How do Organisms Reproduce?

How living things produce offspring: asexual methods, sexual reproduction in flowering plants and in humans, and why variation matters.

Key ideas

• Reproduction copies DNA; small copying changes create variation, which helps a species survive changes in its surroundings.
• Asexual methods: fission (Amoeba, Plasmodium), fragmentation (Spirogyra), regeneration (Planaria), budding (Hydra, yeast), spores (Rhizopus) and vegetative propagation.
• In a flower, the stamen (anther and filament) is the male part and the pistil (stigma, style and ovary) the female part.
• Pollination carries pollen to the stigma; fertilisation joins the male and female gametes to make a zygote.
• After fertilisation the ovule becomes the seed and the ovary becomes the fruit.
• In humans, the testes make sperm and the ovaries make eggs; fertilisation happens in the oviduct and the embryo grows in the uterus.

Remember

Watch out

• Mixing up pollination (pollen to stigma) and fertilisation (gametes joining).
• Saying asexual reproduction gives much variation (offspring are almost identical).
• Calling the anther a female part.

Worked example