Fertilisation
Fertilisation is the joining of a sperm (male sex cell) and an ovum (female sex cell). It usually happens in the oviduct. The joined cell is called a zygote. This single cell then divides again and again to form a growing ball of cells.
Key idea
sperm + ovum → (fertilisation) → zygote → grows into a foetus in the uterus
Pregnancy
Pregnancy is the time when a baby grows and develops inside the mother's uterus. The zygote moves from the oviduct to the uterus and settles into the thick lining. As it grows, it becomes a foetus. Human pregnancy lasts about 9 months (around 40 weeks).
Feeding the growing baby
Inside the uterus, the foetus is joined to the mother by the umbilical cord and the placenta. Through these, the foetus gets oxygen and food from the mother's blood, and passes waste back for the mother to remove.
Example
Nutrients and oxygen from the mother's blood cross the placenta, travel along the umbilical cord, and reach the foetus. Carbon dioxide and waste travel back the same way.
Remember
- Fertilisation = sperm + ovum joining, usually in the oviduct.
- The joined cell is the zygote; it grows into a foetus.
- Human pregnancy lasts about 9 months; the placenta and umbilical cord feed the foetus.