Q11. What is the primary function of myelin sheath in nerve cells?
a) Transmitting nerve signals
b) Protecting nerve cells
c) Insulating nerve fibers
d) Regenerating nerve cells
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Correct Answer: c) Insulating nerve fibers
Explanation: The myelin sheath is a fatty layer that covers nerve fibers, providing insulation and increasing the speed of electrical transmission along the nerve cells. This sheath enables efficient transmission of nerve impulses, particularly in neurons that need to rapidly transmit signals over long distances, such as those in the brain and spinal cord.
Q12. Which hormone regulates the body’s metabolic rate?
a) Insulin
b) Adrenaline
c) Thyroxine
d) Cortisol
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Correct Answer: c) Thyroxine
Explanation: Thyroxine, a hormone produced by the thyroid gland, plays a crucial role in regulating the body’s metabolic rate. It influences the rate at which cells use energy, thus affecting body temperature, weight, energy levels, and heart rate. Proper functioning of the thyroid gland and adequate production of thyroxine are essential for overall health and metabolism.
Q13. Which part of the human brain is responsible for memory and learning?
a) Medulla oblongata
b) Hypothalamus
c) Cerebellum
d) Cerebrum
Correct Answer: d) Cerebrum
Explanation: The cerebrum, the largest part of the brain, is primarily responsible for memory, learning, and intelligence. It encompasses areas involved in processing sensory information, reasoning, problem-solving, emotions, and controlling voluntary movements. The cerebral cortex, particularly the hippocampus, is crucial for forming and retrieving memories.
Q14. What is the term used for the body’s ability to maintain a stable internal environment?
a) Metabolism
b) Hemostasis
c) Homeostasis
d) Symbiosis
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Correct Answer: c) Homeostasis
Explanation: Homeostasis refers to the body’s ability to maintain a stable internal environment despite changes in external conditions. This involves regulating factors like temperature, pH balance, and fluid balance, ensuring that bodily functions operate within a narrow range of normalcy. Homeostasis is vital for health and survival.
Q15. Which part of the eye is responsible for its color and controls the size of the pupil?
a) Lens
b) Retina
c) Iris
d) Cornea
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Correct Answer: c) Iris
Explanation: The iris is the colored part of the eye that controls the size of the pupil. It contains muscles that adjust the pupil size in response to light intensity. When it’s bright, the iris contracts making the pupil smaller, and in dim light, the iris dilates, enlarging the pupil to allow more light to enter.
Q16. Which part of the human brain coordinates voluntary muscle movements?
a) Cerebellum
b) Cerebrum
c) Medulla oblongata
d) Hypothalamus
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Correct Answer: a) Cerebellum
Explanation: The cerebellum plays a crucial role in coordinating voluntary muscle movements. Located at the back of the brain under the cerebrum, it ensures that voluntary movements such as walking, speaking, and writing are smooth and precise. It doesn’t initiate movement but contributes to coordination, precision, and accurate timing.
Q17. What is the function of synapses in the nervous system?
a) To produce neurotransmitters
b) To connect muscles to bones
c) To transmit signals between neurons
d) To filter blood
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Correct Answer: c) To transmit signals between neurons
Explanation: Synapses are junctions where neurons communicate with other neurons, muscle cells, or gland cells. They transmit signals between neurons through the release and reception of neurotransmitters. These signals can be excitatory or inhibitory, which can stimulate or inhibit the action of the receiving neuron.
Q18. Which hormone is known as the “stress hormone”?
a) Adrenaline
b) Cortisol
c) Insulin
d) Estrogen
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Correct Answer: b) Cortisol
Explanation: Cortisol is often referred to as the “stress hormone” because of its role in the body’s stress response. Produced by the adrenal glands, cortisol helps the body manage stress by increasing blood sugar levels, enhancing the brain’s use of glucose, and increasing the availability of substances that repair tissues. It also suppresses nonessential functions that might be detrimental in a fight-or-flight situation.
Q19. What part of the human eye changes shape to focus light on the retina?
a) Cornea
b) Lens
c) Pupil
d) Iris
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Correct Answer: b) Lens
Explanation: The lens of the human eye changes shape to focus light onto the retina. This flexible, crystalline structure adjusts its thickness (a process known as accommodation) to bend light rays, ensuring they properly hit the retina. This allows for clear vision of objects at varying distances.
Q20. What is proprioception?
a) The sense of smell
b) The sense of touch
c) The body’s ability to perceive its position and movement
d) The ability to taste
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Correct Answer: c) The body’s ability to perceive its position and movement
Explanation: Proprioception is the body’s ability to sense its own position, movement, and action in space. It is often referred to as the “sixth sense.” Proprioceptors, located in muscles, tendons, and joints, provide information about body position and muscle tension, allowing for coordinated and skilled movements.