Answer;
Nitro.
Explanation:
By far, the most abundant gas in the Earth's atmosphere is nitrogen, which accounts for about 78% of the mass of dry air. Oxygen is the next most abundant gas, present at levels of 20 to 21%. Although humid air seems like it contains a lot of water, the maximum amount of water vapor that air can hold is only about 4%.
A is the sun hope this can help
Explanation:
Whereas primary tissues allow for vertical growth, secondary tissues allow for lateral growth: they allow stems and roots to become wider. In roots, the formation of both secondary meristems involves the pericycle.
Natural selection is the process that result in the adaptation of an organism to environment by means of selectively reproducing changes in its genotype, or genetic constitution. It is the a key mechanism of evolution. Charles Darwin popularised the term "natural selection" contrasting it with artificial selection, which is intentional, whereas natural selection is not.
To make it simple, let's have a group of beetle composing of green and some are brown as an example. here, there is a variation in traits. Since the environment could not support continuous population growth, not all species can reproduce to their full potential. Green beetles can easily be eaten by other species like birds compared to brown beetles. The surviving brown beetles will then generate brown offsprings because their trait has a genetic basis. Since more brown beetles survive and becomes more common in the population, the process continues until all individuals will eventually be brown. so basically, if you have variation, differential reproduction, and heredity, you will have evolution by natural selection as an outcome.
This is an example of negative feedback.
After a big meal, glucose levels in the bloodstream increases. The body recognises this change and goes through homeostasis, or the regulation of bodily state or internal environment.
The pancreas secretes insulin, which then binds to insulin receptors. This will result in the uptake of excess glucose from the bloodstream into cells and converted into glycogen to be stored in cells as energy storage molecules.
Since there is the counter effect of body (i.e. when blood-glucose concentration increases, the body sends a signal to decrease the blood-glucose concentration, this is called a negative feedback (instead of a positive feedback, which occurs if for e.g. the body signals cells to increase blood-glucose concentration even after blood-glucose concentration increased after a heavy meal).
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