Why does the body cells of all organisms that reproduce sexually have even numbers of chromosomes?

Answer 1

An animal must have an even amount of chromosomes because, every trait has to have a pair. All chromosomes have to have an even number of chromosomes, otherwise the organisms would not be correctly formed.

Answer 2

If you take humans (or any mammal or bird or reptile) as a simple example - one gamete fuses with another - a sperm cell fuses with an ovum. That is one gamete + another gamete gives two gametes. 1 + 1 = 2. This is the joining of two haploid cells, giving the diploid chromosome-complement and this is doublethe haploid complement. Any double mathematically is an even number. In humans, 23 individual chromosome types and this is how it is per gamete. Restore the diploid number of 46 via fertilisation and this 46 is an even number. Chimpanzees have 24 as the haploid number and 48 as the diploid number. This is also an even number.

Thus it is the behaviour of fertilisation, doubling the amount of genetic material in the final zygote by fusing two haploid (genetically halved) cells that results in the final diploid number always being even.

Answer 3

Most humans have an even number of chromosomes because they receive an equal amount (23 chromosomes) from both parents. 23 + 23 = 46

Most animals have an even number of chromosomes for the same reason, but some - like mules - have an odd number of chromosomes. This is because the mule receives 31 chromosomes from its donkey parent, and 32 from its horse parent.

Answer 4

In the cells of most organisms that reproduce sexually, chromosomes occur in pairs: One chromosome is inherited from the female parent, and one is inherited from the male parent.

Answer 5

chromosomes come in pairs, one in each pair is from the mother and the other from the father.