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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 are Mendel's laws?
- A. Law of inheritance, law of expression
- B. Law of segregation, law of independent assortment
- C. Law of dominance, law of recessiveness
- D. Law of mutation, law of crossing over
Correct Answer: B
Rationale: The correct answer is B. Mendel's laws consist of the law of segregation, which states that each parent passes one allele for each trait, and the law of independent assortment, which explains that genes for different traits are inherited independently. Choice A is incorrect because 'law of expression' is not one of Mendel's laws. Choice C is incorrect because 'law of dominance' and 'law of recessiveness' do not represent the two main laws proposed by Mendel. Choice D is incorrect because 'law of mutation' and 'law of crossing over' are not part of Mendel's original laws.
What is the function of valves in arteries?
- A. To maintain high blood pressure for the proper diffusion of nutrients in capillaries.
- B. To prevent backflow of blood due to high pressure away from the heart.
- C. As a vestigial trait from evolution, like the appendix, that serves no purpose.
- D. Valves are absent in arteries but present in veins.
Correct Answer: B
Rationale: Valves in arteries serve the crucial function of preventing backflow of blood. Arteries carry blood at high pressure away from the heart, and the valves ensure that blood flows in one direction, towards the capillaries, to maintain efficient circulation. Without these valves, there would be a risk of blood flowing backward, compromising the effectiveness of blood circulation in the body. Choices A, C, and D are incorrect. Choice A incorrectly suggests that valves maintain high blood pressure for nutrient diffusion in capillaries, which is not their function. Choice C inaccurately compares valves to vestigial traits, like the appendix, implying they serve no purpose, which is untrue. Choice D is incorrect as valves are indeed present in arteries to regulate blood flow, not just in veins.
Which part of the brain controls the pituitary gland and regulates hunger, thirst, and body temperature?
- A. Thalamus
- B. Hypothalamus
- C. Medulla oblongata
- D. Cerebellum
Correct Answer: B
Rationale: The correct answer is B - Hypothalamus. The hypothalamus plays a crucial role in controlling the pituitary gland and regulating essential functions such as hunger, thirst, and body temperature. It acts as a vital link between the nervous system and the endocrine system, contributing to the maintenance of homeostasis in the body. Choice A, the Thalamus, is incorrect as it is primarily involved in relaying sensory information to the cerebral cortex. Choice C, the Medulla oblongata, is not responsible for regulating hunger, thirst, and body temperature; instead, it controls autonomic functions like breathing and heart rate. Choice D, the Cerebellum, is primarily associated with coordination and balance, not the regulation of endocrine functions or basic physiological needs.
Which type of tissue provides support and structure to the body?
- A. Muscle tissue
- B. Connective tissue
- C. Nervous tissue
- D. Epithelial tissue
Correct Answer: B
Rationale: Connective tissue is the correct answer as it provides support, structure, and strength to the body by holding tissues and organs in place. Muscle tissue is primarily responsible for movement, nervous tissue for communication, and epithelial tissue for covering and lining surfaces. While muscle tissue allows for voluntary and involuntary movement, nervous tissue transmits electrical signals, and epithelial tissue acts as a protective barrier and is involved in absorption and secretion. Therefore, in the context of providing support and structure, connective tissue is the most appropriate choice.
Which types of glial cells are in the PNS?
- A. Schwann cells, satellite cells
- B. Astrocytes, oligodendrocytes
- C. Microglia, ependymal cells
- D. Satellite cells, oligodendrocytes
Correct Answer: A
Rationale: The correct answer is A, which includes Schwann cells and satellite cells as the types of glial cells found in the peripheral nervous system. Schwann cells support neurons and myelinate axons, while satellite cells provide structural support and regulate the microenvironment around neurons in the PNS. Options B, C, and D are incorrect as they refer to glial cell types that are typically found in the central nervous system, not the peripheral nervous system. Astrocytes and oligodendrocytes are primarily located in the CNS, where they perform functions such as providing structural support and forming the blood-brain barrier. Microglia are immune cells found in the CNS responsible for immune defense and maintenance of neural environment, while ependymal cells line the cerebral ventricles and the central canal of the spinal cord, contributing to the production and circulation of cerebrospinal fluid.