Xylem is the answer......
<span>The chemoreceptor trigger zone is the area most responsible for the vomiting reflex. This is a part of the medulla, which is in the lower, more base, part of the brainstem. The vomiting center is a large group of axons and receptors that, when stimulated, produce an emetic response and will lead to a person vomiting.</span>
<span>The correct answer:
copper is important in the synthesis of collagen.</span>
Copper activates an enzyme called lysyl oxidase that's required for collagen maturation.Lysyl oxidase catalyzes the formation of aldehydes from lysine residues in collagen and this results in cross-linking collagen (stabilization of collagen fibrils).
Explanation:
For question no 19
Force (F) = 20N
distance (d) = 5m
Work = F * d
= 20 * 5
= 100 J
Now
For question no 20
D. No matter how much force is applied the object must have motion for work to be done.