AP BIOLOGY

Detailed explanation-1: -There is a point during early embryonic development, called the “phylotypic stage”, when all animals with backbone, also known as vertebrates, resemble one another. At this stage, a chicken embryo looks almost indistinguishable from a rabbit or a human at a similar stage.

Detailed explanation-2: -So why do these embryos look so much alike? The basic design of all these animals is more similar than you might think. Since all vertebrates (animals with backbones) evolved from a common ancestor, the genetic information that guides their development is nearly the same.

Detailed explanation-3: -An embryo is an unborn (or unhatched) animal or human young in its earliest phases. Embryos of many different kinds of animals: mammals, birds, reptiles, fish, etc. look very similar and it is often difficult to tell them apart. Many traits of one type of animal appear in the embryo of another type of animal.

Detailed explanation-4: -Vertebrates during the early stages of embryonic development are all quite similar due to common ancestry. The genes that direct embryonic development are the same among vertebrates.

Detailed explanation-5: -The early stages of embryonic development, such as fertilization, cleavage, blastula formation, gastrulation, and neurulation, are crucial for ensuring the fitness of the organism. Fertilization is the process in which gametes (an egg and sperm) fuse to form a zygote.