ALBIOLOGYPAPER1+2.docx

1、ALBIOLOGYPAPER1+22000 BiologyPaper 1ASection AAnswer ALL questions.Answers should he written in the AL(C)l Answer Book.Begin your answer to each question (not the sub-part of a question) on a separate page in the answer book.1. Name two organelles that are found abundantly in mammalian liver cells.

2、Relate their abundance to the functions of the liver cells.(4 marks)Cell Biology2. The following flow charts show the stages of gamete formation in flowering plants and mammals. State the type of nuclear division involved in each of the processes (a), (b), (c) and (d).(2 marks) Flowering plants Mamm

3、als microspore mother cell (2n) germ cell (2n)(c)(a) microspore (pollen grain) spermatogonium(d)(b) male gamete spermReproduction3. Photomicrographs P, Q and R on the opposite page show a structure at different developmental stages observed in a mammalian organ. They are not arranged according to th

4、e sequence of development of this structure.(a) Show the correct sequence of development of the structure by listing the letters of the photomicrographs. (1 mark)(b) The normal development of the structure can be artificially interrupted. Suggest one way to bring about this interruption and explain

5、the mechanism involved. (4 marks)(c) Name the structure in P and state its function.(2 marks)Photomicrograph P (40) Photomicrograph Q (75)Photomicrograph R (120)Growth4. Which of the following graphs represents the growth pattern of a rice plant? Explain your answer. (2.5 marks)Growth5. The key belo

6、w can be used to identify the echinoderm species illustrated on the opposite page.1a Possess a stalk, sessile Cenocrinus asterias1b Lack a stalk, not sessile 22a No arms 62b Arms present 33a Arms sharply marked off from the central disc 43b Arms not sharply marked off from the central disc 54a Five

7、pairs of shields on central disc Ophiothrix fragilis4b Central disc without shields Ophiarachna incrassata5a Long arms with relatively small central disc Archaster typicus5b Short arms with relatively large central disc Rosaster alexandri6a Cushion-shaped, with many spines 76b Elongated in shape, wi

8、thout spines Thyonella gemmata7a Long, fine, and sharp spines Lytechinus variegatus7b Thick and pen-shaped spines Heterocentrus mammilatus(a) Using this key, identify the echinoderms D, F and H shown on the opposite page. In each case state the key sequence you would go through in making the identif

9、ication. (3 marks)(b) State the scientific name of species A and the genus name of species B.(2 marks)(c) Where do you expect to find the locomotory organs of D?(1 mark) Classification6. Yeast produces an extracellular invertase to break down sucrose into glucose and fructose. Design an experiment t

10、o show the presence of extracellular invertase activities in a yeast culture and state two appropriate controls.(7 marks)Enzymes7. Mammals living in deserts are found to have a well-developed posterior lobe of the pituitary. Explain how this feature enables such mammals to adapt for survival in dese

11、rts(4 marks)Hormones8. The following photomicrograph was taken under a light microscope showing the larval stage of a marine crab:(a) Make a 2 whole specimen drawing to show the features of the larva.(5 marks)(N.B. You are NOT required to label the features or give a title to your drawing)(b) On you

12、r drawing, use an arrow / arrows to point to the appendage(s) that you think is / are locomotory in function.(0.5 mark)(c) Give two ways in which this larval stage is significant to the marine crab.(2 marks)GrowthPaper 1B1Answer ALL questions.There are two questions in this Question-Answer book. The

13、y do not carry equal marks.Put your answer in the spaces provided.9. (a) Figure 1 shows a standard curve obtained by using a colorimetric method for determining the concentration of protein solutions.In an experiment to study the effect of heat treatment on the digestibility of a protein substrate a

14、nd the effect of raw bean extract (taken from bean X) on protease activity, various reaction mixtures were prepared and were incubated for 30 minutes. The protein concentration of each reaction mixture at the beginning and at the end of the incubation period was determined by the colorimetric method

15、. Intensities of colour developed are shown in Table 1.Table 1Incubation period / minColour intensity of the reaction mixtures / arbitrary unitHeated protein substrate + proteaseUnheated protein substrate + proteaseUnheated protein substrate + raw bean extract + protease010101030479(N.B. The protein

16、 content of the raw bean extract added is negligible.)(i) Use the curve shown in Figure 1 to determine(1) the protein concentration of the reaction mixtures at the beginning of the incubation period(0.5 mark)(2) the protein concentration of the following reaction mixtures after digestion by the prot

17、ease for 30 minutes:mixture with the heated protein substrate mixture with the unheated protein substrate (1 mark)(ii) Which is more digestible by the protease, the heated or the unheated substrate? Justify your choice by interpreting the experimental data. (1.5 marks)(iii) Based on the structure of

18、 protein molecules, account for the effect of heat treatment on the digestibility of this protein substrate.(3 marks)(iv) What is the effect of the raw bean extract on protease activity?(0.5 mark)(b) In another experiment, die nutritive value of beans was studied. Rats were fed with diets partly rep

19、laced with either raw bean flour or heated bean flour. The average initial body mass of the rats was 80 g per rat. After 30 days, the average body masses of the rats were recorded. The total dietary protein intake of the rats during die experiment was determined. The results are shown in Table 2.Tab

20、le 2DietTotal dietary protein intake per rat / gAverage body mass per rat / gA. Control diet40.0295B. Diet partly replaced with raw bean flour36.2253C. Diet partly replaced with heated bean flour39.5328(N.B. The protein contents of die three diets were die same. The bean flour used was obtained from

21、 bean X.)(i) The nutritive value of a protein diet can be measured by its protein efficiency ratio (PER). PER is defined as die gain in body mass of the tested animal per gram dietary protein intake. Calculate the PER of the following diets and complete Table 3.Table 3DietPERA. Control diet5.38B. Di

22、et partly replaced with raw bean flourC. Diet partly replaced with heated bean flour(2 marks)(ii) Based on die above PER values, which diet is most nutritive? (1.5 mark)(iii) Compare and account for die difference in nutritive value between the following diets.(1) diets A and B (1.5 marks)(2) diets

23、B and C (2.5 marks)Total: 13 marksEnzymes10. A diploid plant species is capable of both self and cross pollination. Two purebred varieties, Y and Z, of this plant species were identified. Individuals of variety Y have heights ranging from 21-25 cm. They all have round leaves and are resistant to the

24、 herbicide glyphosate. Individuals of variety Z have heights ranging from 56-60 cm. They all have wrinkled leaves and are sensitive to the herbicide glyphosate. When Y was crossed with z, all F1 progeny had round leaves and were glyphosate resistant. Their height distribution is shown in Table 1.Tab

25、le 1Height / cmNumber of plants26-30231-351036-405441-455146-50851-553When the F1 plants were self-pollinated, the F2 progeny had the following phenotypes:Table 2Height / cmNumber of plantsRound leaf andResistant to glyphosateWrinkled leafandResistant to glyphosateRound leafandSensitive to g1yphosat

26、eWrinkled leafandSensitive to glyphosate21-251510526-3088222831-35114433536-40152554841-45152564746-50116443651-5586232756-6013004Sub-total7362323230(a) Are the alleles responsible for wrinkled leaves and glyphosate resistance dominant or recessive? Briefly explain your answer (3 marks)(b) How many

27、genes control the glyphosate response? Explain your answer with reference to the data shown in Table 2. (4 marks)(c) (i) Discuss whether the inheritance of leaf shape and glyphosate response follows Mendels Law of Independent Assortment.(4.5 marks)(ii) What is the relationship between the genes cont

28、rolling leaf shape and glyphosate response?(1 mark)(d) Based on the data shown in Tables I and 2, state and explain the nature of genetic control of height in this plant species.(4 marks)GeneticsAnswer ALL questions.There are two questions in this Question-Answer book. They do not carry equal marks.

29、Put your answers in the spaces provided.11. An experiment was conducted to investigate the effect of plant extract E on the plasma glucose level of normal rats.(a) Two groups of normal rats were fasted (not given any food) overnight. After fasting, E was administered to one group. Then both groups o

30、f rats were given the same oral dose of glucose solution. Figure 1 shows their plasma glucose levels at various time intervalsFigure 1(i) What is the importance of fasting the rats overnight before the administration of E? (2 marks)(ii) In this experiment, plasma has to be prepared from the blood sa

31、mple after collection as soon as possible, otherwise a change of plasma glucose level would result. Why would there be such a change?(1 mark)(iii) Account for the rise and subsequent fall in plasma glucose level in the control rats.(4.5 marks)(iv) State the effect of E on plasma glucose level Suggest two possible ways in which E might have produced this effect. (2.5 marks)(b) In order to study how E produces its effect, a further