NIOS Class 12 Biology Chapter 17 Coordination and Control: The Nervous and Endocrine System

NIOS Class 12 Biology Chapter 17 Coordination and Control: The Nervous and Endocrine System Solutions to each chapter is provided in the list so that you can easily browse throughout different chapters NIOS Class 12 Biology Chapter 17 Coordination and Control: The Nervous and Endocrine System Notes and select need one. NIOS Class 12 Biology Chapter 17 Coordination and Control: The Nervous and Endocrine System Question Answers Download PDF. NIOS Study Material of Class 12 Biology Notes Paper 314.

NIOS Class 12 Biology Chapter 17 Coordination and Control: The Nervous and Endocrine System

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Also, you can read the NIOS book online in these sections Solutions by Expert Teachers as per National Institute of Open Schooling (NIOS) Book guidelines. These solutions are part of NIOS All Subject Solutions. Here we have given NIOS Class 12 Biology Chapter 17 Coordination and Control: The Nervous and Endocrine System Solutions, NIOS Senior Secondary Course Biology Solutions for All Chapter, You can practice these here.

Coordination and Control: The Nervous and Endocrine System

Chapter: 17




1. With the help of a flow chart write down the basic components of the nervous system in the space given below.


Ans: See fig. here:

2. Name the ganglia which:

(a) forms the brain.

Ans: The Supraoesophageal Ganglion.

(b) lies below the oesphagus and is joined to brain.

Ans: (b) The Suboesophageal Ganglion.

3. Which part of nervous system of cockroach can be compared to our spinal cord though our spinal cord is dorsal and this part of nervous system of cockroach is ventral? 

Ans: Ventral Nerve cord.

4. Name the main parts of the brain. 

Ans: The cerebrum, cerebellum, medulla oblongata, thalamus and hypothalamus are main parts of brain.

5. Mention the one function of each:

(i) Cerebrum ___________.

Ans: Intelligence/thinking/reasoning/memory.

(ii) Cerebellum __________.

Ans: Balance/muscular coordination.

(iii) Medulla oblongata ___________.

Ans: Involuntary actions.

(iv) Hypothalamus ___________.

Ans: homeostasis or Steddy state.

3. What are the:

(i) gray matter. and

Ans: The gray matter is composed of neu-ron cell bodies.  

(ii) white matter made of? 

Ans: White matter composed of axon fibres. 

4. Name the fluid in the cavities of the brain.

Ans: Cerebrospinal fluid (CSF).


1. What are the two subdivisions of the autonomic nervous system?

Ans: (i) Sympathetic nervous system. and 

(ii) Parasympathetic nervous system.

2. Name the specific subdivisions of the autonomic nervous system concerned with the following:

(i) Slowing down heart beat __________.

Ans: Parasympathetic Nervous Systems.

(ii) Increasing salivary secretion ___________.

Ans: Parasympathetic Nervous System.

(iii) Dilation of the pupil ___________.

Ans: Sympathetic Nervous System.

(iv) Increasing intestinal peristalsis ___________.

Ans: Parasympathetic Nervous System.

(v) Muscle contraction of the urinary bladder giving the feeling for the need for urination ___________.

Ans: Parasympathetic Nervous System.

3. Why is the peripheral nervous system called so?

Ans: As it connects periphery (surface) of the body.

4. State the alternative terms for sensory and motor nerves.

Ans: (i) Sensory=Afferent.

(ii) Motor = Efferent.


1. Given below are a few examples of reflexes. Write against each, the category of reflex, whether simple or conditioned.

(i) Knee jerk ____________.

Ans: Simpler.

(ii) Salivation on seeing a favourite dish ___________.

Ans: conditioned.

(iii) Tying of shoe laces while talking ___________.

Ans: conditioned.

(iv) Closing of eyelids if a strong beam of light is flashed across ___________.

Ans: simple.

(v) Mistaking a coiled rope as snake if you happen to step on it in darkness ___________.

Ans: conditioned.


1. State the functions of the following parts of the eye:

(i) Iris.

Ans: Iris contracts and dilates pupil.

(ii) Ciliary muscles.

Ans: Ciliary muscles help in near vision/contracts to make lens thicker.

(iii) Pupil.

Ans: Pupil controls amount of light entering the eye.

(iv) Vitreous humour.

Ans: Vitreous humour maintains shape of the eyeball and protects the retina.

(v) Retina.

Ans: Retina produces nerve impulses into the optic nerve.

2. Name the following:

(i) Area of sharp vision in the eye __________.

Ans: Yellow shot.

(ii) The kind of lens used for correcting nearsightedness __________. 

Ans: concave lens.

(iii) The condition in which the lens of eye turns opaque __________. 

Ans: cataract.

(iv) The capacity of eye to focus objects at different distances __________. 

Ans: accommodation. 


1. Which part of the ear is involved when:

(i) a gymnast performs various balancing feats __________. 

Ans: Vestibule.

(ii) you hear a song __________. 

Ans: Cochlea.

2. Name the following:

(i) The part into which the sound waves are directed by the ear pinna.

Ans: Auditory meatus.

(ii) The kind of balance with which the semicircular canals are concerned.

Ans: static balance.

(iii) Any two sensations felt through free nerve endings in the skin.

Ans: touch/pressure/warmth/cold.


1. Name the following:

(i) The organ in the neck on the trachea close to which thyroid is located. 

Ans: Larynx.

(ii) The condition caused due to oversecretion of thyroxin. 

Ans: Cretinism.

(iii) The hormone concerned with facing dangers. 

Ans: Adrenaline.

(iv) The condition of passing much glucose in the urine. 

Ans: Diabetes mellitus.

(v) The source gland of ADH.

Ans: Posterior pituitary gland.

2. What are pheromones?

Ans: It is “a secretion from one individual which is given out into environment; it elicits a response in other members of the same species.”


1. Name the two divisions of the nervous system.

Ans: Two divisions of nervous system are:

(i) CNS (central neurons system). and 

(ii) PNS (peripheral nervous system).

2. What is gray matter?

Ans: The gray matter is made of neuron cell bodies.

3. Name the chemical involved in the transmission of nerve impulse across a synapse.

Ans: Acetylcholine.

4. Give two examples of sensory nerves.

Ans: The cranial nerves received from the 

(i) eyes. and 

(ii) ears.

5. Name the respective areas of the retina concerned with best vision and no vision.

Ans: (i) Best vision = Yellow spot.

(ii) No vision = Blind spot.

6. What is the role of the eustachian tube in the ear?

Ans: It maintains the balance of air/pressure on both the sides of eardrum and allows it to vibrate freely.

7. Name the hormone and its source glands, whose deficiency leads to diabetes insipidus.


HormoneSource glandDeficiency
1. ADH or PosteriorPosterior lobe of Pituitary glandCauses diabetes insipidus

8. What are pheromones?

Ans: Pheromones: They are chemical subs-tances produced by the individuals. They affect another individual. Pherin means bears, and mone means of hormone. Example: The common ants follow the same path on floor or wall as the path is laid down by a secretion of pheromones from the body of travelling ants. Some other examples are given below:

(a) The female of a moth species gives out a scent to attract a male from a distance of about 3-4 kilometres.

(b) When honey-bees are hurt or disturbed they give an alarm pheromone from their sting and mandibles to alert all other members of the colony to face the problem created. 

9. Name and explain the event that happens immediately when a nerve fibre gets stimulated.

Ans: The initiation of nerve impulse is done by depolarisation of an axonal membrane. So it propagates due to opening of some Na⁺ on channel. It facilitates opening of other adjacent channels creating a wave of depolarization to travel down axonal membrane. The stimulus need to open through Na+ channels to initiate depolarization is threshold stimulus. Impulse traversing a given nerve fibre have same amplitude differing only in frequency. Nerve follow “all or none law. Saltatory conduction occurs in myelinated fibres. 

10. Are the endocrine glands and the ductless glands one and the same thing? Give one example.

Ans: Endocrine glands: Unicellular organisms coordinate their different activities and respond to various stimuli. But in the body of higher animals these are certain glands which produce certain chemical substances known as hormones. It is poured directly in the blood without the help of any duct. These glands, therefore, are termed as ductless glands or endocrine glands.

The secretions of such glands are known as hormones or autocoids.

The word endocrine means internal secretion and hormone means to excite, to stir up or stimulate. Example is pituitary gland.

11. Describe any one example of condition reflex in the humans.

Ans: You apply brakes in your car or cycle when you see somebody suddenly approaching in front of you.

12. List the functions of medulla oblongata.

Ans: Functions of Medulla Oblongata: It is last part of brain that remains connected to spinal cord. Its functions are:

(a) Center for breathing, coughing and swallowing.

(b) Controls heart beat, movement of alimentary canal and several other involuntary actions.

13. Differentiate between sympathetic and parasympathetic nervous systems. 

Ans: Difference between Sympathetic and Parasympathetic Nervous System:

Sympathetic Nervous SystemParasympathetic Nervous System
1. The components of parasympathetic nervous system are consolidated.The components parasym-pathetic nervous system are isolated.
2. The ganglia are linked up to form a chain.The ganglia remain isola-ted.
3. The preganglionic fibres emerge with spinal nerves only (thoracicolum-ber outflow).The preganglionic fibres emerge with cranial as well as spinal nerves (craniosacral outflow).
4. Its preganglionic fibres branch, enter several ganglia and transmit nerve impulses to many postganglionic fibres. Therefore, they produce a widespread effect.Its preganglionic fibres do not branch, each enters a single ganglion and transmits nerve impulses to a single postganglionic fibre. They produce a limited effect.
5. Preganglionic fibres are shorter than the postganglionic fibres.Preganglionic fibres are much longer than the postganglionic fibres.
6. Postganglionic fibres are mostly adrenergic.Postganglionic fibres are cholinergic.

14. What are the two principal tasks of insulin?

Ans: The two principal tasks of Insulin are:

(i) Insulin promotes glucose utilisation by body cells.

(ii) Insulin stimulates deposition of extra glucose in blood as glycogen in liver.

15. Explain following terms:

(i) synapse.

Ans: Synapse: It is a junction between two neurons.

(ii) stimulus. and 

Ans: Stimulus: An agent/a sudden change of external or internal environment which results in a change in activities of an organism.

(iii) impulse.

Ans: Impulse: “It is a wave of electrical disturbance which travels across nerve cell and its fibre”.

16. Draw a diagram to show the arrangement of the bones inside the middle ear. 

Ans: (See Fig.)

Fig. 17.13. Ear of man showing 3 bones of middle ear-incus, malleus and stapes.

17. Write short notes on the following:

(i) myopia.

Ans: Myopia: Eye defect in which a person is able to see the nearby objects clearly and not the distant objects.

(ii) taste buds.

Ans: Taste buds: They give taste sense and are about 9000 in humans on their tongue.

(iii) accommodation of the eye.

Ans: Accommodation: It is focussing the image of retina.

18. How do sympathetic and parasympathetic nervous system act differently on 

(i) pupil of the eye. and 

(ii) urinary bladder?


OrganAction of Sympathetic nervous systemAction of Parasympathetic nervous system
(i) Pupil of eyeIt dialatesIt constricts.
(ii) Urinary bladderIt relaxesIt constricts.

19. Draw a labelled diagram of the cross section of the spinal cord and the nervous pathway of a simple reflex concerned with it. 

Ans: (See Fig.)

Fig. 17.14. Nerve pathways in a Simple Reflex Action.

20. Explain the role of ciliary muscles in our eyes.

Ans: Role of ciliary muscles in our eyes: They regulate the size of pupil and this controls the amount of light passing to retina.

21. Taking the example of thyroxine secretion, explain what is meant by feedback mechanism?

Ans: Feedback Mechanism of Thyroid Activity: The hypothalamus releases TSH-RH (TSH-Releasing Hormone) that instructs anterior pituitary gland release to TSH (thyroid stimulating hormone. TSH stimulates thyroid to release thyroxine hormone). If level of thyroxine in blood increases, pituitary stops release of TSH. If level of thyroxine become still higher, then inhibition of release of thyroxine occurs level of pituitary and at the level of hypophysis to inhibit release of TSH-RH. When level of thyroxine falls in blood, thyroid gets stimulated to secrete more of it. The starting point of an activity receives back information either to continue or to increase, or even to slow down or even to stop also.

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