Class 10 - Biology - Control and Coordination

Question 1.

Which of the following is a plant hormone?

  • Insulin
  • Thyroxin
  • Oestrogen
  • Cytokinin

Answer.

Insulin, oestrogen and thyroxin are hormones found in humans. Cytokinin is a plant hormone. Hence, the answer is (d) cytokinin.

Question 2.

The gap between two neurons is called a

  • dendrite
  • synapse
  • axon
  • impulse

Answer.

The gap between two neurons is called as synapse. Hence, the answer is (b) synapse.

 

 

Question 3.

The brain is responsible for

  • thinking
  • regulating the heart beat
  • balancing the body
  • all of the above

Answer.

The brain is responsible for thinking, regulating the heartbeat and balancing the body. Hence, the answer is (d) all of the above.

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 the sensory structures in our body. They are present in our sense organs (eyes, ears, skin, nose, tongue).

They receive the signals from environment and send this signal to our brain and brain responds to the external stimuli.

For example, if eyes see a dog running towards you, your eyes will send this signal to brain and you will escape to a safe place.

If these receptors do not function properly, our brain will not receive signals about the external stimulus.

For example, if our hands accidently touch a hot object, damaged receptors cannot perceive the external stimuli of heat and pain.

 

 

Question 5.

Draw a structure of neuron and explain its function.

Answer.

The structure of neuron is below.

 

A neuron is divided into three parts:

  • Cell body: contains cytoplasm and nucleus.
  • Dendrites: small fibers around the cell body.
  • It receives information from axon of another cell and conducts messages towards the cell body.
  • Axon: longest fibers in the neuron. It conducts messages away from cell body.

Function of Neuron:

Neurons are the functional unit of nervous system. They help in conduction of information.

Dendrite receives information from another neuron and passes it to the axon.

Finally axon ending passes the information into next neuron at the synapse.

Chemicals in neurons pass on the impulse to next neuron, these are called as neurotransmitters.

 Class_10_Biology_Control_&_Coordination_Neuron

 

Question 6.

How does phototropism occur in plants?

Answer.

The growth of plants in response to light stimulus is called phototropism.

Roots are negatively phototropic, as they grow away from light.

Shoots are positively phototropic, they grow towards light. Sunflower is positively phototropic and hence moves with sun from east to west.

 

 

Question 7.

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

Answer.

If spinal cord is disrupted, following signals will be disrupted:

  • Reflex action – involuntary actions controlled by spinal cord.
  • Impulses from brain and various parts of the body will not be conducted as all the nerves of the body meet in spinal cord.

 

 

Question 8.

How does chemical coordination occur in plants?

Answer.

Plants do not have nervous system as animals. But they respond to stimuli by showing movements.

Plants have chemical substances called hormones which control and coordinate the growth, development and response to the environment.

When sunlight falls on the shoot from one side, auxins move toward shady portion causing shady region to grow faster and shoot bends towards light.

 

 

Question 9.

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

Answer.

An organism is composed of various organs which need to work in a coordinated way.

All the movements occurring in our body are carefully controlled and coordinated.

In animals, nervous system controls and coordinates these movements.

The nervous system sends messages to and away from the brain. The spinal cord plays an important role in the relays of these messages.

In the absence of this system our body will not be able to function properly.

 

 

Question 10.

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

Answer.

Involuntary actions cannot be consciously controlled. For example: contraction of muscles, heartbeat and breathing.

These are regulated by medulla oblongata.

Reflex actions are spontaneous and are produced in response to a stimulus. They are controlled by spinal cord.

For example: removal of hand when we accidently touch a hot object.

 

 

Question 11.

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

Answer.

 

Nervous Mechanisms

Hormonal Mechanisms

1

Made up of neurons.

Made up of glands.

2

Messages are transmitted in the form of electrical impulses.

Messages are transmitted in form of chemicals called hormones.

3

Messages are transmitted by nerve fibers.

Messages are transferred via blood stream.

4

Rapid transmission of messages and quick responses.

Slow transmission of messages and slow responses.

 

 

 

Question 12.

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

Answer.

Movement in our legs is due to the pull in the leg muscles. Movement in plants say in Mimosa occurs due to external stimulus touch.

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