It is useful for an ecologist to identify the keystone species in an ecosystem because the keystone species is important to maintaining the stability of an ecosystem, and any changes in the keystone species population shows that there is changes in ecosystem health.
From what I can tell, The answer is either A or B. Mammals have what is called an Endoskeleton, which means that their skeletons are inside their bodies. A way to remember this is Exo- is similar to exit and when you exit something then you are going outside. Endo- sounds like into, which can relate to being on the inside. Insects have Exoskeletons, which are made from Chitin. Now Agonists are also called Prime Mover muscles, which means they are practically the same thing.
Scientists found that the first living things were likely prokaryotic because eukaryotic are evolved from the prokaryotic only.
<h3>What do you mean by Natural selection?</h3>
Natural selection may be defined as favorable variations that assist the organisms to survive and reproduce in a particular habitat.
Individuals that are better suited to their environment are likely to have more offspring and pass their genetic material on to future generations. This theory is referred to as Natural selection.
Scientists hypothesize that oxygen began to accumulate in the Earth's atmosphere after the appearance of living things with the ability to Photosynthesize.
To learn more about Photosynthesis, refer to the link:
brainly.com/question/19160081
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