Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2022 Summer Zone 2

Fig. 1.1 shows a spongy mesophyll cell from the leaf of a plant. The arrows show the net direction of movement of carbon dioxide molecules during daylight.
[Image_Fig_1.1]

(a) The scale bar in Fig. 1.1 represents 0.01 mm. Convert 0.01 mm to micrometres.
........................................................... μm [1]

(b) Table 1.1 shows:
- the functions of some of the structures in plant cells
- some of the names of the structures where these functions occur
- some of the letters that label these structures in Fig. 1.1.
Complete Table 1.1.
[Table_1.1]

function | structure | letter in Fig. 1.1
nucleus | |
chloroplast | |
aerobic respiration | |
contains cell sap and stores water | | A [5]

(c) Carbon dioxide is a raw material for photosynthesis.

(i) State the process by which carbon dioxide travels into the leaf from the air.
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(ii) Describe the pathway taken by a molecule of carbon dioxide, from the air outside a leaf to a spongy mesophyll cell.
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(d) Low concentrations of carbon dioxide in the air may restrict the rate of photosynthesis in plants.

(i) State the term given to something present in the environment in such short supply that it restricts life processes.
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(ii) State one other feature of the environment that may also restrict the rate of photosynthesis.
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(e) Researchers have devised a process of artificial photosynthesis. They use gold nanoparticles as a catalyst to utilise green light to convert carbon dioxide to fuels, such as propane.
Suggest the advantages to the environment of using artificial photosynthesis on a large scale.
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(a) (i) State the name of structure P.
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(ii) Blood vessel Q has the highest blood pressure. Suggest why.
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(iii) The structures labelled S on Fig. 2.2 are microvilli. Explain the importance of the microvilli on the surface of these cells.
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(b) Table 2.1 shows the concentrations of some substances in blood plasma and in the regions labelled 1 and 3 on the tubule shown in Fig. 2.1.



Outline how the kidney tubules function to produce urine from the substances in blood plasma. Use the information in Fig. 2.1, Fig. 2.2 and Table 2.1 to support your answer.
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(c) The kidneys are examples of organs that help the body to maintain a constant internal environment.
(i) State the term for maintaining a constant internal environment by negative feedback.
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(ii) Explain how negative feedback controls the blood glucose concentration of a person who has not eaten for a day.
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The eye is adapted for focusing on near and distant objects.

Fig. 3.1 shows the parts of the eye involved in focusing. The eye is focused on a distant object.

(a)

(i) State the term used to describe what happens to light as it passes from the air into the cornea. [1]

(ii) Describe and explain the changes that occur in the eye when adjusting focus from a distant object to a near object. [3]

(b) Rods and cones are the receptors in the retina of the eye.

(i) Describe the functions of rods and cones in the eye. [4]

(ii) Fig. 3.2 is a photograph showing regions of a human retina, as viewed through the pupil at the front of the eye.

Complete Table 3.1 to show the distribution of rods and cones across the retina.

Use these words to complete the table, each word may be used once, more than once or not at all: 

(3)

(c) Colour blindness can be caused by a mutation in a gene. The gene is located on the X chromosome.

Fig. 3.3 is a pedigree diagram of a family which has several people who are colour-blind.

(i) Colour blindness is sex-linked.

State the evidence from Fig. 3.3 that supports the idea that colour blindness is sex-linked. [1]

(ii) State the genotype of person 5.

Use the symbols X and Y for the sex chromosomes and A for the dominant allele and a for the recessive allele of the gene for colour blindness. [2]

(iii) Use the information in Fig. 3.3 to complete the genetic diagram to show the probability of person 3 and person 4 having another child with colour blindness.  [5]

Fig. 4.1 is a diagram of a virus.
[Image_1: Diagram of virus with labels N and O]
(a) Identify the parts of the virus labelled N and O.

N .............................................................
O .............................................................
[2 marks]

(b) The human immunodeficiency virus (HIV) infects and destroys lymphocytes.

The number of lymphocytes in the blood of a person infected with HIV was measured over a period of 84 months.

The results are shown in Fig. 4.2.
[Image_2: Graph showing number of lymphocytes per mm^3 of blood over time]
(i) Use the information shown in Fig. 4.2 to calculate the percentage change in the number of lymphocytes from month 10 to month 60.
Give your answer to two significant figures.
Space for working.
............................................................. %
[3 marks]

(ii) Describe the changes in the number of lymphocytes, over the 84 months following infection with HIV, shown in Fig. 4.2.
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[2 marks]

(iii) Outline the consequences of the changes in the number of lymphocytes for the health of the person infected with HIV.
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[4 marks]

(iv) Explain why antibiotics are not used to treat viral infections.
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[2 marks]

Fig. 5.1 is a diagram of the human gas exchange system.



(a) (i) Identify the parts of the gas exchange system labelled X, Y and Z in Fig. 5.1.

X ..............................................................................................................................
Y ..............................................................................................................................
Z .............................................................................................................................. [3]

(ii) State the name of the tissue that prevents the collapse of Y and Z during breathing.

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(b) Breathing involves the movement of the ribs and the diaphragm.
Describe the process of inspiration.
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(c) State the name of the gas exchange surface in the lungs.
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(a) Complete the sentence about ecosystems.
An ecosystem can be defined as a unit containing the ................................................. of organisms and their ................................................., interacting together. [2]
Fig. 6.1 is a photograph of a coral reef.

(b) Fig. 6.2 is part of a food web for a coral reef ecosystem which is similar to the one shown in Fig. 6.1.
(i) State the number of secondary consumers shown in Fig. 6.2. ...................................................................................................................[1]
(ii) State the name of a species that feeds at more than one trophic level in Fig. 6.2. ...................................................................................................................[1]
(iii) State the number of different organisms in the shortest food chain in Fig. 6.2. ...................................................................................................................[1]
(iv) State the evidence from the food web in Fig. 6.2, that phytoplankton are producers. ...................................................................................................................[1]
(v) It is rare for there to be more than five trophic levels in an ecosystem.
Explain what limits the number of trophic levels in food webs. .........................................................................................................................
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(c) One threat to aquatic ecosystems, such as coral reefs, is global climate change.
Discuss the threats to aquatic ecosystems, other than climate change. .........................................................................................................................
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