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WAHuman BiologyQuick questions
Unit 4: Human Variation and Evolution
Quick questions on Sources of human variation: WACE Year 12 Human Biology Unit 4
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is mutation?Show answer
A mutation is a permanent change in the DNA base sequence. Mutations are the ultimate source of all new alleles and therefore all new genetic variation. They occur randomly and can be caused or increased by mutagens such as radiation and certain chemicals.
What is meiosis?Show answer
Meiosis is the cell division that makes gametes and it introduces variation in two ways.
What is random fertilisation?Show answer
Fertilisation combines one gamete from each parent at random. Because each parent can produce an enormous number of genetically different gametes, and any sperm can fertilise any egg, the number of possible offspring genotypes is vast. This multiplies the variation generated by meiosis.
What is the environment as a source of variation?Show answer
Not all variation is genetic. The environment affects how genes are expressed. Diet affects height and body mass, exposure to ultraviolet light affects skin colour, and exercise affects muscle development. Identical twins have the same DNA but can differ because of environmental influences.
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