Answer:
The presence of cholesterol in the plasma membranes of some animal cells <u>enables the membranes to stay fluid when cell temperature drops</u>.
Explanation:
Cholesterol is an essential lipid in the basic structure of cell membranes. The membranes must have a fluid structure so that the proteins integrated in them can move ''horizontally'' to interact with their ligands and with other proteins. With excess saturated fat the membranes become rigid, but only with the necessary unsaturated fat the membranes are extremely fluid, and very sensitive to changes in temperature. Cholesterol stabilizes the structure of the membranes; preventing the collapse and crystallization between lipid chains that would lead to loss of fluidity and excessive rigidity in the membrane. By decreasing the temperature; as temperatures drop, fluidity decreases, an effect that partially counteracts the presence of cholesterol.
Biosphere. Bio means life, and Biosphere means ALL life on earth.
Answer:
Positive natural selection.
Explanation:
The positive natural selection is a type of natural selection that increases the frequency of an allele or trait when it is advantageous for the population. What happened in the example is that the mouth with the slight change in morphology (trait) was more advantageous for the population in the south in relation to the ancestral morphology (still preserved in the population in the north), and therefore its frequency increased. This, in turn, is due to the fact that the food (prey) is not the same in the two habitats (north and south). The specific prey in the south, caused the new morphology to be selected, (increasing the frequency of individuals with the new mouth), becasue probably that trait allows the trouts in the south to hunt more effectively.
The westerlies wind from Mediterranean sea cause the more rainfall in winter in western part so winter crpos grow well in western part of nepal.
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