The group of lipids that represents the general structure of most steroids would be provided in option A. Notable ring type of structures that are fused and may or may not display certain functional groups that can provide different functions to this steroid depending on the functional groups present.
<span>b The growth of teeth in chickens supports the hypothesis of a common ancestor between birds and reptiles. This is a generally accepted hypothesis, and i'd go with this answer. Obviously we can't say whether chickens will have teeth with certainty, the chickens with teeth are clearly still chickens, and a baby croc isn't hatching out of a chicken egg any time soon.
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The most likely explanation for the variation is the offspring were produced from different combination of genes. A single pair of gold fish mentioned in the question means a male and a female gold fish. The two of them mated and contributed different genes to the fertilized fish eggs, this results in production of various body shape and colouration which is known as variation.
The free nerve endings
can detect pain, temperature, itch and hair movement. Merkel's disks can detect pressure, position and static touch features. Pacinian corpuscles are sensitive to vibration while Meissner's corpuscles are sensitive to light and touch.