May/June 2023

Which description is correct for a red blood cell?

Specialised cells, tissues and organs

Under which conditions does a plant experience the greatest rate of transpiration?

Transpiration and translocation

Which disease may result from a dietary shortage of both a mineral ion and a vitamin?

Diet

A student says: ‘When circular muscles contract, the contents are driven onwards.’ Which process is this describing?

Human digestive system

An investigation is performed into digestion and absorption in the alimentary canal. The diagram shows the apparatus used. The Visking tubing allows small molecules such as glucose to pass through, but it does not allow large molecules such as starch to pass through. After one hour, the water samples in the beaker are tested using Benedict’s solution and iodine solution. Which colours are obtained?

Absorption and assimilation

Each of the students was given the apparatus shown. They put the mouthpieces into their mouths and then gently breathed in and out through the apparatus ten times. Which statement describes what occurred as they breathed in and out?

Human gas exchange

From the breakdown of two molecules of glucose in aerobic respiration, how many molecules of carbon dioxide are produced?

Aerobic respiration

Which equation represents the type of respiration that can lead to an ‘oxygen debt’ in muscles during vigorous exercise?

Anaerobic respiration

Measurements of blood pressure were taken in the pulmonary artery, pulmonary capillaries and pulmonary vein. Which blood pressure readings could be correct?

Blood vessels

Which blood component engulfs pathogens?

Blood

What measure would help to reduce the transmission of malaria?

Disease

A plant with green leaves produces spores. Which group does it belong to?

Features of organisms

The table presents death rates from lung cancer in a country for smokers and non-smokers. What conclusions can be drawn from the data?

Disease

What is one method by which the development of antibiotic-resistant bacteria can be reduced?

Antibiotics

How does the human immunodeficiency virus (HIV) affect the immune system?

Immunity

The blood in the renal vein has a different composition from the blood in the renal artery. In what way is the blood in the renal vein different?

Urinary system

The diagram illustrates a reflex arc. A person had an accident and injured their arm. The sensory neurones at X have been cut. Which statement describes what occurs if this person touches a hot object with their finger?

Mammalian nervous system

A person’s pupil diameter is recorded while the light intensity is changed. In which time interval does the light intensity rise most rapidly?

Mammalian sense organs

On a hot, sunny day, a swimmer gets out of a pool and sits on the side to dry off. After a few minutes, the swimmer’s skin starts to feel cold. What has caused this to happen?

Temperature control

A genetic disorder leads to insulin being secreted in excessive amounts. What effect does the secretion of too much insulin have?

Blood glucose control

Auxin is a chemical made by plants. What role does auxin have?

Coordination and response in plants

The diagram illustrates cell X, which has 24 chromosomes. It divides by mitosis to form cells Y and Z. How many chromosomes are present in cell Z?

Nuclear division

Which statement is correct in all cases for both diffusion and osmosis?

Diffusion and osmosis

Which characteristic is associated with asexual reproduction in a plant?

Asexual and sexual reproduction

The diagram shows the parts of a flower. Which labelled part will become a seed after fertilisation?

Sexual reproduction in plants

The diagram illustrates the 28 days in a typical menstrual cycle. The letters placed around the outside represent different stages in the cycle. Which row correctly identifies the stages in the cycle?

Sexual reproduction in humans

The diagram illustrates how the blood vessels are arranged in the wall of the uterus and the placenta of a pregnant woman. Which substance will have an increased concentration in the blood as it passes from 1 to 2?

Sexual reproduction in humans

In one population of lizards, some individuals had leg bones that were longer than those of others. These lizards could climb more effectively than the ones with shorter legs, which helped them avoid predators on the ground. As time passed, the lizards with shorter legs died out, so every lizard in the population now has longer legs. Which process has led to this change in the lizard population?

Selection

The genotype for an organism’s height is shown as Tt. Which conclusion can be drawn?

Inheritance

The diagram illustrates apparatus arranged for the production of alcohol by fermentation. What is the function of the layer of oil?

Anaerobic respiration

The diagram depicts a biomass pyramid. What percentage of biomass is transferred from the primary consumer to the secondary consumer?

Energy flow

The diagram illustrates part of the carbon cycle. Which row gives the correct labels for the numbered boxes?

Nutrient cycles

Which human activity is most likely to make the greatest contribution to global warming?

Effects of humans on ecosystems

The graph illustrates how oxygen affects ion uptake in two groups of barley plants. Apart from oxygen availability, both groups were grown under the same conditions. Which process is occurring to account for the difference between the two curves?

Active transport

Run-off from fields that have had nitrogen-containing fertilisers applied may cause fish to die in rivers. Which sequence of events explains what happens when fish die because of water pollution by nitrogen-containing fertilisers?

Effects of humans on ecosystems

A learner examined a food sample, and the findings were as follows. Colour after adding Benedict’s solution and heating: red. Colour after adding biuret reagent: purple. Colour after adding iodine solution: yellow/brown. Which nutrients were present in the food?

Biological molecules

The graph illustrates how substrate concentration affects the rate of an enzyme-controlled reaction. The results were obtained with a constant enzyme concentration at a temperature of 30^{\circ}C. Which statement explains the graph’s shape from X to Y?

Enzyme action

The graph illustrates how a plant’s rate of photosynthesis changes with light intensity. Which of the statements are correct?

Photosynthesis

The diagram illustrates a section of a leaf cut across its width. What are the chief functions of the three labelled regions?

Leaf structure

Which description of the role of root hairs is correct?

Specialised cells, tissues and organs

In a plant cell, how permeable are the cell wall and the cell membrane?

Cell structure and function

A herbaceous plant, growing in a nutrient solution, is placed inside a container with strong light. Humid air is blown through the container. The diagram shows a section through part of the plant. The rates of movement of the fluids in tissues R and S are measured. The humid air is then changed to dry air, and the rates of movement of the fluids are measured once more. Which effect does the switch to dry air have on the measurements?

Transpiration and translocation

The nutrients present in sweet potatoes are given below. 1 calcium 2 fibre 3 iron 4 vitamin C. Which nutrient would help to prevent each disease?

Diet

Four organs of the alimentary canal are named: J colon, K duodenum, L oesophagus, M stomach. Which sequence shows the route food takes through these organs?

Human digestive system

Someone with coeliac disease has flattened villi in their ileum. If such a person consumes the same amount and kinds of food as someone without the disease, the glucose level in their hepatic portal vein will be lower. Which row gives the reason for this?

Absorption and assimilation

Which process does not cause a net loss of energy from the organism?

Energy flow

During anaerobic respiration in yeast cells, what substance is used, and which substances are formed?

Anaerobic respiration

Which word equation describes aerobic respiration?

Aerobic respiration

Which chamber in the heart has the thickest muscular walls?

Heart

The diagram illustrates the human circulatory system. At which location is the pressure of the blood flowing through the blood vessels greatest?

Blood vessels

Which diagram shows the roles of a mosquito and $\text{Plasmodium}$ in malaria?

Disease

The picture shows an arthropod. By following the key, which option correctly identifies the arthropod shown? Key: 1 has wings $\rightarrow$ go to 2 does not have wings $\rightarrow$ A 2 has 2 body parts $\rightarrow$ B has 3 body parts $\rightarrow$ go to 3 3 has 6 legs $\rightarrow$ C has 8 legs $\rightarrow$ D

Concept and use of a classification system

The bar chart displays the percentage of women who gave birth to babies with low birth weight. Among these women, some smoked and others did not. What does the bar chart show?

Disease

Which illness could be treated successfully using an antibiotic?

Antibiotics

Newborn babies already have some passive immunity. What conditions are necessary for passive immunity to be produced?

Immunity

Which structure contains fluid with a low concentration of urea?

Urinary system

A person blinks when an insect enters their eye. What causes this reflex action?

Mammalian nervous system

The graph illustrates how a person’s pupil diameter changes while they are outside on a sunny day. At what time did the person remove their sunglasses?

Mammalian sense organs

The graph displays a person's blood glucose concentration during the hours following breakfast eaten at 07:00. Which blood glucose concentration level is approximately the set point?

Blood glucose control

Which hormone lowers the concentration of blood glucose?

Blood glucose control

Which statement concerning auxin is correct?

Coordination and response in plants

The diagram illustrates several stages of cell division in a fruit fly. Cell X has 8 chromosomes. How many chromosomes are present in cell Y and in cell Z?

Nuclear division

Which of the following statements about diffusion are correct?

Diffusion and osmosis

Which statement is correct for organisms that reproduce asexually?

Asexual and sexual reproduction

What role do the sepals of most flowers play?

Sexual reproduction in plants

Which diagram shows the hormones matched to their roles in preparing for pregnancy?

Mammalian hormones

Which row shows how substances are exchanged at the placenta?

Sexual reproduction in humans

A DNA strand has 100 nucleotide pairs. Of the nucleotides present, 46 contain the base A. How many nucleotides in this DNA strand contain the base T?

DNA

Two brothers had different blood groups: one had blood group A while the other had blood group B. What conclusion can be drawn about the blood group genotypes of their parents?

Inheritance

The diagram illustrates a fermenter used for culturing the fungus Penicillium in order to make penicillin. What is the role of the outer water jacket?

Biotechnology

The diagram illustrates four ecological pyramids. In one food chain, cows feed on grass. Insects live on the cows’ skin. Birds eat the insects. Which one is the pyramid of biomass and which one is the pyramid of numbers in this food chain?

Energy flow

The diagram illustrates a simplified nitrogen cycle. At stage X, which process occurs in the cycle?

Nutrient cycles

Which alteration would result in an increase in biodiversity in an area?

Ecosystems and biodiversity

Several ways that molecules can travel into and out of cells are given. 1 Molecules move from a region of higher concentration to a region of lower concentration. 2 Molecules move from a region of lower concentration to a region of higher concentration. 3 Molecules move from a region of higher concentration to a region of lower concentration through a partially permeable membrane. Which statement is the correct one?

Diffusion and osmosis

Parts of tropical rainforests are frequently felled and cleared. Once the trees have been cut down, the land is usually set on fire. What are the effects of this activity?

Effects of humans on ecosystems

A solution that contained biological molecules was tested using food tests. The table displays the results of these tests.

Biological molecules

The graph indicates the concentration of maltose formed as amylase breaks down starch at different pH values. What accounts for the pattern of the graph between point X and point Y?

Effects of temperature and pH

The diagram shows a cross-section through part of a leaf from a dicotyledonous plant. Which cells perform photosynthesis?

Leaf structure

Which row explains why plants require magnesium ions and nitrate ions?

Mineral nutrition

Root hairs absorb water and ions from the soil. Which table indicates the correct concentrations of water and ions in the root hair?

Uptake and transport of water and ions

The human body makes more than fifty distinct hormones.

Mammalian hormones

Meerkats are small mammals that inhabit deserts, which are dry, open habitats. Desert conditions are very hot in the daytime but cold at night. Meerkats are carnivores that look for food in daylight.

Concept and use of a classification system

Fig. 3.1 shows a young tomato plant growing beside a window. Cells from two different positions in the stem are also illustrated. The cells at X divide continuously. They then enlarge, and some develop into mature cells such as the one shown from position Y.

Coordination and response in plants

Fig. 4.1 displays a label from a snack bar.

Diet

Myopia is a disorder of the eye. A person with myopia can see nearby objects clearly, but objects that are distant appear unclear. This may occur when the eyeballs are a little too long, as shown in Fig. 5.1.

Mammalian sense organs

The human heart pushes blood through blood vessels so that it circulates all around the body.

Circulatory system

The carbon cycle is a vital part of every ecosystem. Carbon is moved repeatedly between living organisms and the atmosphere, as illustrated in Fig. 7.1.

Nutrient cycles

Table 1.1 shows three gases that are found in the atmosphere.

Aerobic respiration

Describe the physical digestion that takes place in humans and explain why it matters.

Immunity

The nervous system controls and coordinates body activities. Fig. 3.1 contains two diagrams, each of which shows parts of the nervous system in a human.

Mammalian nervous system

In the United States of America, Lake Washington is a large lake of fresh water. From 1941 to 1963, ever larger quantities of untreated sewage contaminated the lake.

Selection

Fig. 5.1 shows a photomicrograph of the middle region of a plant root.

Specialised cells, tissues and organs

Fig. 6.1 illustrates the pattern of results from an investigation into how increasing light intensity affects the rate of photosynthesis.

Photosynthesis

DNA stores genetic information as genes.

DNA

In a laboratory, a student used the apparatus in Fig. 1.1, a potometer, to study water uptake by a leafy plant stem. As transpiration causes water to leave the leaves, water is drawn into the cut end of the stem. The water meniscus in the capillary tube then shifts towards the cut end of the stem. At the start of the investigation, the student recorded where the meniscus was on the scale. This was the starting position. The apparatus was then left for 20 minutes, after which the meniscus position was read from the scale again. This was the ending position. Fig. 1.2 shows the starting and ending positions of the meniscus.

Transpiration and translocation

Fig. 2.1 shows a photograph of a small animal possessing an external shell.

Features of organisms

A group of students investigated water movement by osmosis using potato tissue. They were given: • a balance • five cylinders of potato tissue with equal diameters • five different concentrations of sodium chloride (salt) solution at room temperature • five test-tubes • a sharp knife • a white tile • a marker pen / pencil • paper towels. They carried out the method below: • label the test-tubes 0%, 2%, 4%, 6% and 8% • cut each potato cylinder so that each one has a mass of $3.0\,\text{g}$ • put one potato cylinder into each test-tube • add the corresponding salt solution to each test-tube so that the potato cylinder inside is covered, as shown in Fig. 1.1 • note the time and leave the potato cylinders in the solutions for 40 minutes • after 40 minutes remove the potato cylinders from the test-tubes • dry each potato cylinder with a paper towel • measure and record the mass of each potato cylinder.

Diffusion and osmosis

Fig. 2.1 shows a photograph of a leaf from a potato plant.

Leaf structure