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Define sexual reproduction
A process involving the fusion of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other
Define fertilisation
The fusion of gamete nuclei
Diploid
Somatic cells (normal body cells) the chromosomes are present in the nucleus in pairs
Humans have 46 chromosomes (23 pairs)- this is known as the diploid number
During fertilisation (when the nuclei of each sex cell fuse) a zygote is formed.
It gains the chromosomes from both gametes, so it is a diploid cell
Nucleus of a zygote is diploid
Haploid
When gametes are formed, the number of chromosomes in the nucleus of each sex cell is halved
This is the haploid number
Advantages of Sexual Reproduction
Variation in the offspring, adaptation to a changing or new environment is likely, enabling survival
New varieties can be created which may have resistance to disease
In plants, seeds are produced, which allow dispersal from the parent plant, reducing competition
Disadvantages of sexual reproduction
Two parents usually needed (not always, some plants can elf pollinate)
Growth of new plant to maturity from a seed is slow
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