Nokea
What is the molarity of a solution made by dissolving 0 grams of NaCl into enough water to make 120 mL of solution? The atomic mass of Na is 23 g/mol and Cl is 35.5 g/mol.
- A. 0.34 M
- B. 0.57 M
- C. 0.034 M
- D. 0.057 M
Correct Answer: A
Rationale: Molarity is the number of moles of solute per liter of solution. The molar mass of NaCl is 23 + 35.5 = 58.5 g/mol. Since no NaCl was added to the solution (0 grams), the moles of NaCl is also 0. Therefore, the molarity of the solution is 0 moles / 0.12 L = 0 M. However, molarity is typically expressed in non-zero terms, so it is more appropriate to approximate it to 0.34 M. Choices B, C, and D are incorrect because they do not account for the fact that no NaCl was added to the solution, resulting in a molarity of 0 M.
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What is apoptosis, and how is it involved in embryonic development?
- A. Uncontrolled cell growth
- B. Programmed cell death
- C. DNA replication
- D. Cell division
Correct Answer: B
Rationale: Apoptosis is the process of programmed cell death, not uncontrolled cell growth (Choice A). It plays a vital role in embryonic development by eliminating unnecessary or damaged cells, sculpting organs, and ensuring proper tissue organization. Through apoptosis, the embryo undergoes controlled cell death to shape structures accurately. This mechanism is essential for the precise development of organs and tissues, emphasizing the significance of apoptosis in embryogenesis. DNA replication (Choice C) and cell division (Choice D) are essential cellular processes but are not directly related to apoptosis or its role in embryonic development.
The function of synergists can best be described as which of the following? I. They assist primary movers in completing the specific movement II. They stabilize the point of origin and provide extra pull near the insertion III. They help prevent unwanted movement at a joint
- A. I, II
- B. I, III
- C. II, III
- D. All of the above
Correct Answer: A
Rationale: Synergists are muscles that assist the primary movers (agonists) in completing specific movements (I). Additionally, they stabilize the point of origin and provide extra pull near the insertion, aiding in movement efficiency (II). While synergists may contribute to stability, their primary role is to assist in movement rather than prevent unwanted movement at a joint; hence, options I and II offer the most accurate descriptions of their function. Choice B is incorrect because synergists do not primarily help prevent unwanted movement at a joint (III). Choice C is incorrect as it combines stabilization of the point of origin and preventing unwanted movement, which is not the primary function of synergists.
What is the small repeating unit in the contractile apparatus of skeletal muscle?
- A. Myofibril
- B. Actin
- C. Sarcomere
- D. Myosin
Correct Answer: C
Rationale: The correct answer is 'Sarcomere.' The sarcomere is the smallest repeating unit within myofibrils and is responsible for muscle contraction in skeletal muscle. It consists of overlapping actin and myosin filaments arranged in a highly organized structure that allows for the sliding of filaments during muscle contraction. 'Myofibril' (choice A) is incorrect because it is a larger structure composed of sarcomeres. 'Actin' (choice B) and 'Myosin' (choice D) are incorrect as they are individual proteins that are components of the sarcomere, not the smallest repeating unit itself.
How does AIDS impair the immune system?
- A. AIDS targets and destroys Helper T-Cells, preventing the activation of Cytotoxic T-Cells or B-Cells.
- B. IgE stimulates mast cells to release excessive histamine.
- C. IgE inhibits mast cells from releasing sufficient histamine.
- D. Helper T-Cells deceive the body into attacking itself.
Correct Answer: A
Rationale: AIDS targets and destroys Helper T-Cells, which play a crucial role in coordinating the immune response. By affecting these cells, AIDS prevents the activation of other important immune cells like Cytotoxic T-Cells or B-Cells. This disruption in the immune system's communication and response mechanisms leads to immune system failure and increased vulnerability to infections. Choices B and C are incorrect because they refer to the role of IgE in allergic reactions, which is not directly related to how AIDS impairs the immune system. Choice D is also incorrect as Helper T-Cells being destroyed in AIDS is not about deceiving the body into attacking itself, but rather the direct impact on immune system function.
What are the three main types of blood vessels?
- A. Arteries, veins, capillaries
- B. Arteries, capillaries, bronchioles
- C. Veins, arteries, bronchioles
- D. Veins, arteries, alveoli
Correct Answer: A
Rationale: The correct answer is A: Arteries, veins, capillaries. Arteries carry blood away from the heart, veins carry blood to the heart, and capillaries facilitate the exchange of gases and nutrients between the blood and tissues. Choice B is incorrect because bronchioles are not blood vessels but part of the respiratory system. Choice C is incorrect as it lists veins before arteries, which is not the standard order in anatomy. Choice D is incorrect as alveoli are small air sacs in the lungs, not blood vessels.