Transcription: Sexual reproduction happens when two organisms get together, they're male and female usually, and a male sperm fertilizes a female egg. This creates a new organism, a baby. This new organism, let's call it Trevor, has got half its father's chromosomes and half its mother's. Chromosomes contain your genes, remember. So Trevor has twice the number of genes that he actually needs. So what happens in Trevor then? Well, he's got two copies of every gene, but he'll use only one of them. The dominant gene. The other gene, the recessive one, doesn't appear. Although Trevor still has it, and he'll be a ...
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