Nokea
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.
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What is the main function of the nervous system?
- A. To fight infection
- B. To control body movement and coordination
- C. To regulate metabolism
- D. To transport oxygen
Correct Answer: B
Rationale: The main function of the nervous system is to control body movement and coordination by transmitting signals between different parts of the body. Choice A is incorrect because the immune system, not the nervous system, is primarily responsible for fighting infections. Choice C is incorrect as regulating metabolism is primarily handled by the endocrine system. Choice D is incorrect because the transportation of oxygen is mainly the function of the circulatory system, specifically the blood.
Which part of the heart receives oxygenated blood from the lungs?
- A. Left atrium
- B. Right atrium
- C. Left ventricle
- D. Right ventricle
Correct Answer: A
Rationale: The correct answer is A, the left atrium. The left atrium receives oxygenated blood from the lungs, which is then pumped into the left ventricle and out to the rest of the body. The right atrium receives deoxygenated blood from the body and sends it to the right ventricle to be pumped to the lungs for oxygenation. Choices B, C, and D are incorrect as they do not directly receive oxygenated blood from the lungs.
What term refers to the mechanical act of breathing?
- A. Diffusion
- B. Perfusion
- C. Respiration
- D. Ventilation
Correct Answer: D
Rationale: Ventilation is the correct answer as it specifically refers to the mechanical process of breathing air in and out of the lungs. Diffusion (choice A) is the movement of molecules from an area of high concentration to low concentration, not related to the mechanical act of breathing. Perfusion (choice B) is the process of blood flow through the tissues and organs, not directly related to breathing mechanically. Respiration (choice C) involves the exchange of oxygen and carbon dioxide at the cellular level, different from the mechanical act of breathing.
Which type of muscle is responsible for moving the skeleton?
- A. Cardiac muscle
- B. Skeletal muscle
- C. Smooth muscle
- D. Voluntary muscle
Correct Answer: B
Rationale: Skeletal muscle is the correct answer as it is responsible for moving the skeleton. Skeletal muscles are under voluntary control, meaning they can be consciously controlled by the individual. Cardiac muscle (Choice A) is found in the heart and is responsible for pumping blood, not moving the skeleton. Smooth muscle (Choice C) is found in internal organs and is responsible for involuntary movements like digestion. Voluntary muscle (Choice D) is not a specific type of muscle; it refers to muscles that can be consciously controlled, which includes skeletal muscles.
Which type of joint connects the bones of the skull?
- A. Synovial
- B. Fibrous
- C. Cartilaginous
- D. Ball-and-socket
Correct Answer: B
Rationale: Fibrous joints connect the bones of the skull. These joints are immovable or provide very limited movement, providing stability and protection to the brain. Synovial joints (Choice A) are found in the limbs and allow for a wide range of movements. Cartilaginous joints (Choice C) are connected by cartilage and allow limited movement. Ball-and-socket joints (Choice D) allow for a wide range of motion, such as the hip and shoulder joints, but they do not connect the bones of the skull.