which of the following describes the process of osmosis

HESI A2

HESI A2 Practice Test Anatomy and Physiology

1. Which of the following describes the process of osmosis?

A. Diffusion of solutes across a membrane
B. Movement of water across a selectively permeable membrane
C. Movement of gases across a membrane
D. Active transport of ions across a membrane

Correct answer: B

Rationale: Osmosis is the process where water molecules move across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. This movement of water helps to equalize the concentration of solutes on both sides of the membrane. The correct description of osmosis is the movement of water across a selectively permeable membrane, making choice B the right answer. Choices A, C, and D are incorrect because osmosis specifically refers to the movement of water molecules, not solutes, gases, or ions across a membrane.

2. What is the primary function of white blood cells?

A. To carry oxygen
B. To fight infections
C. To transport nutrients
D. To clot blood

Correct answer: B

Rationale: White blood cells, also known as leukocytes, play a crucial role in the immune system by primarily fighting off infections caused by pathogens like bacteria, viruses, and other invaders. They help the body recognize and destroy these harmful agents, contributing to the body's defense mechanisms against diseases. Choice A is incorrect because the primary function of red blood cells, not white blood cells, is to carry oxygen. Choice C is incorrect as the transportation of nutrients is mainly carried out by the bloodstream as a whole, not specifically by white blood cells. Choice D is incorrect as the process of blood clotting is primarily managed by platelets in the blood, not white blood cells.

3. What is the function of the stomach in digestion?

A. To absorb nutrients
B. To break down food
C. To secrete digestive enzymes
D. To store glucose

Correct answer: B

Rationale: The correct answer is B: 'To break down food.' The stomach's primary function in digestion is to break down food mechanically and chemically. It accomplishes this by mixing food with gastric acid and digestive enzymes, resulting in the formation of chyme, a semi-liquid mixture that moves on to further digestion in the small intestine. Choice A is incorrect because the absorption of nutrients occurs mainly in the small intestine, not in the stomach. Choice C is incorrect because while the stomach does secrete digestive enzymes like pepsin, its primary role is not just limited to enzyme secretion. Choice D is incorrect because the storage of glucose primarily occurs in the liver and muscles, not in the stomach.

4. What are muscle contractions that normally move food along the human digestive system known as?

A. defecation
B. osmosis
C. peristalsis
D. circulation

Correct answer: C

Rationale: Muscle contractions that move food along the human digestive system are known as peristalsis. Peristalsis consists of a series of coordinated muscular contractions and relaxations that help propel food through the esophagus, stomach, and intestines, facilitating efficient digestion and nutrient absorption. Defecation refers to expelling waste from the body, osmosis is the movement of water across a membrane, and circulation relates to the movement of blood in the body's circulatory system, not directly involved in food transportation along the digestive tract.

5. What is the primary function of the small intestine in digestion?

A. Breaking down fats
B. Absorbing nutrients
C. Secreting digestive enzymes
D. Storing bile

Correct answer: B

Rationale: The correct answer is B: Absorbing nutrients. The small intestine plays a crucial role in digestion by absorbing nutrients. It is where the majority of nutrient absorption occurs, allowing digested food to pass into the bloodstream for distribution to the body's cells. Choice A (Breaking down fats) is incorrect because the breakdown of fats primarily occurs in the small intestine with the help of bile from the liver and enzymes from the pancreas. Choice C (Secreting digestive enzymes) is incorrect because while the small intestine does produce some digestive enzymes, its primary role is absorption. Choice D (Storing bile) is incorrect as the storage of bile occurs in the gallbladder, not the small intestine.