Nokea
At what pH does the digestion of protein by pepsin in the stomach require?
- A. 1.8 and 3.5.
- B. 4.8 and 7.0.
- C. 6.8 and 8.5.
- D. 7.8 and 10.0.
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.
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The hormone secretin stimulates production of a buffering solution for the duodenum by the:
- A. stomach.
- B. liver.
- C. pancreas.
- D. oxyntic cells.
Correct Answer: C
Rationale: The correct answer is C: pancreas. Secretin stimulates the pancreas to release bicarbonate, which acts as a buffering solution to neutralize the acid entering the duodenum from the stomach. This process helps in maintaining the pH balance in the small intestine. Choice A, stomach, is incorrect as the stomach does not produce the buffering solution needed for the duodenum. Choice B, liver, is incorrect because secretin does not directly stimulate the liver to produce a buffering solution. Choice D, oxyntic cells, is also incorrect as these cells in the stomach are responsible for producing gastric acid, not the buffering solution needed in the duodenum.
What is the cause of gas formation in the colon?
- A. Consuming refined foods.
- B. Drinking excess water.
- C. Swallowing air while eating.
- D. Bacterial action on organic compounds.
Correct Answer: D
Rationale: Gas formation in the colon is primarily due to bacterial fermentation of undigested carbohydrates. Choice A, consuming refined foods, is incorrect as gas formation is not directly linked to refined foods but rather undigested carbohydrates. Choice B, drinking excess water, is incorrect as water consumption does not lead to gas formation in the colon. Choice C, swallowing air while eating, is incorrect as this may cause belching but not gas formation in the colon. The correct answer is D because bacterial action on organic compounds, specifically undigested carbohydrates, leads to gas production in the colon.
In addition to active transport, which process is involved in absorbing food in the small intestine?
- A. pinocytosis
- B. excretion
- C. phagocytosis
- D. electrochemical diffusion
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.
How many different amino acids make up human proteins?
- A. 9
- B. 13
- C. 15
- D. 20
Correct Answer: D
Rationale: The correct answer is D: 20. There are 20 different amino acids that combine to form proteins in the human body. Each amino acid has a unique side chain that determines its properties. Choices A, B, and C are incorrect as they do not represent the total number of different amino acids found in human proteins.
What is the main constituent of blood plasma, interstitial fluid, and intracellular fluid?
- A. potassium
- B. sodium
- C. water
- D. calcium
Correct Answer: C
Rationale: The correct answer is C: water. Water is the main component of blood plasma, interstitial fluid, and intracellular fluid. It plays a crucial role in various bodily functions, including transporting nutrients, regulating body temperature, and maintaining cell structure. Choices A, B, and D are incorrect because while potassium, sodium, and calcium are essential electrolytes found in the body, they are not the main constituents of these fluids as water is.