Nitrogen,<span>The atmosphere is composed of ~78% nitrogen and ~21% oxygen, with small amounts of other gases. The bulk composition of the earth by weight is mostly, iron, oxygen, silicon and magnesium, in that order, with all the other elements making up only about 5% of the earth's weight.</span>
The answer is C) The death rate begins to fall, but the birth rates remain high for a time. No countries in the world are currently in Stage 1 or demographic transition. However, many are in stage 2, which is why many governments are concerned about overpopulation.
Answer:
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Answer:
The answer to the given question is C.
Explanation:
Natural selection:
The population contains both superior as well as inferior organisms where natural resources are limiting so it will cause competition between organisms. As a result of competition, it will select superiors, and inferiors are deleted and they are given reproductive advantages. Due to this reproductive advantage new population emerges. It is more suitable for the environment.
Natural selection divides into three parts that are directional, disruptive, and stabilizing selection.
This is an example of natural selection. Environmental conditions create pressure on the individuals and if they can survive and become fittest, their number increases in the population. This is according to Darwin's theory in the struggle for existence. These organisms survived as the fittest organisms to match climatic conditions.
Stabilizing selection: This operates when features coincide with the optimal environmental conditions and the organisms survive in a population. Stabilizing selection pressures do not promote evolutionary change but tend to maintain stability within the population from generation to generation.
In the beginning, directional selection - the organism develops characters to survive in response to gradual changes in the environmental conditions. It works on a range of phenotypes existing within a population and exerts selection pressure which moves the mean phenotype to one phenotypic extreme. When the mean phenotype overlaps with the new optimum environmental conditions, stabilizing selection will take over.
