ce-biology-2000-paper i

8/10/2019 CE-Biology-2000-Paper I

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Hong Kong Examinations Authority

All Rights Reserved 2000

2000-CE-BIO 11

HONG KONG EXAMINATIONS AUTHORITY

HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 2000

BIOLOGY PAPER 1

8.30 am 10.00 am (1 hours)

This paper must be answered in English

1. Attempt THREEquestions 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 areNOTnecessarily drawn to scale.

2000-CE

BIO

PAPER 1


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2000-CE-BIO 12 1

1. (a) The diagram below outlines a clinical test used to examine whether a human

foetus has any abnormality in its chromosomes :



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2000-CE-BIO 13 2 Go on to the next page

(i) The cells of A and the cells of the foetus have the same genetic

composition. How would you explain this ? (2 marks)

(ii) (1) With reference to the chromosomes in the diagram, state the sex

of the foetus. (1 mark)

(2) Describe how the sex of this foetus is determined at the time of

fertilization. (3 marks)

(iii) What abnormality is found in the chromosomes of the foetus ?

(1 mark)

(iv) As the uterine wall may be stimulated to contract when removing cells

from A, what would be the risk associated with this test ? (1 mark)

(v) State two differences between the blood entering the foetus and that

leaving the foetus. (2 marks)



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2000-CE-BIO 14 3

1. (b) The diagram below shows part of a section of a leaf :

(i) Name tissues A and B. (2 marks)

(ii) Regions 1 and 2 have the same area. Work out the ratio of the densityof chloroplasts in region 1 to that in region 2. (2 marks)

(iii) With reference to your answer to (ii), what would be the significance

of this pattern of chloroplast distribution in the leaf ? Explain your

answer. (4 marks)

(iv) It is suggested that cell type C is responsible for the transport of water

from the stem to the leaf. Design an investigation to test this ideausing a leafy shoot. (4 marks)



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1. (c) The diagram below shows the structure of an air sac of the human lung. The

tidal air refers to the air that can be breathed in and out of the body in eachbreath. The residual air refers to the air that cannot be exchanged with the

atmosphere during breathing.

(i) Describe how oxygen in the tidal air reaches the blood. (3 marks)

(ii) (1) If a person breathes deeply, how will the volume of tidal air

inhaled be affected ? (1 mark)

(2) Based on your answer to (1), explain the effect of deep breathing

on the rate of oxygen uptake in the blood. (2 marks)

(iii) Explain oneeffect of smoking on the process described in (i).

(2 marks)



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2000-CE-BIO 16 5

2. (a) In order to lose weight, an 18-year-old girl, Jane, had a diet as shown in the

table below :

Energy

(kJ)

Protein

(g)

Fat

(g)

Carbo-

hydrate

(g)

Calcium

(mg)

Iron

(mg)

Vitamin

C

(mg)

Vitamin

D

(g)

Bread 900 8 1 44 80 2.3 0 0

Jam 300 0 0 20 5 0.4 3 0

Breakfast

Coffee 400 3 2 20 90 0 0 0

Hamsandwich

1050 16 13 15 12 2.5 0 0

L

unch

Coffee 400 3 2 20 90 0 0 0

Fish 540 20 5 0 300 2.7 0 8.0

Rice 3000 12 2 174 8 1.0 0 0

Dinner

Lettuce 30 1 0 1 23 1.0 15 0

Total intake per day 63 25 294 608 9.9 18 8.0

Average daily requirement 58 * * 600 15 30 2.5

* Amount variable

(i) If the average daily energy requirement for Jane is about 9200 kJ,

explain why this diet will be effective in helping her to lose weight.

(3 marks)

(ii) Protein in the diet can be absorbed into the body as amino acids.

Explain how amino acids can provide energy for Janes daily activity.

(3 marks)

(iii) If Jane continues this diet for several months, what disease will she

probably develop as a result of mineral deficiency ? (1 mark)

(iv) Describe a food test to show that fat is present in ham. (3 marks)



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2. (b) An investigation was carried out to study the effect of light on the pupil of

the eye. A person sat in a room in which the light intensity could be varied.The size of the pupil of the person was measured at different light

intensities. The graph below shows the results of the investigation :

(i) Referring to the graph, describe the effect of light intensity on the sizeof the pupil. (2 marks)

(ii) Explain the significance of the change in pupil size in response to an

increase in light intensity. (2 marks)

(iii) The pupil response to light intensity is a reflex action coordinated by

the brain. By means of a flowchart, show the nervous pathway

involved.

(Hint: This nervous pathway is similar to that of a spinal reflex arc.)

(3 marks)

(iv) People have different eye colours, such as brown, blue or green, but

their pupils always appear to be black. Explain why the pupil alwaysappears to be black. (2 marks)



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2000-CE-BIO 18 7

2. (c) The diagram below shows a section of a pea flower :

(i) Under natural conditions, pea flowers are self-pollinated, i.e. the

stigma receives pollen grains from the same flower.Suggest one advantage and one disadvantage of this method of

pollination. (2 marks)

(ii) In a genetic experiment, a scientist wanted to ensure that the stigma of

a pea flower only received the pollen grains of another pea flower.

Suggest how the scientist could achieve this by making use of a plastic

bag and a brush. (3 marks)



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(iii) The colour of the pea pod (fruit) is controlled by a pair of alleles. The

scientist first crossed a pea plant homozygous for green pods withanother pea plant homozygous for yellow pods to produce the first

filial generation (F1). She then allowed the F1plants to self-pollinate

to produce the second filial generation (F2). The results of the crossesare summarized in the table below :

Result of the first cross All F1plants produced green pods

Result of the second cross428 F2plants produced green pods

152 F2plants produced yellow pods

(1) What can you conclude from the result of the first cross ?(1 mark)

(2) Use a genetic diagram to show how the pod colours of the F2plants were inherited from the F1plants. (5 marks)



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2000-CE-BIO 110 9

3. (a) The photomicrograph below shows some muscle cells of the human small

intestine and their associated blood vessels :

(i) (1) What type of blood vessel is A ? (1 mark)

(2) Based on the photomicrograph, state onefeature of A to support

your answer to (1). (1 mark)

(ii) The muscle cells in the photomicrograph are surrounded by a fluid.

Explain how this fluid is formed from the blood in blood vessel A.

(2 marks)

(iii) Draw a labelled diagram to show what you would see in the crosssection made along line BC. (3 marks)

(iv) By means of a flowchart, show the route by which a red blood cellfrom the small intestine reaches the lung. Indicate the major bloodvessels and organs involved. (3 marks)



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3. (b) Diabetes mellitus is a disease found in humans and other mammals. The

main symptom of this disease is the presence of glucose in the urine. In theearly twentieth century, the cause of diabetes mellitus was still unknown. In

order to study this disease, a scientist performed the following experiments

on dogs :

ExperimentExperimental

subjectTreatment Result

1 Healthy dogs Removing the pancreasSymptoms of

diabetes appeared

2 Diabetic dogsfrom experiment 1 Injecting extracts ofpancreas

Symptoms of

diabetesdisappeared

(a) Injecting extracts

of pancreas which

had been treated

with protease

Symptoms of

diabetes remained

3Diabetic dogs

from experiment 1 (b) Injecting extractsof pancreas which

had been treated

with lipase

Symptoms ofdiabetes disappeared

(i) Comparing the results of experiments 1 and 2, what conclusion can be

drawn ? (2 marks)

(ii) What is the aim of performing experiment 3 ? (2 marks)

(iii) Based on the results of experiments 2 and 3 (a), explain whether the

diabetic dogs would show symptoms of the disease if they were

treated with the extracts of pancreas by feeding instead of by injection.

(3 marks)

(iv) Based on your biological knowledge, explain why the urine of a

diabetic person usually contains glucose. (5 marks)



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2000-CE-BIO 112 11

3. (c) To study the effect of sucrose solution on plant cells, a student used the

lower epidermis of aRhoeo discolor leaf, the cells of which contain a redpigment. He mounted a piece of the lower epidermis in a sucrose solution.

He then observed the epidermis under the microscope immediately and after

10 minutes.

The photomicrographs below show the conditions of the same epidermal

cells under the low power of the microscope :

(i) Describe and explain the change in the appearance of cell A

10 minutes after mounting. (4 marks)

(ii) Suggest a reason why cell B did not show the same change as cell A.

(1 mark)

(iii) The student wanted to examine cell A under the high power of the

microscope.

(1) State oneaction that he might need to take before turning to the

high power objective. (1 mark)

(2) State twoactions that he might need to take after turning to the

high power objective. (2 marks)



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4. (a) In the production of beer, the raw material used is barley grains, which

contain a large amount of starch. When barley grains germinate, amylase isproduced. The grains are then crushed and mixed with warm water. After

several hours, yeast is added to the mixture for fermentation.

(i) What is the action of amylase on the starch in the barley grains ?

(1 mark)

(ii) After the crushed grains are mixed with warm water, why is itnecessary to wait for several hours before adding the yeast ? (1 mark)

An investigation was carried out to study the effect of temperature on the

activity of barley amylase. For each temperature, the same amount of

crushed grains and water were used. The amylase activity was estimated bythe rate of disappearance of starch using the iodine test. The results

obtained are shown in the graph below :

(iii) What conclusions can be drawn from the graph about the effect of

temperature on amylase activity ? (3 marks)

(iv) If you want to store the mixture of crushed grains and water with

minimal reaction so that it can be used several days later, what

temperature would you choose ? Why ? (3 marks)

(v) Suggest another method to estimate the amylase activity for this

investigation. (2 marks)

0

12

3

4

5

6

7

8

9

10

0 10 20 30 40 50 60 70 80 90

Temperature (C)

Amylase activity

(arbitrary unit)



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2000-CE-BIO 114 13

4. (b) To monitor the quality of seawater in Hong Kong, water samples were taken

for analysis from four different sites A, B, C and D as shown in the mapbelow :



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The quantities of suspended solids and bacteria in each water sample are as

follows :

SiteSuspended solids

(mg L1)

Bacteria

(number per 100 mL)

A 8.3 105

B 6.0 1986

C 5.5 23 140

D 2.5 15

(i) (1) Explain how the concentration of suspended solids may affect

the population of producers in seawater. (3 marks)

(2) Hence, predict which site has the largest population of producers.

(1 mark)

(ii) In Hong Kong, domestic sewage is the main source of organicpollutants in seawater.

(1) Explain how the bacterial population in seawater may be affectedby the amount of organic pollutants present. (3 marks)

(2) Deduce which site would contain the greatest amount of organic

pollutants. (1 mark)

(3) Suggest onereason for the presence of a large amount of organic

pollutants at this site. (1 mark)

(iii) Certain regions of Hong Kong waters have been designated as marineparks. What is the significance of this for conservation ? (1 mark)



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2000-CE-BIO 116 15

4. (c) The table below shows the rates of water loss in different ways from a

persons body under two conditions :

Rate of water loss (mL h1)Condition

Sweat Urine Exhaled air

At rest 4 58 15

During heavy exercise 208 21 27

(i) Compare the rate of sweat production of the person under the two

conditions. Explain why there was such a difference. (3 marks)

(ii) Account for the decrease in the rate of urine production of the person

during heavy exercise. (3 marks)

(iii) (1) Explain how exhalation may lead to water loss from the body.(2 marks)

(2) Why did the rate of water loss through exhalation increase during

heavy exercise ? (2 marks)

END OF PAPER


ce-biology-2000-paper i

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