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NCERT Exemplar Class 11 Biology solutions chapter 21 explores the concept of Neural Control and Coordination in living beings. In NCERT Exemplar Class 11 Biology chapter 21 solutions students will get to learn about the coordination system of the human body. They will be able to answer questions like- How does the neural system in humans work? What is the central neural system? What is Reflex Action and Arc? How do the endocrine system and neural system function altogether? All of these are detailed in the Class 11 NCERT Exemplar solutions Biology chapter 21 which by utilising the NCERT Exemplar Class 11 Biology chapter 21 solutions PDF Download students can make learning even more convenient.
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Question:1
Chemicals which are released at the synaptic junction are called
(a) Hormones
(b) Neurotransmitters
(c) Cerebrospinal fluid
(d) Lymph
Answer:
The answer is the option (b) NeurotransmittersQuestion:2
Potential difference across the resting membrane is negatively charged. This is due to differential distribution of the following ions
a. Na+ and K+ ions
b. CO3++ and Cl- ions
c. Ca++ and Mg++ ions
d. Ca4+ and Cl- ions
Answer:
Potential difference across resting membrane is negatively charged. This is due to differential distribution of Na+ and K+ ions.Question:3
Resting membrane potential is maintained by
(a) Hormones
(b) Neurotransmitters
(c) Ion pumps
(d) None of the above
Answer:
Ans. The answer is the option (c) Ion pumpsQuestion:4
The function of our visceral organs is controlled by
(a) Sympathetic and somatic neural system
(b) Sympathetic and para sympathetic neural system
(c) Central and somatic nervous system
(d) None of the above
Answer:
The answer is the option (b) Sympathetic and para sympathetic neural systemQuestion:5
Which of the following is not involved in Knee-jerk reflex?
(a) Muscle spindle
(b) Motor neuron
(c) Brain
(d) Inter neurons
Answer:
The answer is the option (c) BrainQuestion:6
An area in the brain which is associated with strong emotions is
(a) Cerebral cortex
(b) Cerebellum
(c) Limbic system
(d) Medulla
Answer:
The answer is the option (c) Limbic systemQuestion:7
Mark the vitamin present in Rhodopsin
(a) Vit A
(b) Vit B
(c) Vit C
(d) Vit D
Answer:
The answer is the option (a) Vit AQuestion:8
Human eyeball consists of three layers and it encloses
(a) Lens, iris, optic nerve
(b) Lens, aqueous humor, and vitreous humor
(c) Cornea, lens, iris
(d) Cornea, lens, optic nerve
Answer:
The answer is the option (b) Lens, aqueous humor, and vitreous humorQuestion:9
Wax gland present in the ear canal is called
(a) Sweat gland
(b) Prostate gland
(c) Cowper's gland
(d) Sebaceous gland/ ceruminous gland
Answer:
The answer is the option (d) Cowper's glandQuestion:10
The part of internal ear responsible for hearing is
(a) Cochlea
(b) Semicircular canal
(c) Utriculus
(d) Sacculus
Answer:
The answer is the option (a) CochleaQuestion:11
The organ of corti is a structure present in
(a) External ear
(b) Middle ear
(c) Semi-circular canal
(d) Cochlea
Answer:
The answer is the option (d) CochleaQuestion:1
Answer:
Neurotransmitters help in the transmission of impulses at the junction between two neurons called chemical synapse. In the synapse, there exists synaptic vessels in the axon terminal called synaptic knob. These vessels contain neurotransmitters. The impulses from the nerves reaches the axon terminal and travel through it as electrical signals. When the impulse reaches the end of the axon, it picks up the neurotransmitters present in it and attaches it to the chemo-receptors that are present on the dendrite membrane of next neuron. This attaching of chemicals (acetylcholine) with chemo-receptors leads to depolarization of membrane generating a nerve impulse across the nerve fiber.Acetylcholine is inactivated and hydrolyzed by the enzyme found in the post synaptic membrane- acetylcholinesterase. The hydrolyses facilitates the repolarization of the membrane.
Question:2
Name the parts of human forebrain indicating their respective functions.
Answer:
The forebrain comprises of the cerebrum, thalamus and hypothalamus. Their functions are as follows:Question:3
Explain the structure of middle and internal ear with the help of diagram.
Answer:
Ans. The structure of human ear is divided into three parts- the external ear, middle ear and internal ear.Structure of Middle Ear: The middle ear is composed of three bones or ossicles- malleus, incus, and stapes. All of three bones are attached to each other in a chain-like manner. Malleus is attached to tympanic membrane and stapes is attached to a membrane of cochlea called the oval window. The tympanic membrane is the one that separates the middle ear from external one. It is also called the ear drum. Not only that, it also helps in catching the sound waves and transmitting them to the bony ossicles. From the bony ossicles, the waves are transferred to the inner ear. The eustachian tube connects the pharynx to the middle ear. tympanic membrane and bony ossicles. Tympanic membrane separates middle ear from external ear and the middle ear is connected to pharynx by eustachian tube.
Structure of Inner Ear: Inner ear is composed of a fluid filled chamber called labyrinth. It is divided into two parts- an outer bony labyrinth and an inner membranous labyrinth. The bony labyrinth consists of channels which is filled with a fluid called endolymph. The portion which is coiled in the labyrinth is the cochlea. Cochlea consists of two large ear canals- upper vestibular canal and lower vestibular canal. The two canals are separated by a cochlear duct. Semi-circular canals help in maintaining balance and posture of the body and cochlea helps in sending audio signals to the brain.
Question:1
Answer:
Question:2
What is the difference between electrical transmission and chemical transmission?
Answer:
Ans:Electrical transmission | Chemical transmission |
(i) Transmission takes place in the form of electric potential. | (i) Transmission takes place through chemicals. |
(ii) It transmits the signals in the neural system. | (ii) It transmits the signals in the hormonal system. |
(iii) It transmits faster. | (iii) It transmits slower. |
Question:3
Answer:
Question:4
If someone receives a blow on the back of neck, what would be the effect on the person's CNS?
Answer:
A blow on the back of the neck can cause serious damage to the medulla oblongata and the spinal card which in turn can cause serious problems in the normal functioning of respiratory, cardiovascular, and gastric systems. It can also cause paralysis.Question:5
What is the function described to Eustachian tube?
Answer:
Ans.Question:6
Label the following parts in the given diagram using arrows.
(a) Aqueous chamber
(b) Cornea
(c) Lens
(d) Retina
(e) Vitreous chamber
(f) Blind spot
Answer:
Question:1
Answer:
Dendrites, Cell body, Axon, Axon terminal, Synaptic knob.Question:2
Comment upon the role of ear in maintaining the balance of the body and posture.
Answer:
The vestibular apparatus present in the internal ear consists of semi-circular canals and otolith. The semi-circular canals send signals to the brain in order to maintain balance and posture of the body.Question:4
Answer:
External auditory canal, Ear drum, Malleus, Incus, Stapes, Cochlea, Cochlear nerve.Question:6
Name the structures involved in the protection of the brain.
Answer:
The skull and Cerebrospinal Fluid (CSF).Question:7
Answer:
The limbic system and hypothalamus is related to emotions.Question:8
What do grey and white matter in the brain represent?
Answer:
The outer region of cerebrum is composed of grey matter which is also called cerebral cortex.The grey matter represents the high concentration of cell bodies of the neuron. The inner region of cerebrum is composed of white matter which is also called cerebral medulla. The white matter represents the high concentration of axons which gives it lighter appearance. Hence, medulla is lighter in color and is called white matter.Question:9
Where is the hunger center located in human brain?
Answer:
The hunger center is located in the Hypothalamus in the human brain.Question:10
Which sensory organ is involved in vertigo (sensation of oneself or objects spinning around)?
Answer:
Ears: semi-circular canals in the internal ears are involved in sense of vertigo.Question:12
Complete the statement by choosing appropriate match among following-
(a) Resting potential | (i) chemicals involved in the transmission of impulses at synapses. |
(b) Nerve impulse | (ii) gap between the pre-synaptic and post synaptic neurons |
(c) Synaptic cleft | (iii) electrical potential difference across the resting neural membrane |
(d) Neurotransmitters | (iv) an electrical wave like response of a neuron to a stimulation. |
Answer:
(a)-(iii)The neural system of a human consists of two parts mainly, these are the Central Neural System (CNS), and the Peripheral Neural System (PNS). The information related to the changes in the environment is transmitted through CNS with the help of sensory organs which are processed and analysed.
The Peripheral Neural System (PNS) is the division of the nervous system, which contains all the nerves that lie outside the CNS. The primary and foremost role of the PNS is to connect the CNS to the organ’s limbs and skin of the human body.
Class 11 Biology NCERT Exemplar solutions chapter 21 includes details about Human Neural Systems, Neurons, CNS, PNS, Reflex action and reflex arc Sensory reception and processing are important topics which students should pay extra attention to.
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The students will also learn about the transmission of nerve impulsion, impulse conduction across a synapse, and the functioning of reflex action. The neural system of a human body coordinates and integrates functions as well as metabolic and homeostatic activities of the whole organ system.
Chapter 1 | |
Chapter 2 | |
Chapter 3 | |
Chapter 4 | |
Chapter 5 | |
Chapter 6 | |
Chapter 7 | |
Chapter 8 | |
Chapter 9 | |
Chapter 10 | |
Chapter 11 | |
Chapter 12 | |
Chapter 13 | |
Chapter 14 | |
Chapter 15 | |
Chapter 16 | |
Chapter 17 | |
Chapter 18 | |
Chapter 19 | |
Chapter 20 | |
Chapter 21 | |
Chapter 22 |
The chapter includes topics like a neuron, central neural system, reflex arc, reflex action, sensory reception, etc.
Yes, these NCERT Exemplar Class 11 Biology solutions chapter 21 are a good way to revise the entire NCERT syllabus in a single go.
One can easily download these solutions by clicking on the given link on the same page of NCERT chapter-wise solutions.
Multiple questions are solved with diagrams, charts, and points for better clarity in Class 11 Biology NCERT Exemplar solutions chapter 21.
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