Answer:
A. These homologous structures indicate that these four organisms all share a common ancestor.
Explanation:
Homologous structures mean the organs will have similar structure, but not necessarily function (human arm vs whale's flipper). While analogous structures are similar in function but not structure (wings of an airplane vs wings of a bird). Since the question states that they are similar in skeletal structure, we know they must be homologous structures, thereby eliminating B and C. D is not a choice because the question does not provide anything about the order of evolution. Therefore the answer is A. These homologous structures indicate that these four organisms all share a common ancestor.
The given statement is False.
The bacterial cells walls are composed of peptidoglycan, also known as murein. It comprises polysaccharide chains cross-linked by unusual peptides, involving D-amino acids. The bacterial cell walls are distinct from cell walls of fungi and plants that are made up of chitin and cellulose, respectively.
The cell walls in bacteria allow small molecules to pass through them freely, however, do not permit large molecules to pass through them, in this manner, it function as a coarse filter.
The main function of the cells wall is to sustain the shape of the cell and inhibit the cell from bursting due to osmotic pressure. The cell wall allows the components to pass, which are essential for bacterial nutrition.
Melanin provides pigmentation to the skin and it also provides UV ray protection (which is its role in the epidermis).
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