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 correct answer would be “All of the Above”
Answer:
Use the drawing tools to form the correct answer on the graph.
Graph the line that represents this equation:
Explanation:
It is believed that this happens because some signals that regulate development are the same between different species and because <span>they share ancient genes. </span>These ancient genes are expressed during a middle "phylotypic stage" of embryonic development for all species.
For example, human and animal embryos go through very similar stages of early development and share similar features such as tails and gill-like structures. The major difference appears to be how long it takes to reach each of these same stages.
