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

A public-health laboratory examines head lice collected from several schools. Fig. 1 shows lice exposed to a treatment lotion in a shallow dish. Most lice stop moving, but a small number recover and later lay eggs. The laboratory reports that resistance is inherited and is not caused by a child failing to wash their hair. Parents are advised to check close contacts and use the treatment exactly as directed. Lice can move between heads during close contact, but they do not fly. The aim is to prevent resistant lice from producing many offspring.

(a) Identify the lice that are likely to survive a second treatment with the same lotion. [1]
(b) Explain why checking close contacts can help reduce the spread of resistant lice. [2]
(c) Give one observation the laboratory could record to compare the effectiveness of two lotions. [1]
(d) Use the information to state how lice usually move between people. [1]

The diagram in Fig. 1 shows a dog breeder comparing coat types in a litter. The mother and father both have short coats, but one puppy has a long coat. The breeder uses S for the dominant short-coat allele and s for the recessive long-coat allele. All puppies receive one allele from each parent. The breeder wants to predict which puppies might pass the long-coat allele to their own offspring.

(a) Identify the genotype of the long-coat puppy. [1]
(b) Explain why both short-coat parents must have genotype Ss. [2]
(c) Calculate the percentage chance that another puppy from these parents has a long coat. [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 mountain rescue volunteer after carrying equipment uphill on a cold island. Sensors in the skin and in the blood detect a fall in body temperature. The thermoregulatory centre in the brain coordinates several responses. Blood vessels near the skin become narrower, skeletal muscles contract repeatedly and hairs on the skin may rise. These changes reduce heat loss or increase heat production so that enzyme activity in body cells remains close to normal.

(a) Identify the brain region that coordinates body temperature. [1]
(b) Identify the response shown by the blood vessel at A. [1]
(c) Explain how response A reduces heat transfer from the body surface. [3]
(d) Explain how the response labelled B helps increase body temperature. [2]
(e) Use Fig. 1 to describe the negative feedback sequence when body temperature falls below its normal value. [4]
(f) Calculate the decrease in body temperature if the volunteer’s temperature changes from 37.0 degrees C to 35.6 degrees C. [2]
(g) Suggest one reason why the volunteer should be given warm, sugary water only if they are fully conscious. [1]

This pond is beside a school sports field, and Fig. 1 shows a freshwater amoeba viewed through a microscope. Rainwater has made the pond water dilute compared with the amoeba's cell contents. Water continually enters the cell. A contractile vacuole fills and then empties at regular intervals.

(a) Identify the process by which water enters the amoeba. [1]
(b) Explain why water enters the cell from the pond. [2]
(c) Use the figure to explain the role of the contractile vacuole. [2]

Fig. 1 shows a nurse taking a blood sample from a student before breakfast and again after the student eats a bowl of cereal. The nurse places each sample onto a glucose test strip. Table 1 shows the readings obtained. The student had not eaten for 12 hours before the first test. The cereal contains starch, which is digested to glucose. The nurse explains that blood glucose concentration must be kept within a narrow range so that body cells have a reliable supply of glucose for respiration.

(a) Identify the sample with the highest blood glucose concentration. [1]
(b) Use Table 1 to calculate the decrease in blood glucose concentration between 45 minutes and 2 hours after breakfast. [2]
(c) Explain why the student’s blood glucose concentration rises after eating cereal. [1]

This field study is carried out on an island where two lizard species live on different coloured rocks. Fig. 1 shows a pale lizard on limestone and a dark lizard on volcanic rock. A student observes from a hide and records attacks by kestrels on clay models of each lizard colour. Ten pale and ten dark models are placed on each rock type for one hour. No real animals are used, so the study does not injure the lizards.

(a) Identify the adaptation that may help a pale lizard on limestone. [1]
(b) Explain how this adaptation can affect survival and offspring. [3]
(c) Use the investigation to suggest which model colour should receive fewer attacks on volcanic rock. [1]
(d) Explain why both colours of model are placed on each rock type. [2]
(e) Give one ethical advantage of using clay models. [1]

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 doctor uses the scan in Fig. 1 to discuss an early pregnancy with a patient. The developing fetus is inside a fluid-filled sac in the uterus. A cord connects the fetus to a disc-shaped placenta attached to the uterine wall. Substances pass between the mother’s blood and the fetus without their blood normally mixing directly.

(a) Identify the structure labelled X. [1]
(b) Identify the structure labelled Y. [1]
(c) Explain how oxygen reaches the fetus from the mother. [2]
(d) Give one substance, other than oxygen, that moves from mother to fetus. [1]

A conservation team on an island uses Fig. 1 to study a rare pitcher plant. Insects fall into a liquid held by the modified leaf. Glands in the leaf release digestive enzymes, and the plant absorbs mineral ions from the insect's body. This helps it grow in soil with very little nitrate.

(a) Identify the organ of the plant modified to make the pitcher. [1]
(b) Explain why the plant benefits from digesting insects in nitrate-poor soil. [2]
(c) Which substance made by the plant contains nitrogen and is needed to make new cells? [1]
(d) Use the figure to identify the tissue that carries water to the pitcher. [1]

Fig. 1 shows a water-treatment worker testing how rapidly sodium thiosulfate reacts with dilute hydrochloric acid. A black cross is placed beneath a beaker. Sulfur forms during the reaction and makes the liquid cloudy. The worker records the time at which the cross can no longer be seen through the solution. In all tests, the same observer views the cross from above.

(a) Identify the dependent variable. [1]
(b) Calculate the rate for the test taking 24 s, using rate = 1/time. [2]
(c) Explain why adding water increases the time needed for the cross to disappear. [2]

Fig. 1 shows a plant cell from a young bean plant placed in a concentrated sugar solution. The cell membrane has pulled away from the cell wall. The same plant needs enough water in its cells to keep leaves firm and expose a large surface to light for photosynthesis.

(a) Identify the name of the condition shown in Fig. 1. [1]
(b) Explain why the cell membrane has moved away from the cell wall. [2]
(c) Suggest why a plant with many cells in this condition may wilt. [2]

The table below shows how long a young rat took to find a food box in a maze during ten daily trials. The route was unchanged. At the end of the route, the rat received a small piece of banana. The student cleaned the maze between trials so that scent marks from the rat did not guide it. Water was available in its home cage after each trial.

(a) Describe the pattern in the rat's times. [2]
(b) Calculate the decrease in time between trial 1 and trial 10. [1]
(c) Explain why receiving food may cause the rat to repeat the successful route. [2]

A wildlife researcher compares arctic foxes in summer and winter. In winter their fur is thicker and they reduce the blood flow to skin on their feet when standing on snow. In summer, the same species sheds much of its insulating coat. The researcher notes that an animal must balance the benefit of retaining thermal energy against the risk that tissues near the skin receive too little oxygen in very cold conditions. Blood transports oxygen and glucose to cells, but it can also carry thermal energy around the body.

(a) Identify the change in blood vessels that reduces blood flow to the skin. [1]
(b) Explain how thick winter fur helps the fox in cold air. [2]
(c) Explain why blood flow to the feet cannot be reduced completely for a long time. [2]
(d) Give one advantage of shedding fur in summer. [1]