Q21. What is the primary role of the somatic nervous system?
a) Regulating internal organ functions
b) Controlling voluntary muscle movements
c) Managing the body’s stress response
d) Regulating hormonal secretions
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Correct Answer: b) Controlling voluntary muscle movements
Explanation: The somatic nervous system primarily controls voluntary muscle movements. It is part of the peripheral nervous system and includes motor nerves that are responsible for relaying information from the brain and spinal cord to muscles, thereby enabling conscious movement and reflex reactions.
Q22. What part of the human brain is essential for forming new memories?
a) Cerebrum
b) Cerebellum
c) Hippocampus
d) Medulla oblongata
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Correct Answer: c) Hippocampus
Explanation: The hippocampus, a small region in the brain, is essential for forming new memories. It is a part of the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory, as well as in spatial memory that enables navigation.
Q23. Which hormone is released during the “fight or flight” response?
a) Insulin
b) Oxytocin
c) Adrenaline (epinephrine)
d) Progesterone
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Correct Answer: c) Adrenaline (epinephrine)
Explanation: Adrenaline (epinephrine) is released during the “fight or flight” response. It prepares the body to react to a perceived threat or stress by increasing heart rate, elevating blood pressure, boosting energy supplies, and enhancing the brain’s ability to make quick decisions.
Q24. What is the main function of rods in the human eye?
a) Detecting color
b) Focusing on details
c) Vision in bright light
d) Vision in low light
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Correct Answer: d) Vision in low light
Explanation: The main function of rods in the human eye is vision in low light conditions. Rods are more sensitive to light than cones but do not mediate color vision. They are primarily responsible for night vision and peripheral vision, helping us see in dimly lit environments.
Q25. Which gland in the human body regulates circadian rhythms?
a) Adrenal gland
b) Thyroid gland
c) Pineal gland
d) Pituitary gland
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Correct Answer: c) Pineal gland
Explanation: The pineal gland regulates circadian rhythms in the human body, primarily through the secretion of the hormone melatonin. This gland responds to light-dark cycles and helps regulate sleep patterns by increasing melatonin production in the dark (nighttime) and decreasing it in light (daytime), thus influencing the sleep-wake cycle.
Q26. What type of muscle is controlled by the autonomic nervous system?
a) Skeletal muscle
b) Cardiac muscle
c) Smooth muscle
d) Both b) and c)
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Correct Answer: d) Both b) and c)
Explanation: The autonomic nervous system controls both cardiac and smooth muscles. Cardiac muscle makes up the heart and is responsible for pumping blood throughout the body. Smooth muscle is found in the walls of internal organs such as the stomach, intestines, and blood vessels, and it helps regulate functions like blood flow and digestion. Unlike skeletal muscle, which is under voluntary control, cardiac and smooth muscles operate involuntarily.
Q27. Which part of the brain is primarily responsible for regulating heart rate and breathing?
a) Cerebrum
b) Cerebellum
c) Hypothalamus
d) Medulla oblongata
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Correct Answer: d) Medulla oblongata
Explanation: The medulla oblongata, a part of the brainstem, is primarily responsible for regulating vital body functions such as heart rate and breathing. It contains centers that control autonomic functions, including the cardiac center to regulate heart rate and the respiratory center to control the rate and depth of breathing.
Q28. What is the primary function of acetylcholine as a neurotransmitter in the human body?
a) Inducing sleep
b) Regulating mood
c) Stimulating muscle contraction
d) Controlling body temperature
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Correct Answer: c) Stimulating muscle contraction
Explanation: Acetylcholine’s primary function as a neurotransmitter is to stimulate muscle contraction. It is released at neuromuscular junctions and binds to receptors on muscle cells, triggering a series of events that lead to muscle contraction. Acetylcholine is also involved in many other functions in the nervous system, including memory and learning.
Q29. What is the term for the minimum level of stimulus required to activate a neuron?
a) Threshold
b) Capacitance
c) Resistance
d) Impedance
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Correct Answer: a) Threshold
Explanation: The term ‘threshold’ refers to the minimum level of stimulus required to activate a neuron. It is the critical level to which a membrane potential must be depolarized to initiate an action potential, which is an electrical impulse that travels along the nerve fiber. When the threshold is reached, the neuron fires, transmitting information.