Sexual reproduction
Exam-ready definition
A process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other.
How this is marked
Examiners pay for 'fusion of nuclei of two gametes' and for the genetic variation it produces. A common error is writing 'fusion of two gametes' without 'nuclei', or forgetting that gametes are haploid so the zygote is diploid. The variation point is what links this to survival in changing environments and is often the explain mark in Paper 4.
In an exam answer
Defining the term: 'Sexual reproduction involves the fusion of the nuclei of two haploid gametes to form a diploid zygote, producing offspring that show genetic variation.'
Full topic guide: Reproduction
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