Question

Which of the following actions are reflex actions?
I. Movement of the diaphragm during respiration
II. Coughing
III. Yawning
IV. Sneezing
V. Removal of hand on being touched by hot object

A. II and V only
B. III, IV and V only
C. IV and V only
D. I, II, III, IV and V

Answer 1

Hint: A reflex, also known as a reflex action, is an involuntary, unplanned, and nearly instantaneous movement in response to a stimulus in biology. Reflexes are made possible by reflex arcs, which are neuronal circuits that can act on an impulse before it reaches the brain. A reflex is an involuntary reaction to a stimulus that does not require or receive conscious cognition.

Complete answer:
Let us solve this question by analyzing each of the given actions and will determine which of the provided examples are reflex actions.
1. Movement of diaphragm during respiration is an involuntary action and is not a reflex action.
2. Coughing is an example of reflex action as it is an unplanned involuntary action in response to irritants entering our respiratory tract.
3. Yawning is not a reflex action as it occurs involuntarily when our body has a deficit of oxygen.
4. Sneezing also occurs involuntarily and is not a reflex action.
5. Removal of hands on being touched by hot objects is a reflex action as it occurs involuntarily in an unplanned sequence of events as our senses and motor neurons act altogether in an arc.
Based on the above analysis we can easily predict that Option A is correct which states Coughing and removal of hands on being touched by hot objects as examples of reflex actions.
Thus, Option: B, C and D are incorrect.

Note:
A reflex arc is the neural pathway followed by a reflex action. A simple reflex arc, for example, occurs when we inadvertently touch something hot.
1. A stimulus is detected by a skin receptor (the change in temperature).
2. A relay neuron / interneuron in the CNS's spinal cord receives electrical impulses from a sensory neuron. Sensory neurons and motor neurons are connected by relay neurons.
3. An effector receives electrical signals from a motor neuron.
4. A response is produced by an effector (muscle contracts to move the hand away).