Most Repeated MDCAT Biology: Nutrition MCQs

Explanation

Secretin is the correct answer because it is a hormone released by the small intestine in response to acidic chyme. It stimulates the pancreas to secrete bicarbonate, which neutralizes stomach acid and promotes liver bile production, thus facilitating digestion. In contrast, gastrin primarily stimulates the stomach's activity; HCl is a gastric secretion rather than a hormone, and enterokinase is an enzyme that activates other digestive enzymes but does not stimulate secretion from the liver or pancreas.

Explanation

[A] Symbiotic bacteria are bacteria that live in a symbiotic relationship with other organisms. It benefits both the organisms like Escherichia coli live in symbiotic association in human intestine and produce large quantities of vitamin K and in human intestine. [B] An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy. [C] parasite bacteria live on or in a host organism and get their food from or at the expense of its host.

Explanation

Glycogen is the correct answer because it is the storage form of glucose in animals, including humans. The liver converts excess glucose into glycogen to store it for later use when the body needs energy. This process helps maintain blood sugar levels. Starch, on the other hand, is how plants store glucose. Maltose is not a storage form but a product of starch and glycogen breakdown. Finally, cellulose is a structural component in plants, not a storage form of sugar.

Explanation

Peristalsis is the contraction of muscle tissue that helps move and break down foodstuffs. The walls of the alimentary canal include layers of smooth muscle controlled by the autonomic nervous system. The alternating contraction and relaxation of these muscles is called peristalsis.

Explanation

The word Chemoautotrophic nutrition means energy produced through chemical reactions taking place. The primary work is on inorganic compounds used to synthesise different organic compounds.

Explanation

Zymase is an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide. It occurs naturally in yeasts. Zymase activity varies among yeast strains. Zymase is also the brand name of the drug pancrelipase.

Explanation

Option A: Ptyalin is a form of amylase found in the saliva of humans and some other animals. It digests only carbohydrates, not proteins. Hence, Option A is incorrect.Option B: Saliva consists of Water and mucus, Sodium bicarbonate and other salts, and Ptyalin or amylase. Saliva contains the enzyme amylase, also called ptyalin, which is capable of breaking down starch into simpler sugars such as maltose that can be further broken down in the small intestine. But saliva does not contain enzymes for protein digestion. Hence, Option B is incorrect. Option C: Pepsin is an enzyme responsible for protein digestion and is released in the form of pepsinogen in the stomach.

Explanation

Incisors: These are the sharp, flat teeth at the front of your mouth used for biting and cutting food into smaller pieces. Canines: Located next to the incisors, these pointed teeth are used for tearing and gripping food. Premolars: Situated behind the canines, premolars have a flat surface and are used for crushing and shredding food. Molars: These are the large, flat teeth at the back of your mouth that are designed for grinding and crushing food to prepare it for swallowing.

Explanation

An autotroph is an organism that can produce its own food using light, water, carbon dioxide, or other chemicals. Because autotrophs produce their own food, they are sometimes called producers. Plants are the most familiar type of autotroph, but there are many different kinds of autotrophic organisms.

Explanation

Pepsin is the primary enzyme in the stomach that breaks down proteins into smaller peptides. It is secreted by chief cells as an inactive precursor, pepsinogen, which is then activated by the stomach's hydrochloric acid. This process is crucial for protein digestion and requires the highly acidic environment of the stomach, where pepsin is most active.

Explanation

Pepsin is a powerful protein-digesting enzyme and is quite capable of destroying a cell's internal structure and thus is produced in inactive form, pepsinogen, by the cell. It is converted into its active form only in the digestive tract, where it is required to be active. Hence, option D is correct.

Explanation

Bile does not contain digestive enzymes. Instead, it contains bile salts and other substances that aid in the digestion and absorption of fats through a physical process called emulsification.

Explanation

Enterokinase's primary function is to activate the digestion of proteins by converting pancreatic enzymes from their inactive forms into active ones. It achieves this by cleaving trypsinogen into its active form, trypsin. Once activated, trypsin goes on to activate other inactive pancreatic proenzymes like chymotrypsinogen, procarboxypeptidase, and proelastase.

Explanation

Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or peptide substrates.It is produced and secreted by glands of the small intestine.