Amino Acids Quiz

Essential amino acids are _____.

• those that contain nitrogen

• obtained only by eating plants

• obtained only by eating animals

• all of the amino acids required to make proteins

• those that cannot be made in the body

Answer explanation

Essential amino acids are those that cannot be synthesized by the body and must be obtained through diet. This makes the correct choice 'those that cannot be made in the body', as they are vital for protein synthesis.

A complete digestive tract, or alimentary canal, differs from a gastrovascular cavity in that only the complete tract _____.

• permits extracellular digestion

• has teeth and tentacles to help with ingestion

• uses its surface area for nutrient absorption

• has specialized compartments

• allows elimination of undigested wastes

Answer explanation

A complete digestive tract allows for the elimination of undigested wastes, which is not possible in a gastrovascular cavity where digestion and absorption occur in the same space.

In humans, the first opportunity for ingested food to undergo enzymatic hydrolysis is in the _____.

• mouth

• stomach

• liver

• small intestine

• large intestine

Answer explanation

In humans, the mouth is where food first encounters saliva, which contains enzymes like amylase that begin the process of enzymatic hydrolysis, breaking down carbohydrates. Thus, the correct answer is the mouth.

Tags

NGSS.MS-LS1-7

Hydrochloric acid in the stomach _____.

• splits polypeptides into amino acids

• splits fats into fatty acids and glycerol

• activates pepsinogen into pepsin

• initiates the development of stomach ulcers

• inhibits the production of epithelial cells

Answer explanation

Hydrochloric acid in the stomach activates pepsinogen into pepsin, which is essential for protein digestion. The other options do not accurately describe the role of hydrochloric acid in the digestive process.

Secretin modulates digestion by ______.

• acting as an enzyme in the stomach

• triggering bile release into the intestine

• triggering buffer release from the pancreas

• triggering acid release in the stomach

• acting as an enzyme in the duodenum

Answer explanation

Secretin primarily functions to stimulate the pancreas to release bicarbonate, which buffers stomach acid in the small intestine, aiding digestion. Thus, it modulates digestion by triggering buffer release from the pancreas.

Tags

NGSS.HS-LS1-3

The bile salts function in fat digestion by _____.

• hydrolyzing fat molecules to glycerol and fatty acids

• separating individual fat molecules from each other

• dissolving fats in water

• dispersing big droplets of fats to small droplets

• triggering the secretion of pancreatic lipase

Answer explanation

Bile salts aid in fat digestion by emulsifying large fat droplets into smaller ones, increasing the surface area for enzymes to act on, which is crucial for effective fat digestion.

A fatty acid absorbed into an intestinal cell ______.

• is hydrolyzed to smaller fragments

• enters a lacteal vessel as a carbohydrate

• becomes part of a chylomicron

• is bound to bile salts

• exits the cell to directly enter the blood

Answer explanation

A fatty acid absorbed into an intestinal cell is reassembled into triglycerides and packaged into chylomicrons, which are then released into the lymphatic system, not directly into the blood.

Mutualistic bacteria aid digestion in many herbivores, including those where this function resides primarily in the large intestine, as in the _____.

• horse

• goat

• cow

• deer

• sheep

Answer explanation

The horse primarily digests food in the large intestine, where mutualistic bacteria help break down fibrous plant material, making it the correct answer. In contrast, cows, goats, deer, and sheep primarily utilize the rumen.

Glucagon, a pancreatic hormone, functions to _____.

• stimulate hunger

• inhibit activity in the small intestine

• increase fat storage in fat cells

• reduce glucose levels in the blood

• stimulate the liver to release glucose

Answer explanation

Glucagon primarily stimulates the liver to release glucose into the bloodstream, increasing blood sugar levels. This is crucial during fasting or low glucose conditions, making 'stimulate the liver to release glucose' the correct choice.

Tags

NGSS.HS-LS1-3

Increased appetite is the typical result of increased levels in the blood of which hormone?

• PYY

• insulin

• leptin

• secretin

• ghrelin

Answer explanation

Ghrelin is known as the 'hunger hormone' and stimulates appetite. Increased levels of ghrelin in the blood lead to an increased desire to eat, making it the correct answer.