explain how light energy is used during photosynthesis.

It is converted into chemical energy to produce glucose.

6.

Explain why plants need carbon dioxide to make glucose.

Carbon dioxide provides the carbon needed to make glucose.

4.4.1.2 Rate of Photosynthesis

1.

State one factor that affects the rate of photosynthesis.

Light intensity. (Also accept carbon dioxide concentration, temperature or chlorophyll concentration.)

2.

What is meant by a limiting factor?

A factor that limits the rate of photosynthesis.

3.

How does increasing light intensity affect photosynthesis rate?

The rate increases until another factor becomes limiting.

4.

How does carbon dioxide concentration affect the rate of photosynthesis?

The rate increases until another factor becomes limiting.

5.

Explain why increasing temperature does not always increase the rate of photosynthesis.

At high temperatures, enzymes denature, causing the rate to decrease.

6.

Explain how two limiting factors can interact to affect photosynthesis rate.

Increasing one factor will not increase the rate if another factor is limiting.

Required Practical 6: Investigating Light Intensity and Photosynthesis

1.

Which organism can be used to investigate the effect of light intensity on photosynthesis?

Pondweed (e.g. Cabomba).

2.

What is measured to calculate the rate of photosynthesis in this practical?

The number of oxygen bubbles produced per minute. (Or the volume of oxygen produced.)

3.

Why is the distance from the lamp changed during the investigation?

To change the light intensity.

4.

Why must variables such as temperature be controlled?

To ensure a fair test.

5.

Calculate the rate of photosynthesis if 60 bubbles are produced in 5 minutes.

12 bubbles per minute.

6.

Explain why repeats are carried out in the photosynthesis investigation.

To improve the reliability of the results.

Graphs and Limiting Factors (HT)

1.

What is shown on the x-axis of a graph showing the effect of light intensity?

Light intensity.

2.

What is shown on the y-axis of a graph showing the rate of photosynthesis?

Rate of photosynthesis.

3.

Why does the rate of photosynthesis eventually stop increasing when light intensity increases?

Another factor becomes limiting.

4.

Identify the limiting factor when increasing one factor no longer increases photosynthesis rate.

Carbon dioxide concentration or temperature.

5.

Explain how greenhouse growers use knowledge of limiting factors.

They increase light intensity, carbon dioxide concentration and temperature to maximise the rate of photosynthesis.

6.

Explain why increasing carbon dioxide, light or temperature has a cost for greenhouse growers.

Heating, lighting and supplying carbon dioxide all have financial costs.

4.4.1.3 Uses of Glucose from Photosynthesis

1.

What product of photosynthesis can be used in respiration?

Glucose.

2.

What substance is glucose converted into for storage in plants?

Starch.

3.

What molecule strengthens plant cell walls?

Cellulose.

4.

What type of molecule is produced when glucose is converted into fats or oils?

Lipids (fats and oils).

5.

What are amino acids used to make?

Proteins.

6.

Explain why plants need nitrate ions as well as glucose to make proteins.

Nitrate ions are needed to make amino acids, which are joined together to make proteins.

4.4.2.1 Aerobic and Anaerobic Respiration

1.

What is respiration?

The process of transferring energy from glucose.

2.

Where does respiration happen in cells?

In mitochondria.

3.

What gas is needed for aerobic respiration?

Oxygen.

4.

Write the word equation for aerobic respiration.

Glucose + oxygen → carbon dioxide + water.

5.

Compare the products of aerobic and anaerobic respiration in muscles.

Aerobic respiration produces carbon dioxide and water; anaerobic respiration in muscles produces lactic acid.

6.

Explain why anaerobic respiration transfers less energy than aerobic respiration.

It does not completely break down glucose, so less energy is transferred.

Aerobic Respiration

1.

What type of reaction is respiration?

A chemical reaction.

2.

Is aerobic respiration an exothermic or endothermic reaction?

Exothermic.

3.

What are the products of aerobic respiration?

Carbon dioxide and water.

4.

What happens to the energy released during respiration?

It is used for processes such as building larger molecules, muscle contraction and maintaining body temperature.

5.

State three processes that require energy from respiration.

Muscle contraction, active transport and building larger molecules.

6.

Explain why organisms need a constant supply of energy from respiration.

Organisms need energy continuously for essential life processes.

Anaerobic Respiration

1.

What does anaerobic mean?

Without oxygen.

2.

When does anaerobic respiration occur in muscles?

When there is not enough oxygen available during vigorous exercise.

3.

What is the product of anaerobic respiration in muscles?

Lactic acid.

4.

What products are made during anaerobic respiration in yeast?

Ethanol and carbon dioxide.

5.

What is fermentation?

Anaerobic respiration in yeast that produces ethanol and carbon dioxide.

6.

Explain why anaerobic respiration is useful despite releasing less energy.

It allows energy to continue being transferred when oxygen is limited.

4.4.2.2 Response to Exercise

1.

What happens to heart rate during exercise?

It increases.

2.

What happens to breathing rate during exercise?

It increases.

3.

Why do muscles need more oxygen during exercise?

To increase the rate of aerobic respiration and release more energy.

4.

What substance builds up during anaerobic respiration in muscles?

Lactic acid.

5.

What is oxygen debt?

The amount of extra oxygen needed to oxidise lactic acid and return the body to its resting state.

6.

Explain why muscles become fatigued during vigorous exercise.

Lactic acid builds up during anaerobic respiration, causing muscles to become fatigued.

Oxygen Debt and Lactic Acid

1.

Where is lactic acid produced?

In muscle cells.

2.

Why does lactic acid build up during vigorous exercise?

There is insufficient oxygen for aerobic respiration.

3.

Which organ removes lactic acid from the blood?

The liver.

4.

What is lactic acid converted back into in the liver?

Carbon dioxide and water.

5.

Why is extra oxygen needed after exercise?

To oxidise the lactic acid produced during anaerobic respiration.

6.

Explain how the body repays oxygen debt.

Extra oxygen is used to oxidise lactic acid in the liver, repaying the oxygen debt.

Investigating Exercise Effects

1.

What measurements can be taken to investigate the effect of exercise?

Heart rate and breathing rate.

2.

What happens to breathing rate after exercise?

It gradually returns to the resting rate.

3.

What happens to heart rate after exercise?

It gradually returns to the resting rate.

4.

Why should measurements be repeated in an exercise investigation?

To improve the reliability of the results.

5.

Calculate the change in heart rate if it increases from 70 bpm to 130 bpm.

60 bpm.

6.

Explain why exercise increases the demand for energy.

Exercise increases respiration because muscles need more energy for contraction.

4.4.2.3 Metabolism

1.

What is metabolism?

The sum of all the chemical reactions in a cell or the body.

2.

Where do metabolic reactions occur?

In cells.

3.

What molecule is glucose converted into for storage in animals?

Glycogen.

4.

What molecules combine to form lipids?

Glycerol and fatty acids.

5.

What molecules are joined together to make proteins?

Amino acids.

6.

Explain how respiration provides energy for metabolic reactions.

Respiration transfers the energy needed for metabolic reactions.

Metabolism and Biological Molecules

1.

What are the building blocks of proteins?

Amino acids.

2.

What are the building blocks of carbohydrates?

Simple sugars (glucose).

3.

What are the building blocks of lipids?

Glycerol and fatty acids.

4.

What is glycogen used for?

Energy storage in animals.

5.

Explain how plants use glucose to make cellulose.

Glucose molecules are joined together to form cellulose for cell walls.

6.

Explain how glucose and nitrate ions are used to make amino acids.

Glucose provides energy through respiration, while nitrate ions are used to make amino acids, which are joined together to form proteins.

Topic 4 Review

1.

Write the word equation for photosynthesis.

Carbon dioxide + water → glucose + oxygen.

2.

State three factors that affect the rate of photosynthesis.

Light intensity, carbon dioxide concentration and temperature.

3.

Write the word equation for aerobic respiration.

Glucose + oxygen → carbon dioxide + water.

4.

State one difference between aerobic and anaerobic respiration.

Aerobic respiration requires oxygen; anaerobic respiration does not.

5.

Explain why muscles become fatigued during vigorous exercise.

Lactic acid builds up because there is not enough oxygen for aerobic respiration.

6.

Explain how glucose is used in living organisms.

Glucose is used in respiration, stored as starch or glycogen, converted into cellulose, lipids and proteins.

4.5.1 Homeostasis

1.

What is homeostasis?

The maintenance of a constant internal environment within narrow limits.

2.

State one condition in the body that is controlled by homeostasis.

Body temperature / blood glucose concentration / water levels.

3.

What is the role of receptors in a control system?

Receptors detect changes in the internal or external environment.

4.

What is the role of effectors in a control system?

Effectors produce a response to correct a change.

5.

Name the three main parts found in all control systems.

Receptors, coordination centres and effectors.

6.

Explain why maintaining stable internal conditions is important for enzyme action.

Enzymes require stable conditions to work effectively; large changes can reduce activity or denature enzymes.

4.5.2.1 Structure and Function of the Human Nervous System

1.

What is the function of the nervous system?

To detect stimuli and coordinate responses.

2.

What type of signal travels along neurones?

Electrical impulses.

3.

Name the two parts of the central nervous system (CNS).

Brain and spinal cord.

4.

What is the pathway of a nervous response from stimulus to response?

Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response.

5.

What is the difference between a sensory neurone and a motor neurone?

Sensory neurones carry impulses from receptors to the CNS; motor neurones carry impulses from the CNS to effectors.

6.

Explain why nervous responses are usually rapid.

Nervous responses are rapid because electrical impulses travel quickly along neurones.

4.5.2.1 Reflex Arc

1.

What is a reflex action?

A rapid automatic response to a stimulus.

2.

Which type of neurone carries information from a receptor to the CNS?

Sensory neurone.

3.

Which type of neurone carries information from the CNS to an effector?

Motor neurone.

4.

What is the role of a relay neurone?

Relay neurones connect sensory neurones to motor neurones in the CNS.

5.

What happens at a synapse?

Neurotransmitters diffuse across the synapse and trigger an impulse in the next neurone.

6.

Explain why reflex actions do not require conscious thought.

Reflex actions are controlled by the spinal cord, so they happen without conscious thought.

Required Practical 7: Investigating Reaction Time

1.

What is reaction time?

The time taken to respond to a stimulus.

2.

Name one factor that could affect human reaction time.

Age / caffeine / tiredness / distractions / practice.

3.

What equipment can be used to measure reaction time?

Ruler drop test or computer reaction timer.

4.

Why should reaction time experiments be repeated?

To calculate a more reliable mean and reduce the effect of anomalies.

5.

Calculate the mean reaction time from a set of results.

Add all results together and divide by the number of results.

6.

Explain why controlling variables is important when investigating reaction time.

Controlling variables ensures the investigation is fair and only the independent variable affects the results.

4.5.2.2 The Brain (Biology Only)

1.

What organ controls complex behaviour in humans?

The brain.

2.

What type of cells make up the brain?

Neurones.

3.

Which region of the brain controls conscious thought?

Cerebral cortex.

4.

Which region of the brain coordinates movement and balance?

Cerebellum.

5.

Which region of the brain controls unconscious activities such as breathing?

Medulla.

6.

Explain why investigating the brain is difficult.

The brain is difficult to investigate because it is complex, protected inside the skull and studying it can cause damage.

4.5.2.3 The Eye (Biology Only)

1.

What type of stimulus does the eye detect?

Light.

2.

Which part of the eye contains light receptors?

Retina.

3.

What is the function of the optic nerve?

Carries electrical impulses from the retina to the brain.

4.

What is accommodation?

The process of changing the shape of the lens to focus light on the retina.

5.

Describe what happens to the lens when focusing on a near object.

The lens becomes thicker and more curved to refract light more strongly.

6.

Explain how spectacle lenses correct problems with focusing light on the retina.

Spectacle lenses change the direction of light so it is focused correctly onto the retina.

4.5.2.4 Control of Body Temperature (Biology Only)

1.

What is the normal human body temperature?

37°C.

2.

Which part of the brain monitors body temperature?

Hypothalamus.

3.

What happens to blood vessels when the body is too hot?

Blood vessels widen (vasodilation), increasing blood flow near the skin.

4.

What process causes sweat to cool the body?

Evaporation of sweat removes heat energy from the skin.

5.

What happens to muscles when the body is too cold?

Muscles contract rapidly, causing shivering.

6.

Explain how vasodilation helps reduce body temperature.

Vasodilation increases blood flow to the skin, allowing more heat to be transferred to the surroundings.

4.5.3.1 Human Endocrine System

1.

What is a hormone?

A chemical messenger released by glands and transported in the blood.

2.

Where are hormones released from?

Endocrine glands.

3.

How are hormones transported around the body?

Through the bloodstream.

4.

What is the difference between nervous and hormonal coordination?

Nervous coordination uses electrical impulses and is fast; hormonal coordination uses hormones and is slower but longer lasting.

5.

What is the role of the pituitary gland?

Controls the release of hormones from other glands.

6.

Name the glands that produce hormones involved in blood glucose, reproduction and metabolism.

Pancreas, ovaries/testes and thyroid gland.

4.5.3.2 Control of Blood Glucose Concentration

1.

Which organ controls blood glucose concentration?

Pancreas.

2.

Which hormone lowers blood glucose concentration?

Insulin.

3.

What happens to excess glucose in the liver and muscles?

Converted into glycogen and stored in the liver and muscles.

4.

What hormone increases blood glucose concentration?

Glucagon.

5.

What happens in Type 1 diabetes?

The pancreas produces little or no insulin.

6.

Explain how insulin helps return high blood glucose levels to normal.

Insulin causes glucose to move from the blood into cells and converts excess glucose into glycogen, lowering blood glucose concentration.

Type 1 and Type 2 Diabetes

1.

What causes Type 1 diabetes?

Type 1 diabetes is caused by the immune system destroying insulin-producing cells in the pancreas.

2.

What causes Type 2 diabetes?

Type 2 diabetes is caused by body cells becoming less sensitive to insulin and is linked to lifestyle factors.

3.

How is Type 1 diabetes commonly treated?

Insulin injections.

4.

State one risk factor for Type 2 diabetes.

Being overweight / obesity / lack of exercise / poor diet.

5.

How can exercise help someone with Type 2 diabetes?

Exercise increases glucose uptake by muscles and helps control blood glucose levels.

6.

Explain one difference between Type 1 and Type 2 diabetes.

Type 1 diabetes is caused by lack of insulin production; Type 2 diabetes is caused by insulin resistance.

4.5.3.3 Maintaining Water and Nitrogen Balance (Biology Only)

1.

Which organ removes excess water from the body?

Kidneys.

2.

What is urine?

A waste liquid containing water, urea and ions removed from the blood.

3.

Name two substances removed in urine.

Urea and excess water.

4.

Why must excess amino acids be removed from the body?

Excess amino acids cannot be stored and would be harmful if they build up.

5.

What toxic substance is produced when amino acids are broken down?

Ammonia, which is converted into urea in the liver.

6.

Explain how the kidneys help maintain water balance.

The kidneys filter the blood and adjust how much water is removed in urine.

ADH and Kidney Control (HT Only)

1.

What does ADH stand for?

Antidiuretic hormone.

2.

Which gland releases ADH?

Pituitary gland.

3.

When is ADH released into the blood?

When the blood contains too little water or is too concentrated.

4.

What effect does ADH have on kidney tubules?

It increases the permeability of kidney tubules, causing more water to be reabsorbed.

5.

How does ADH help prevent dehydration?

It reduces water loss by producing more concentrated urine.

6.

Explain how negative feedback controls water levels in the body.

Negative feedback keeps water levels stable by increasing or decreasing ADH release depending on water concentration.

4.5.3.4 Hormones in Human Reproduction

1.

Where is oestrogen produced?

Oestrogen is produced by the ovaries.

2.

Where is testosterone produced?

Testosterone is produced by the testes.

3.

What hormone stimulates sperm production?

Follicle-stimulating hormone (FSH).

4.

What is ovulation?

The release of an egg from an ovary.

5.

Which hormone causes the release of an egg?

Luteinising hormone (LH).

6.

Explain the role of progesterone in the menstrual cycle.

Progesterone maintains the uterus lining during the menstrual cycle.

Menstrual Cycle (HT Only)

1.

What is the average length of the menstrual cycle?

Approximately 28 days.

2.

What does FSH cause to happen in the ovary?

FSH causes an egg to mature in the ovary.

3.

What does LH trigger?

LH triggers ovulation.

4.

What happens to the uterus lining during the menstrual cycle?

The uterus lining thickens to prepare for implantation.

5.

Which hormones maintain the uterus lining?

Oestrogen and progesterone.

6.

Explain how FSH, LH, oestrogen and progesterone interact during the menstrual cycle.

FSH causes egg maturation and stimulates oestrogen production; oestrogen stimulates the release of LH; LH causes ovulation; progesterone maintains the uterus lining.

4.5.3.5 Contraception

1.

What is contraception?

Methods used to prevent pregnancy.

2.

Name one hormonal method of contraception.

Oral contraceptive pill / contraceptive implant / contraceptive injection.

3.

How do condoms prevent pregnancy?

Condoms prevent sperm reaching an egg.

4.

What hormone is used in many contraceptive methods?

Oestrogen or progesterone.

5.

How do oral contraceptives prevent ovulation?

They stop ovulation by preventing the release of FSH and LH.

6.

Explain how different contraceptive methods prevent fertilisation or implantation.

Contraceptive methods prevent fertilisation by stopping sperm reaching the egg or prevent implantation by changing the uterus lining.

4.5.3.6 Use of Hormones to Treat Infertility (HT Only)

1.

What is infertility?

The inability to become pregnant naturally.

2.

Which hormones are used in fertility treatment?

FSH and LH.

3.

What is IVF?

In vitro fertilisation, where an egg is fertilised outside the body.

4.

What is the role of FSH during IVF treatment?

FSH stimulates eggs to mature in the ovaries.

5.

What happens to fertilised eggs during IVF?

Fertilised eggs are inserted into the uterus.

6.

Explain how IVF increases the chance of pregnancy.

IVF increases the chance of pregnancy by controlling egg maturation, fertilisation and embryo implantation.

4.5.3.7 Negative Feedback (HT Only)

1.

What is negative feedback?

A control system that reverses changes to maintain a stable internal environment.

2.

Which gland produces adrenaline?

Adrenal glands.

3.

What effect does adrenaline have on heart rate?

It increases heart rate and prepares the body for action.

4.

Which gland produces thyroxine?

Thyroid gland.

5.

What does thyroxine control?

Thyroxine controls the metabolic rate.

6.

Explain how negative feedback controls thyroxine levels.

If thyroxine levels become too high, the release of hormones stimulating the thyroid is reduced; if levels are too low, more is released.

4.5.4.1 Plant Hormones: Control and Coordination (Biology Only)

1.

What chemical controls plant growth responses?

Auxin.

2.

What is phototropism?

The growth response of plants towards light.

3.

What is gravitropism?

The growth response of plants in response to gravity.

4.

Where is auxin produced in plants?

Auxin is produced in the tips of shoots and roots.

5.

How does auxin affect shoot growth towards light?

Auxin causes cells on the shaded side of a shoot to elongate, making the shoot grow towards light.

6.

Explain how unequal distribution of auxin causes plant growth responses.

Unequal distribution of auxin causes different rates of cell elongation, producing growth responses.

Required Practical 8: Plant Responses to Light or Gravity

1.

What is auxin?

Auxin is a plant hormone that controls growth responses.

2.

What type of plant is used to investigate responses to light or gravity?

Seedlings such as cress seedlings.

3.

What is measured when investigating seedling growth?

The direction or length of seedling growth.

4.

What is meant by the independent variable?

The variable that is changed by the investigator.

5.

Why should measurements be repeated when investigating plant growth?

To improve reliability and calculate a more accurate mean.

6.

Explain how auxin causes seedlings to grow towards light.

Auxin moves to the shaded side of the shoot, causing cells there to elongate more, making the shoot bend towards light.

4.5.4.2 Uses of Plant Hormones (HT Only)

1.

What plant hormone is used as a weed killer?

Auxin.

2.

What hormone is used to promote rooting?

Auxin.

3.

Which hormone controls fruit ripening?

Ethene.

4.

How are gibberellins used in agriculture?

Gibberellins are used to increase seed germination and promote flowering and growth.

5.

How is ethene used commercially?

Ethene is used to control fruit ripening during storage and transport.

6.

Explain how plant hormones can be used to control plant growth.

Plant hormones can be used to control growth, increase crop production, prevent weed growth and improve farming practices.

4.6.1.1 Sexual and Asexual Reproduction

1.

What type of cell division produces genetically identical cells?

Mitosis.

2.

What type of cell division produces genetically different cells?

Meiosis.

3.

What is sexual reproduction?

Sexual reproduction is the process where genetic material from two parents combines to produce offspring.

4.

What happens when male and female gametes fuse during sexual reproduction?

Male and female gametes fuse to form a fertilised egg cell (zygote).

5.

Why does sexual reproduction produce variation in offspring?

It combines genetic information from two parents, creating genetically different offspring.

6.

What are the main features of asexual reproduction?

It involves one parent, no fusion of gametes, produces genetically identical offspring and uses mitosis.

4.6.1.2 Meiosis

1.

What is the purpose of meiosis?

To produce genetically different gametes with half the normal chromosome number.

2.

Where does meiosis occur in organisms?

In reproductive organs such as the ovaries and testes.

3.

How does meiosis change the chromosome number in gametes?

It halves the chromosome number so gametes are haploid.

4.

How many gametes are produced from one cell during meiosis?

Four gametes.

5.

Why are gametes produced by meiosis genetically different?

Chromosomes are shuffled during meiosis, creating different combinations of alleles.

6.

How does fertilisation restore the normal chromosome number?

Fertilisation combines two haploid gametes to restore the normal diploid chromosome number.

4.6.1.3 Advantages and Disadvantages of Sexual and Asexual Reproduction

1.

What is one advantage of sexual reproduction?

It produces variation in offspring, increasing the chance that some survive environmental changes.

2.

Why can variation from sexual reproduction help a species survive?

Variation means some individuals may have adaptations that help them survive and reproduce.

3.

How can humans use selective breeding to increase food production?

Humans select organisms with desirable characteristics and breed them over many generations.

4.

What is one advantage of asexual reproduction?

It is faster and only requires one parent.

5.

Why is asexual reproduction faster than sexual reproduction?

It does not require finding a mate or producing gametes.

6.

Why are offspring from asexual reproduction genetically identical?

Offspring are produced by mitosis, so they have identical genetic information.

4.6.1.4 DNA and the Genome

1.

What chemical makes up genetic material?

DNA (deoxyribonucleic acid).

2.

Where is DNA found inside a cell?

In the nucleus of cells.

3.

What is a gene?

A section of DNA that codes for a protein.

4.

What does a gene code for?

A protein.

5.

What is meant by the genome of an organism?

The entire genetic material of an organism.

6.

Why is understanding the human genome important for medicine?

It helps scientists understand inherited diseases and develop treatments.

4.6.1.5 DNA Structure

1.

What type of molecule is DNA?

A polymer.

2.

What shape does a DNA molecule form?

A double helix.

3.

What are the four bases found in DNA?

Adenine, thymine, cytosine and guanine.

4.

How does the order of bases affect the protein produced?

The order of bases determines the order of amino acids, which determines the protein produced.

5.

What is a mutation?

A change in the DNA sequence.

6.

How can a mutation affect the protein made by a gene?

It may change the amino acid sequence, producing an altered protein.

4.6.1.6 Genetic Inheritance

1.

What is an allele?

A different version of a gene.

2.

What is the difference between a dominant and recessive allele?

A dominant allele is expressed when one copy is present; a recessive allele is only expressed when two copies are present.

3.

What is the difference between genotype and phenotype?

Genotype is the alleles an organism has; phenotype is the characteristics shown.

4.

What does homozygous mean?

Having two identical alleles.

5.

What does heterozygous mean?

Having two different alleles.

6.

How can Punnett squares be used to predict inheritance?

They show possible allele combinations and the probability of inherited characteristics.

4.6.1.7 Inherited Disorders

1.

Why are some disorders inherited?

Some disorders are caused by faulty alleles that are passed from parents to offspring.

2.

Which type of allele causes polydactyly?

A dominant allele.

3.

Which type of allele causes cystic fibrosis?

A recessive allele.

4.

What is embryo screening?

A process where embryos are tested for genetic disorders before being implanted during IVF.

5.

How can embryo screening help reduce inherited disorders?

It allows embryos without certain faulty alleles to be selected.

6.

What ethical issues are linked to embryo screening?

Concerns include deciding which characteristics should be selected and the possibility of reducing genetic variation.

4.6.1.8 Sex Determination

1.

How many pairs of chromosomes are found in human body cells?

23 pairs.

2.

Which chromosomes determine biological sex in humans?

Sex chromosomes.

3.

What sex chromosomes do females have?

XX.

4.

What sex chromosomes do males have?

XY.

5.

How is sex inheritance shown using a genetic cross?

Using a genetic cross showing the possible combinations of X and Y chromosomes from the parents.

6.

What is the probability of producing a male or female child?

50% chance of a male child and 50% chance of a female child.

4.6.2.1 Variation

1.

What is variation?

Differences between individuals of the same species.

2.

What causes genetic variation?

Differences in genes caused by mutation and sexual reproduction.

3.

What causes environmental variation?

Differences caused by environmental conditions.

4.

How do genes and the environment interact to influence phenotype?

Genes provide potential characteristics, while the environment affects how these characteristics develop.

5.

What effect do most mutations have on organisms?

Most mutations have no effect or are harmful.

6.

How can a beneficial mutation affect a population?

A beneficial mutation may give an advantage, causing individuals with it to survive and reproduce more successfully.

4.6.2.2 Evolution

1.

What is evolution?

The change in inherited characteristics of populations over generations.

2.

How does natural selection cause evolution?

Natural selection causes individuals with advantageous characteristics to survive and reproduce, passing on their alleles.

3.

Why are organisms with advantageous characteristics more likely to survive?

They are more likely to survive, reproduce and pass on their genes.

4.

How are advantageous characteristics passed to future generations?

They are inherited through genes passed from parents to offspring.

5.

How can populations become separate species?

Populations become isolated and accumulate different mutations over time.

6.

What is meant by a species?

A group of organisms that can reproduce to produce fertile offspring.

4.6.2.3 Selective Breeding

1.

What is selective breeding?

The process of choosing parents with desirable characteristics to produce offspring.

2.

Why do humans use selective breeding?

To produce organisms with useful characteristics such as increased yield or disease resistance.

3.

How are organisms chosen for selective breeding?

Organisms with desired features are selected as parents.

4.

How does selective breeding continue over many generations?

The process is repeated over many generations to increase the desired characteristic.

5.

What are the benefits of selective breeding?

Increased food production, improved characteristics and useful traits.

6.

What problems can be caused by inbreeding?

Inbreeding can reduce genetic variation and increase the chance of inherited disorders.

4.6.2.4 Genetic Engineering

1.

What is genetic engineering?

Changing an organism’s DNA using technology.

2.

What is transferred during genetic engineering?

A desired gene.

3.

What are genetically modified crops?

Crops that contain genes introduced using genetic engineering.

4.

Why are some crops genetically modified?

To increase yield, improve resistance to pests or increase nutritional value.

5.

How are bacteria genetically engineered to produce insulin?

A human insulin gene is inserted into a bacterial plasmid, and the bacteria produce insulin.

6.

What are the potential risks of genetic engineering?

Possible risks include effects on ecosystems and unknown long-term impacts.

4.6.2.5 Cloning

1.

What is cloning?

Producing genetically identical copies of organisms or cells.

2.

Why are cloned organisms genetically identical?

They contain the same genetic material from the same original organism.

3.

How can plants be cloned using tissue culture?

Small groups of plant cells are grown in sterile conditions with nutrients and hormones to produce identical plants.

4.

How are cuttings used to clone plants?

A piece of plant stem is cut and grown into a new genetically identical plant.

5.

What happens during adult cell cloning?

The nucleus from an adult body cell is inserted into an egg cell with its nucleus removed, then stimulated to divide.

6.

What are the benefits and risks of cloning?

Benefits include producing organisms with desirable characteristics and preserving endangered species; risks include reduced genetic variation and ethical concerns.

4.6.3.1 Theory of Evolution

1.

Who proposed the theory of evolution by natural selection?

Charles Darwin.

2.

What evidence did Darwin collect to support evolution?

He collected evidence from fossils and observations of organisms, including species on the Galapagos Islands.

3.

How does natural selection change populations over time?

Individuals with advantageous characteristics survive and reproduce more, causing these characteristics to become more common.

4.

Why do organisms with useful characteristics reproduce more successfully?

They are more likely to survive, reproduce and pass on their alleles.

5.

Why was Darwin’s theory controversial when first published?

It challenged religious beliefs and there was limited evidence and understanding of genetics at the time.

6.

Why did understanding genetics help explain evolution?

Genetics explained how characteristics were inherited and passed on through genes.

4.6.3.2 Speciation

1.

What is speciation?

The formation of new species.

2.

Who independently proposed the theory of natural selection with Darwin?

Alfred Russel Wallace.

3.

What happens when populations become isolated?

They experience different environmental conditions and develop different adaptations.

4.

How do new species form?

Populations become isolated, accumulate different mutations and eventually become unable to breed successfully.

5.

Why can different species no longer produce fertile offspring?

They have become genetically different and cannot produce fertile offspring together.

6.

How did Wallace contribute to understanding evolution?

Wallace independently developed ideas about natural selection and supported Darwin’s theory.

4.6.3.3 Understanding of Genetics

1.

Who carried out important experiments on inheritance in plants?

Gregor Mendel.

2.

What did Mendel discover about inheritance?

He discovered that characteristics are inherited through separate factors passed from parents to offspring.

3.

What did Mendel call the units of inheritance?

Factors (now called genes).

4.

Where are genes located?

On chromosomes.

5.

How did scientists discover the structure of DNA?

Scientists used techniques such as X-ray diffraction and work by scientists including Watson, Crick, Franklin and Wilkins.

6.

How has our understanding of genetics changed over time?

Understanding has developed from discovering inheritance patterns to identifying DNA, genes and genetic technologies.

4.6.3.4 Evidence for Evolution

1.

What evidence supports the theory of evolution?

Fossils, antibiotic resistance, DNA evidence and observations of organisms.

2.

How do fossils provide evidence for evolution?

Fossils show how organisms have changed over time and provide evidence of extinct species.

3.

How does antibiotic resistance provide evidence for evolution?

Resistant bacteria survive antibiotic treatment and pass on resistance genes, showing evolution in action.

4.

Why are genes important evidence for evolution?

Similarities in DNA sequences show relationships between organisms.

5.

Why is evolution now widely accepted by scientists?

Large amounts of evidence from different scientific areas support the theory.

6.

How does evidence from different sources support evolution?

Evidence from fossils, genetics and observations all provide consistent support for evolution.

4.6.3.5 Fossils

1.

What are fossils?

The remains or traces of organisms that lived millions of years ago.

2.

How can fossils form when organisms do not decay?

They can be preserved when conditions prevent decay, such as lack of oxygen.

3.

How can minerals replace parts of organisms to form fossils?

Minerals replace hard parts of organisms, creating fossil structures.

4.

What are preserved traces of organisms?

Footprints, burrows or impressions left by organisms.

5.

Why is the fossil record incomplete?

Many organisms do not fossilise and many fossils have been destroyed.

6.

What can fossils tell scientists about evolution?

They provide evidence about how organisms have changed over time.

4.6.3.6 Extinction

1.

What is extinction?

The permanent loss of a species.

2.

When does a species become extinct?

When no individuals of that species remain alive.

3.

What environmental changes can cause extinction?

Changes in climate, new diseases, new predators, competition and habitat loss.

4.

How can competition contribute to extinction?

If organisms cannot compete successfully for resources, their population may decrease and become extinct.

5.

How can human activity cause extinction?

Human activities such as deforestation, pollution, hunting and climate change can cause extinction.

6.

Why is extinction evidence that species change over time?

Extinction shows that species are not fixed and can disappear as environments change.

4.6.3.7 Resistant Bacteria

1.

Why can bacteria evolve rapidly?

Bacteria reproduce quickly and mutations can occur during reproduction.

2.

How do mutations create antibiotic-resistant bacteria?

Mutations can create genes that make bacteria resistant to antibiotics.

3.

Why do resistant bacteria survive antibiotic treatment?

Resistant bacteria survive antibiotic treatment and reproduce.

4.

How does antibiotic resistance spread through a population?

They reproduce and pass the resistance gene to future generations, increasing the resistant population.

5.

How can the spread of resistant bacteria be reduced?

Using antibiotics correctly, completing courses and reducing unnecessary use.

6.

Why is developing new antibiotics difficult?

Bacteria can quickly evolve resistance, making it difficult to find antibiotics that remain effective.

4.6.4 Classification of Living Organisms

1.

Why are organisms classified into groups?

To organise organisms, identify them and show relationships between species.

2.

Who developed the Linnaean classification system?

Carl Linnaeus.

3.

What are the main levels of classification?

Kingdom, phylum, class, order, family, genus and species.

4.

What is the binomial system of naming organisms?

A two-part naming system using the genus and species names.

5.

What are the three domains used in modern classification?

Archaea, Bacteria and Eukarya.

6.

How do evolutionary trees show relationships between organisms?

They show evolutionary relationships and how closely related organisms are.

4.7.1.1 Communities

1.

What is an ecosystem?

A system made up of all the organisms living in an area and the physical environment they interact with.

2.

What is meant by a community?

All the populations of different species living in an area.

3.

Name two things plants compete for.

Light, water, space, nutrients, minerals.

4.

Name two things animals compete for.

Food, mates, territory, shelter.

5.

What is meant by interdependence?

Organisms depend on each other for survival.

6.

Explain why removing one species from a community can affect other species.

Removing one species can affect food chains and cause changes in population sizes of other species.

4.7.1.2 Abiotic Factors

1.

What does abiotic mean?

Non-living factors that affect organisms.

2.

Give three examples of abiotic factors.

Temperature, light intensity, water availability.

3.

How does light intensity affect plant growth?

Greater light intensity increases photosynthesis, allowing plants to grow faster.

4.

Why does temperature affect organisms?

Temperature affects enzyme activity and the rate of biological reactions.

5.

Explain how soil pH can affect plant growth.

Soil pH affects enzyme activity and the availability of nutrients needed for plant growth.

6.

Explain how a change in an abiotic factor can affect the distribution of a species.

Changes in abiotic factors can make an environment more or less suitable, affecting where species can survive.

4.7.1.3 Biotic Factors

1.

What does biotic mean?

Living factors that affect organisms.

2.

Give two examples of biotic factors.

Competition and predation.

3.

How can food availability affect a population?

Less food availability reduces survival and reproduction, decreasing population size.

4.

How can new predators affect a community?

New predators may reduce prey populations and affect other species in the food web.

5.

Explain how pathogens can affect population size.

Pathogens can cause disease and reduce population size.

6.

Explain how one species outcompeting another can affect biodiversity.

A species that outcompetes another can reduce its population, lowering biodiversity.

4.7.1.4 Adaptations

1.

What is an adaptation?

A feature that helps an organism survive and reproduce in its environment.

2.

Name the three types of adaptation.

Structural, behavioural and functional adaptations.

3.

Give an example of a structural adaptation.

Thick fur in polar bears.

4.

Give an example of a behavioural adaptation.

Migration or changing activity patterns.

5.

What are extremophiles?

Organisms that live in extreme environments.

6.

Explain how adaptations help organisms survive in their environment.

Adaptations increase an organism’s chances of survival and reproduction.

4.7.2.1 Levels of Organisation

1.

What is a producer?

An organism that produces its own food, usually through photosynthesis.

2.

What is a consumer?

An organism that obtains energy by eating other organisms.

3.

What is a predator?

An organism that hunts and kills other animals for food.

4.

What is prey?

An organism that is hunted and eaten by predators.

5.

Why do all food chains begin with producers?

Producers convert light energy into chemical energy, providing energy for all other organisms.

6.

Explain how predator and prey populations affect each other.

Predator numbers increase when prey numbers are high; prey numbers decrease when predator numbers increase.

4.7.2.2 How Materials Are Cycled

1.

Name the two cycles studied in ecology.

The carbon cycle and the water cycle.

2.

What gas is used by plants during photosynthesis?

Carbon dioxide.

3.

What process releases carbon dioxide into the atmosphere?

Respiration and combustion.

4.

What role do microorganisms play in the carbon cycle?

Microorganisms break down dead material and release carbon dioxide through respiration.

5.

Describe the water cycle.

Water evaporates, condenses into clouds and returns as precipitation.

6.

Explain why materials must be recycled in ecosystems.

Materials are limited, so ecosystems must recycle them to support life.

4.7.2.3 Decomposition

1.

What is decomposition?

The breakdown of dead organisms and waste materials.

2.

Which organisms cause decay?

Microorganisms such as bacteria and fungi.

3.

Name three factors that affect the rate of decay.

Temperature, oxygen availability and water availability.

4.

Explain how temperature affects decomposition.

Higher temperatures increase enzyme activity, increasing decomposition rate up to an optimum.

5.

Why is compost useful for plants?

Compost provides nutrients and minerals for plant growth.

6.

Explain how anaerobic decay can produce methane.

Anaerobic decay produces methane gas as microorganisms break down material without oxygen.

4.7.2.4 Impact of Environmental Change (HT)

1.

Name three environmental changes that affect species distribution.

Temperature change, water availability and changes in atmospheric gases.

2.

How can temperature changes affect organisms?

Temperature changes can affect survival, reproduction and distribution of organisms.

3.

How can water availability affect species?

Changes in water availability can affect where species can live and reproduce.

4.

How can changes in atmospheric gases affect ecosystems?

Changes in gases such as carbon dioxide can alter climate and affect ecosystems.

5.

Explain how human activity can change species distribution.

Human activities such as pollution, deforestation and climate change can alter habitats and species distribution.

6.

Explain why environmental changes may cause extinction.

Environmental changes can make conditions unsuitable, causing populations to decline and species to become extinct.

4.7.3.1 Biodiversity

1.

What is biodiversity?

The variety of different species living in an area.

2.

Why is biodiversity important?

Biodiversity provides resources, maintains ecosystems and supports stability.

3.

How does biodiversity increase ecosystem stability?

A greater variety of species makes ecosystems more resistant to change.

4.

Name three human activities that reduce biodiversity.

Deforestation, pollution, farming and climate change.

5.

How does deforestation reduce biodiversity?

Deforestation destroys habitats, reducing the number of species that can survive.

6.

Explain why humans need to maintain biodiversity.

Humans depend on biodiversity for food, medicines, materials and ecosystem services.

4.7.3.2 Waste Management

1.

Why does human population growth increase waste production?

A larger population produces more waste from homes, industry and agriculture.

2.

Name three types of pollution.

Air pollution, water pollution and land pollution.

3.

How can sewage affect ecosystems?

Sewage can introduce harmful microorganisms and nutrients into water ecosystems.

4.

How can fertilisers cause pollution?

Fertilisers can cause eutrophication by increasing nutrient levels in water.

5.

Explain how pollution reduces biodiversity.

Pollution can kill organisms and reduce the number of species in an ecosystem.

6.

Explain why waste management is important.

Waste management prevents pollution and protects ecosystems.

4.7.3.3 Land Use

1.

Name three ways humans use land.

Farming, building and conservation.

2.

How does building reduce biodiversity?

Building destroys habitats and reduces available resources for organisms.

3.

Why are peat bogs important?

Peat bogs store carbon and provide habitats for many species.

4.

How does peat destruction increase carbon dioxide?

Destroying peat releases stored carbon dioxide into the atmosphere.

5.

Explain the conflict between using peat and conserving peatlands.

Peat can be used as fuel or compost, but destroying peatlands damages biodiversity and increases carbon emissions.

6.

Explain how changes in land use affect ecosystems.

Changes in land use can destroy habitats, alter food webs and reduce biodiversity.

4.7.3.4 Deforestation

1.

What is deforestation?

The removal of forests.

2.

Why are tropical forests cleared?

Tropical forests are cleared for farming, timber, mining and building.

3.

Give two reasons for deforestation.

Agriculture and logging.

4.

How does deforestation reduce biodiversity?

It destroys habitats, causing species loss and reduced biodiversity.

5.

How does deforestation affect carbon dioxide levels?

Fewer trees means less carbon dioxide is removed by photosynthesis, increasing atmospheric carbon dioxide.

6.

Explain the environmental impacts of deforestation.

Deforestation causes habitat destruction, biodiversity loss, soil erosion and increased greenhouse gases.

4.7.3.5 Global Warming

1.

What is global warming?

The increase in the Earth’s average temperature due to greenhouse gases.

2.

Which gases contribute to global warming?

Carbon dioxide, methane and water vapour.

3.

Why are carbon dioxide levels increasing?

Burning fossil fuels and deforestation increase carbon dioxide levels.

4.

How can global warming affect species?

It can change habitats, alter food availability and cause species extinction.

5.

Explain how climate change can alter habitats.

Climate change changes temperature and rainfall patterns, affecting where organisms can survive.

6.

Explain why climate change evidence is based on many scientific studies.

Evidence is based on many scientific studies, measurements and observations collected over time.

4.7.3.6 Maintaining Biodiversity

1.

What is conservation?

Protecting and managing species and habitats.

2.

Why are breeding programmes used?

To increase populations of endangered species.

3.

How does protecting habitats maintain biodiversity?

Protected habitats provide safe areas where organisms can survive and reproduce.

4.

How do hedgerows support biodiversity?

Hedgerows provide habitats and food sources for many species.

5.

How does recycling help ecosystems?

Recycling reduces waste, pollution and the use of natural resources.

6.

Evaluate methods used to maintain biodiversity.

Conservation methods can protect species, but they may be expensive and require careful management.

4.7.4.1 Trophic Levels

1.

What is a trophic level?

A position in a food chain showing an organism’s feeding level.

2.

What trophic level are producers?

First trophic level.

3.

What are primary consumers?

Organisms that eat producers.

4.

What are secondary consumers?

Organisms that eat primary consumers.

5.

What are apex predators?

Top predators with no natural predators.

6.

Explain the role of decomposers.

Decomposers break down dead material and recycle nutrients back into the ecosystem.

4.7.4.2 Pyramids of Biomass

1.

What is biomass?

The mass of living material in an organism or group of organisms.

2.

What does a pyramid of biomass show?

The amount of biomass at each trophic level in a food chain.

3.

Which trophic level is at the bottom of a pyramid of biomass?

Producers.

4.

Why does biomass decrease at higher trophic levels?

Biomass decreases because energy and materials are lost between trophic levels.

5.

How are pyramids of biomass constructed?

They are constructed by measuring the total dry mass of organisms at each trophic level.

6.

Explain why pyramids of biomass are usually pyramid shaped.

Less biomass is available at each higher trophic level, so the pyramid becomes narrower.

4.7.4.3 Transfer of Biomass

1.

What percentage of biomass is transferred between trophic levels?

Approximately 10%.

2.

Why is some biomass lost as faeces?

Some biomass is lost as faeces and is not absorbed by the organism.

3.

Why is biomass lost through respiration?

Energy is lost during respiration and released as heat.

4.

Why are there fewer organisms at higher trophic levels?

Less biomass and energy are available at higher trophic levels.

5.

How is biomass transfer efficiency calculated?

Biomass transfer efficiency = (biomass available after transfer ÷ biomass available before transfer) × 100.

6.

Explain why food chains are usually short.

Food chains are usually short because energy is lost at each trophic level.

4.7.5.1 Factors Affecting Food Security

1.

What is food security?

Having enough food available for the population.

2.

How does population growth affect food security?

A growing population increases demand for food.

3.

How can pests affect food production?

Pests damage crops and reduce food production.

4.

How can climate change affect food production?

Climate change can affect temperature, rainfall and crop growth.

5.

How can conflict affect food availability?

Conflict can prevent food production and distribution.

6.

Explain why sustainable methods are needed to feed the population.

Sustainable methods help produce enough food without damaging the environment.

4.7.5.2 Farming Techniques

1.

How can farmers increase food production?

Use fertilisers, pesticides, selective breeding, irrigation and intensive farming.

2.

Why are animals kept in controlled conditions?

To control conditions and increase growth and productivity.

3.

Why are animals fed high protein foods?

To increase growth rate and meat production.

4.

Explain how intensive farming improves efficiency.

Intensive farming allows more food to be produced using less land.

5.

Give one advantage of intensive farming.

Increased food production and efficient use of land.

6.

Give one disadvantage of intensive farming.

It can cause pollution, reduce animal welfare and decrease biodiversity.

4.7.5.3 Sustainable Fisheries

1.

Why are fish stocks decreasing?

Overfishing reduces fish populations faster than they can reproduce.

2.

What is sustainable fishing?

Fishing methods that allow fish populations to remain at sustainable levels.

3.

How do fishing quotas help conservation?

They limit the number of fish caught, allowing populations to recover.

4.

Why are net sizes controlled?

Larger nets allow young fish to escape and reproduce.

5.

Explain how fishing methods affect fish populations.

Some methods can damage habitats or catch unwanted species.

6.

Explain why sustainable fisheries are important.

Sustainable fisheries protect fish populations and maintain future food supplies.

4.7.5.4 Role of Biotechnology

1.

What is biotechnology?

The use of biological organisms or processes to make useful products.

2.

Which fungus is used to produce mycoprotein?

Fusarium.

3.

What conditions are needed to grow Fusarium?

Warm conditions with oxygen and nutrients.

4.

How are bacteria used to produce insulin?

Bacteria are genetically modified to produce human insulin.

5.

How can GM crops improve food production?

GM crops can increase yield, improve resistance to pests and improve nutritional value.

6.

Explain how biotechnology can help feed a growing population.

Biotechnology can increase food production and provide alternative food sources for a growing population.

Biology

Paper 1

Topic 1 – Cell Biology

4.1.1.1 Eukaryotes and Prokaryotes

4.1.1.2 Animal and Plant Cells

Sub-cellular Structures and Their Functions

Required Practical 1: Using a Light Microscope

Scale and Size of Cells

4.1.1.3 Cell Specialisation

4.1.1.4 Cell Differentiation

4.1.1.5 Microscopy

4.1.1.6 Culturing Microorganisms (Biology Only)

Aseptic Technique

Required Practical 2: Antibiotics and Antiseptics

4.1.2.1 Chromosomes

4.1.2.2 Mitosis and the Cell Cycle

4.1.2.3 Stem Cells

4.1.3.1 Diffusion

Surface Area to Volume Ratio

Exchange Surfaces

4.1.3.2 Osmosis

Required Practical 3: Osmosis in Plant Tissue

4.1.3.3 Active Transport

Topic 1 Review

Topic 2 – Organisation

4.2.1 Principles of Organisation

4.2.2.1 The Human Digestive System

Enzymes and Metabolism

Digestive Enzymes

Bile

Required Practical 4: Testing for Biological Molecules

Required Practical 5: Effect of pH on Amylase

4.2.2.2 The Heart and Blood Vessels

Structure of the Heart

The Lungs and Gas Exchange

Blood Vessels

4.2.2.3 Blood

4.2.2.4 Coronary Heart Disease: A Non-Communicable Disease

Treatments for Cardiovascular Disease

4.2.2.5 Health Issues

4.2.2.6 The Effect of Lifestyle on Some Non-Communicable Diseases

Risk Factors and Data

4.2.2.7 Cancer

4.2.3.1 Plant Tissues

Leaf Structure

4.2.3.2 Plant Organ System

Root Hair Cells, Xylem and Phloem

Transpiration and Stomata

Measuring Transpiration

Topic 2 Review

Topic 3 – Infection and Response

4.3.1.1 Communicable (Infectious) Diseases

4.3.1.2 Viral Diseases

Measles

HIV

Tobacco Mosaic Virus (TMV)

4.3.1.3 Bacterial Diseases

Salmonella

Gonorrhoea

4.3.1.4 Fungal Diseases

4.3.1.5 Protist Diseases

4.3.1.6 Human Defence Systems

White Blood Cells

4.3.1.7 Vaccination

4.3.1.8 Antibiotics and Painkillers

4.3.1.9 Discovery and Development of Drugs

Drug Testing

4.3.2.1 Producing Monoclonal Antibodies

4.3.2.2 Uses of Monoclonal Antibodies

4.3.3.1 Detection and Identification of Plant Diseases

Plant Ion Deficiencies

4.3.3.2 Plant Defence Responses

Topic 3 Review

Topic 4 – Bioenergetics

4.4.1.1 Photosynthetic Reaction

Photosynthesis and Chloroplasts

4.4.1.2 Rate of Photosynthesis

Required Practical 6: Investigating Light Intensity and Photosynthesis

Graphs and Limiting Factors (HT)

4.4.1.3 Uses of Glucose from Photosynthesis