Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2018 Summer Zone 3

Two functions of the alimentary canal are mechanical digestion and chemical digestion.

(a) Outline where and how mechanical digestion occurs in the alimentary canal.
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(b) Enzymes catalyse the reactions of chemical digestion. Table 1.1 gives information about chemical digestion in three parts of the alimentary canal.
Complete Table 1.1.

Table 1.1
[Table_1]
part of the alimentary canal | enzyme | substrate | product(s)
mouth | | starch |
stomach | | | peptides
| | fat | fatty acids and glycerol

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(c) Substances that are absorbed from the alimentary canal may enter cells and become part of the cells.
(i) State the storage carbohydrate made from glucose in liver cells.
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(ii) State the type of protein used in the immune system that is produced from amino acids by lymphocytes.
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(iii) Fat is produced from fatty acids and glycerol by cells in the fatty tissue beneath the skin.
State one function of this layer of fat.
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(a) (i) State two features, visible in Fig. 2.1, that identify Arctic wolves as mammals.
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(a) (ii) Arctic wolves show many adaptive features to a cold environment.
Explain what is meant by the term adaptive feature.
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(b) The food available to animals in the Arctic tundra is limited. There is a short growing season for plants and the environmental conditions do not favour high rates of photosynthesis and growth compared with temperate and tropical ecosystems.
State three conditions that limit plant growth rates.
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(c) Arctic wolves are the top carnivores in the food web in the tundra.
Explain why the number of Arctic wolves is so small in this ecosystem.
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Fig. 3.1 is a scanning electron micrograph of a vertical section through part of the leaf of a broad bean plant, Vicia faba.
(a) (i) State the names of the tissues labelled A and B.
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(ii) The cells in regions B and C in Fig. 3.1 have a large surface area. Explain why this is necessary for the functioning of the leaf cells.
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(iii) Explain why there are many interconnecting air spaces within the leaf.
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(b) When water is in short supply, plants can wilt as shown in Fig. 3.2.
(i) State two conditions that are likely to increase the chances of wilting.
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(ii) Explain what happens to the cells of a leaf to cause wilting.
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(iii) Wilting may look harmful, but it is often a strategy for survival. Suggest the advantages to a plant of wilting.
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(a) The endocrine system in mammals produces hormones.
Define the term hormone.
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(b) The responses of the human body to danger are coordinated by the nervous and endocrine systems.
Fig. 4.1 shows the sequence of events that occurs in response to a dangerous situation that is detected by the eyes.

[Image: Fig. 4.1]

(i) State the tissue in the eye that converts light energy into nerve impulses.
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(ii) State the part of the eye that has the highest concentration of light-sensitive cells and gives the most detailed image.
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(iii) State the type of neurone that conducts impulses from the eye to the brain.
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(iv) State the nerve that contains these neurones that conduct impulses from the eye to the brain.
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(v) Identify the organ labelled P.
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(vi) Identify the gland labelled Q.
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(c) Complete Table 4.1 to describe the effects of the hormone released when a person is in a dangerous situation.

[Table: Table 4.1]

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(d) Explain the advantages of coordinating the response to a dangerous situation using both the nervous system and the endocrine system.
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(e) (i) Plants also make hormones.
State the name of one hormone made by plants.
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(ii) Some plant hormones are manufactured and applied to crops to alter aspects of plant growth.
Describe how the synthetic plant hormone 2,4-D is used in agriculture.
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(a) State the balanced chemical equation for aerobic respiration.
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(b) Students investigated the rate of respiration of crickets (a type of insect) using a carbon dioxide sensor and laptop as shown in Fig. 5.1. The sensor was fitted inside an airtight glass jar. The apparatus was set up in a room with a constant temperature of 17°C.

The students found that the concentration of carbon dioxide inside the jar increased by 50 ppm in 120 seconds.
Calculate the rate of carbon dioxide production as ppm per second.
Show your working and express your answer to two significant figures.
.............................................. ppm s⁻¹

(c) After 10 minutes, the students opened the jar by removing the sensor. They left the jar open for 5 minutes but made sure that the crickets remained in the jar. They then replaced the sensor and took more readings for another 10 minutes.
State and explain one reason for opening the jar after 10 minutes.
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(d) During the investigation the temperature inside the jar increased. The temperature outside the jar remained constant.
Explain why the temperature inside the jar increased.
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(e) Researchers in Chile also investigated the rate of respiration in crickets.
They investigated the effect of temperature and body mass on the rate of respiration. They measured the rate of oxygen consumption in crickets with different body masses, at different temperatures.
The researchers’ results are shown in Fig. 5.2.

State two conclusions that can be made from the data in Fig. 5.2 and support each conclusion with evidence from the graph.
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(a) Fig. 6.1 is a half-flower drawing of pride of Barbados, Caesalpinia pulcherrima.



Complete Table 6.1 by stating the letter from Fig. 6.1 that indicates the organ where each function occurs and the name of the organ.

Table 6.1

| function | letter from Fig. 6.1 | name of the organ |
|-------------------------------------|----------------------|-------------------|
| meiosis to produce pollen grains | | |
| pollination | | |
| development of seeds | | |
| protection of flower in the bud | | |

(b) Fig. 6.2 is a scanning electron micrograph of some pollen grains from wind-pollinated flowers and insect-pollinated flowers.



(i) Write the formula that would be used to calculate the actual diameter of pollen grain $H$.

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(ii) The actual diameter of pollen grain $H$ is 0.082 mm.
Convert this value to micrometres ($\mu$m).
Space for working.

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(iii) Explain how the pollen grain labelled $J$ is adapted for insect pollination.

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(c) Pollen grains grow tubes, which contain haploid male gamete nuclei.

(i) One of these male gamete nuclei fuses with the female gamete.
State the part of the flower that contains the female gamete.

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(ii) Define the term $haploid \ nucleus$.

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(iii) Explain why it is important for gametes to be haploid.

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