Answer: Membrane transport proteins are specific and selective for the molecules they move, and they often use energy to catalyze passage. Also, these proteins transport some nutrients against the concentration gradient, which requires additional energy.
Explanation:
Answer:
B
Explanation:
<em>The correct answer would be that when sticklebacks don't use their armor, it shrinks. Then they pass lighter armor to their offspring.</em>
According to the theory of natural selection, adaptive traits that enable organisms to survive in an environment are selected by the forces of natural selection.
<u>When a particular trait is not needed for survival in an environment, the trait gradually degenerates within the population as natural selection ignores the existence of such trait. The degenerated trait is inherited by the subsequent generations of the population.</u>
The mechanism is also consistent with the law of use and disuse of organs by Jean Larmack.
The correct option is B.
Answer:
The radii of the arterioles constrict by humoral control and by nervous control.
Explanation:
The vascular system regulation is performed by the smooth muscle of the arterioles, which constitute the maximum resistance point. The smooth muscle relaxation provokes vasodilation, increasing its diameter. On the contrary, smooth muscle contraction provokes a decrease in the arteriole´s diameter, reducing the blood flow.
This muscle is under the control of the autonomous nervous system and certain hormones.
Substances such as adrenaline, noradrelanine, angiotensine, vasopresin, and endotelines cause vasoconstriction.
Also, there are many vasoconstrictor fibers of the sympathetic nerves that increase resistance and modify blood flow.
Just want some points sorry
I believe that the answers are physical and chemical barriers.
