3A Reproduction

Time: 55 minutes

Total marks available: 55

Total marks achieved:

Q1.

Plants and animals can reproduce asexually and sexually.

(a) Give an example of a way that plants can reproduce asexually.

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(b) Complete the table showing features of sexual reproduction in plants and animals.

(1)

(3)

(c) Suggest why the number and size of human male gametes differs from the number and size of human female gametes.

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(2)

(Total for question = 6 marks)

Q2.

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

B

C

D

(b) The diagram shows a fertilised egg dividing into an embryo.

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(i) What is another name used to describe a fertilised egg?

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(ii) Name the type of cell division used to produce the embryo.

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(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.

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(3)

(Total for question = 9 marks)

Q3.

(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.

(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.

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(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.

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(1)

(1)

(Total for question = 8 marks)

Q4.

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.

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)

Q5.

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.

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

was below 37.0 °C?

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(ii) On which day was an egg probably released from her ovary?

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(iii) Suggest how the woman could accurately determine her body temperature.

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(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.

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(ii) Name hormone B.

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(iii) How do these hormones travel from the ovary to the uterus?

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(iv) Give two female secondary sexual characteristics.

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(2)

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(Total for question = 9 marks)

Q6.

The diagram shows part of a lily. A lily is an insect-pollinated flower.

(a) Name the structures labelled A and B.(2)

A ....................................................................................................................................................................................................B ....................................................................................................................................................................................................

(b) Describe what is meant by the term insect-pollination.

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(c) Give two ways in which the structure of a wind-pollinated flower would differ from the lily flower shown in the diagram.

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(d) Describe the events that follow pollination and how they lead to seed formation.

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(6)

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(Total for question = 12 marks)

Q7.

The diagram shows the apparatus used in a seed germination experiment.

(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.

(1)

(ii) Give a biological explanation for the difference in the temperature of flask A compared to flask B.

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(b) The seeds in both flasks were washed in disinfectant before being put into the flasks.

Suggest why this was done.

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(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.

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(d) The seeds used in the experiment were from the same species.

Suggest one other variable that needs to be controlled in this experiment.

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(2)

(1)

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(1)

(Total for question = 6 marks)

Q1.

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.

Q2.

(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.

Q3.

In (a), candidates were required to place stages of human reproduction in order 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.

Q4.

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.

Q5.

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 almost70% gaining two marks.

Q6.

This question showed a diagram of a lily flower. In part a) almost all candidates could label the stigma and the anther. In part b) many candidates earned two marks for correctly describing insect-pollination as the transfer of pollen by an insect from the anther to the stigma. In part c) most could give two structural differences between the flower shown and a wind-pollinated flower. Some failed to earn marks by giving other differences such as scent, nectar or amount of pollen produced. In part c) the best candidates were able to describe the events from pollination toseed formation. This seemed to vary between centres. Some candidates had no knowledge of the growth of the pollen tube and how fertilisation occursin flowering plants. Others confused germination of the pollen grain with germination of a seed.

Q7.

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.

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