I would select A because cells have to divide into smaller cells depending on where they are.
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.
Answer:
Derived trait
Explanation:
An ancestral (or primitive) trait/character is a feature inherited from the common ancestor of the species/group of interest, while derived traits are those that were absent in the last common ancestor of the group of interest. For example, considering mammals as the target group, the presence of hair is a shared derived trait relative to other vertebrates, i.e., amphibians, reptiles, and birds. However, this trait (hair) is ancestral for humans since the genetically closest species to humans (e.g., chimpanzees) also have hair.
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