How does meiosis contribute to sexual reproduction?

Meiosis contributes to sexual reproduction by producing genetically diverse haploid cells needed for fertilisation.

Meiosis is a type of cell division that results in four daughter cells, each with half the number of chromosomes of the parent cell. This process is crucial for sexual reproduction as it produces the sex cells, or gametes (sperm in males and eggs in females), which are haploid. Haploid cells contain only one set of chromosomes, as opposed to the diploid cells in the rest of the body, which contain two sets.

The key feature of meiosis that contributes to sexual reproduction is the genetic diversity it introduces. This is achieved through two mechanisms: crossing over and independent assortment. During the first division of meiosis, homologous chromosomes pair up and exchange segments of DNA in a process known as crossing over. This results in new combinations of genes, increasing genetic diversity. In the second division, these chromosomes are randomly distributed to the daughter cells, a process known as independent assortment. This further increases the genetic diversity of the offspring.

The haploid cells produced by meiosis are crucial for the process of fertilisation. When a sperm and an egg cell combine during fertilisation, their haploid sets of chromosomes merge to form a new, unique diploid organism. This combination of genetic material from two parents results in offspring that are genetically distinct from both parents and from each other.

In summary, meiosis contributes to sexual reproduction by producing the haploid cells necessary for fertilisation and introducing genetic diversity. This diversity is a key factor in evolution, as it provides a wide range of genetic variations on which natural selection can act.