Reproduction Marking Scheme

This is the marking scheme for quiz: B16 - Reproduction Quiz
Topic Guide: B16 - Reproduction

Total: 32 marks

Q1 [1 mark]

Answer: B. Two gamete nuclei fuse to form a diploid zygote.

Q2 [1 mark]

Answer: B. Transfer of pollen from anther to stigma.

Q3 [1 mark]

Answer: A. Water, oxygen, and a suitable temperature.

Q4 [1 mark]

Answer: B. LH.

Q5 [1 mark]

Answer: C. HIV is an STI-causing virus that may lead to AIDS.

Q6 [3 marks]

  • Pollination is the transfer of pollen from anther to stigma. (1)
  • Fertilisation is the fusion of a male nucleus in pollen with the female nucleus in an ovule. (1)
  • Fertilisation in a flowering plant occurs in an ovule, inside the ovary. (1)

Accept “fusion of gamete nuclei” for fertilisation. Do not award the first mark for describing fertilisation as pollen transfer.

Q7 [3 marks]

  • Anther produces pollen grains containing male nuclei. (1)
  • Stigma receives pollen and allows it to stick or germinate. (1)
  • Ovary contains ovules. (1)

Q8 [2 marks]

  • If fertilisation does not occur, oestrogen and progesterone levels fall (1), the uterus lining breaks down, and menstruation occurs. (1)

Q9 [3 marks]

  • Flagellum propels the sperm towards the egg. (1)
  • Mitochondria release energy for movement of the flagellum. (1)
  • Acrosome contains enzymes that help the sperm penetrate the egg cell’s jelly coat. (1)

Q10 [3 marks]

  • FSH from the pituitary gland stimulates an ovarian follicle to develop and produce oestrogen. (1)
  • A rise in LH from the pituitary gland causes ovulation. (1)
  • LH also causes the post-ovulation follicle to develop into a structure that produces progesterone. (1)

Q11 [8 marks]

Asexual reproduction:

  • involves one parent and no fusion of gamete nuclei. (1)
  • produces genetically identical offspring. (1)
  • advantage: it is rapid, requires no mate, or preserves successful features; context must be clear. (1)
  • disadvantage: low genetic variation means offspring may all be affected by the same disease or environmental change. (1)

Sexual reproduction:

  • involves fusion of nuclei from gametes, usually from two parents. (1)
  • produces genetically different offspring. (1)
  • advantage: variation may allow some offspring to survive environmental change or disease. (1)
  • disadvantage: it requires a mate, takes more time/energy, or may produce less suitable offspring. (1)

Accept a clearly explained crop-production example, such as uniform asexual crops being easy to grow but vulnerable to one disease, or sexual variation producing useful but inconsistent crop features.

Q12 [3 marks]

Placenta and umbilical cord:

  • The placenta allows oxygen, glucose, amino acids, and other useful substances to pass from maternal blood to fetal blood. (1)
  • Carbon dioxide and urea pass from fetal blood to maternal blood for removal. (1)
  • The umbilical cord connects fetus to placenta and contains blood vessels transporting substances between them. (1)

Q13 [2 marks]

HIV transmission control: award one mark for each correctly described method, up to two:

  • use condoms or avoid sexual contact with an infected person;
  • test, trace, and treat infections;
  • screen donated blood;
  • use sterile needles and never share needles; or
  • use medical care to reduce transmission from an infected mother to her child.