Reflex action

Correct answer: A. Spinal cord

A reflex action must occur quickly to protect the body. In a typical reflex arc, the sensory impulse enters the spinal cord, is processed through an interneuron, and a motor impulse is sent to the effector muscle. The brain may receive information afterward, but it is not required to initiate the immediate response. Therefore, option A, the spinal cord, is correct; the heart, liver, and stomach do not serve as the main reflex-control centre.

Correct answer: A. Reflex action

Touching a hot object stimulates pain and temperature receptors in the skin. The sensory impulse travels through a sensory neuron to the spinal cord, where a rapid response pathway activates muscles to withdraw the hand before conscious awareness is complete. This automatic protective response is a reflex action. Therefore option A is correct; voluntary, growth, and hormonal actions do not describe this immediate withdrawal.

Correct answer: A. Spinal cord

During a typical reflex action, the sensory impulse reaches the spinal cord, which rapidly coordinates the motor response through a reflex arc. This short route helps protect the body by withdrawing the hand before the brain fully interprets the pain. The brain receives information afterward and can become aware of the event, but the spinal cord mainly organizes the immediate response. Hence option A is correct.

Correct answer: A. Reflex arc

A reflex arc is the complete neural pathway followed during a reflex action. It usually includes a receptor, sensory neuron, relay neuron in the spinal cord, motor neuron, and effector. The pathway carries information from the stimulus to the responding muscle or gland. A neuron is only one cell, while hormonal and blood paths are not the named neural route. Therefore, option A is correct.

Correct answer: B. Reflex action

A reflex action is a rapid, automatic response to a stimulus that protects the body before deliberate conscious thinking is completed. For example, touching a hot object can cause the hand to withdraw through a reflex arc involving sensory neurons, the spinal cord and motor neurons. Thus option B is correct. Digestion, respiration and growth are important physiological processes, but they do not describe this immediate protective response.

Correct answer: B. Giving quick response

A reflex arc is the neural pathway followed during a reflex action. It commonly carries information from a receptor through a sensory neuron to the spinal cord and then through a motor neuron to an effector, allowing a rapid response to danger. Hence option B is correct. Detecting taste may involve sensory receptors, digestion involves the digestive system, and filtering blood is a kidney function; none defines a reflex arc.

Correct answer: A. In escaping danger quickly

A reflex action is a rapid, automatic response to a stimulus. In many protective reflexes, the pathway through the spinal cord produces an immediate response before conscious analysis by the brain is complete. This shortens reaction time and helps prevent injury, so option A is correct. Slow growth, food storage, and sleep are regulated processes, but they are not the main situations requiring a rapid reflex response.

Correct answer: A. It produces a quick response to a harmful stimulus

A reflex action is a rapid, automatic response to a potentially harmful stimulus, such as withdrawing the hand from a hot object. Receptors detect the stimulus, the spinal cord organizes the immediate response, and muscles move before conscious decision-making is complete. Thus option A is correct; the other options have no role in reflex protection.