Answer: feed-back
When the product of a metabolic pathway accumulates, it may be able to slow down or turn off the pathway by inhibiting the activity of an enzyme that catalyzes an early step in the pathway. This is referred to as feed-back inhibition.
Explanation:
Feed-back inhibition is said to occur when the final product of a biochemical pathway signal the inactivation of the starting materials of the pathway.
For example: when pyruvate signal the inactivation of phosphofructokinase, the glycolytic pathway gets turned off.
Cellulose is another long polymer of glucose. Plant cells make their cell walls out of cellulose. In fact, 100 billion tons of cellulose is made every year on earth. Cellulose is indigestible in most animals, including us. Ever eat a cardboard box? You get the picture. We simply lack cellulase, the enzyme that can break it down. Some bacteria, some single-celled protists, and fungi have the enzyme. Animals that feed on cellulose harbor these microbes that help them digest it. Even though, we cannot break down this molecule, we do need cellulose in our diet. We call it “fiber”. Cellulose stimulates the colon to produce regular bowel movements and helps make the stools large and soft. A diet rich in fiber can prevent a painful intestinal disorder called diverticulosis. Hard impacted stools can sometimes cause the walls of the colon to form blind outpockets called diverticula which can periodically inflame. So what makes cellulose different from starch? Isn’t it made of glucose? Well it is but the glucose monomers are organized in an interesting fashion. The orientation of the glucose molecules alternates. So if the first one is right side up, the next one is upside down and then the next is right side up and the next one is upside down. Apparently this is a tricky arrangement for an enzyme to break.
Answer:
D. Longshore currents
Explanation:
Longshore currents are characterized as the sediment transport that occurs in the surf zone, due to the oblique incidence of the waves, along the beach. A current develops between the beach and the surf zone parallel to the coast, normally between 0.3 and 1 m / s. It is this process that is responsible for accumulating and removing sand that results in displacement of barrier islands.
Answer:
A point mutation is a change in the base sequence of a DNA molecule.
Explanation:
