What is a major structure of the limbic system?
- A. Brainstem
- B. Spinal cord
- C. Hypothalamus
- D. Cerebral cortex
Correct Answer: C
Rationale: The correct answer is C: Hypothalamus. The hypothalamus is a significant structure of the limbic system responsible for regulating various functions such as emotions, autonomic functions, and hormone production. It plays a crucial role in maintaining homeostasis and orchestrating responses to stress and emotional stimuli. Choices A, B, and D are incorrect. The brainstem, although a vital part of the brain, is not a major structure of the limbic system. The spinal cord is not part of the limbic system; it is primarily involved in transmitting sensory and motor information between the brain and the rest of the body. The cerebral cortex is responsible for higher cognitive functions but is not a major structure within the limbic system.
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Which structure do cells rely on for movement?
- A. Flagellum
- B. Microtubule
- C. Pili
- D. Vesicle
Correct Answer: A
Rationale: The correct answer is A: Flagellum. Cells rely on flagella for movement, which are whip-like structures that propel the cell forward through their whipping motion. Flagella provide motility to single-celled organisms and certain cells in multicellular organisms. Microtubules, on the other hand, provide structural support to the cell and play a role in intracellular transport. Pili are short, hair-like structures used for attachment to surfaces or other cells, not for movement. Vesicles are membrane-bound sacs involved in intracellular transport, aiding in the movement of substances within the cell, but not in the movement of the cell itself.
A scientist wants to measure how far a person can run in 30 minutes. Which of the following units should be used to record this measurement as a small number?
- A. Gigameters
- B. Kilometers
- C. Megameters
- D. Terameters
Correct Answer: B
Rationale: Kilometers are commonly used for shorter distances and would provide a small and practical number to measure distance in this context. Gigameters, Megameters, and Terameters are much larger units of measurement and would result in very large numbers, making them impractical for measuring the distance a person can run in 30 minutes. Therefore, the correct choice is Kilometers as it is a suitable unit for measuring such distances within a reasonable range.
How does the developing fetus primarily eliminate metabolic wastes?
- A. The developing fetus does not produce metabolic wastes.
- B. Fetal waste is excreted as feces, which pass into the mother's anus.
- C. Fetal waste is passed down the umbilical cord to the mother's circulatory system.
- D. Fetal waste is passed down the umbilical cord and leaves the mother's body via the vagina.
Correct Answer: C
Rationale: Metabolic wastes produced by the developing fetus are eliminated primarily by being passed down the umbilical cord to the mother's circulatory system. Once in the mother's blood, these wastes are then filtered and excreted by the mother's kidneys. Choice A is incorrect because the developing fetus does produce metabolic wastes. Choice B is incorrect as fetal waste does not pass into the mother's anus. Choice D is incorrect as fetal waste does not leave the mother's body via the vagina.
Which muscle causes a joint to bend?
- A. Cardiac
- B. Extension
- C. Flexor
- D. Smooth
Correct Answer: C
Rationale: The correct answer is C: Flexor. A flexor muscle contracts to bend a joint, such as bending the elbow or knee. Flexor muscles are responsible for flexing or bending a joint, while extensor muscles are responsible for extending or straightening a joint. Choice A, Cardiac, is incorrect as cardiac muscle is found in the heart and is responsible for pumping blood. Choice B, Extension, is incorrect as extension refers to the straightening or extending movement of a joint, which is opposite to bending. Choice D, Smooth, is incorrect as smooth muscles are involuntary muscles found in organs like the intestines and blood vessels, not directly responsible for bending joints.
At what stage is urine formed in the kidney?
- A. After fluid reaches the bladder.
- B. When fluid fills the collecting duct.
- C. Before blood enters the glomerulus.
- D. During fluid transport to the urethra.
Correct Answer: B
Rationale: Urine is formed when fluid fills the collecting duct in the kidney. The collecting duct is where the final concentration of urine occurs after the filtration process in the nephron. Choice A is incorrect because urine formation happens before fluid reaches the bladder. Choice C is incorrect because urine formation occurs after blood has been filtered in the glomerulus. Choice D is incorrect because urine formation happens before fluid is transported to the urethra for elimination.