Sexual ReproductionCambridge IGCSE Biology: Flashcards
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Define sexual reproduction.
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- Define sexual reproduction.
- A process involving the fusion of the nuclei of two gametes to form a zygote, producing offspring that are genetically different from each other.
- What is fertilisation?
- The fusion of the nuclei of two gametes.
- Are gametes haploid or diploid?
- Haploid — they contain a single set of chromosomes.
- Is a zygote haploid or diploid?
- Diploid — it contains two sets of chromosomes, formed by fusion of two haploid gametes.
- Define pollination.
- The transfer of pollen grains from an anther to a stigma.
- Distinguish self-pollination from cross-pollination.
- Self-pollination transfers pollen to a stigma on the same plant; cross-pollination transfers pollen to a stigma on a different plant of the same species.
- Give two features of an insect-pollinated flower.
- Large, brightly coloured, scented petals and sticky or spiky pollen grains (also nectar).
- Give two features of a wind-pollinated flower.
- Small, dull petals, feathery stigmas hanging outside the flower, and small, light, smooth pollen produced in huge numbers.
- What three conditions are needed for seed germination?
- Water, oxygen and a suitable temperature.
- What is the function of the testes?
- To produce sperm and testosterone.
- What is the function of the oviduct?
- To carry the egg towards the uterus; it is usually the site of fertilisation.
- Name two adaptive features of a sperm cell.
- A flagellum for swimming and many mitochondria to provide energy (also enzymes in the acrosome).
- Name two adaptive features of an egg cell.
- Energy stores for the embryo and a jelly coat that changes after fertilisation to prevent entry of further sperm.
- What is the function of the placenta?
- To allow the exchange of dissolved nutrients, gases and excretory products between the blood of the mother and the fetus.
- Which hormones control the menstrual cycle?
- FSH, LH, oestrogen and progesterone.