Reproduction in Animals

Syllabus tag: KCSE | Biology | Form 3 | Topic 3 Reproduction

Lesson objectives

By the end of this topic, you should be able to:

• Distinguish external from internal fertilisation and state their advantages.
• Describe the structure of the human reproductive systems.
• Explain gametogenesis, the menstrual cycle and fertilisation.
• Describe pregnancy, the placenta, birth and the role of hormones.

Summary

Animals reproduce sexually, fusing a sperm and an ovum to form a zygote. Fertilisation may be external, in water, or internal, within the female body. Internal fertilisation needs far fewer gametes because far fewer are wasted. In humans the menstrual cycle prepares the uterus each month, and if fertilisation occurs the embryo implants and is nourished through the placenta.