Control and Coordination

Class 10 NCERT Science


1   What is the difference between a reflex action and walking?

Solution :

A reflex action is a rapid, automatic response to a stimulus. It does not involve any thinking. For example, we close our eyes immediately when the bright light is focused. Walking, on the other hand, is a voluntary action. It is under our conscious control. The response to the reflex action is generated at the spinal cord whereas walking is under the control of the motor area of the brain.

2   What happens at the synapse between two neurons?

Solution :

A very small gap that occurs between the last portion of axon of one neuron and the dendron of the other neuron is known as a synapse. It acts as a one way valve to transmit impulses in one direction only. This uni-direction transfer of impulses occurs as the chemicals or neurotransmitters are produced in only one side of the neuron i.e., the axon’s side. From axon, the impulses travel across the synapse to the dendron of the other neuron.A synapse or neuromuscular junction

3   Which part of the brain maintains posture and equilibrium of the body?

Solution :

Cerebellum, a part of hindbrain is responsible for maintaining posture and equilibrium of the body.

4   How do we detect the smell of an agarbatti (incense stick)?

Solution :

The thinking part of our brain is the forebrain. It has separate areas that are specialized for hearing, smelling, sight, taste, touch, etc. The forebrain also has regions that collect information or impulses from the various sensory receptors. When the smell of an incense stick reaches us, our olfactory receptors detect it . Then, the forebrain interprets it by putting it together with the information received from other receptors and also with the information already stored in the brain as memory.

5   What is the role of the brain in reflex action?

Solution :

Reflex actions are sudden and involuntary responses, which do not involve any thinking. The sensory nerves that detect the stimulus are connected to the motor nerves that move the muscles. Such a connection of detecting the signal from the receptors (input) and responding to it quickly (output) through effectors is called a reflex arc. The reflex arc is the pathway for signaling between receptors and effectors in a reflex action. The signaling is through the actions of the sensory and motor neuron which connect to each other in the spinal cord. Reflex arcs are formed in the spinal cord but the information (input) reaches the brain. The brain is only aware of the signal and the response that has taken place. Brain stores this information in the memory. This is helpful in conditioning of certain reflexes. However, the brain has no role to play in the creation of the response.