The process of breaking down body protein into amino acids for energy is known as:

Correct Answer: D

Rationale: The correct answer is D: Catabolism. Catabolism involves the breakdown of body proteins into amino acids to be used as energy when there is an inadequate dietary intake. Choices A and B, deamination and transamination, involve the removal and transfer of amino groups, respectively, but not the breakdown of body proteins. Choice C, transcription, is a process in genetics where DNA is used to create mRNA, not related to breaking down body proteins.

Correct Answer: C

Rationale: The correct answer is H. pylori. This bacterium is known to be associated with the development of peptic ulcers and an increased risk of gastric cancer. Lactobacillus (Choice A) and Bifidobacterium (Choice B) are probiotic bacteria that are beneficial to human health and not associated with causing these conditions. E. coli (Choice D) is a diverse group of bacteria, some of which can be pathogenic, but they are not primarily linked to peptic ulcers and gastric cancer like H. pylori.

Correct Answer: A

Rationale: The correct answer is A: 1.8 and 3.5. Pepsin, an enzyme involved in protein digestion, functions optimally in an acidic environment, specifically between pH 1.8 and 3.5. This low pH is necessary for pepsin to break down proteins effectively. Choices B, C, and D are incorrect because pepsin requires a highly acidic environment, ruling out the pH ranges listed in those options.

Correct Answer: A

Rationale: The correct answer is pinocytosis. Pinocytosis is a process where cells in the small intestine absorb nutrients by engulfing them. This process is different from phagocytosis, which involves engulfing large particles, and excretion, which is the removal of waste products. Electrochemical diffusion is not directly involved in the absorption of food in the small intestine.

Correct Answer: D

Rationale: The correct answer is D, amylase. Amylase is an enzyme produced by the salivary glands that initiates the digestion of carbohydrates in the mouth. Pepsin (choice A) is produced in the stomach to digest proteins, trypsin (choice B) is produced in the pancreas to digest proteins, and sucrase (choice C) is produced in the small intestine to break down sucrose. Therefore, choices A, B, and C are incorrect in the context of an enzyme secreted by the salivary glands.

Correct Answer: D

Rationale: The correct answer is the amino group. Amino acids consist of an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a variable side chain attached to a central carbon atom. The amino group is essential for the formation of proteins. The carboxyl group is not the base component but another important functional group in amino acids. Carbon chain and radicals are not specific chemical structures that form the base component of an amino acid.

Correct Answer: B

Rationale: The correct answer is B: chyme. Chyme is the partially digested food that forms a semifluid mass after mixing with gastric juices. A is incorrect because a bolus refers to a rounded mass of food ready to be swallowed. C, rennin, is an enzyme involved in the digestion of milk proteins and not the term for the semifluid mass after food mixing with gastric secretions. D, glycogen, is a form of stored glucose in the body and is not the term used to describe the partially digested food mass in the stomach.

Correct Answer: D

Rationale: The correct answer is D: Absorption of water. The primary nutritional function of the large intestine is to absorb water from the indigestible food residue that enters it from the small intestine. This absorption of water helps to form solid waste, which is then eliminated from the body. Choices A, B, and C are incorrect because the large intestine is not primarily responsible for the absorption of fats, excretion of waste products, or excretion of bacteria. While the large intestine does play a role in waste elimination and contains bacteria beneficial for digestion, its main function in terms of nutrition is the absorption of water.

Correct Answer: C

Rationale: The correct answer is 'C: fiber.' Feces are primarily made up of indigestible material, such as fiber. Bile (choice A) is produced by the liver to aid in digestion but is not a major component of feces. Enzymes (choice B) are involved in digestion but are not a significant component of feces. Chyme (choice D) is the semi-fluid mass of partially digested food that moves from the stomach to the small intestine and is not a major component of feces.