Ch. 41

Essential amino acids are:

• all of the amino acids required to make proteins

• those that cannot be made in the body

• those that contain nitrogen

• obtained only by eating plants

• obtained only by eating animals

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

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

• mouth

• stomach

• liver

• small intestine

• large intestine

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

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

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

Increased glucose levels in blood, after a meal, trigger _____.

• glucagon release from the pancreas

• insulin release from the pancreas

• secretin release from the duodenum

• cholecystokinin release from the pancreas

• activation of amylase in the blood

In which of the following structures does absorption of water, vitamin K, and salt occur?

• large intestine

• small intestine

• liver

• stomach

• pancreas

Which of the following organisms is most likely to have an extremely large cecum?

• carnivore

• ruminant herbivore

• nonruminant herbivore

• insectivore

What is a lacteal?

• a vessel within each villus

• part of the vertebrate immune system

• a type of liver sinusoid

• a globule containing phospholipid, cholesterol, and protein