That it would keep the animal safe
The best answer to the question above would be letter d. The sentence presented which is 'Researchers helped further the biological perspective when they demonstrated that electrical stimulation of the brain could evoke emotional responses in animals.' demonstrates how new discoveries can influence perspectives.
Answer: c
Explanation: Plants and animals need nitrogen to make proteins but they cannot take it in from the air. Because nitrogen is unreactive as a gas, it has to be transformed into a new molecule. When bacteria in the soil takes nitrogen from the air, it becomes nitrates. Finally, it can move through the food chain in this form.
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.
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It is the answer
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