For evolution to occur:
There must be genetic variation in a population. This provides variation on which natural selection can act. Then natural selection can act by selecting those species which are better adapted to the environmental conditions. Over time those animals that are best suited to the environment only will survive and reproduce. Those organisms successful genes will be preserved and eventually the gene frequency in the population will change, changing the overall characteristics of a population. This is how evolution occurs.
no because Separation of oxygenated and deoxygenated blood in the heart of three types of animals. The three-chambered frog heart mixes oxygenated and deoxygenated blood in the ventricle. Therefore, the body never receives fully oxygen-rich blood.
Answer:
1. sperm cell
2.testicles
3.egg
4.ovary
5.fertilization
6.fertilized egg = foetus
Explanation:
not all but most of them do