The menstrual<span> cycle </span>occurs<span> due to the rise and fall of hormones</span>
Using kilometers in space is useless, as the distances between objects is drastically incred. A lightyear is 9.5 kilometers. It is simpler to say "Alpha Centauri is 4.1 light years away" than it is to say "Alpha Centauri is 28.95 Trillion kilometers away"<span />
Answer;
-Chitin is a structural carbohydrate that forms their exoskeleton
Explanation;
-Chitin is the main component in the exoskeletons of arthropods and crustaceans and is also in the cell walls of fungi.
-It is a linear long chain polymer consisting of repeated units of N-acetyl-glucosamine.
-The main function of the chitin-containing exoskeleton is to keep the inner soft tissue safe from any sort of injury and also prevents the delicate tissues from drying (acts as a water tight barrier against dehydration).
I am not sure what the answer(s) for, "which is not a major function of the kidney?" is but I can guess that your answer for that question might be, regulation of blood cell size. Also, the normal ph range of urine in humans is 6! I hope this helps!
I think the answer is evolution.
