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What is the function of the myelin sheath in a neuron?
- A. To transmit electrical impulses
- B. To insulate and speed up electrical signals
- C. To produce neurotransmitters
- D. To protect the neuron from damage
Correct Answer: B
Rationale: The myelin sheath serves to insulate neurons and accelerate the transmission of electrical signals along the axon. This insulation helps in the efficient conduction of nerve impulses by preventing signal loss or leakage. Choice A is incorrect because the myelin sheath does not transmit electrical impulses itself but rather helps in the conduction. Choice C is incorrect as the myelin sheath is not responsible for producing neurotransmitters. Choice D is also incorrect as the primary function of the myelin sheath is not to protect the neuron from damage. Therefore, the correct answer is B, as it accurately describes the function of the myelin sheath in a neuron.
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What is the muscular tube that connects the outer surface to the cervix in a woman's birth canal referred to as?
- A. The uterus
- B. The cervix
- C. The vagina
- D. The ovaries
Correct Answer: C
Rationale: The correct answer is C, 'The vagina.' The muscular tube that connects the outer surface to the cervix in a woman's birth canal is called the vagina. The vagina serves as the passageway for menstrual flow, sexual intercourse, and childbirth. The cervix, not the uterus, connects the vagina to the uterus. The ovaries, on the other hand, are the organs responsible for producing eggs and female hormones, but they are not the muscular tube connecting the outer surface to the cervix in the birth canal.
What is the diastole cycle in the heart?
- A. Relaxation of the heart
- B. Contraction of the heart
- C. Pulse rate of the heart
- D. Blood circulation
Correct Answer: A
Rationale: The diastole cycle in the heart refers to the relaxation phase, where the heart chambers relax and fill with blood. This phase is crucial for the heart to refill and prepare for the next contraction (systole), which pumps blood out of the heart. Therefore, the correct answer is choice A, 'Relaxation of the heart.' Choices B, C, and D are incorrect in the context of cardiac physiology. Choice B, 'Contraction of the heart,' refers to systole, the phase of heart contraction. Choice C, 'Pulse rate of the heart,' is related to the number of heartbeats per minute, not the diastole cycle specifically. Choice D, 'Blood circulation,' is a broader term that encompasses the entire circulatory system rather than focusing on the heart's specific relaxation phase.
Which hormone is produced by the thyroid gland?
- A. Insulin
- B. Thyroxine
- C. Adrenaline
- D. Cortisol
Correct Answer: B
Rationale: The correct answer is B: Thyroxine. The thyroid gland produces thyroxine, a hormone essential for regulating metabolism. Insulin is produced by the pancreas to regulate blood sugar levels. Adrenaline is produced by the adrenal glands to prepare the body for the 'fight or flight' response. Cortisol is produced by the adrenal cortex in response to stress, not by the thyroid gland.
Four different groups of the same species of peas are grown and exposed to differing levels of sunlight, water, and fertilizer as documented in the table below. The data in the water and fertilizer columns indicate how many times the peas are watered or fertilized per week, respectively. Group 2 is the only group that withered. What is a reasonable explanation for this occurrence? Group Sunlight Water Fertilizer 1 partial sun 4 mL/hr 1 2 full sun 7 mL/hr 1 3 no sun 14 mL/hr 2 4 partial sun 3 mL/hr 2
- A. Insects gnawed away at the stem of the plant.
- B. The roots rotted due to poor drainage.
- C. The soil type had nutritional deficiencies.
- D. This species of peas does not thrive in full sunlight.
Correct Answer: D
Rationale: Group 2, the only group that withered, was exposed to full sun. This suggests that the species of peas being studied does not thrive in full sunlight, leading to its deterioration compared to the other groups with different light exposures. Choices A, B, and C are not the correct explanations for the withering of Group 2. There is no mention of insects in the stem, poor drainage, or soil nutritional deficiencies in the scenario provided. The key factor that sets Group 2 apart from the others is the full sunlight exposure, indicating that the species of peas is not suited for such conditions.
Which of the following substances has an acidic pH?
- A. Lemon juice
- B. Blood
- C. Urine
- D. Salt water
Correct Answer: A
Rationale: The correct answer is A, Lemon juice, which has an acidic pH typically around 2 due to its citric acid content. Blood, urine, and salt water are not typically acidic in nature. Blood has a slightly basic pH, urine can vary but is usually slightly acidic to neutral, and salt water is neutral to slightly alkaline. Lemon juice is a commonly known acidic substance, often used in cooking and cleaning due to its acidic properties.