Answer:
Chitin is a fibrous material made up of polysaccharides that is found in the exoskeletons of arthropods and the cell walls of fungus. Chitin is an important biopolymer found in nature. Fungi, arthropods, and nematodes are the principal producers. In insects, it acts as a scaffold, supporting the epidermis and trachea cuticles, as well as the peritrophic matrices that line the gut epithelium.
Explanation:
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Ribosomes attached to the ER
The correct answer is - D) covered by warm shallow seas.
The fact that the crinoids are have an abundance in the fossil records in Pennsylvania in the Mississippian Period, tells us that this area was covered with shallow and warm seas. The reason why we can get that conclusion is that the crinoids live only in that kind of environment, so it simply a logical conclusion.
The geological data is also confirming this, as it is easily noticeable in the layers that during this period of the geologic past, what is now Pennsylvania, was covered with shallow sea waters. Also, this waters were warm too, as the climate was warm and humid and that period, so it was a perfect environment for the crinoids to flourish.
When AncestryDNA launched in 2012, we compared your DNA against 22 possible regions. We now have more than 1,500.
Answer: Winter solstice, also called hibernal solstice, the two moments during the year when the path of the Sun in the sky is farthest south in the Northern Hemisphere (December 21 or 22) and farthest north in the Southern Hemisphere (June 20 or 21).
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