Name: Reproduction. Plant and Human. Date: Time: 1 hour 5 minutes. Total marks available: 65. Total marks achieved:

Transcription

1 Name: Reproduction Plant and Human Date: Time: 1 hour 5 minutes Total marks available: 65 Total marks achieved:

2 Q1. The diagram shows the female reproductive system. (a) Put a cross in the correct box to show (i) where the egg is released A B C D (ii) where the egg is fertilised A B C D (iii) where the embryo becomes surrounded by amniotic fluid A

3 B C D (b) The diagram shows a fertilised egg dividing into an embryo. (i) What is another name used to describe a fertilised egg?... (ii) Name the type of cell division used to produce the embryo.... (iii) Complete the table by ticking the box that shows the correct description of each cell in the embryo. (c) Describe how the developing embryo is supplied with nutrients.

4 (3) (Total for question = 9 marks) Q2. (a) There are several different stages during the process of human reproduction. Some of these stages are shown in the box. Complete the table by writing the name of the stages in each empty box to show the correct order in which they occur. (4)

5 (b) The diagram shows a section through the heart of a fetus. The arrows show the direction of blood flow. Describe two differences, shown in the diagram, between the heart of a fetus and an adult heart. (2)

6 ... (c) The sex chromosomes in the cells of a mother are XX. The sex chromosomes in the cells of a father are XY. (i) Use this information to give the sex chromosomes in the cells of their male fetus.... (ii) Give the number of chromosomes in a body cell of the male fetus.... (Total for question = 8 marks) Q3. The diagrams show the female and male reproductive systems. The table lists some events that take place in the female reproductive system, some that take place in the male reproductive system, and some that take place in both.

7 Complete the table by giving the letter, or letters, to indicate where each event takes place. The first one has been done for you. (5) (Total for question = 5 marks) Q4. The use of a pesticide may result in an increase in the number of pest organisms that are resistant to the pesticide. Use your knowledge of natural selection to explain the increase in the number of pest organisms that are resistant to the pesticide. (5)......

8 (Total for question = 5 marks) Q5. Plants and animals can reproduce asexually and sexually.

9 (a) Give an example of a way that plants can reproduce asexually (b) Complete the table showing features of sexual reproduction in plants and animals. (3) (c) Suggest why the number and size of human male gametes differs from the number and size of human female gametes. (2) (Total for question = 6 marks)

10 Q6. The peacock is a bird found in the jungle in India. The male has a large, colourful tail that he displays during courtship to attract a female to mate with. Use your knowledge of natural selection to suggest how the peacock's tail has evolved. (5)

11 (Total for question = 5 marks) Q7. For a woman to become pregnant, a sperm must fertilise one of her eggs. At the time the egg is released, the body temperature rises slightly. A woman wanted to become pregnant. She measured her body temperature each day for 28 days, starting on the first day of her menstrual cycle. The chart she kept is shown below.

12 (a) (i) What was the total number of days that the body temperature of the woman

13 was below 37.0 C?... (ii) On which day was an egg probably released from her ovary?... (iii) Suggest how the woman could accurately determine her body temperature. (2) (b) During the 28 days the ovary of the woman released two different hormones, A and B. The table shows some of the roles of these hormones. (i) Name hormone A.... (ii) Name hormone B.... (iii) How do these hormones travel from the ovary to the uterus?

14 ... (iv) Give two female secondary sexual characteristics. (2) (Total for question = 9 marks) Q8. The diagram shows the apparatus used in a seed germination experiment.

15 (a) The two samples of seeds started at the same temperature of 18 C. The diagram shows the temperature reading on each thermometer after 48 hours. (i) Complete the table to show the temperature of flask A and flask B.

16 (ii) Give a biological explanation for the difference in the temperature of flask A compared to flask B. (2) (b) The seeds in both flasks were washed in disinfectant before being put into the flasks. Suggest why this was done (c) The cotton wool kept the thermometers in place and prevented the seeds from falling out of the flasks. Suggest why cotton wool was used rather than a rubber bung....

17 ... (d) The seeds used in the experiment were from the same species. Suggest one other variable that needs to be controlled in this experiment.... (Total for question = 6 marks) Q9. Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow.

18 (a) Explain what is meant by the term gene (line 3).

19 (2) (b) Suggest what is meant by the term superovulate (line 2) (c) In which part of the surrogate mother are the embryos implanted (lines 6 to 7)?... (d) Name the human behaviour that can lead to emphysema (line 11).... (e) What percentage of eggs produced by Tracy were known to contain transgenic DNA (lines 13 to 14)? (f ) (i) To be able to work, the blood clotting factors must be extracted from the milk.

20 Suggest why drinking milk containing blood clotting factors will not help to clot blood (line 17) (ii) Suggest why it is an advantage to increase the ability of cattle to digest cellulose (line 22). (2) (g) Suggest the benefits of producing transgenic hearts. (3)

21 ... (Total for question = 12 marks) Q1. (a) (i) The correct answer of B was seen on many scripts with A being the most common incorrect response. (ii) The correct answer of A was seen on many scripts with C being the most common incorrect response. (iii) The correct answer of C was seen on many scripts with A being the most common incorrect response. (b) (i) Zygote was the correct answer and was seen on many scripts. Common incorrect answers were embryo and fetus. There were also weak answers that simply described the process of fertilisation. (ii) Mitosis was the correct answer and was seen on many scripts. The term meiosis was the most common incorrect term seen. Candidates need to be careful when spelling biological terms as the examiners are not allowed to credit words spelt incorrectly, for example, meitosis. (iii) This question was surprisingly challenging for students. The correct answer required a tick in the box beside 'diploid with 46 chromosomes'. This was in evidence, but many candidates ticked this box and one other, or ticked a wrong box. This suggests that the terms haploid and diploid are not understood or that candidates cannot recall the number of chromosomes in a body cell. (c) Many candidates were aware that diffusion of nutrients from the mother's blood takes place at the placenta. Further credit was given for a valid description of how the structure of the placenta is adapted to its function. Credit was also given if the umbilical cord was mentioned. The question discriminated very well with the better answers giving excellent descriptions and the weaker answers expressing confusion, often making general references to human reproduction. Q2. In (a), candidates were required to place stages of human reproduction in order

22 and most responses were correct. Candidates then had to identify the differences between a diagram of a fetal heart and an adult heart in (b). Most were able to identify the gap between the atria and the joining of the aorta and pulmonary artery. In (c), most could identify the gender and give the correct number of chromosomes. Q3. This question tested knowledge about the male and female reproductive systems. Correct responses were common but it was clear that some students wrongly think that the testes release oestrogen, and that implantation and gamete formation occur in the oviduct. Q4. This question gave students the opportunity to write a longer prose answer explaining the development of pesticide resistance in a population. About half of the answers scored full marks and these answers included the idea of variation caused by a random gene mutation that allows a pest to survive. This variety would then reproduce and pass on its resistance allele to the next generation so that over time resistance would increase. Weaker students wrote about 'survival of the fittest' but gave no context or explained what that means in this case. Some wrote about immune response. Q5. This question was about reproduction in plants and humans. In (a), a large number of candidates could not give an example of how a plant reproduces asexually. Many described cuttings or even self-pollination. In (b) most could identify the male gamete in animals but many could not name the site of fertilisation in animals or in plants. Uterus and ovary were the most common answers. In part (c) the best candidates observed that human male gametes are much smaller and more numerous than female gametes and explain why. Q6. This also required a longer prose response on the evolution of the peacock's tail.

23 The best responses described how competition exists between male birds to attract a female to mate with. A genetic mutation that gave a larger or more attractive tail would therefore confer an advantage on those birds. These would reproduce more and the genotype would increase in frequency over many generations. Most candidates were able to gain some marks for their accounts. Q7. This question explored events in the body of a female linked to reproduction. The correct answer in part (a) (i) was 15 days but it was not uncommon to find the incorrect answer of 14 days. These candidates most probably failed to see the temperature of 36.9 on day 28 in the table. Days 14 or 15 were accepted in part (ii) and most gained candidates credit. A pleasing number understood the term 'accurately' in part (iii) and mentioned that a thermometer needed to be digital or clinical and that it needed to be placed in a part of the body that most closely reflected the true body temperature. In part (b) (i) and (ii), only the least able candidates failed to name oestrogen and progesterone correctly. Occasionally these hormones were listed in the wrong order, and sometimes FSH and LH were incorrectly named. A surprising number of candidates seem unaware that hormones travel in the blood to their target. As such, answers to part (iii) were disappointing. The examiners believe this might be another example of students not reading the question carefully because the term 'oviduct' was often chosen, presumably candidates thinking that the question was asking how the 'egg' travels from the ovary to the uterus. Candidates did very well in part (iv) with almost 70% gaining two marks. Q8. This question provided students with a diagram showing an experiment to investigate germination and energy release in seeds. In part (a) (i) almost all students correctly read the temperatures from the thermometer scales. In part (ii) about half of the responses could explain the results from the two flasks despite the fact that this experiment is referred to in the specification. In part (b) most could explain that washing the seeds in disinfectant prevents the growth of bacteria. However, in part (c) very few students could suggest why cotton wool is used rather than a rubber bung. Only the best students could suggest that it allows oxygen in and carbon dioxide to escape from the flask. In part (d) most response correctly gave a variable that should be controlled. Q9.

24 (a) The concept of a gene being a section of DNA that codes for a protein was known by the more able candidates. The idea that genes determine characteristics was also credited as an alternative to coding for a protein. Many answers simply discussed the fact that they are inherited or made loose references to chromosomes or nuclei. (b) The examiners were looking for answers that expressed the idea that superovulation would result in a greater quantity of eggs than normal. Many appreciated this and gained the mark. However, there were an abundance of answers that showed that the word 'super' was not understood and nor was the process of 'ovulation'. Poor answers simply reiterated information from the comprehension. (c) Most candidates recalled that the uterus is the place where embryos would implant in the surrogate mother, though a variety of other named female organs were named in the poorer answers. The non-technical term 'womb' was credited. (d) Most candidates were aware of the link between smoking and emphysema. Weaker answers showed no understanding of emphysema and tended to describe general aspects of human behaviour or make reference to AAT. (e) The correct answer of 50% was seen in most scripts. (f) (i) There were some very good answers that were able to make a link between what might happen in the gut of a person which would not assist the clotting of blood. The passage stated that 'human proteins could be made in other mammals and extracted from their milk' so the examiners were looking for a comment that made it clear that the blood clotting factors (protein) would not be able to enter the bloodstream because they would be digested. Many candidates got close to being credited by making it clear that the blood clotting factors would not be able to get into the blood but then failed to say why. Many candidates simply repeated the wording of the question stating that blood clotting factors have to be extracted before being used, and many simply noted that blood clotting factors are needed to clot blood. (ii) Candidates described the role of cellulose as roughage to help peristalsis in the gut. This suggests that candidates should be encouraged to read questions carefully. The question required an appreciation that cellulose is made from glucose which is used in respiration and could help to increase cattle growth or milk and meat production. A surprising number of candidates seem to think that cellulose has a role in immunity. (g) Many candidates appreciated that producing transgenic hearts would increase availability for transplantation which would save lives, and also that the transgenic hearts are less likely to be rejected by the host. This question discriminated well with the better candidates making reference to at least three of these points and the weaker candidates only referring to one or none.

25 Q1. Q2.

26 Q3.

27 Q4.

28 Q5. Q6.

29 Q7.

30 Q8.

31 Q9.

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