(a) Explain briefly how the structure of each of the following cells relate to their...
BIOLOGY
WAEC 2018
(a) Explain briefly how the structure of each of the following cells relate to their functions:
(i) Sperm cell
(ii) Palisade cell.
(b) Make a drawing, 8cm to -10cm long of the front view of the female reproductive system in humans and label fully.
(c) State two differences between reproduction in mammals and in amphibians.
(d) State two methods of birth control in humans.
Explanation
(a) Structure of the cell relating to its function
(i) Sperm cell
- Has a long/whip-like tail/flagellum, with which it swims to reach the egg/ovum of the female organism.
- Has a head with acrosome; for digesting/penetrating egg membrane
- Has a nucleus in its head; which fuses with the nucleus of the ovum/egg cell during fertilisation to form zygote
- Its middle piece contains mitochondria; for supply of energy/ATP.
(ii) Palisade cell
- Has thin wall; for easy penetration of light
- Has numerous chlorosplasts in peripheral cytoplasm for maximum absorption of sunlight
- Has large vacuole containing cell sap; for temporary stor-age of products of photosynthesis.
(b) Diagram of the front view of the female reproductive system
| Mammals | Amphibians |
| fertilisation is internal | fertilisation is external |
| Development of offspring is internal / viparous born young ones alive | development of offspring is external / oviparous/ lay eggs |
| placenta is present | placenta is absent |
| shows parental care | does not show parental care |
| produce fewer eggs / offspring | Produce numerous eggs/offspring |
(d) Methods of birth control in humans
- Abstinence
- Use of contraceptive pills/injection of hormonal drugs
- Coitus interruptus/withdrawal method
- Safe period/rhythm method
- Sterilization of men/vasectomy
- Sterilisation of women/tubal ligation
- Use of condoms/female condom/male condom
- Use of spermicide/foam
- Use of implant/Norplant
- Use of IUD/intra-uterine devices
- Use of diaphragm.
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