Sexual and Asexual Reproduction. GCSE Science Biology

Refer to these timings to cover:

1. Reproduction 0:08
2. Sexual Reproduction 0:33
3. Asexual Reproduction 3:21

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1. Introduction 0:08
Reproduction is when species produce their own kind. These newly made smaller species are called offspring. Reproduction is done in order to pass the genetic material to the next generation. Therefore, due to reproduction, the genetic information of a species are conserved.

2. Sexual Reproduction 0:33
Sexual reproduction involves two parents. Sperm from the male and egg from the female fuse together in a process known as fertilisation and so the offspring has a genetic combination of both parents. Both, sperm and egg provide 23 chromosomes and so the fertilised egg, which is called zygote, end up with 46 chromosomes (23 pairs of chromosomes). This zygote grows into an embryo by cell division (mitosis), then into a foetus and finally into a baby.

This child will have a combination of both parents as the child's DNA are equally given by both parents. This increases variation which is an advantage. Increasing variation allows the organism to adapt to the changing environment and so such species have higher chance of survival. Hence increasing variation increases the chance of survival so therefore less likely to become extinct.

3. Asexual Reproduction 3:21
Sexual reproduction involves only one parent and so the offspring will look identical to its parent. These offspring are called CLONES and clones contain identical genes (this is the reason why they look alike). Fertilisation doesn't happen and therefore these species do not produce sex cells which are sperm and egg cells.

Bacteria and few plants are good example of species which undergo asexual reproduction. In asexual reproduction, the cells undergo cell division called MITOSIS, which is also involved in growth and repair of damaged tissue.

DISADVANTAGE of asexual reproduction. There is no genetic variation in asexual reproduction as the offspring are clones. So these offspring cannot adapt to the changing environment therefore the population of such species can decrease and eventually become EXTINCT.

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Licensed under Creative Commons: By Attribution 3.0

Licensed under Creative Commons: By Attribution 3.0

[angusflint]

Finding your videos really helpful thanks

[josephehab]

If you could add more details about sexual reproduction such as the sex organs in both male and female, the menstrual cycle and it's hormones and maybe even puberty. Thanks.