Quick Answer. Collagen is the protein that all animals have in common, even single-celled animals and creatures such as sponges that lack differentiated bodies. Collagen is a cable-like protein that can calcify into bone, shell or other hard structures.
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A is the ans for this question
Answer:
The correct answer is the endocrine system.
Explanation:
The sympathetic division of the autonomic nervous system and the endocrine system are the two prime systems that take part in the stress response.
At the time of acute or chronic stress, the endocrine system first makes the hypothalamus to discharge CRH or corticotropin-releasing hormone into the bloodstream. The release of CRH further makes the anterior pituitary to discharge ACTH or adrenocorticotropic hormone into the blood. This further stimulates the adrenal cortex to discharge cortisol, that is, one of the glucocorticoid hormone into the bloodstream.
The cortisol finally makes the organs and tissues present within the body to effectively cope up with the initial stress stimulus.
Answer:
The option 'All cells contain a nucleus' is not a part of the cell theory.
Explanation:
The cell theory proposed by scientists illustrates that every organism whether prokaryotic or eukaryotic is made up of a cell or different kinds of cells. It also that explains that cells are made from living things. According to the cell theory, cells are termed as the basic unit of life, without which life is not possible.
The cell theory does not claim that every cell must have a nucleus because many cells like cells of prokaryotes lack nucleus. Their genetic material is dispersed in the cytoplasm.