Oct/Nov 2025

State one role of a plant cell wall.

Cell structure and function

Hydrogencarbonate indicator alters its colour depending on the concentration of carbon dioxide present. The table displays these colour changes. Four test-tubes were prepared under different conditions. The colour of the hydrogencarbonate indicator in each test-tube at the beginning of the experiment and after one hour is also shown. Which test-tube shows that the rates of photosynthesis and respiration are equal?

Photosynthesis

The diagrams illustrate transverse sections of a dicotyledonous root, stem and leaf. The vascular tissues are marked with the numbers 1-6. The cut ends of root pieces, stem pieces and leaf stalks are put into water that contains a red dye. After several hours, the coloured water has moved through some of the vascular tissues. Which vascular tissues are shown in red?

Uptake and transport of water and ions

Deficiency of which nutrient results in scurvy?

Diet

Which muscle groups contract to make the body breathe in?

Human gas exchange

Which processes make use of energy released during respiration?

Respiration

During strenuous exercise, lactic acid accumulates in the muscles. Blood flowing away from these muscles will contain a high concentration of lactic acid. Which process is responsible for removing most of the lactic acid from the blood?

Anaerobic respiration

The table gives the mean blood flow rate in several blood vessels. Which row names the blood vessels correctly?

Blood vessels

What occurs during blood clotting?

Blood

Which statement describes the link between smoking tobacco and emphysema?

Disease

What prevents pathogens from getting into the human body?

Disease

The international system used to name organisms is the binomial system. Which two parts make up the scientific name?

Concept and use of a classification system

A doctor takes some bacteria from an infected patient. These bacteria are cultured in a Petri dish that contains nutrient agar jelly. The bacteria form a grey layer on the agar jelly. The doctor then places three paper discs, each with a different antibiotic, onto the dish. The diagram shows the Petri dish after 24 hours. What conclusion can the doctor draw from these results?

Antibiotics

The table lists the concentration of five substances in the blood entering the kidney, in fluid entering the nephron and in the urine. Which substances are completely reabsorbed into the blood from the nephron?

Urinary system

The graph plots blood glucose concentration across a 6-hour period during one day. What set point for blood glucose concentration is indicated by this graph?

Blood glucose control

Which hormone may be used to treat Type 1 diabetes?

Blood glucose control

An athlete has a resting body temperature of 37.0^{\circ}C. Following vigorous exercise lasting 30 minutes, this rises to 38.6^{\circ}C. The athlete then rests for 10 minutes. After this rest period, the body temperature is checked again and found to be 37.2^{\circ}C. Which processes occur in the athlete’s body during the 10-minute rest that reduce the body temperature?

Temperature control

Which endocrine gland is responsible for producing follicle-stimulating hormone?

Mammalian hormones

The diagram shows a plant that has been grown horizontally without light. Which row explains the responses shown by the roots and the shoot?

Coordination and response in plants

The growing shoot tips of a plant are removed and set onto small blocks of jelly that contain no auxin. In some of the jelly blocks, small pieces of transparent but impermeable glass are inserted, as shown in diagram X. In diagram Y, some of the shoot tips are separated by pieces of transparent impermeable glass. The tips are then left on the small jelly blocks while light shines from only one side. After 12 hours, the number of arbitrary units of auxin in each jelly block is measured and the means, shown in the diagrams, are worked out. A student recorded these conclusions from the results. 1. Auxin moves downwards out of the shoot tip. 2. The distribution of auxin in a shoot tip is affected by light intensity. 3. Some auxin is destroyed by light. 4. Auxin moves from areas of more light to areas of less light. Which of the student’s conclusions are correct?

Coordination and response in plants

Which part of the flower later becomes a fruit?

Sexual reproduction in plants

Chromosomes, DNA molecules and genes are units of inherited material that differ in size. Which statement describes how these units of inherited material are related?

DNA

A student has sketched six different arthropods that live in woodland. When making a dichotomous key, which question could be used to distinguish arthropods 2, 5 and 6 from arthropods 1, 3 and 4?

Concept and use of a classification system

As a nucleus divides by meiosis, alterations may occur that create a gamete with an abnormal number of genes or an abnormal number of chromosomes. Which alteration can lead to a child with Down’s syndrome?

Inheritance

Which row indicates possible consequences of natural selection?

Selection

Every organism within the same species displays variation. Several characteristics of different kinds of variation are given. Which statements describe discontinuous variation?

Variation

Bacteria multiply by dividing into two cells. Under ideal conditions, with enough water and food and at a warm temperature, this can occur every 20 minutes. Usually, very small numbers of bacteria do not cause illness. A student removes her lunch from the fridge when it has 4 bacteria. Two hours later, while it is at room temperature, it has 256 bacteria. From the moment the food is taken out of the fridge, how long will it be before her food contains 16 384 bacteria?

Nuclear division

What might be one advantage of genetically modifying crop plants?

Genetic modification

An experiment is carried out to determine how well different biological washing powders break down protein. Four cubes of cooked egg white (protein), each the same size, are prepared and their masses are recorded. The protein cubes are then placed in test-tubes containing $10\text{ cm}^3$ of solutions made from four different biological washing powders, all at the same concentration. The cubes are kept in the solutions at room temperature. After 24 hours, the protein cubes are taken out of the test-tubes and their masses are measured again. What is the percentage decrease in mass of the cube of protein in the most effective washing powder given to one decimal place?

Enzyme action

Which enzyme is added to fruit to help juice production?

Enzyme action

The diagram illustrates a food web. Which organisms in this food web are primary consumers?

Energy flow

The processes shown take place in living organisms in a food chain. 1 excretion 2 photosynthesis 3 respiration Which of these processes cause energy to be lost from a food chain?

Energy flow

Trees in a forest require a continual supply of nitrates so that they can keep growing. The diagram illustrates some of the stages in the nitrogen cycle that supply the needed nitrates. Which stage in this cycle is not caused by living bacteria?

Nutrient cycles

Contact lenses are worn on the surface of the eye to correct vision defects. One kind of contact lens is partially permeable and is usually kept in a sterile sodium chloride solution. The sodium chloride solution has the same concentration as the fluid covering the surface of the eye. A person accidentally stores their contact lenses in distilled water instead of sodium chloride solution. They then put a contact lens onto the surface of their eye. Which pair of statements describes what happens next?

Diffusion and osmosis

What is one way to maintain fish stocks?

Conservation

Which process involves molecules moving against a concentration gradient?

Active transport

A large number of reactions in cells depend on enzyme activity. Which statement about enzymes is not correct?

Enzyme action

What changes take place in the air spaces of a green leaf during a sunny day?

Leaf structure

Which diagram accurately connects the carbohydrates produced by photosynthesis with the ways in which they are used?

Photosynthesis

An investigation was carried out into the rate of photosynthesis under different environmental conditions. The graph shows the results. Which conditions could have produced the results for curve R?

Photosynthesis

Which row correctly identifies structures X and Y on the plant cell diagram?

Cell structure and function

Which graph illustrates how light intensity affects the rate of transpiration?

Transpiration and translocation

A woman visited the doctor because she had these symptoms: intense pain in her joints and legs; gums that were swollen and bled; skin that bruised very easily. What should the doctor check the woman’s blood for?

Diet

Four people all carry out the same physical exercise. The graph displays their breathing rate in breaths per minute before, while doing, and after the exercise. One of the people is a professional athlete. Which line represents the results for the professional athlete?

Respiration

Villi and alveoli share some common features. Which feature is not found in villi and alveoli?

Absorption and assimilation

The graph illustrates the concentration of substance X in a person’s blood before exercise, during exercise and after exercise. Which substance is X?

Respiration

The apparatus shown is used to investigate the volume of gas produced by yeast during anaerobic respiration. What is the reason for covering the yeast mixture with a thin layer of oil during this investigation?

Anaerobic respiration

The equation represents aerobic respiration: $X + 6O_2 \rightarrow Y + 6CO_2 + \text{energy}$. What substances do X and Y stand for?

Aerobic respiration

What is the role of the hepatic vein?

Circulatory system

A student measures the thickness of the walls of the four chambers in a heart. The results are $15\text{ mm}$, $9\text{ mm}$, $3\text{ mm}$ and $3\text{ mm}$. Which row gives the correct chamber measurements for the heart?

Heart

Each $\text{mm}^3$ of blood contains about 5 million red blood cells. The average diameter of a red blood cell is $0.007\,\text{mm}$. Which row shows this information correctly in standard form?

Blood

Viruses are able to reproduce only within cells. Inside a living cell, a single Herpes simplex virus multiplies quickly and makes 4000 copies in 12 hours. What is the highest number of viruses that could be formed in 36 hours from one Herpes simplex virus?

Disease

What effect does regular excessive consumption of alcohol have?

Disease

What can lower the chance of bacteria developing resistance to antibiotics?

Antibiotics

Which statement correctly describes active immunity?

Immunity

Which term describes the release of oxygen by plants?

Photosynthesis

The diagram illustrates several structures in the skin. Which structure raises its secretions when the body becomes too hot?

Temperature control

What change takes place when the blood glucose concentration rises?

Blood glucose control

Which of the following is not an example of homeostasis that uses a negative feedback mechanism?

Homeostasis

Which statement gives a correct example of phototropism?

Coordination and response in plants

An experiment is arranged to find out the conditions needed for seeds to germinate. In which flask will the seeds germinate first?

Asexual and sexual reproduction

The diagrams depict some plant cells and animal cells. They are not drawn to the same scale. Which cells have haploid nuclei?

DNA

Which of the following statements about osmosis is correct?

Diffusion and osmosis

Which of the following are examples of continuous variation? 1 the length of seedlings 2 the mass of bananas 3 human skin colour

Variation

A man shows six fingers on each hand and six toes on each foot. This inherited genetic condition is controlled by a dominant allele. He is heterozygous for this condition. His wife does not show the condition. What is the probability that a child of this couple will be born with the condition?

Inheritance

The diagram presents a family tree showing how eye colour is inherited. The allele for brown eyes is dominant, while the allele for blue eyes is recessive. Which individuals must be heterozygous for eye colour?

Inheritance

A karyotype is a photograph displaying the chromosomes of an individual. Which description corresponds to an individual with this karyotype?

DNA

Three statements about natural selection are given. Which of the statements are correct?

Selection

Bread is produced from a blend of flour, sugar, water and yeast. The mixture is kept in a warm place so that it can rise before it is baked. Which process causes the bread to rise?

Anaerobic respiration

Several stages in the manufacture of human insulin are given below. 1. Genetically modified E. coli bacteria are cultivated in large fermenters. 2. The gene for human insulin is placed into the DNA of an E. coli bacterium. 3. The gene for human insulin is taken from human pancreas cells. 4. Human insulin is removed and purified. Which sequence of stages is correct?

Genetic modification

The diagram represents a food chain: large tree → small insect → small bird → large bird. Which pyramid of numbers corresponds to the food chain shown?

Energy flow

The diagram illustrates the transfer of carbon within the carbon cycle in gigatonnes per year. How many gigatonnes of carbon are transferred by respiration each year?

Nutrient cycles

Energy passes out of a food chain as it moves from one trophic level to the next. In which ways is energy lost from a food chain? 1. by egestion 2. by respiration 3. by photosynthesis 4. by excretion

Energy flow

Globulin is a substance that the biuret test can detect. Globulin belongs to which type of substance?

Biological molecules

The diagram illustrates the nitrogen cycle. Which stages include bacteria?

Nutrient cycles

Both cellulose and glucose are carbohydrates. A cellulose molecule is a large molecule formed from a long chain of smaller glucose molecules. The length of one cellulose molecule is $0.01\,\text{mm}$. The length of one glucose molecule is $0.001\,\mu\text{m}$. How many glucose molecules are present in this cellulose molecule?

Biological molecules

Four test-tubes are each filled with starch solution and amylase. As shown in the table, they are kept in water-baths at different temperatures and at different pHs. All the other conditions remain unchanged. After 30 minutes, iodine solution is added to every test-tube. The mixture in three of the test-tubes becomes blue-black. In which test-tube do the contents remain yellow-brown? A: temperature $35^\circ\text{C}$, pH $2.5$ B: temperature $35^\circ\text{C}$, pH $6.9$ C: temperature $75^\circ\text{C}$, pH $2.5$ D: temperature $75^\circ\text{C}$, pH $6.9$

Enzyme action

The diagram shows a cross-section of a dicotyledonous leaf. Which structures are nearly transparent, helping to raise the rate of photosynthesis in the leaf?

Leaf structure

Oxygen is formed in leaf cells during photosynthesis and diffuses out from the leaf. Through which route does the oxygen diffuse?

Diffusion and osmosis

Why are newly germinated seeds unable to develop into healthy plants if magnesium ions are absent?

Mineral nutrition

Fig. 1.1 is a front view of the female human reproductive system. The labels shown are A, B, C, D and E.

Sexual reproduction in humans

Fig. 2.1 presents a cross-section of the human eye. The labels shown are J, K, L, M and N.

Mammalian sense organs

Fig. 3.1 summarises protein metabolism in the body. Diagram text: 'protein broken down in the stomach by enzyme A'; 'protein broken down in the small intestine by enzyme B'; 'amino acids absorbed into the bloodstream'; 'blood vessel C'; 'surplus amino acids changed into urea in the liver'; 'urea removed from the blood in the kidney and excreted'. Table 3.1 gives the results of an investigation. Group X ate bread, jam, orange juice, lettuce, fruit. Group Y ate nuts, milk, bread, cheese, meat. Early the next morning, urine was tested for urea concentration.

Human digestive system

Chlorophyll is present in every organism that carries out photosynthesis. Fig. 4.1 shows mistletoe growing on a tree branch. Most plants contain about 1 mg of chlorophyll in 100 g of their leaves. Mistletoe, however, contains about 0.4 mg of chlorophyll in 100 g of its leaves. Birds attach mistletoe seeds to tree branches. When the seeds germinate, they form special roots that grow into the phloem of the tree branch.

Photosynthesis

Fig. 5.1 presents a model of the human circulatory system. Diagram labels: blood vessel Z, lungs, body cells, pump, direction of blood flow. Fig. 5.2 presents a heart with a labelled 'hole in heart'.

Heart

Biofuels are derived from plant material or animal waste. They act as substitutes for fossil fuels such as petrol and oil. Fossil fuels formed over very long timescales, millions of years ago. Biofuels may be a sustainable resource, or they may not be. Fig. 6.1 provides data on alcohol production and deforestation in Brazil from 2012 to 2016.

Biotechnology

HIV and MRSA are two distinct microorganisms that are pathogens.

Disease

Fig. 8.1 illustrates a synapse between a sensory neurone and a relay neurone. The sensory neurone takes in information from a pain receptor. Fig. 8.2 shows the shape of some analgesic drug molecules.

Mammalian nervous system

Hormones are made by glands in the body. They change the activity of particular target organs.

Mammalian hormones

Apple juice is produced by chopping up apples and crushing them. If apple tissue is cut and crushed, its colour may deepen and it can turn brown. Some students studied how vitamin C affected colour change in apples after they were cut and crushed. The students carried out these steps: • Put a label on a large test-tube and pour in 5 cm3 of vitamin C solution. • Put a label on a second large test-tube and pour in 5 cm3 of distilled water. • Put a label on a third large test-tube and leave it without any liquid. • Prepare three apple cubes, each measuring 1 cm × 1 cm × 1 cm. Exclude all skin and core. • Slice each cube into many small pieces. Keep the pieces from each cube separate. • Place the pieces from one cube into the test-tube containing vitamin C solution. • Place the pieces from the second cube into the test-tube containing distilled water. • Place the pieces from the third cube into the test-tube with no liquid added. • With a glass rod, carefully crush the apple pieces at the bottom of each test-tube. • Wash the glass rod between uses in the different test-tubes. • Begin timing. At the start of timing, the students observed that the apple tissue in each test-tube was white. They checked the colour of the apple tissue in each test-tube after 5, 10 and 15 minutes and wrote down their observations. Fig. 1.1 shows part of one notebook: vitamin C: white → white → white distilled water: white → pale yellow → dark yellow no added liquid: yellow → dark yellow → brown

Enzyme action

Yeast is used in bread making. Flour is combined with water and yeast to make dough. The yeast breaks down the starch in the flour to form sugar. It then uses this sugar in respiration, releasing bubbles of carbon dioxide. These bubbles become trapped in the dough, causing it to rise in volume before baking. Some students investigated the effect of yeast in four doughs made from different types of flour: wheat, rye, buckwheat and maize. They assessed the action of the yeast by measuring the amount by which the dough increased in volume. The same mass of each flour was mixed with the same volume of water and the same mass of yeast to make a dough. Four 100 cm3 measuring cylinders were labelled and dough was placed into each one. The volume of dough in each cylinder was measured and written down at 15-minute intervals. Some of the results are shown in Table 2.1. Table 2.2 presents some of the biological molecules in the four flours.

Biological molecules

A student examined a plant in which some stems carried flowers and other stems did not have flowers. The student took one leaf from a stem with flowers and one leaf from a stem with no flowers. Fig. 3.1 shows the two leaves. Leaf from stem with flowers: magnification \times1. Leaf from stem with no flowers: magnification \times2.

Variation

Hydrogen peroxide is a toxic waste product found in living cells. Catalase is the enzyme that breaks hydrogen peroxide down into water and oxygen. Some students investigated catalase in tissues from different plants. They used small filter paper discs. These discs were placed on the cut surface of plant tissues so that they could soak up liquid from the cells. That cell liquid may have contained catalase. Fig. 1.1 shows how the students could determine whether catalase was present in tissues from different plants. Fig. 1.1 text: beaker containing hydrogen peroxide solution; filter paper disc soaked in liquid from plant cells; filter paper disc containing trapped bubbles of oxygen. A filter paper disc soaked in liquid from plant cells was dropped into the hydrogen peroxide solution and sank to the bottom. If catalase was present, bubbles of oxygen formed. The bubbles of oxygen were trapped in the filter paper disc making it float to the surface. The students were supplied with 2 cm \times 2 cm \times 2 cm cubes of tissue from three different plants labelled A, B and C, small filter paper discs and a beaker of hydrogen peroxide solution. The students carried out the following steps. • Cut the piece of plant tissue A in half. • Use forceps to put a filter paper disc onto a cut surface of plant tissue A, so that it could absorb liquid from the cells. • After 1 minute, use forceps to lift the filter paper disc off the cut surface of plant tissue A. • Drop the filter paper disc into the beaker of hydrogen peroxide solution and start timing at once. The filter paper disc will sink to the bottom of the beaker. • Watch the filter paper disc until it reaches the surface of the hydrogen peroxide solution, then stop timing. If a filter paper disc does not float within 4 minutes (240 seconds) stop timing and record the time taken for the filter paper disc to reach the surface as >240. • Record the time taken, to the nearest whole second, for the filter paper disc to reach the surface of the hydrogen peroxide solution. • Use forceps to take the filter paper disc out of the beaker of hydrogen peroxide solution and put it in the waste container provided. • Rinse and dry the forceps. • Repeat the procedure two more times with filter paper discs on the same cut surface of plant tissue A. • Carry out the whole procedure again for filter paper discs on plant tissue B and then once more for plant tissue C. Fig. 1.2 shows a student's notebook. The student has written their results to the nearest whole second. The result for the third filter paper disc on plant tissue A is missing from their notes. Fig. 1.2 text: repeat discs. plant A: 10, 10. plant B: 21, 16, 20. plant C: no disc floated at 4 minutes. Fig. 1.3 shows the time taken for the third filter paper disc on plant tissue A to reach the surface. Fig. 1.3 display: 9.31 SEC.

Enzyme action

Lemna is a tiny green plant that floats on the water surface in ponds and lakes. It is made up of leaves that float and a root that trails down into the water. Fig. 2.1 shows one plant with four leaves. D and E show the maximum length of two of the plant's leaves. Fig. 2.1 labels: plant leaves on surface of water; root; magnification \times12. This plant population increases because each plant splits into two smaller plants. These smaller plants then produce new leaves and divide again. Some students chose to investigate Lemna growth. They put six plants in a small beaker containing nutrients in distilled water (nutrient solution). A lamp was used to give constant light. The students decided to measure growth by counting the total number of leaves at the same time each day. At the beginning of the investigation there were 16 leaves in total on the plants. Fig. 2.2 shows the beaker viewed from above on day 4. Table 2.1: Time/days and total number of leaves: 0 → 16 2 → 20 3 → 29 4 → [blank] 5 → 55 6 → 83 7 → 91

Asexual and sexual reproduction

Fig. 3.1 is a photomicrograph showing cells from a plant epidermis after treatment so that some of the cells are plasmolysed. Fig. 3.1 labels: cytoplasm in non-plasmolysed cell X; cytoplasm in plasmolysed cell Y; cell wall of plasmolysed cell Y; magnification \times150.

Diffusion and osmosis