Question

Statements (A, B, C, D) in List I have to be matched with statements (p, q, r, s) in List II.

List I	List II
A-Cyton	p-The body of the nerve cell that contains the organelles.
B-Dendrite	q-Receives the stimuli sent from another nerve or the outside environment.
C-Axon	r-A fatty substance that covers the axon of the nerve cell and speeds.
D-Myelin sheath	s- The long, thin section of the nerve cell where the impulse is transmitted across.

A) A-p, B-q, C-s, D-r
B) A-r, B-q, C-s, D-p
C) A-r, B-s, C-q, D-p
D) A-r, B-s, C-p, D-q

Answer 1

Hint: The cyton, axons, dendrite and myelin sheath are the structures present in the neuron. Neurons are the structural and functional unit of the nervous system. All these structures together help in transmission of impulses.

Complete answer:
To answer this question, we must know the structure of neurons. The neurons are the structural and functional unit of the nervous system. They receive electrical and chemical signals through which they help in maintaining the coordination of our body.

The neurons comprise of the following parts-
Cyton- It is known as the body. It contains a nucleus. It receives the nerve impulses from the dendrites of the other neurons. (Correct match is p)
Dendrite- Dendrite are the fine cellular projections from the cyton. They receive the impulses and pass it to the cyton. (Correct match is q)
Axon- They are the nerve fibers which are the projections of the nerve cell. It carries the nerve impulses from the cyton. (Correct match is s)
Myelin sheath- These are the sheets made up of lipids surrounding the axons. It prevents any leakage of the impulses from the axons. (Correct match is r)

The diagram below represents the structure of neurons.

Thus the correct answer is option ‘A’.

Additional Information: Neurons are absent in the nervous system of sponges and placozoa.Plants and fungi do not have nerve cells.
And also some unknow facts about neurons
- Average no. of neurons in the human brain = 100 billion.
- Average no. of neurons in the octopus brain = 300 million.
- Rate of neuron growth during fetal development in utero = 250,000 neurons/minute

Note: Synapse is the small gap at the end of the neurons. The two neurons are joined by a synapse. It secretes neurotransmitters like acetylcholine which helps in transmission of impulses. At synapse, one neuron sends the message or impulse to the other.