HONG KONG EXAMINATIONS AUTHORITY HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 1998

BIOLOGY PAPER I 1.Attempt THREE questions only 2.Each question consists of three parts. 3.All questions carrry equal marks . 4.In each question, 2 additional marks will be awarded for effective communecation. 5.The diagrams in this paper are NOT necessarity draw to scale. 1. (a) In a marine museum, living marine animals are kept in different exhibition areas according to their animals group. Some of the animals in the museum are shown in the diagrams below:

(i) Using the letters provided, state all the animal(s) that should be placed in the exhibition area for reptiles. (1 mark) (ii) B and E are kept in the same exhibition area. Name the animal group to which they belong. (1 mark) (iii) State two structure differences between A and C which explain why that of C. Suggest an explanation for this. (2 marks) (iv) The amount of daily food intake unit mass of A is much greater than that of C. Suggest an explanation for this. (4 marks) (v) The population of F in Nature has decreased continuously in recent years. Suggest two ways of preventing the extinction of F. (2 marks) 1. (b) Two similar pieces of dialysis tubing were set up as shown in the following diagrams. The concentrations of the sucrose solution and the glucose solution were the same.

The height of the solution column in each capillary tube was measured and recorded in the table below.

Height of solution column in the capillary tube Time (min) Set-up A(mm) Set-up B(mm)

0 0 0 10 103 25 20 170 40 30 200 45 40 205 46 50 205 44 60 205 41

(i) Present the results in the form of a graph. (4 marks) (ii) Explain the change in the solution level in the capillary tube of set-up A during 0-20 minutes. (3 marks) (iii) Explain the difference in the rate of change of solution levels between set-ups A and B during 0-20 minutes. (3 marks) 1. (c) In humans, there are different causes for the disease diabetes is a hereditary disease. Whether a person has this type of diabetes or not is controlled by a pair of alleles. The pedigree below shows the inheritance of this type of diabetes in a family:

(i) Deduce, with reasons, whether the allele for this type of diabetes is dominant or recessive. (Marks will not be awarded for genetic diagrams.) (5 marks) (ii) State the possible genotype(s) of individual 5. Define the symbols you use.

(3 marks) (iii) Give two suggestions to a diabetic person in order for him to maintain a normal blood glucose level. (2 marks) 2. (a) The photomicrographs below show the transverse of a leaf and a young root of the same plant:

(i) State one function that is common to cell type A and cell type F. (1 mark) (ii) With reference to the photomicrographs, explain how each of the following cell types is structurally adapted to its specific function: (1) cell type A (3 marks) (2) cell type F (3 marks) (iii) Using the letters provided, construct a flowchart to outline the route of transport of organic food from the site of production in the leaf to the site of storage in the root. (2 marks) (iv) Draw a labeled diagram to shown the possible appearance of a cell of G when a section of the root is mounted in a concentrated salt solution. (3 marks) 2. (b) Hepatitis B is a disease of the liver caused by a virus. There members of a family, P, Q and R, took a blood test to find out if they are immune to this disease. The results of the blood test are shown in the table below: P Q R Hepatitis B antigen in the blood Absent Absent Present

Level of antibody against hepatitis B in the blood (unit per dm3)

0 297 0

(i) (1) P was advised to have a hepatitis B vaccination. Explain how P could become immune against the disease after vaccination. (4 marks)

(2)Would this vaccination allow P to become immune to other types of hepatitis? Why? (2 marks) (ii) Both Q and R have not received any hepatitis B vaccination before. Suggest a reason to explain the difference in their blood test results. (2 marks) (iii) Hepatitis b is transmitted through contact with the body fluid of an infected person. Apart from vaccination, suggest two measures that can prevent the transmission of this disease. (2 marks) 2. (c) The diagram below shows part of the human skeleton:

(i) Joints A, B, C and D can be classified into two types according to their freedom of movement. Name these two types of joints. Classify A, B, C and D into these two types.(4 marks) (ii) State how the vertebrae help to maintain the upright posture of a person. (2 marks) (iii) Osteoporosis is a condition in which the bone material of a person decrease and the bones become more porous and lighter than normal. It is more common in old people. Suggest, with a reason, one way in which people could reduce the chance of getting osteoporosis. (2 marks) 3. (a) The diagram below shows part of the circulatory system and its neighbouring

cells:

(i) P is in the form of a highly branched network. Explain the importance of this feature to the function of P. (4 marks) (ii) Describe how fluid B is formed from fluid A. (3 marks) (iii) (1) Substances in fluid C will eventually reach the heart. Which chamber of the heart first receives these substances? (1 mark) (2) Describe how the continuous flow of fluid C towards the heart is maintained. (2 marks) 3. (b) The diagrams below show some of the steps carried out by a farmer in the reproduction of a certain species of plant:

(i) What is the purpose of (1) removing the anthers. (1 mark) (2) covering the flower with a plastic bag? (1 mark) (ii) Describe the events that lead to the formation of the Zygote after pollen grains are brushed onto the stigma. (3 marks)

(iii) Suggest the advantage of employing the shown in the above diagrams for reproducing the plant. (2 marks) (iv) This species of plant is usually reproduced by means of its stem tubers. Give two reasons to explain why farmers prefer to grow the plant from its tubers. (4 marks) 3. (c) The diagram below shows a set-up used to measure the rate of respiration of a rat at 30 ℃:

A rat was first put onto the bell jar and the weight of flask A was measured. Air was then pumped through the set-up for 30 minutes and the weight of flask A was measured again: Then the drying agent and the solutions in all three flasks were renewed. The procedures were repeated without the rat in the bell jar. The weights of flask A were recorded as shown in the below: Set-up Initial weight of flask A (g) Final weight of flask A (g) Experimental (with rat) 211.8 211.8 Control (without rat) 206.7 206.1 (i) Write a word equation for aerobic respiration. (1 mark) (ii) What is the use of the potassium hydroxide solution in flask A? (1 mark) (iii) (1) The decrease in weight of flask A in the control set-up is due to the evaporation of water from the potassium hydroxide solution. Using this information, explain the result in the experimental set-up. (3 marks) (2) Calculate the rate of respiration of the rat. (2 marks) (iv) Suggest two precautions that have to be taken if the set-up is used to measure the rate of respiration of a potted plant. (2 marks) 4 (a) The diagram below shows a boy, Bill, sitting for an examination in the school hall. Before the examination started, Bill took off his glasses and relaxed.

(i) Bill looked at the clock on the wall. It was 9:00 a.m. Draw the image of the two hands of the clock formed on the retina of his eye. (1 mark) (ii) Describe how the image on the retina generates vision in the brain. (4 marks) (iii) After looking at the clock, Bill turned to his watch to check the time. Describe the changes that occurred in his eyes when he tried to focus on his watch. (3 marks) (iv) Through Bill could clearly see the clock, he could not see his watch clearly without putting on his glasses. Draw a ray diagram to show how his eye defect is corrected by his glasses. (3 marks) 4. (b) In some parts of China, farms cut and burn trees, and build terraces for farming on hill slopes as shown in the photograph below:

(i) Explain why the removal of trees may lead to serious soil erosion. (2 marks)

(ii) A scientist suggested that the harmers should grow some leguminous plants along the edge of the field. At the end of the year, the fruits of these plants were harvested. The leaves and roots were ploughed into the field. (1) State two uses of the fruits. (2 marks) (2) Explain how the soil fertility can be increased by growing leguminous plants and returning their leaves and roots into the field. (4 marks) (iii) The scientist pointed out that the yield of the crop would decrease if the farmers grew the same type of crop in the same field over the years even though they adopted the above suggestion. Give two reasons to explain why the yield would decrease. (4 marks) 4. (c) Four test tubes containing equal volumes of coagulated egg white cubes were set up. Different solutions were then added to the test and they were allowed to stand at 30℃. The table below shows the solutions added to the test tubes and the results observed after 24 hours.

Tube 1 2 3 4 Hydrochloric acid 2 cm3 - 2 cm3 -

Solution A 2 cm3 2 cm3 - - Solutions

added Distilled water - 2 cm3 2 cm3 4 cm3

Result after 24 hours × ˇ ˇ ˇ Key : ˇ= egg white cube present

×=egg white cube absent (i) (1) What can be deduced from the results of tubes 1 and 3? (1 mark) (2) What can be further deduced if the result of tube 2 is also taken into

consideration? (1 mark) (ii) How would you confirm that the results obtained are due to the action of an

enzyme in solution A? (3 marks) (iii) A digestive juice from the human body contains an enzyme which will produce

the same result as solution A. (1) Name this digestive juice. (1 mark) (2) Apart from digestion, state another function of this digestive juice. (1 mark) (iv) 2 cm3 of juice sodium hydroxide solution and a few drops of copper sulphate solution are added to 5 cm3of solution A. What can be observed ? Explain your answer. (2 marks)