B. Subgroups
<span>When constructing a dichotomous key, the first step is to look at the group of objects or organisms and separate them into two groups based on a single distinguishing characteristic. Then continue to separate each of the groups until each object has its own separate set of characteristics.</span>
Put a end to aggressively
Answer:
There are many ways.
Explanation:
Humans have a combined respiratory and circulatory system, whereas insects do not. In humans, the air is brought in through the mouth/nose, through the windpipe, and into the lungs, the oxygen is absorbed into the bloodstream where it can be transported to muscles and organs. However, insects take in air through tiny holes in their thorax and abdomen. These are called spiracles. The oxygen is stored in many dorsal air sacs to be used. Then carbon dioxide is expelled through the spiracles.
