Digestion and Absorption MCQs

With respect to gastric digestion in the stomach, select the correct combination of statements:

I. The stomach stores food for 4 to 5 hours.
II. The food mixes with acidic gastric juice by churning movements of the muscular wall and is called chyme.
III. Pepsinogen is converted to active pepsin by exposure to bile salts.
IV. Pepsin converts proteins into proteoses and peptones (peptides).

Read the following statements about protection mechanisms in the stomach and gastric secretions:

I. Mucus and bicarbonates in gastric juice protect mucosal epithelium from excoriation by concentrated HCl.
II. HCl in the stomach provides an acidic pH of 1.8 which is optimal for pepsin activity.
III. Rennin is a proteolytic enzyme in gastric juice of infants helping in milk protein digestion.
IV. Small amounts of lipases are also secreted by gastric glands.

Evaluate the statements regarding pancreatic juice composition and activation:

I. Pancreatic juice contains inactive trypsinogen, chymotrypsinogen, and procarboxypeptidases.
II. Pancreatic juice also contains active amylases, lipases, and nucleases.
III. Trypsinogen is activated by enterokinase, which is secreted by the pancreatic cells.
IV. Active trypsin autocatalytically activates other enzymes in the pancreatic juice.

Which of the following statements regarding bile composition and actions are correct?

I. Bile contains bilirubin, biliverdin, bile salts, cholesterol, and phospholipids.
II. Bile contains proteolytic enzymes that assist pancreatic juice.
III. Bile emulsifies fats by breaking them down into very small micelles.
IV. Bile activates pancreatic lipases.

Read the following statements about succus entericus (intestinal juice) and Brunner's glands:

I. Intestinal juice contains a variety of enzymes such as disaccharidases, dipeptidases, lipases, and nucleosidases.
II. Brunner's glands (sub-mucosal glands) help protect duodenal mucosa from acid and provide an alkaline pH of 7.8.
III. Succus entericus contains nucleases that hydrolyse DNA and RNA into nucleotides.
IV. The final steps of digestion occur very close to the mucosal epithelial cells of the intestine.

Evaluate the statements regarding passive transport mechanisms of absorption across the human intestinal mucosa:

I. Small amounts of glucose, amino acids, and some electrolytes like chloride ions are generally absorbed by simple diffusion.
II. Simple diffusion depends entirely upon concentration gradients.
III. Fructose and amino acids are absorbed with the help of carrier proteins, a process called facilitated transport.
IV. Facilitated transport requires direct cellular energy expenditure in the form of ATP.

Read the statements about active transport across the human gastrointestinal mucosa and select the correct combination:

I. Active transport occurs against a concentration gradient and therefore requires cellular energy.
II. Nutrients like amino acids, monosaccharides like glucose, and electrolytes like Na⁺ are absorbed into the blood by this mechanism.
III. Water transport occurs against the concentration gradient via active ATP-driven pumps.
IV. Chloride ions (Cl^-) are strictly absorbed by active transport only.

With respect to fat absorption in the small intestine, evaluate the following statements:

I. Fatty acids and glycerol, being insoluble, cannot be absorbed directly into the blood.
II. Fatty acids are first incorporated into small, water-soluble droplets called micelles.
III. In the mucosal cells, they are packaged into very small, protein-coated fat globules called chylomicrons.
IV. Chylomicrons are transported directly from mucosal cells into blood capillaries of the villi.

Identify the correct matching sequence of the absorption sites and their respective principal absorbed substances:

I. Mouth: Certain drugs coming in contact with the mucosa of the mouth and lower side of the tongue.
II. Stomach: Absorption of water, simple sugars, and alcohol.
III. Small Intestine: Principal organ for absorption of nutrients where digestion is completed.
IV. Large Intestine: Absorption of water, some minerals, and drugs.

Read the following statements regarding the human large intestine and choose the correct combination:

I. The large intestine consists of the caecum, colon, and rectum.
II. No significant chemical digestive activity occurs in the large intestine.
III. It is primarily involved in the absorption of water, some minerals, and certain drugs.
IV. It secretes mucus which helps in adhering waste particles and lubricating them for passage.