which part of the eye is responsible for color vision

HESI A2

HESI A2 Anatomy and Physiology 2023

1. Which part of the eye is responsible for color vision?

A. Cornea
B. Iris
C. Retina
D. Lens

Correct answer: C

Rationale: The correct answer is option C: Retina. The retina contains photoreceptor cells, including cones that are responsible for color vision. Cones are sensitive to different wavelengths of light, allowing us to perceive and differentiate various colors. Choice A, Cornea, is the transparent outer layer of the eye that helps focus light. It does not play a direct role in color vision. Choice B, Iris, is the colored part of the eye that controls the size of the pupil and regulates the amount of light entering the eye. While it is essential for adjusting light levels, it is not directly involved in color vision. Choice D, Lens, is responsible for focusing light onto the retina. It helps to form clear images on the retina but does not play a role in color vision.

2. What is the function of the lungs in the respiratory system?

A. To filter blood
B. To exchange gases
C. To produce energy
D. To remove waste products

Correct answer: B

Rationale: The correct function of the lungs in the respiratory system is to exchange gases. The lungs facilitate the exchange of oxygen and carbon dioxide between the air we breathe in and the blood, ensuring oxygen is absorbed and carbon dioxide is removed during respiration. Choice A is incorrect as the kidneys, not the lungs, filter blood. Choice C is incorrect as energy production primarily occurs in cells, not in the lungs. Choice D is incorrect as waste removal, such as the excretion of carbon dioxide, is a function of the lungs, but the primary function is the exchange of gases.

3. Why might certain young people be underweight?

A. They are growing in height faster than they are gaining weight.
B. They eat little protein and too much fat and sugar.
C. They eat several meals a day and fail to exercise enough.
D. They seldom eat a meal that contains foods from all food groups.

Correct answer: A

Rationale: Certain young people might be underweight because they are growing in height faster than they are gaining weight. During periods of rapid growth, the body's energy requirements are primarily directed towards height growth rather than weight gain, resulting in some individuals being underweight despite consuming sufficient calories. Choice B is incorrect because the question focuses on reasons related to growth rather than diet composition. Choice C is incorrect as it suggests overeating rather than the specific growth-related issue of height surpassing weight gain. Choice D is incorrect as it addresses nutritional variety rather than the growth dynamics affecting weight.

4. What is the term for red blood cell production?

A. Hematopoiesis
B. Erythropoiesis
C. Phagocytosis
D. Thrombopoiesis

Correct answer: B

Rationale: The correct term for red blood cell production is erythropoiesis. This process specifically refers to the production of red blood cells, mainly occurring in the bone marrow. Hematopoiesis is a broader term that encompasses the production of all blood cells, including red blood cells, white blood cells, and platelets. Phagocytosis is the process of engulfing and digesting particles by cells like macrophages, not related to red blood cell production. Thrombopoiesis is the production of platelets, not red blood cells.

5. Which enzyme functions to break down lactose, a specific sugar found in milk and dairy products?

A. Catalase
B. Lipase
C. Protease
D. Lactase

Correct answer: D

Rationale: Lactase is the enzyme responsible for breaking down lactose, a sugar present in milk and dairy products. When lactase breaks down lactose, it splits it into two simpler sugars, glucose, and galactose, which can then be absorbed and used by the body. Catalase is involved in breaking down hydrogen peroxide into water and oxygen. Lipase breaks down fats into fatty acids and glycerol. Protease breaks down proteins into amino acids. Therefore, choices A, B, and C are incorrect for the specific breakdown of lactose.