NCERT Class X Science Solutions: Chapter 7 – Control and Coordination Part 1

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Question 1:

Which of the following is a plant hormone?

  1. Insulin

  2. Thyroxin

  3. Oestrogen

  4. Cytokinin

Answer:

The molecule that is responsible for this was named kinetin. Soon after, a substance that had the same biological effect as kinetin was found in plants, it stimulated plant cells to divide when in culture with Auxin.

Cytokinins are produced in the root apical meristems and travel upward hitching a ride with water and traveling up the stem through the xylem.

Cytokinins are the fountain of youth in plants. They delay senescence or the natural aging process that leads to death in plants.

Question 2:

The gap between two neurons is called a

  1. Dendrite.

  2. Synapse.

  3. Axon.

  4. Impulse.

Answer:

The gap between two neurons is called a synapse. It forms a physical gap between the pre-synaptic and post-synaptic neurons.

An action potential cannot cross the synaptic gap, so it triggers the release of chemicals to continue the signal.

This diagrma shows gap between two neurons is a Synapse

Gap between Two Neurons is a Synapse

Question 3:

The brain is responsible for

  1. Thinking.

  2. Regulating the heartbeat.

  3. Balancing the body.

  4. All of the above.

Answer:

The brain is responsible for thinking, regulating the heart beat and balancing the body. In short, brain is responsible for every physical and mental activity of the body.

It is made of white and grey matter. The four major structure of the brain: Cerebrum, Cerebellum, Diencephalon and Brain Stem

Question 4:

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

Answer:

Receptors are sensory structures (organs/tissues or cells) present all over the body. The receptors are either grouped in case of eye or ear, or scattered in case of skin.

Functions of receptors:

  • They sense the external stimuli such as heat or pain.

  • They also trigger an impulse in the sensory neuron which sends message to the spinal cord.

When the receptors are damaged, the external stimuli transferring signals to the brain are not felt. For example, in the case of damaged receptors, if we accidentally touch any hot object, then our hands might get burnt as damaged receptors cannot perceive the external stimuli of heat and pain.

Question 5:

Draw the structure of a neuron and explain its function.

Answer:

Neurons are the functional units of the nervous system. The three main parts of a neuron are axon, dendrite and cell body.

Result for structure of a neuron

Structure of a Neuron

Functions of the three parts of a neuron:

  • Axon: It conducts messages away from the cell body. D

  • Dendrite: It receives information from axon of another cell and conducts the messages towards the cell body.

  • Cell body: It contains nucleus, mitochondria, and other organelles. It is mainly concerned with the maintenance and growth.

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