Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2018 Winter Zone 2

(a) Complete Table 1.1 by giving the name of one organism from the food web in Fig. 1.1 for each row.

Table 1.1

| | name of organism from Fig. 1.1 |
|-----------------------|--------------------------------|
| producer | |
| secondary consumer | |
| an animal that feeds | |
| at two trophic levels | |


(b) State the name of process A in Fig. 1.2 and give the type of organism that converts ammonium ions to nitrate ions.

A ..........................................................................................................................

type of organism .........................................................................................................................
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(c) Describe how nitrate ions enter the roots of plants shown by arrow C on Fig. 1.2.
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(d) State the name of the structure in plant cells where process D occurs.
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(e) State the process that occurs at B.
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(f) A pyramid of numbers for the wetland ecosystem showed that there were very large numbers of organisms at the base of the pyramid and very few at the top.

Explain why.
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Fig. 2.1 shows a dwarf sunflower and a tall sunflower, $Helianthus$ $annuus$. The height of the dwarf sunflower is 0.45 m and the height of the tall sunflower is 4.5 m.
[Image_1: Fig. 2.1 shows a dwarf and a tall sunflower.]

Dwarf plants like the one in Fig. 2.1 have mutant alleles.
(a) Define the term allele.
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(b) Shoot growth in plants is controlled by auxins. An enzyme in shoot tips converts molecules of an amino acid into auxins as shown in Fig. 2.2.
[Image_2: Fig. 2.2 shows conversion of amino acid to auxin by enzyme.]
Explain how a mutation in DNA results in an abnormal enzyme which does $not$ catalyse the reaction shown in Fig. 2.2.
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(c) Two tall sunflower plants were crossed. 25% of the offspring produced were dwarf.
Explain how it is possible for two tall parent plants to have this percentage of dwarf offspring.
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(d) Fig. 2.3 shows how several strawberry plants can be formed from one parent plant.
[Image_3: Fig. 2.3 shows reproduction process of strawberry plants.]
(i) Explain the type of reproduction that produces plants by the method shown in Fig. 2.3.
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(ii) Explain the $disadvantages$ of the type of reproduction shown in Fig. 2.3.
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(a) Fig. 3.1 is a photomicrograph of some xylem vessels. Fig. 3.1

(i) State one structural feature of xylem vessels and explain how this is related to the function of water transport.
feature ..............................................................................................................................
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explanation .........................................................................................................................
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(ii) Explain the mechanism that is responsible for the movement of water in xylem vessels.
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(iii) State one role of xylem vessels other than transport.
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(b) The rate of transpiration is affected by several factors including the temperature and the humidity of the air.
State and explain the effect of an increase in temperature on the rate of transpiration.
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Insulin is a hormone that regulates the concentration of glucose in the blood.

(a) Define the term hormone.
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(b) Two people, A and B, visited a doctor to discuss their similar symptoms. The doctor thought that their blood glucose concentrations were not very well controlled. A glucose tolerance test was carried out on both people. A and B did not eat or drink anything other than water for eight hours before the test. They then drank a glucose solution. Blood samples were taken at 30 minute intervals. The samples were tested for glucose concentration.

The results are shown in Fig. 4.1.



(i) Use Fig. 4.1 to state the blood glucose concentrations of A and B at 180 minutes.
A ...................................................................................................................... mg per 100 cm³
B ...................................................................................................................... mg per 100 cm³
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(ii) Calculate the percentage increase in the blood glucose concentration in person A between 60 and 90 minutes.
Give your answer to the nearest whole number.
Show your working.
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(iii) Describe how the response of person A differs from the response of person B in Fig. 4.1.
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(iv) Explain the results of the glucose tolerance test shown by person B.
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(v) The doctor thought that person A had Type 1 diabetes.
Describe three symptoms of Type 1 diabetes.
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Fig. 5.1 shows a photomicrograph of human blood.

(a) Describe the differences in appearance and the roles of the three cells labelled in Fig. 5.1.

(b) Fig. 5.2 shows some of the stages of blood clotting.

(i) Complete Fig. 5.2 by filling in the two empty boxes.

(ii) State two roles of blood clotting.

(c) Haemophilia is a sex-linked blood disorder in which blood takes a long time to clot. Fig. 5.3 is a pedigree diagram showing the inheritance of haemophilia.

(i) State the genotypes of the people identified as P, Q and R in Fig. 5.3.
P ............................................................................................................................
Q ............................................................................................................................
R ............................................................................................................................

(ii) The couple S and T are expecting another child. What is the probability that the child will have haemophilia?
Space for working
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(iii) Define the term sex-linked characteristic.

The diagram shows the Galapagos iguana, Amblyrhynchus cristatus.


(a) (i) State two features that are used to classify animals, such as the Galapagos iguana, as reptiles.
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(ii) State two features that are present in plant cells that are not present in the cells of reptiles.
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(b) Galapagos iguanas feed on seaweed which contains starch and other carbohydrates.
(i) State the name of the enzyme that digests starch.
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(ii) State the names of two parts of the alimentary canal where starch is digested.
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(c) There are many threats to wildlife in the Galapagos.
Describe ways in which endangered species can be conserved.
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(d) One aim of conservation is to maintain resources in natural ecosystems.
State three resources that natural ecosystems provide for humans.
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