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NCERT Solutions for Class 11 Biology Chapter 21 - Neural Control and Coordination: The chapter-by-chapter answers to every question in the Class 11 NCERT textbook are provided to students in NCERT Solutions for Class 11. You may have learned in earlier classes that the functions of our organs and organ systems in our body have been coordinated with the neuron system. The most recent CBSE Syllabus has been updated in NCERT Solutions.
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CBSE NCERT Solutions for Class 11 Biology Chapter 21 Neural Control and Coordination will also walk you through the fact that the supply of oxygen increases while performing physical activities. For example, when you do physical exercises, you will see the energy demand increase to maintain the increased muscular activity. You will understand in Neural Control and Coordination NCERT that this increased supply of oxygen necessitates an increase in the rate of respiration, heartbeat, and blood flow via blood vessels. When you stop physical exercise, the activities of the nerves, lungs, heart, and kidneys gradually return to their normal conditions. You will find questions based on these concepts in Class 11 Chapter 21 Biology NCERT Solutions.
Biology Class 11: In NCERT Solutions for Class 11 Biology Chapter 21 - Neural Control and Coordination, you will get answers to the topics related to the functions of muscles, lungs, heart, blood vessels, kidneys, and other organs. You will study in Neural Control and Coordination NCERT Solutions that the neural system and the endocrine system jointly coordinate and integrate the activities of all the organs so that they function in a synchronized manner. If you are looking for an answer from any other chapter, even from any other class, then go with NCERT Solutions. You will get all the answers to NCERT easily, including Class 11 Biology Chapter 21 NCERT Solutions.
After going through the solutions of Neural Control and Coordination NCERT, you must be able to understand all the answers of the following questions:
According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 18.
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The detailed solutions for in-text and exercise questions of Chapter 21 Biology Class 11 are provided below:
Q1. Briefly describe the structure of the following:
(a) Brain
Answer:
The brain is the main coordinating center of the body. It is a part of the nervous system that controls and monitors every organ of the body.
It is well protected by cranial meninges that are made up of an outer layer called dura mater, a thin middle layer called arachnoid, and an inner layer called pia mater.
It is divided into three regions —
Forebrain:
It is the main thinking part of the brain. It consists of the cerebrum, thalamus, and hypothalamus.
1. Cerebrum: The cerebrum is the largest part of the brain and constitutes about four-fifths of its weight. It is divided into two cerebral hemispheres by a deep longitudinal cerebral fissure. These hemispheres are joined by a tract of nerve fibre known as the corpus callosum.
2. Thalamus: Thalamus is the main center of coordination for sensory and motor signaling. It is wrapped by the cerebrum.
3. Hypothalamus: Hypothalamus lies at the base of the thalamus and contains a number of centers that regulate body temperature and the urge for eating and drinking. Some regions of the cerebrum, along with hypothalamus, are involved in the regulation of sexual behavior and expression of emotional reactions such as excitement, pleasure, fear, etc.
Midbrain:
It is located between the thalamus region of the forebrain and pons region of hindbrain. The dorsal surface of midbrain consists of superior and inferior corpora bigemina and four round lobes called corpora quadrigemina.
Hindbrain:
It consists of three regions - pons, cerebellum, and medulla oblongata.
Class 11 Ch 21 Bio NCERT Solutions
Q1. Briefly describe the structure of the following:
(b) Eye
Answer:
Eye: We know that eyes are in spherical structures that consist of three layers.
1. The outer layer is composed of sclera and cornea.
2. The middle layer of eye is vascular in nature and contains choroid, ciliary body, and iris.
3. The innermost nervous coat of eye contains retina. The retina is the innermost layer. It contains three layers of cells — inner ganglion cells, middle bipolar cells, and outermost photoreceptor cells. The receptor cells present in the retina are of two types — rod cells and cone cells.
Class 11 Chapter 21 Biology NCERT Solutions
Q1. Briefly describe the structure of the following:
(c) Ear
Answer:
Ear: Ear is the sense organ for hearing and equilibrium. It consists of three portions external ear, middle ear, and internal ear.
1. External ear: It consists of the pinna, external auditory meatus, and a tympanic membrane. Pinna is a sensitive structure that collects and directs the vibrations into the ear to produce sound. External auditory meatus is a tubular passage supported by cartilage in the external ear. The tympanic membrane is a thin membrane that lies close to the auditory canal. It separates the middle ear from the external ear.
2. Middle ear: It is an air-filled tympanic cavity that is connected with pharynx through the eustachian tube. The eustachian tube helps to equalize air pressure in both sides of the tympanic membrane. The middle ear contains a flexible chain of three middle bones called ear ossicles. The three ear ossicles are malleus, incus, and stapes that are attached to each other.
3. Internal ear: It is also known as the labyrinth. The labyrinth is divided into the bony labyrinth and a membranous labyrinth. The bony labyrinth is filled with perilymph while a membranous labyrinth is filled with endolymph.
The membranous labyrinth is divided into 2 parts.
Neural Control and Coordination NCERT Solutions
(a) Central neural system (CNS) and Peripheral neural system (PNS)
Answer:
Central Neural System (CNS) | Peripheral Neural System (PNS) |
1. CNS is made of the brain and the spinal cord. | 1. PNS consists of cranial nerves and spinal nerves. |
2. Brain is protected by the skull and the spinal cord by the vertebral column. | 2. There are no protective structures for PNS. |
3. CNS does not have any subdivisions. | 3. PNS is divided into somatic nervous system and autonomic nervous system. |
4. CNS processes the information and controls the response to impulses. | 4. Nerves of PNS carry impulses to the CNS and responses from the CNS to different organs of the body. |
5. Group of neurons in CNS is called nuclei. | 5. Group of neurons in PNS is called ganglia. |
(b) Resting potential and action potential
Answer:
Resting Potential | Action Potential |
1. It is the potential difference (difference in electric charge) across the membrane when the neuron is at the resting phase. | 1. It is the potential difference (difference in the electric charge) across the membrane when the neuron is stimulated or excited. |
2. The outer side of the neuron is positively charged and the interior of the neuron is negatively charged. | 2. The outer side of the neuron is negatively charged and the interior of the neuron is positively charged. |
3. The plasma membrane of the neuron is more permeable to K + ions. | 3. The plasma membrane of the neuron is more permeable to Na + ions. |
4. The sodium-potassium-ATPase pump is active and sends Na + ions outside the neuron to maintain the resting potential. | 4. The sodium-potassium-ATPase pump functions in a reverse manner and sends Na + ions into the neuron. |
(c) Choroid and retina
Answer:
Choroid | Retina |
1. It is the middle coat of the eye ball. | 1. It is the inner coat of the eye ball. |
2. It does not have photoreceptor cells. | 2. It has two kinds of photoreceptor cells-rods and cones. |
3. It is the vascular layer of the eyeball. | 3. It is the neurosensory layer of the eyeball. |
4. It nourishes the retina and prevents reflection of light in the eye. | 4. It imparts vision. |
Q3. Explain the following processes:
(a) Polarisation of the membrane of a nerve fibre
Answer:
Polarisation of the membrane of a nerve fibre:
Q3. Explain the following processes:
(b) Depolarisation of the membrane of a nerve fibre
Answer:
Chapter 21 Biology Class 11 Question Answer
Q3. Explain the following processes:
(c) Conduction of a nerve impulse along a nerve fibre
Answer:
Q3. Explain the following processes:
(d) Transmission of a nerve impulse across a chemical synapse
Answer:
Class 11 Biology Chapter 21 NCERT Solutions
Q4. Draw labelled diagrams of the following:
(a) Neuron
Answer:
Neuron-
Q5. Write short notes on the following:
(a) Neural coordination
Answer:
Q5. Write short notes on the following:
(b) Forebrain
Answer:
The forebrain consists of these three:
Cerebrum, Thalamus and Hypothalamus .
Cerebrum:
Thalamus:
Hypothalamus:
Class 11 Biology Chapter 21 NCERT Solutions
Q5. Write short notes on the following:
(c) Midbrain
Answer:
The midbrain consists of cerebral peduncles and corpora quadrigemina.
Cerebral Peduncles:
Corpora Quadrigemina:
Q5 . Write short notes on the following:
(d) Hindbrain
Answer:
The hindbrain consists the cerebellum, pons varolii, and medulla oblongata:
Cerebellum:
Pons Varolii:
Medulla oblongata:
Class 11 Biology Chapter 21 Question Answer
Q5. Write short notes on the following:
(e) Retina
Answer:
Retina is the innermost, neurosensory, thin layer of the eyeball. The external surface of the retina is in contact with the choroid and its inner surface is in contact with the vitreous humour. The retina is the site of image formation.
Pigmented layer:
Rods:
Cones:
Blind spot:
Macula lutea:
Chapter 21 Biology Class 11:
Q5. Write short notes on the following:
(f) Ear ossicles
Answer:
Q5. Write short notes on the following:
(g) Cochlea
Answer:
NCERT Neural Control and Coordination:
Q5. Write short notes on the following:
(h) Organ of Corti
Answer:
Q5. Write short notes on the following:
(i) Synapse
Answer:
Synapse:
(a) Mechanism of synaptic transmission
Answer:
The mechanism of synaptic transmission at the electrical synapse:
The mechanism of synaptic transmission at the chemical synapse:
(b) Mechanism of vision
Answer:
Neural Control and Coordination Class 11 NCERT PDF:
(c) Mechanism of hearing
Answer:
Mechanism of hearing is given below:
Q7. Answer briefly:
(a) How do you perceive the colour of an object?
Answer:
Cone cells present in the retina of the eye are responsible for colour vision. There are three kinds of cone cells which respond to red, green and blue light. Different cone cells get stimulated at different wavelengths of light. The other colours are detected by the simultaneous stimulation of more than one kind of cone cells. When all the three types of cells are stimulated simultaneously, a sensation of white light is produced.
Q7. Answer briefly:
(b) Which part of our body helps us in maintaining the body balance?
Answer:
Crista ampullaris present in the three semicircular canals, the macula utriculi present in the utricle and the macula sacculi present in the saccule of the inner ear help us in maintaining body balance.
Q7. Answer briefly:
(c) How does the eye regulate the amount of light that falls on the retina.
Answer:
Light enters the eye through the pupil, an aperture present in the centre of the iris. The iris has two types of muscles-circular smooth muscles and radial smooth muscles-which regulate the amount of light which falls on the retina.
The smooth circular muscles contract in bright light which makes the pupil smaller in size; hence, lesser amount of light falls on the retina. In dim light, the pupil is widened by the contraction of radial smooth muscles so that sufficient amount of light falls on the retina.
NCERT Neural Control and Coordination
(a) Role of Na+ in the generation of action potential.
Answer:
Sodium ions diffuse from the outside to the intracellular fluid because of the electrochemical gradient. The potassium ions move out, and the membrane becomes negatively charged from outside and positively charged from inside. This sudden change in the membrane potential is called the action potential, and the membrane is said to be depolarised.
( b) Mechanism of generation of light-induced impulse in the retina.
Answer:
The photosensitive compounds (photo pigments) in the human eye are composed of opsin and retinal. Light induces dissociation of retinal and opsin which changes the structure of opsin. It generates an action potential in the bipolar neurons. These impulses/action potential are transmitted by the optic nerves to the visual cortex of the brain where the neural impulses are analysed and the erect image is recognised.
(c) Mechanism through which a sound produces a nerve impulse in the inner ear.
Answer:
From the perilymph, the vibrations are transferred to the scala vestibuli of the cochlea and then to the scala media through Reissner's membrane and stimulate the sensory hair of the organ of Corti. The impulses thus received by the hair cells are carried to the brain through the auditory nerve where the sensation of hearing is felt.
Q9. Differentiate between: (a) Myelinated and non-myelinated axons
Answer:
Myelinated Axons | Non-myelinated Axons |
1. Myelin sheath is present. | 1. Myelin sheath is absent. |
2. Nodes of Ranvier are present. | 2. Nodes of Ranvier are absent. |
It is found in the grey matter of the brain, spinal cord, and autonomous nervous system. | 3. It is found in the white matter of the brain, spinal cord and autonomous nervous system. |
4. The conduction of nerve impulse is node to node. | 4. The conduction of nerve impulse is smooth. |
5. The speed of conduction of impulse is 50 times faster than in non-myelinated axon. | 5. The speed of conduction of impulse is slow. |
Q9. Differentiate between: (b) Dendrites and axons
Answer:
Dendrites | Axons |
1. They are short processes. | 1. Axons are long processes. |
2. Dendrites carry impulses towards the cell body of the neuron. | 2. Axons carry impulses away from the cell body of the neuron. |
3. Dendrites are always branched. | 3. Axons may or may not be branched. |
4. Nissl's granules are present in the neuroplasm. | 4. Nissl's granules are absent in the neuroplasm. |
(c) Rods and cone
Answer:
Rods | Cones |
1. They are sensitive to dim light. | 1. They are sensitive to bright light. |
2. Rods contain the pigment rhodopsin. | 2. Cones contain the pigment iodopsin. |
3. They have no role to play in colour vision. | 3. They are responsible for colour vision. |
4. Only one kind of rods exist. | 4. There are three kinds of cones-red, blue and green. |
(d) Thalamus and Hypothalamus
Answer:
Thalamus | Hypothalamus |
1. It is made of only grey matter. | 1. It is made of white and grey matter. |
2. The thalamus does not secrete any hormone. | 2. The hypothalamus secretes certain hormones which control the activity of the pituitary gland. |
3. It is situated superior to the midbrain. | 3. It is situated at the base of the thalamus. |
4. It contains the centres of sensations such as heat, cold and pain. | 4. It contains the centres which control body temperature, blood pressure and homeostasis. |
(e) Cerebrum and Cerebellum
Answer:
Cerebrum | Cerebellum |
1. It is the largest part of the brain. | 1. It is the second-largest part of the brain. |
2. It is part of the forebrain. | 2. It is part of the hindbrain. |
3. The cerebrum is divided into two cerebral hemispheres. | 3. The cerebellum is divided into three lobes-central vermis and the two lateral cerebellar hemispheres. |
4. It is the site of memory and intelligence. | 4. It is the site of body equilibrium and posture. |
Chapter 21 of NCERT Solutions for Class 11 Biology
(a) Which part of the ear determines the pitch of a sound?
Answer:
The cochlea determines the pitch of a sound.
(b) Which part of the human brain is the most developed?
Answer:
The cerebrum is the most developed.
(c) Which part of our central neural system acts as a master clock?
Answer:
The hypothalamus of the central neural system acts as a master clock.
Q11. The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the
(a) fovea
(b) iris
(c) blind spot
(d) optic chaisma
Answer:
(c) Blind spot
The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the blind spot. Photoreceptors are absent in this region.
Q12. Distinguish between:
(a) afferent neurons and efferent neurons
Answer:
Afferent Neurons | Efferent Neurons |
1. They conduct sensory impulses from the receptors to the central nervous system. | 1. They conduct motor impulses from the central nervous system to the effector organs such as muscles. |
2. They are present in the sense organs. | 2. They are present in the brain and the spinal cord. |
3. They are sensory neurons. | 3. They are motor neurons. |
Q12. Distinguish between:
(b) impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre
Answer:
Impulse Conduction in a Myelinated Nerve Fibre | Impulse Conduction in Non-myelinated Nerve Fibre |
1. Impulse travels from node to node. | 1. Impulse travels along the length of the entire nerve fibre. |
2. The speed of conduction is 50 times faster than the non-myelintaed nerve fibre. | 2. The speed of conduction is slower. |
3. Energy expenditure during impulse transmission is less. | 3. Energy expenditure during impulse transmission is more. |
Q12. Distinguish between:
(c) aqueous humor and vitreous humor
Answer:
Aqueous Humour | Vitreous Humour |
1. It is present in the aqueous chamber between the lens and the cornea. | 1. It is present in the vitreous chamber between the lens and the retina. |
2. It is secreted by the ciliary processes. | 2. It is secreted by the retina of the eye. |
3. It is a jelly-like fluid. | 3. It is a watery fluid. |
4. It supports the lens. | 4. It supports the lens and retina. |
Q12. Distinguish between:
(d) blind spot and yellow spot
Answer:
Blind Spot | Yellow Spot |
1. It is the point on the retina at which the optic nerve leaves the eye and retinal blood vessels enter the eye. | 1. It is the point on the retina which lies exactly opposite the centre of the cornea. |
2. It is void of photoreceptor cells. | 2. It contains two kinds of photoreceptor cells-rods and cones. |
3. It is insensitive to light. | 3. It is very much sensitive to light. |
4. It has no function with respect to vision. | 4. It is the area of most distinct vision. |
Q12. Distinguish between:
(f) cranial nerves and spinal nerves.
Answer:
Cranial Nerves | Spinal Nerves |
1. There are 12 pairs of cranial nerves. | 1. There are 31 pairs of spinal nerves. |
2. They arise from the brain and extend to the other parts of the body. | 2. They arise from the spinal cord and extend to other parts of the body. |
3. They may be sensory, motor or mixed. | 3. They are mixed nerves. |
Highly qualified academic professionals with vast subject knowledge developed the NCERT Solutions for Class 11 as per the latest CBSE syllabus. Plus one zoology neural control and coordination is part of the CBSE Syllabus 2022–23 and is categorized under Unit–5 Human Physiology. Overall, there are roughly 18 marks total assigned to this unit, which represents 25% of the total weight of the question paper. It is a field of science that examines how typical human tissues, organs, and bodies function physically, mechanically, and biochemically.
If you have any problem in understanding the solutions in neural control and coordination NCERT pdf then, don't worry and go through that neural control and coordination NCERT and try to understand all the concepts of every topic and then write the answers of all these questions by your own and then compare them. You will see that your knowledge, as well as the understanding of these concepts, will increase and you will be able to explain the answers in a better way.
The important topics and sub-topics of neural control and coordination class 11 NCERT pdf are listed below:
21.1 Neural System
21.2 Human Neural System
21.3 Neuron as Structural and Functional Unit of Neural System
21.3.1 Generation and Conduction of Nerve Impulse
21.3.2 Transmission of Impulses
21.4 Central Neural System
21.4.1 Forebrain
21.4.2 Midbrain
21.4.3 Hindbrain
21.5 Reflex Action and Reflex Arc
21.6 Sensory Reception and Processing
21.6.1 Eye
21.6.1.1 Parts of an eye
21.6.1.2 Mechanism of Vision
21.6.2 The Ear
20.6.2.1 Mechanism of Hearing
The human neural system consists of two parts:
The CNS consists of the brain and spinal cord. The brain can be divided into three major parts:
The forebrain consists of the cerebrum, thalamus, and hypothalamus. The cerebrum is longitudinally divided into two halves that are connected by the corpus callosum. A very important part of the forebrain called the hypothalamus controls body temperature, eating and drinking. NCERT Solutions for Class 11 Biology offers students solutions to all the chapters in a downloadable format.
Chapter 1 | The Living World |
Chapter 2 | Biological Classification |
Chapter 3 | |
Chapter 4 | Animal Kingdom |
Chapter 5 | Morphology of Flowering Plants |
Chapter 6 | Anatomy of Flowering Plants |
Chapter 7 | Structural Organisation in Animals |
Chapter 8 | Cell: The Unit of Life |
Chapter 9 | Biomolecules |
Chapter 10 | Cell Cycle and Cell Division |
Chapter 11 | Transport in Plants |
Chapter 12 | Mineral Nutrition |
Chapter 13 | Photosynthesis in Higher Plants |
Chapter 14 | Respiration in Plants |
Chapter 15 | Plant Growth and Development |
Chapter 16 | Digestion and Absorption |
Chapter 17 | Breathing and Exchange of Gases |
Chapter 18 | Body Fluids and Circulation |
Chapter 19 | Excretory Products and their Elimination |
Chapter 20 | Locomotion and Movement |
Chapter 21 | Neural Control and Coordination |
Chapter 22 | Chemical Coordination and Integration |
NCERT solutions for Class 11 Maths |
NCERT solutions for Class 11 Chemistry |
NCERT solutions for Class 11 Physics |
The benefits of NCERT solutions of Class 11 Biology chapter 21 are listed below:
These are the important topics of NCERT solutions for class 11 biology chapter 21:
Dendrites | Axons |
1. They are short processes. | 1. Axons are long processes. |
2. Dendrites carry impulses towards the cell body of the neuron. | 2. Axons carry impulses away from the cell body of the neuron. |
3. Dendrites are always branched. | 3. Axons may or may not be branched. |
4. Nissl's granules are present in the neuroplasm. | 4. Nissl's granules are absent in the neuroplasm. |
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