Answer:
when you try to stand or stretch your legs to relieve the discomfort.
Explanation:
n turn, the brain directs a response through the spinal cord, which sends impulses through the motor neurons. In turn, the motor neurons direct the muscles to execute the response. The end result is when you try to stand or stretch your legs to relieve the discomfort.
Answer:
D. Active transport.
Explanation:
Active transport is the method that uses the ATP's energy to move ions and molecules from one side to the other of the membrane. The elements move from a place of lower concentration to one of a higher concentration. They move against their concentration gradient, which is why they need the energy to do it. There are two types of active transport, primary and secondary.
The primary active transport is ion pumps that hydrolyze ATP using one of the phosphates of the ATP to change the pump's shape and move the elements against their concentration gradient. It uses the ATP's energy directly.
The secondary active transport does not use ATP directly. It uses the electrochemical gradient that the primary transport had created when hydrolyzing ATP to transport the ions and molecules.
Answer:
1. Newton believed that gravity was a force.
3. The law of universal gravitation offers a mathematical explanation for the attraction between the moon and Earth.
Explanation:
Law of gravitation states that force is directly proportional to masses of objects and inversely proportional to the distance between from their center. Directly means if mass increases, force of attraction also increased while inversely means if distance decrease between objects, force of attraction is also increased. Gravity is measured in weight because weight ia a force which attracts things towards its center.
Answer:
Because natural selection selects for it. Thus it persists.
Explanation:
You have to understand heterozygote advantage. Basically, it's where heterozygotes have an advantage over homozygotes. In the case of sickle cell disease, heterozygotes have an advantage, and natural selection favors whatever is advantageous. Thus, because heterozygotes each have one recessive sickle-cell allele, as natural selection favors the heterozygotes, the recessive sickle-cell allele persists and remains in the gene pool.
