Mitochondrial DNA can be traced for generations. It is because of the fact that unlike nuclear DNA, mitochondrial DNA rarely gets mutated. The frequency of mutations in the mitochondrial DNA is approximately one every 3,500 years per nucleotide. That is why mitochondrial DNA of a person is almost similar to his/her direct maternal ancestor. So, it can be used to match lineages amongst people.
White Blood cells or WBC's are the cells of your immune system. They are your first defense in fighting off foreign invaders and infectious diseases.
-Medical Student (College Level)
Answer:
Here are the answers:
a. 4 Cell determination as an issue in the *rest is missing*
b. 4 They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned.
c. 4 I and III only
Explanation:
The passage demonstrates the importance of two factors in the development of an embryo: cleavage planes of division of embryonic cells and cell differentiation.
Cleavage Planes:
Cleavage basically refers to the division of the zygote into a large number of cells called blastomeres. Cleavage planes are geometrical lines or orientations along which cleavage takes place. Since, all embryonic cells are the precursors of some type of body cells, the cleavage planes determine if the cells are adequate for growth and development.
Cell Differentiation:
Cell differentiation is the transition of an undifferentiated cell into a specialized one. For example, stem cells are undifferentiated cells that develop into progenitor cells that mature into a specific cell lineage. For an embryo to regenerate, the presence of adequate embryonic stem cells is crucial. Embryonic stem cells are present in abundance before the gastrulation phase of embryonic development, after which they rapidly start differentiating.
The process by which oxygen is taken to the lungs is called Inhalation or Inspiration.
