Science Class- 10

Class 10 - Chapter 6: Control and Coordination

NCERTChapter 6Solution

Q1. Which of the following is a plant hormone?

Answer: (d) Cytokinin.

Cytokinin is a plant hormone that promotes cell division and growth in plants.

Q2. The gap between two neurons is called a

Answer: (b) Synapse.

A synapse is the junction between two neurons where nerve impulses are transmitted through chemical signals.

Q3. The brain is responsible for

Answer: (d) All of the above.

The brain controls thinking, regulates heartbeat and breathing, and helps in maintaining body balance.

Q4. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

Receptors are specialized sensory cells that detect changes (stimuli) in the environment and send information to the brain or spinal cord.

Functions of Receptors:

Detect light, sound, smell, taste and touch.
Receive information from the surroundings.
Initiate appropriate responses.

If receptors do not function properly:

Eyes may fail to detect light, causing vision problems.
Ears may fail to detect sound, causing hearing loss.
Skin may not detect pain or temperature changes.
Nose and tongue may lose the ability to smell and taste.

Q5. Draw the structure of a neuron and explain its function.

       Dendrites
          /|\
         / | \
        /  |  \
      Cell Body
          |
          |
        Axon
          |
          |
   Axon Terminals

Function of Neuron:

A neuron is the structural and functional unit of the nervous system.

Dendrites receive impulses.
Cell body processes information.
Axon carries impulses away from the cell body.
Axon terminals transmit impulses to another neuron or effector organ.

Q6. How does phototropism occur in plants?

Phototropism is the growth movement of a plant in response to light.

When light falls on one side of the shoot, the plant hormone auxin moves to the shaded side.

The cells on the shaded side grow faster, causing the shoot to bend towards the light.

Q7. Which signals will get disrupted in case of a spinal cord injury?

The spinal cord carries messages between the brain and different parts of the body.

Injury to the spinal cord disrupts:

Sensory signals from body parts to the brain.
Motor signals from the brain to muscles.
Reflex actions controlled by the spinal cord.

This may lead to loss of sensation, movement and reflex responses below the injured region.

Q8. How does chemical coordination occur in plants?

Chemical coordination in plants occurs through plant hormones called phytohormones.

These hormones regulate various activities such as growth, flowering, fruit ripening and response to stimuli.

Examples:

Auxins – promote growth.
Gibberellins – stimulate stem elongation.
Cytokinins – promote cell division.
Abscisic acid – inhibits growth.

Q9. What is the need for a system of control and coordination in an organism?

Control and coordination help different organs and organ systems work together efficiently.

Importance:

Maintains balance within the body.
Allows response to environmental changes.
Coordinates activities of different organs.
Ensures survival and proper functioning of the organism.

Q10. How are involuntary actions and reflex actions different from each other?

Involuntary Actions	Reflex Actions
Occur automatically without conscious control.	Occur instantly in response to a stimulus.
Controlled mainly by the brain.	Controlled mainly by the spinal cord.
Examples: Heartbeat, breathing, digestion.	Examples: Withdrawal of hand from a hot object, blinking.
Usually continuous processes.	Usually sudden and protective responses.

Q11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Nervous System	Hormonal System
Uses nerve impulses.	Uses hormones.
Signals travel through neurons.	Signals travel through blood.
Acts very quickly.	Acts relatively slowly.
Effects are short-lived.	Effects are long-lasting.
Controls immediate responses.	Controls growth, development and metabolism.

Q12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?

Sensitive Plant (Mimosa)	Movement in Human Legs
Movement occurs due to changes in water content (turgor pressure) in cells.	Movement occurs due to contraction and relaxation of muscles.
No muscles are present.	Muscles and bones are involved.
Response is controlled by plant hormones and electrical signals.	Response is controlled by the nervous system.
Movement is generally slow.	Movement is usually faster.