Following fertilization, the single-celled zygote undergoes cleavage, where it is then divided into numerous tiny cells. After 3 to 4 days of fertilization, the cleavage produces a 16 celled embryonic stage known as morula, which is contained within the zona pellucida.
After about 4-5 days of fertilization, cleavage produces a sphere mass of cells known as blastomeres, which is covered by a layer known as trophoblast and has a fluid-filled cavity in the center, known as blastocoel. The blastomeres then migrate inward, changing position and undergoing rearrangements. This is known as gastrulation.
Gastrulation then causes the development of three germ layers: ectoderma, endoderma, and mesoderma. The interaction of cells and the rearrangement of tissues and organs occurs only after the formation of germ layers.
It is known that all living things are either the eukarya, bacteria, or the archaea. These three broadest categories in the classification of life are called domains. These also known by the "Three Domain System." The correct answer is A.
The correct answer in the question above is the second statement. The reviewers can determine the experiment’s validity. That is why a <span>chemistry journal requires that all new research papers be peer reviewed by other scientists before they are published.</span>
The messages of the endocrine system are moved around the body by the blood stream into the brain which, then electrical impulses are sent to the heart and other essential organs and/or muscles.