Combined Science Double Award 9204 | Paper 1 Mock 01 | Biology

A food technician uses Fig. 1 to check the activity of amylase in a bread-making mixture. Starch from flour is mixed with amylase before yeast is added. The technician keeps the mixture near body temperature because the enzyme must first convert starch into smaller sugar molecules.

(a) Identify the product of starch digestion by amylase. [1]
(b) Explain why a much higher temperature can stop amylase working. [2]
(c) Use the figure to identify the part of an enzyme where starch binds. [1]
(d) Calculate the mass of starch digested each minute if 18 g is digested in 6 minutes. [2]

This field observation is from an orchard where aphids feed on young apple trees. Some aphids carry a plant virus between trees as they pierce leaves and take sap. The orchard manager releases ladybirds, which eat aphids, and removes heavily infected trees. Leaves on infected trees show a mosaic pattern and make less glucose by photosynthesis. Fewer fruits develop on badly affected plants.

(a) Identify the vector carrying the virus between apple trees. [1]
(b) Explain why releasing ladybirds may reduce the spread of the plant disease. [2]
(c) Give one reason why infected leaves making less glucose can lead to fewer fruits. [1]
(d) Which type of pathogen is causing the mosaic disease? [1]

A sports club offers influenza vaccination to players before the winter season. The club doctor explains that the vaccine may not stop every infection because influenza viruses can change. Vaccinated players are still advised to cover coughs, wash hands and stay away from training when they have a fever. The club wants to protect players with asthma, because a respiratory infection can affect their breathing more severely.

(a) Identify the pathogen group that causes influenza. [1]
(b) Explain why a new influenza vaccine may be needed in a later year. [1]
(c) Give two actions, other than vaccination, that can reduce spread of influenza at the club. [2]
(d) Which body system is mainly affected by influenza? [1]

Fig. 1 shows a doctor tapping below a patient's kneecap during a routine examination. A lower-leg muscle contracts and the foot moves forwards. The doctor uses this response to check that sensory and motor neurones are working. The movement happens without a decision by the patient.

(a) Identify the type of response tested by the doctor. [1]
(b) Use the figure to describe the role of a sensory neurone in this response. [2]
(c) Explain why this response is useful when the leg is suddenly stretched. [2]

The diagram shows a pea seed beginning to germinate in a jar. Cotton wool at the bottom is moist, and the jar is kept at 22 degrees C. The seed coat splits, a root grows down and a shoot grows up. At this stage there are no green leaves to make glucose by photosynthesis. The embryo uses stored food in the cotyledons. A second jar is kept in a refrigerator, while a third jar contains dry cotton wool. The student checks how many seeds germinate in each jar.

(a) Identify the structure that develops into the first root. [1]
(b) Explain why the seed needs water before germination can begin. [2]
(c) Which condition is tested by placing seeds in a refrigerator? [1]
(d) Identify the process that releases energy from stored food in the embryo. [1]

Fig. 1 shows an enlarged section of skin from a person who has been outside on a cold, windy day. The hairs are raised and the blood vessels close to the surface are narrow. The body is responding to a fall in internal temperature and reducing energy loss to the air.

(a) Identify the response shown by the narrow blood vessels. [1]
(b) Explain how this response reduces heat loss from the blood. [2]
(c) Use the figure to explain how raised hairs can reduce heat loss. [2]

Fig. 1 shows a field biologist measuring the forearms of bats caught briefly beside a newly cleared woodland corridor. Before trees were removed, most bats travelled through a sheltered route between two caves. The open corridor is now windy and contains fewer insects. Within this bat species, forearm length varies. Bats with longer forearms may fly more efficiently across the exposed space, so they may obtain more food and produce more offspring. The biologist released every animal after recording its measurements.

In the first year, the mean forearm length was 41 mm. After 12 years, the mean was 46 mm.

(a) Identify the type of variation shown by forearm length in these animals. [1]
(b) Calculate the change in mean forearm length over the 12 years. [1]
(c) Explain why the proportion of bats with alleles for longer forearms could increase in this population. [4]
(d) Suggest two pieces of evidence, other than forearm measurements, that would strengthen the biologist's conclusion that natural selection has occurred. [2]
(e) Give two reasons why the biologist should return each bat to the same area after measurement. [2]

Fig. 1 shows a seedling placed under a lamp that shines from one side. After two days, the shoot bends towards the lamp. The leaves receive more light on the side facing the lamp. In another part of the investigation, one seedling is rotated slowly on a turntable so that all sides receive similar light exposure. The students measure shoot height and leaf area at the end of one week. They relate the response to the need for leaves to absorb light for photosynthesis.

(a) Identify the name of the response shown by the bending shoot. [1]
(b) Explain how bending towards light can increase the rate of photosynthesis. [2]
(c) Use the investigation to state why the turntable is used. [2]
(d) Give one product of photosynthesis that can be used in respiration by plant cells. [1]

A laboratory is testing a medicine designed to slow the division of cancer cells. Fig. 1 shows two microscope fields from the same type of cultured cell after 24 hours. Dish A received no medicine. Dish B received the medicine. Cells with visible condensed chromosomes are counted as dividing cells. Both dishes had the same starting number of cells, volume of nutrient solution, temperature and oxygen supply.

(a) Use Fig. 1 to identify which dish has more cells in mitosis. [1]
(b) Calculate the difference in the number of dividing cells between the two dishes, using Fig. 1. [1]
(c) Explain why the scientist kept temperature the same for both dishes. [2]

The diagram shows part of the temperature-control system in a human body. Receptors in the skin and in the brain detect changes in the temperature of blood. The control centre sends messages to effectors, including sweat glands and muscles. A student has a fever caused by a disease. At first, the student feels cold even though their measured body temperature is rising. Later, the student sweats as the fever falls. This is an example of negative feedback because responses act to return temperature towards a normal value.

(a) Identify the organ containing the main temperature-control centre. [1]
(b) Use Fig. 1 to state one effector involved when body temperature is too high. [1]
(c) Explain how shivering can raise body temperature. [2]
(d) Explain why temperature control is described as negative feedback. [1]

A laboratory uses Fig. 1 to show students how identical lambs can be produced from cells of a prize ewe. The nucleus is removed from an unfertilised egg cell. A nucleus from a body cell of the prize ewe is put into the egg cell. An electric pulse starts cell division, and the embryo is placed into a surrogate mother.

(a) Identify the technique shown. [1]
(b) Identify which animal provides the genes of the cloned lamb. [1]
(c) Explain why the cloned lamb has the same genetic information as the prize ewe. [2]
(d) Give one advantage of cloning a ewe with high milk production. [1]
(e) Give one concern about producing many cloned animals. [1]

Fig. 1 shows a greenhouse bench containing young tomato plants. A gardener notices that whitefly insects feed from the leaf surface and can transmit plant disease. Some tomato plants have leaves with dense hairs, making it harder for whiteflies to settle and feed. Other plants have smoother leaves. The gardener saves seeds only from healthy plants with hairy leaves, then grows their offspring next season. This is artificial selection, because the gardener chooses the parent plants. In the wild, whitefly feeding could instead act as a natural selection pressure.

(a) Identify the tomato leaf characteristic likely to reduce whitefly feeding. [1]
(b) Explain one difference between artificial selection and natural selection in this situation. [2]
(c) Use the information to suggest why hairy-leaved plants may produce more seeds in the wild. [1]
(d) Which term describes offspring receiving alleles from their parent plants? [1]

The table below records a trial on a coastal barley farm. Wind had carried fungal spores from an infected field onto young plants. Two barley varieties were grown in equal-sized plots. Variety M makes a thick waxy layer on each leaf, whereas variety N has a thinner leaf surface. After three weeks, the farmer counted plants showing brown fungal patches. Resistant plants are useful because fungal disease can reduce glucose production and leave less starch in the grain.

Table 1 shows the results.

(a) Identify which variety is more resistant to the fungal disease. [1]
(b) Use Table 1 to calculate the difference in mean grain mass per plant between the two varieties. [2]
(c) Explain how a waxy leaf surface could reduce infection by fungal spores. [2]
(d) Explain how selective breeding could produce barley plants with improved resistance to this disease. [4]
(e) Suggest three controls needed to make this field comparison fair. [3]

The table below shows results from an investigation with pondweed collected from a freshwater island pond. A lamp was placed at different distances from the pondweed for two minutes. The student counted bubbles of oxygen leaving the cut stem. The water temperature was kept close to 22 degrees C using a water bath. Fig. 1 shows the apparatus, including a ruler used to set the lamp distance. The student repeated each distance three times before calculating a mean.

(a) Record the mean number of bubbles at 30 cm. [1]
(b) Describe the relationship between lamp distance and oxygen bubble production. [2]
(c) Explain why the water temperature was controlled. [1]