What is the primary function of the respiratory system?
- A. To digest food
- B. To transport nutrients
- C. To exchange gases
- D. To regulate body temperature
Correct Answer: C
Rationale: The correct answer is C: To exchange gases. The primary function of the respiratory system is to facilitate the exchange of gases, specifically oxygen and carbon dioxide, between the body and the environment. This process is essential for cellular respiration, where oxygen is taken in and carbon dioxide is removed. Choices A, B, and D are incorrect. Digesting food is primarily the function of the digestive system, transporting nutrients is the role of the circulatory system, and regulating body temperature is primarily managed by the integumentary system and the nervous system, not the respiratory system.
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During which of the following stages does crossing over occur?
- A. Mitosis Prophase
- B. Meiosis Prophase I
- C. Meiosis Prophase II
- D. Interphase
Correct Answer: B
Rationale: Crossing over occurs during Prophase I of meiosis. This stage is specifically associated with genetic recombination, where homologous chromosomes exchange genetic material. This process contributes to genetic diversity by creating new combinations of alleles. Choices A, C, and D are incorrect. In mitosis, crossing over does not occur as it involves the separation of replicated chromosomes. Meiosis Prophase II is focused on the reformation of nuclei and does not involve crossing over. Interphase is a stage where the cell prepares for division and is not associated with crossing over.
DNA has both a 'sense' and 'antisense' strand. What is true about the antisense strand?
- A. It runs 5' to 3'.
- B. It runs 3' to 5'.
- C. It is used in replication.
- D. It is the direction DNA is stored.
Correct Answer: B
Rationale: The correct answer is B: 'It runs 3' to 5'. The antisense strand runs in the 3' to 5' direction, complementing the sense strand. Choice A is incorrect as the antisense strand runs in the opposite direction, which is 3' to 5'. Choice C is incorrect because the antisense strand is not directly involved in replication. Choice D is incorrect as the direction DNA is stored is not determined by the antisense strand.
Which of the following statements regarding the microscopic anatomy of heart muscle is correct?
- A. Cardiac muscle is striated, short, fat, branched, and interconnected
- B. Intercalated discs anchor cardiac cells together and allow the free passage of ions
- C. The connective tissue endomysium acts as both tendon and insertion
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, 'All of the above.' Cardiac muscle is indeed striated, short, fat, branched, and interconnected. Intercalated discs are responsible for anchoring cardiac cells together and allowing the free passage of ions. Additionally, the connective tissue endomysium provides structural support and acts as a tendon-like structure attaching muscle fibers to each other. Therefore, all the statements in choices A, B, and C are accurate when describing the microscopic anatomy of heart muscle. Choices A, B, and C individually represent different aspects of the structural features of cardiac muscle, making choice D the most comprehensive and correct answer.
What type of immunity does a vaccine provide? Choose only ONE best answer.
- A. Naturally acquired passive immunity
- B. Artificially acquired passive immunity
- C. Naturally acquired active immunity
- D. Artificially acquired active immunity
Correct Answer: D
Rationale: The correct answer is D: Artificially acquired active immunity. Vaccines work by stimulating the immune system to produce an active response, leading to the development of immunity against specific pathogens. Choice A, naturally acquired passive immunity, is incorrect as it refers to the temporary immunity passed from mother to child, not through vaccines. Choice B, artificially acquired passive immunity, is also incorrect because passive immunity involves the transfer of pre-formed antibodies, not the stimulation of the immune system by vaccines. Choice C, naturally acquired active immunity, is incorrect since it is acquired through natural exposure to pathogens, not through vaccines.
Which of the following is responsible for producing antibodies?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma
Correct Answer: B
Rationale: White blood cells are responsible for producing antibodies. Antibodies are essential components of the immune system that help the body combat infections by identifying and neutralizing harmful pathogens. Red blood cells are primarily responsible for carrying oxygen, platelets are involved in blood clotting, and plasma is the liquid component of blood that carries nutrients and hormones.
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