South Tuen Mun Government Secondary School
MOCK EXERCISE
BIOLOGY PAPER 2
Secondary 6
Maximum mark : 40
Time allowed : 1 hour
INSTRUCTIONS
(1) There are FOUR sections, A, B, C and D in this Paper. Attempt ALL questions in any TWO sections.
(2) Write your answers in the single-lined sheets provided. Start each question (not part of a question) on a new page.
(3) Present your answers in paragraphs whenever appropriate.
(4) Illustrate your answers with diagrams whenever appropriate.
(5) The diagrams in this paper are NOT necessarily drawn to scale.
SECTION A Human Physiology: Regulation and Control
Answer ALL parts of the question.
1. (a) Patients with kidney failure can be treated by a method using the principle of dialysis. In this method,
the lining of the abdominal cavity – the peritoneum – is used as a dialysis membrane. The peritoneum is
supplied with numerous blood capillaries. The diagrams below outline the procedure of this method:
The table below shows the concentrations of certain substances in the dialysing fluid and in the plasma
of a patient suffering from kidney failure:
ConcentrationSodium ion (mEq L-1) / Glucose (mg/100mL) / Urea (mg/100mL)
Dialysing fluid / 133 / 105 / 0
Plasma / 142 / 100 / 200
(i) Referring to the table above, which of the substance(s) can be removed from the plasma of the patient during the treatment. (1 mark)
(ii) Explain how the substance(s) chosen in (i) can be removed from the plasma. (2 marks)
(iii) Explain why excess intake of salt may threaten the life of the patient even though he / she is treated normally by this dialysis method. (4 marks)
(iv) Apart from the treatment shown above, the principle of dialysis can also be used in kidney machine to treat a patient with kidney failure. The drawing below shows a patient undergoing treatment using kidney machine:
Suggest whether the treatment using periotoneum as a dialysis membrane or the treatment using kidney machine is more effective. Give a reason for your answer. (3 marks)
(b) In an experiment, a naked person was asked to stand still in a room. The temperature of the room was
adjusted but its relative humidity remained constant at 60%. The graphs below show the changes in the
mouth and skin temperatures of the person and the rate of blood flow in the skin under different room
temperatures.
(i) Explain why the skin temperature is always lower than the mouth temperature during the experiment. (2 marks)
(ii) Referring to graph I, describe the change in the mouth temperature with that in the room temperature. Explain the significance of this. (2 marks)
(iii) (1) Referring to graph II, explain the importance of the change in the rate of blood flow in the
skin when the temperature rises above 30℃. (3 marks)
(2) Describe the nervous control and physiological change occurring in the body that brings
about this change in the rate of blood flow. (3 marks)
SECTION B Applied Ecology
Answer ALL parts of the question.
2. (a) The following table shows the quantities of the major types of solid and semi-solid wastes disposed of in
Hong Kong in 1988 and their disposal methods:
Waste type / Quantity (tonnes per day) / Disposal methodDomestic waste / 4600 / Incineration (burnt to ashes); landfill
Animal waste / 2000 / Composting (left to decay); landfill; discharged into local water courses after treatment
(i) Explain TWO undesirable health problem related with the incineration of domestic waste.
(4 marks)
(ii) Some animal waste is discharged into local water courses after treatment.
(1) Suggest how animal waste is normally treated before discharged. (1 mark)
(2) Describe how this treatment can reduce pollution caused by the animal waste. (1 mark)
(3) However, this treatment may not necessarily exclude all harmful effect of the discharge. Describe and explain why the discharge can still lead to the death of aquatic fishes. (3 marks)
(iii) State TWO reasons to explain why composting animal waste is considered a sustainable measure to the society. (2 marks)
(b) The photograph below shows a kind of dolphin that can be found in the coastal areas of Hong Kong. The
dolphin is a protected endangered species.
(i) How can scientists identify a species as “endangered”? (2 marks)
(ii) Describe how TWO human activities might pose threats to the survival of dolphin in Hong Kong waters. Based on the two stated human activities, suggest ways to protect the species.(4 marks)
(iii) Why is it necessary to protect an endangered species like the dolphin? (3 marks)
SECTION C Microorganisms and Humans
Answer ALL parts of the question.
3. (a) Two flasks contained yeast cells growing in equal volumes of a sugar solution. Flask A received a
constant air supply whereas flask B did not have any air supply at all. The graph below shows the
changes in the number of yeast cells with time:
(i) Calculate the difference in the number of yeast cells at hour 20 between the two flasks. Give reasons to explain why there is such a difference. (5 marks)
(ii) There are many methods to measure the number of yeast cells. One method is to measure the optical density of a test tube containing the yeast culture.
(1) What is the principle behind this method? Suggest how the optical density is measured.
(2 marks)
(2) However, there is a disadvantage of this method as a measurement of yeast growth. What is it?
(1 mark)
(3) Describe another way to measure the number of yeast cells that the disadvantage can be overcome. (2 marks)
(iii) Yeast culture can be used to make into a commercial product sold in the supermarket. Suggest how this commercial product is useful to housewife and describe the biological principle behind the use. (3 marks)
(b) (i) Distinguish food borne disease and food poisoning. (2 marks)
(ii) Five Petri dishes with nutrient agar were sterilized and treated as follows:
Dish 1 Dirty fingers were pressed on the agar.
Dish 2 Fingers which had been washed thoroughly were pressed on the agar.
Dish 3 Some human hairs were placed on the agar.
Dish 4 A student coughed over the agar.
Dish 5 The dish was untreated.
The dishes were then incubated at 37℃.
(1) Which TWO dishes will show the least bacterial growth? Using the results obtained from the experiments, suggest THREE methods that could be used to prevent workers in a food factory from contaminating food. (4 marks)
(2) Suggest how the Petri dishes with nutrient agar could be sterilized. (1 mark)
SECTION D Biotechnology
Answer ALL parts of the question.
4. (a) Read the following passage and then answer the questions that follow.
(i) Suggest a reason why it is important that the implanted brain cells for treating Parkinson’s disease have to be capable of dividing rapidly. How can these active dividing cells help remove the symptom of Parkinson’s disease? (2 marks)
(ii) Suggest a possible reason why the use of embryonic tissue is not so efficient in treating patients whose condition is more serious. (2 marks)
(iii) (1) Based on your biological knowledge on the medical use of embryonic tissue, state TWO
limitations of applying this technique to treat Parkinson’s disease. (2 marks)
(2) Suggest ONE method to avoid these limitations. But what are the problems of this new
method? (3 marks)
(iv) Embryonic tissue can be used for “human reproductive cloning”. What is the meaning of “human reproductive cloning? Give TWO reasons why human reproductive cloning is banned in most countries. (3 marks)
(b) The major steps in the production of certain commercial products utilizing genetically engineered bacteria
are illustrated below:
(i) What is plasmid DNA? What is the function of plasmid DNA in the process described in the diagram? (2 marks)
(ii) List TWO features of bacteria that qualify them as ideal tools for genetic engineering technology.
(2 marks)
(iii) After the plasmid has been put into the new bacterial cell, the bacterial cell is described as “transformed”. Describe ONE method to identify the transformed bacterial cell. (2 marks)
(iv) How can the described steps in the diagram be modified to produce a genetically modified maize?
(2 marks)
END
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