ReproductionEdexcel IGCSE Biology: Flashcards

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What is fertilisation?

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What is fertilisation?: The fusion of a male gamete and a female gamete to produce a zygote.
What is the key difference between sexual and asexual reproduction?: Sexual reproduction fuses gametes from two parents, producing genetically different offspring; asexual reproduction involves one parent and produces genetically identical offspring.
Give two examples of natural and artificial asexual reproduction in plants.: Natural: runners; artificial: cuttings.
Name two features of an insect-pollinated flower.: Large, brightly coloured, often scented petals, and nectar to attract insects (also sticky pollen and an enclosed sticky stigma).
Name two features of a wind-pollinated flower.: Small, dull petals with no scent, and anthers/feathery stigma hanging outside the flower to catch or release pollen easily.
What does a pollen tube do?: Grows from a pollen grain down through the style to the ovary, allowing the male gamete to reach and fertilise the female gamete in the ovule.
What three conditions are needed for seed germination?: Water, oxygen and a suitable temperature.
How does a germinating seedling get energy before it can photosynthesise?: It uses stored food reserves (such as starch) within the seed, released through respiration.
What is the role of FSH in the menstrual cycle?: It stimulates an egg to mature in the ovary and stimulates the ovary to produce oestrogen.
What is the role of oestrogen in the menstrual cycle?: It repairs and thickens the uterus lining and stimulates the release of LH.
What does LH trigger?: Ovulation — the release of an egg from the ovary.
What is the role of progesterone?: It maintains the thickened uterus lining, ready for a fertilised egg to implant.
What is the function of the placenta?: It allows nutrients, oxygen and waste to be exchanged between the mother's blood and the embryo's blood without the two blood supplies mixing.
What is the function of amniotic fluid?: It surrounds and protects the developing embryo/fetus in the uterus.
Which hormones cause secondary sexual characteristics at puberty?: Oestrogen (in females) and testosterone (in males).