Answer:
Explanation:
Natural selection is based on Darwin’s observation that individuals most likely to survive and reproduce are those with traits best suited to their current environment.
Once an egg is fertilized by a sperm, a zygote is formed. The zygote divides into multiple cells in a process known as cleavage, triggering the beginning of embryonic differentiation. ... Cells in these three layers will give rise to different parts of the organism. The endoderm eventually becomes the gut.Mar 3, 2011