The correct option is A.
The serosa refers to the outermost layer of loose connective tissues which is often covered by mucus and which contains blood vessels. In the gastrol intestinal tract, the serosa refers to the outermost layer of the wall of the GI tract. One major function of serosa is to reduce friction from muscle movement.
Answer:
Keystone Species: Kangaroo Rat Keystone species are species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system. Hawk (predator)/lizard (prey). scorpion (predator)/insect (prey). if their is no relationship between these two then the scorpions will die off and the insects will thrive.
Explanation:
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A molecule.
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The nucleus contains the <u>DNA</u> (Deoxyribosenucleic Acid). It codes for all the hereditary characteristics an organism has and it is packaged into chromosomes within the nucleus.