Gametes and fertilisationSpec B14.2.3
In short
Fertilisation is the fusion of the nuclei of a sperm and an egg cell; sperm are adapted by a flagellum, mitochondria and enzymes, eggs by energy stores.
In humans, fertilisation is the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell). The fertilised egg is called a zygote.
Quick check
Which part of the male reproductive system carries sperm from the testes to the urethra?
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The sperm duct.
Name the part of the female system where the fetus develops.
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The uterus.
What happens at fertilisation?
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The nucleus of a sperm fuses with the nucleus of an egg cell.
Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026