Answer: D. Extinctions occur at higher rates during times of ecological stress when populations and species are poorly adapted.
Answer:chain-link fence
Explanation:a cell membrane is partial permeable which means that it lets some substances through but not other.
<span>During nitrification, ammonia is changed back into nitrate.</span>
Nitrification is a three-step process of oxidation of ammonia. It is an aerobic process performed by small groups of autotrophic bacteria (<span>Nitrosomonas,
Nitrobacter</span>).
First step- ammonia to hydroxylamine,
Second step-hydroxylamine to nitrite,
Third step-nitrite to nitrate.
Nitrification together with ammonification is part of a nitrogen cycle.
During respiration, members of the animal kingdom use oxygen and then release carbon dioxide as a waste gas.
Members of the animal kingdom have a respiratory system that is composed of muscles, and airways that functions together to transport air into lungs, and the oxygen is used by cells. Carbon dioxide is also transported away from the cells as a waste gas. Respiration relies on other systems, such as the circulatory system, to transport oxygen and carbon dioxide to and from cells.
<span>The steps commonly used by scientists in gathering information to test a hypothesis and solve a problem is called c) scientific method
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