Digestion and Nutrition MCQs for MDCAT

Correct answer: D. Autophagy

Autophagy is the process by which unwanted or damaged cellular structures are engulfed and digested within lysosomes.

Correct answer: C. Endoderm

The endoderm, the innermost embryonic germ layer, forms the lining of the digestive tract and its associated glands.

Correct answer: D. Chyme

Gastric churning mixes food thoroughly with gastric juices to produce a semi-liquid mass called chyme.

Correct answer: A. Symbiotic bacteria

Symbiotic bacteria residing in the large intestine synthesize vitamin K, which is then absorbed by the host.

Correct answer: A. Water and salts

The large intestine primarily absorbs water and salts (electrolytes) from the remaining indigestible material.

Correct answer: B. Three

Gastric glands contain three main cell types: mucous neck cells, chief (zymogenic) cells, and parietal (oxyntic) cells.

Correct answer: D. HCl

Oxyntic (parietal) cells of the gastric glands secrete hydrochloric acid, which activates pepsinogen and creates the stomach's acidic environment.

Correct answer: A. Pyloric Sphincter

Food passes from the stomach into the small intestine through the pyloric sphincter, which regulates gastric emptying.

Correct answer: C. Secondary lysosome

Digestive vacuoles and autophagosomes eventually fuse with lysosomes, forming secondary lysosomes. Secondary lysosomes contain the contents of the digestive vacoules or autophagosomes along with lysosomal enzymes for the breakdown and digestion of the engulfed material.

Correct answer: B. Amylase

Amylase is an enzyme that breaks down complex carbohydrates ino smaller sugars, such as maltose. Amylase is sensitive to the acidic environment of the stomach. The low pH in the stomach denatures amylase, reducing its activity and ultimately leading to its inactivation. Therefore, the action of amylase comes to an end due to acidic pH.

Correct answer: A. Duodenum

Option A is correct. The first segment of the small intestine is the duodenum. The small intestine is a long, coiled tube that is divided into three parts: the duodenum, the jejunum, and the ileum. The duodenum is the shortest and widest part of the small intestine. It is about 10 inches long and curves around the head of the pancreas. The duodenum is responsible for the initial digestion of food. It receives food from the stomach and mixes it with digestive juices from the pancreas and liver. The digestive juices in the duodenum break down carbohydrates, proteins, and fats into smaller molecules that can be absorbed into the bloodstream. The other options are not the first segment of the small intestine: The jejunum is the second segment of the small intestine. It is about 16 feet long and is located between the duodenum and the ileum. The jejunum is responsible for the absorption of most of the nutrients from food. The ileum is the third and longest segment of the small intestine. It is about 20 feet long and is located between the jejunum and the colon. The ileum is responsible for the absorption of the remaining nutrients from food, as well as the absorption of bile salts and water. The colon is the large intestine. It is about 5 feet long and is located between the ileum and the rectum. The colon is responsible for the absorption of water and the storage of waste products.

Correct answer: D. Entrokinase

Trypsinogen is a zymogen (inactive enzyme precursor) that requires activation to become trypsin, an active enzyme essential for protein digestion. The activation occurs primarily in the small intestine, where enteropeptidase (also known as entero kinase) converts trypsinogen into trypsin. This process is crucial for initiating the digestive cascade, as trypsin can further activate other digestive enzymes. Amylase, HCl, and glucokinase do not play a role in this specific activation process. Amylase is involved in carbohydrate digestion, HCl aids in protein denaturation and creates an acidic environment for enzymes, while glucokinase is related to glucose metabolism.