Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2022 Winter Zone 1

(a) Fig. 1.1 is a side view of a human skull indicating the four types of teeth and the jaws.

(i) State the function of human teeth.

(ii) State the name of the visible outer layer of the teeth.

(iii) Explain the process of tooth decay in humans.

(b) Mammals can be classified according to the position and shape of their teeth.

Fig. 1.2 shows the skulls of seven mammals.

(i) Use the key to identify each species shown in Fig. 1.2.

Write the letter of each species $(A$ to $G)$ in the correct box in the key.

(ii) Killer whales, Orcinus orca, are mammals.

State two internal features you would expect to find in a killer whale that you would not find in a fish. (2)

(iii) State the name of a group of animals that includes mammals and fish. (1)

Digestive enzymes catalyse the breakdown of large insoluble molecules.

(a)

(i) Explain why it is important that large insoluble molecules are broken down by chemical digestion. [2]

(ii) State the name of the substance that is the solvent for most molecules that have been digested by enzymes. [1]

(b) The activity of two protease enzymes, $A$ and $B$, was measured at different pHs. Both enzymes are found in the human alimentary canal.

The results are shown in Fig. 2.1.

Description and explanation of the roles of the two protease enzymes, $A$ and $B$, in the alimentary canal.

Use the information in Fig. 2.1 to support your answer. [6]

(c) Maltase is a digestive enzyme that acts in the small intestine.

State the exact location of maltase in the small intestine. [1]

(a) Fig. 3.1 shows some apparatus that was used to investigate water loss from a leafy shoot.

(i) State the name of the process by which leafy shoots lose water.
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(ii) Before the leafy shoot is inserted into the jar shown in Fig. 3.1, it must be recut under water.
Suggest why the end of the leafy shoot was cut under water.
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(iii) State the purpose of the oil layer on top of the water in the burette.
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(iv) Using the information in Fig. 3.1, describe one method that can be used to determine how much water is lost from the leafy shoot.
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(b) The apparatus shown in Fig. 3.1 was used to investigate the effect of temperature on the rate of water loss in a species of plant. The results are shown in Fig. 3.2.

(i) Using the information in Fig. 3.2, calculate how much water would be lost from 1 m² of leaves in 12 hours if the plants were kept at 35 ℃. Include the unit.
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(ii) Using the information in Fig. 3.2, describe and explain the effect of increasing temperature on the rate of water loss in this species of plant.
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(c) The apparatus shown in Fig. 3.1 can also be used to investigate the effects of changing humidity on water loss in plants.
(i) Suggest why the mass of water in the apparatus does not change when the leafy shoot is kept at 100% relative humidity.
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(ii) Even at extremely low relative humidities the leafy shoot did not wilt.
Explain why the leafy shoot shown in Fig. 3.1 did not wilt.
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(iii) The investigation on the effect of temperature was done at a relative humidity of 20%.
The investigation was repeated at a relative humidity of 80% and all other conditions were kept the same.
Predict how the water loss will differ from the trend shown in Fig. 3.2.
Sketch your prediction on Fig. 3.2.
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Chromosomes are made of DNA.

(a) Describe the structure of a DNA molecule. [4]

(b)

(i) Outline how antibiotic resistance develops in a population of bacteria. [3]

(ii) Scientists use differences in antibiotic-resistance genes to distinguish between different strains of the bacterium, methicillin-resistant (S. aureus) (MRSA).

Suggest why scientists use differences in base sequences to classify the strains of MRSA rather than using other methods. [1]

(iii) Explain why scientists are concerned that some strains of bacteria, such as (S. aureus), have become resistant to antibiotics. [2]

(c)

(i) Describe how the use of antibiotics can be managed to reduce the development of resistant strains of bacteria. [2]

(ii) Suggest why MRSA is unlikely to be transmitted from a mother to her unborn fetus. [1]

(d) Many species of bacteria do not cause disease. Bacteria are very important in many biological processes.

State the names of three natural processes involving bacteria that are important to ecosystems. [3]

(a)

(i) State one other natural process that releases carbon dioxide into the atmosphere. [1]

(ii) Carbon dioxide is a greenhouse gas. State the name of one other greenhouse gas. [1]

(b) Data scientists used satellite images to analyse the occurrence of fires globally, during a 14-year period. They tracked all fires that were larger than 0.21 km$^2$ and therefore visible from space.

Table 5.1 summarises some of their data, categorising the fires by location. The locations include natural ecosystems and land that is managed by people. The expansion rate is the speed at which each fire becomes larger.

Table 5.1

(i) Using the information in Table 5.1, compare the data for the two managed locations with the data for the three natural locations. [3]

(ii) Describe how the data in Table 5.1 could be used to estimate the total area that was burnt during the 14-year period, for each location. [2]

(iii) Burning large areas of forest is a cause of habitat destruction. Describe the possible consequences of habitat destruction. [3]

(a) Fig. 6.1 shows part of the human gas exchange system.

(i) Table 6.1 shows the names of some parts of the human gas exchange system, their functions and the letters in Fig. 6.1 that identify the parts.

Complete Table 6.1.

(ii) Describe and explain how the alveoli are adapted for gas exchange. [3]

(b)

(i) Explain the differences in composition between inspired and expired air. [3]

(ii) Physical activity changes the concentration of carbon dioxide in the body.

State where this change is detected and how the body responds to the change. [2]

(iii) State the name of a solution that can be used to test for the presence of carbon dioxide gas. [1]