2002 Biology Paper1

2002-CE BIO

HONG KONG EXAMINATIONS AUTHORITY

PAPER 1

HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 2002

BIOLOGY PAPER 1 8.30 am – 10.00 am (1½ hours) This paper must be answered in English

1.

Attempt THREE questions only.

2.

Each question consists of three parts.

3.

All questions carry equal marks.

4.

In each question, 2 additional marks will be awarded for effective communication.

5.

The diagrams in this paper are NOT necessarily drawn to scale.

香 港 考 試 局

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2002-CE-BIO 1–1

1. (a)

Some plants can be propagated vegetatively using tissue culture. In this method, the culture medium is sterilized before use and it provides essential materials for plant growth. The diagram below shows an outline of an investigation involving tissue culture. The whole process is conducted in the presence of light.

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(i)

Sugar is one of the essential components of the culture medium. Explain why sugar must be added. (3 marks)

(ii)

Compare the genetic make-up of the daughter plants with that of the parent plant. Give a reason for your answer. (2 marks)

(iii) After several weeks, plant B showed signs of yellowing while plant A remained green. Based on the information provided, suggest an explanation for the yellowing of plant B. (3 marks) (iv) Give two advantages of this method of plant propagation over the propagation using seeds. (2 marks)

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1. (b)

The diagram below shows the human skeleton and two muscles of the right arm, M and N :

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(i)

(ii)

Deficiency of vitamin D in childhood will lead to deformity of bones. (1)

Using the letters in the diagram, indicate which part of the skeleton is most easily deformed. Explain your choice. (3 marks)

(2)

Apart from diet, suggest another way by which the body gets vitamin D. (1 mark)

Why are muscles M and N described as an antagonistic (opposing) pair ? (1 mark)

(iii) Draw a diagram to show the lever system involved in lifting the right forearm. Indicate the positions of the load, the effort and the fulcrum in your diagram. In lifting the right forearm, what will form the load, the effort and the fulcrum respectively ? (5 marks)

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1. (c)

In a study, a healthy person and a person with diabetes mellitus fasted for 12 hours. They then stayed at rest in the same room and drank equal volumes of glucose solutions of the same concentration. Their blood glucose levels were measured immediately afterwards and at 30-minute intervals for three hours. The results are shown in the graph below :

(i)

What is the increase in the blood glucose level after 1 hour in (1)

(ii)

the healthy person,

(2)

the diabetic person ?

(2 marks)

Explain why the healthy person had a smaller increase in blood glucose level in the first hour when compared with the diabetic person. (4 marks)

(iii) During the study, a larger volume of urine was produced by the diabetic person than the healthy person. Suggest an explanation for this. (4 marks) 2002-CE-BIO 1–6 −5− 保留版權 All Rights Reserved 2002

2. (a)

The following photograph shows a female condom while the diagram on the right shows the human female reproductive system :

(i)

The female condom is placed in A during sexual intercourse. How does the female condom contribute to contraception ? (2 marks)

(ii)

Give an example of an infectious disease that can be prevented by wearing the condom. (1 mark)

(iii) Another contraceptive method is to tie and cut both the oviducts. State whether or not menstruation will still occur in a young woman who has received this operation. Explain your answer with reference to the physiological processes involved. (4 marks) (iv) The following is a simplified diagram of a cell which is undergoing cell division to form an ovum. (Only two pairs of homologous chromosomes are shown in the diagram.)

Based on the above diagram, make a drawing of the ovum formed showing the chromosomes contained inside. (3 marks) 2002-CE-BIO 1–7 −6− 保留版權 All Rights Reserved 2002

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2. (b)

The photomicrographs below show part of the transverse section of the leaf blade of a terrestrial dicotyledonous plant and that of a moss :

T.S. of the leaf blade of the dicotyledonous plant (magnification x100)

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(i)

(ii)

(1)

Name structure A.

(1 mark)

(2)

Explain one way in which A contributes to the function of cell B under bright sunlight. (2 marks)

The moss above is restricted to damp and shady environments and it is often covered with a thin film of water. (1)

With reference to the leaf structures shown in the two photomicrographs, suggest two reasons why the moss cannot grow well in dry environments. (4 marks)

(2)

Describe how the moss leaf obtains oxygen from the atmosphere at night. (3 marks)

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2. (c)

The following table shows the number of outbreaks of food poisoning due to different causative agents in Hong Kong in 2000 : Causative agent

Period

Bacteria

Agricultural chemicals

Biotoxins

January – March

80

2

11

April – June

97

7

11

July – September

189

10

17

October – December

93

37

6

Total

459

56

45

(i)

Which period had the greatest number of food poisoning outbreaks due to bacteria ? Suggest why the number of outbreaks was the greatest in this period. (3 marks)

(ii)

In some cases of bacterial food poisoning, the patient discharges a large amount of watery faeces. Explain why this condition may be fatal. (1 mark)

(iii) Another kind of food poisoning is caused by the consumption of shellfish (e.g. oysters, clams) which contain a high level of a harmful substance. This substance is actually produced in very small quantities by certain marine microscopic algae. (1)

With reference to the table above, into which type of causative agent would you classify this harmful substance ? (1 mark)

(2)

Explain why shellfish contain such a high level of this harmful substance. (3 marks)

(iv) The following is taken from a pamphlet on the guidelines for lunch box suppliers to Hong Kong schools : Advice for School Lunch Box Suppliers 1. Cook food thoroughly. 2. Keep hot foods at 63oC or higher and cold foods at 4oC or below. 3. Never leave lunch boxes at room temperature for longer than 2 hours. Explain why points 1 and 3 are crucial in ensuring that food in the lunch boxes is safe to eat. (2 marks) 2002-CE-BIO 1–10 −9− 保留版權 All Rights Reserved 2002

3. (a)

The diagram below shows a set-up used to study the water balance of a small plant. The whole set-up was put in a well-ventilated and wellilluminated room for 8 hours.

The initial and final readings in the measuring cylinder and the balance are tabulated below : Initial reading

Final reading Change in reading

Water level in the measuring cylinder (cm3)

45.0

43.5

x

Reading of the balance (g)

117.5

116.3

y

(i)

(1) Find values x and y. (2)

(1 mark)

With reference to the water balance of the plant, what do x and y represent respectively ? (2 marks)

(3) Compare values x and y. Explain the significance of their difference to the healthy growth of the plant. (3 marks) (Given : 1 cm3 of water weighs 1 g) (ii)

Predict, with reasons, the change in value x if the study is repeated with the leaves of the plant smeared with vaseline on both surfaces. (4 marks)

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3. (b)

In an ecosystem, there are various types of bats. One type of bats, A, is shown in photograph 1 below. When a sample of its faeces was examined, pieces of legs and wings of a certain group of animals were found as shown in photograph 2.

Photograph 1 (magnification x

1 ) 5

Photograph 2 (magnification x4) 2002-CE-BIO 1–12 −11− 保留版權 All Rights Reserved 2002

(i)

(ii)

(1)

To which group of vertebrates do bats belong ?

(1 mark)

(2)

Referring to photograph 1, state one external feature of bat A through which it is classified into the group you stated in (1). (1 mark)

With reference to photograph 2, suggest the group of animals that bat A feeds on. (1 mark)

(iii) The faeces of another type of bats, B, are found to contain some seeds. Suggest an explanation for the presence of intact seeds in the faeces of bat B. (2 marks) (iv) A third type of bats, C, feeds on the blood of large animals. Assuming that bats B and C have the same amount of daily food intake, compare the daily amount of faeces they produce. Explain your answer. (2 marks) (v)

Having different types of bats is advantageous to the survival of bats in an ecosystem. Suggest an explanation for this using the information about bats A, B and C given above. (2 marks)

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3. (c)

An inherited abnormality in humans is the occurrence of unusually short fingers. The photographs below show a hand with normal fingers and a hand with this abnormality :

The length of fingers is controlled by a pair of alleles. The allele for short fingers probably arose from a mutation of the allele for normal fingers. The following pedigree shows the inheritance of this abnormality in a family :

2

1

3 Key :

4

5

6

male with normal fingers

female with normal fingers

male with short fingers

female with short fingers

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(i)

(ii)

(1)

What is meant by mutation ?

(1 mark)

(2)

Explain how a mutation in a person may lead to a change in the metabolic activities of his cells. (2 marks)

Deduce which character, normal fingers or short fingers, is dominant. Explain your deduction. (5 marks) (Marks will not be awarded for genetic diagrams.)

(iii) Individual 6 is going to marry a female homozygous for normal fingers. Draw a genetic diagram to show the result of the cross. (Use F to stand for the dominant allele and f for the recessive allele.) (3 marks)

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4. (a)

Diagram 1 below shows the structure of the human ear and its connection to the brain. Electron micrographs X and Y show the surface view of the sensory hair cells at the same site in the ears of two persons as observed under the same magnification :

Diagram 1

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(i)

What will be the change in the loudness of the sound heard if structure A of a person is lost in an accident ? Give a reason for your answer. (2 marks)

(ii)

Using the letters in diagram 1, list all parts of the ear that are filled with liquid. (2 marks)

(iii) Electron micrograph X shows the sensory hair cells taken from part E of a normal ear. (1)

Name part E.

(1 mark)

(2)

Explain the role of the sensory hair cells there.

(2 marks)

(iv) Electron micrograph Y shows the sensory hair cells of a person who has been working at noisy construction sites for a long period of time. Suggest why his sensory hair cells are different from those shown in electron micrograph X. (2 marks) (v)

If the ear is normal but structure D is damaged completely at point P, how will hearing be affected ? Explain your answer. (3 marks)

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4. (b)

The graph below shows the changes in blood pressure and velocity of blood flow as the blood travels from the heart to the leg and returns to the heart :

(i)

Compare the blood pressure in the artery with that in the vein. Suggest two reasons for the difference. (3 marks)

(ii)

Explain the importance of the low velocity of blood flow in the capillary. (2 marks)

(iii) In the vein of the leg, the blood pressure is very low while the velocity of blood flow is quite high. Describe how such a high velocity of blood flow in the vein is maintained. (2 marks) (iv) Using the same x-axis given above, sketch a graph to show the change in the oxygen content of the blood as it passes through the blood vessels. (3 marks)

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4. (c)

A kind of Chinese dessert is made by mixing milk with ginger juice so that the milk becomes coagulated. The coagulation of milk is due to the conversion of a soluble milk protein into an insoluble form. To find out the conditions for milk coagulation, a person mixed milk at different temperatures with some fresh ginger juice. The mixtures were observed for 15 minutes to see if coagulation would occur. The results are shown in the table below :

Temperature of milk (oC)

Result

20

No sign of coagulation after 15 minutes

40

Fully coagulated in 14 minutes

60

Fully coagulated in 1 minute

80

Fully coagulated in 1 minute

100

No sign of coagulation after 15 minutes

Note : The same study was repeated using boiled ginger juice and the milk did not coagulate at any temperature.

(i)

Referring to the above results, describe the effect of milk temperature on the rate of milk coagulation by ginger juice. (3 marks)

(ii)

How would you explain the action of fresh ginger juice in bringing about the coagulation of milk ? Give evidence to support your answer. (2 marks)

(iii) Milk protein also coagulates at low pH. In which part of the alimentary canal does this coagulation occur ? Based on your biological knowledge, suggest why the coagulation of milk protein can facilitate its digestion in that part of the alimentary canal. (3 marks)

END OF PAPER

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