ZIMSEC O Level Combined Science Notes: Reproduction in Humans
- Human being produce sexually
- The process involves the fusion (joining) of the nuclei (sex cells) of the male gamete (sperm)
- and the female gamete (ovum)
- To form a zygote
- The human and female sexual organs take part in this process
- Each of these have adapted in a way that ensures that fertilization takes place
- Both male and female bodies become sexually mature during the puberty period
- The bodies undergo changes in appearance and behavior
- They start to produce mature sex cells
- Sex cells are also known as gametes
- Sex hormones are released to continue this sexual development
Puberty
- Is a time when a girl or boy starts to become sexually mature
- It usually happens between ages 10 and 14 for girls and ages 12 and 16 for boys
- It causes various changes in the physical and emotion in the maturing child:
- In boys:
- Pubic hair starts to grow around sexual organs and under armpits
- Voice deepens
- Facial hair starts to grow
- Sexual organs grow
- Mood swings
- Acne (pimples may appear on skin)
- Adam’s apple may grow
- Sexual feelings and wet dreams
- May become muscular
- Possible body odours
- In girls:
- Breast development
- Pubic hair grows
- Uterus and follicles grow bigger
- Menustration begins
- Possible body odour
- Possible Acne
NB The onset of puberty differs from person to person.
To access more topics go to the Combined Science Notes page