NCERT Exemplar Class 10 Science Chapter 7 Control And Coordination
NCERT Exemplar Class 10 Science Chapter 7 Control And Coordination are part of NCERT Exemplar Class 10 Science. Here we have given NCERT Exemplar Class 10 Science Chapter 7 Control And Coordination.
NCERT Exemplar Class 10 Science Chapter 7 Control And Coordination
Multiple Choice Questions (MCQs)
Question. 1 Which of the following statements is correct about receptors?
(a) Gustatory receptors detect taste while olfactory receptors detect smell
(b) Both gustatory and olfactory receptors detect smell
(c) Auditory receptors detect smell and olfactory receptors detect taste
(d) Olfactory receptors detect taste and gustatory receptors smell
Answer. (a)
Explanation: Gustatory receptors are the taste receptors which are present on the surface of tongue in the form of taste buds. Olfactory receptors help to sense the smell and are located over the roof of nasal cavity.
Question. 2 Electrical impulse travels in a neuron from
(a) Dendrite → Axon → Axonal end → Cell body
(b) Cell body → Dendrite → Axon → Axonal end
(c) Dendrite → Cell body → Axon → Axonal end
(d) Axonal end → Axon → Cell body → Dendrite
Answer.(c)
Explanation: Dendrite receives signals from sensory receptors or other neurons. Axon serves to conduct the nerve impulse away from the cell body.
Question. 3 In a synapse, chemical signal is transmitted from
(a) Dendritic end of one neuron to axonal end of another neuron
(b) Axon to cell body of the same neuron
(c) Cell body to axonal end of the same neuron
(d) Axonal end of one neuron to dendritic end of another neuron
Answer. (d)
Explanation: Neurotransmitters are released from axon of one neuron to dendrite of next neuron.
Question. 4 In a neuron, conversion of electrical signal to a chemical signal occurs at/in
(a) Cell Body
(b) Axonal end
(c) Dendritic end
(d) Axon
Answer. (b)
Explanation: Neurotransmitters are released from axonal end of one neuron and transmit the electrical signal to dendrite of next neuron.
Question. 5 Which is the correct sequence of the components of a reflex arc?
(a) Receptors → Muscles → Sensory neuron → Motor neuron → Spinal cord
(b) Receptors → Motor neuron → Spinal cord → Sensory neuron → Muscle
(c) Receptors → Spinal cord → Sensory neuron → Motor neuron → Muscle
(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle
Answer. (d)
Explanation: A stimulus received by the receptors present on skin, is transmitted to the sensory neuron which carries it to the central nervous system (the spinal cord and brain). A motor neuron carries the message from the central nervous system to the effector which could be a muscle, a gland or both.
Question. 6 Which of the following statements are true?
(i) Sudden action in response to something in the environment is caller reflex action
(ii) Sensory neurons carry signals from spinal cord to muscles.
(iii) Motor neurons carry signals from receptors to spinal cord.
(iv) The path through which signals are transmitted from a receptor tomuscle or a gland is called reflex arc.
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i) (ii) and (iii)
Answer. (c)
Explanation: Reflex arc is a simple nervous pathway and consists of sensory receptor, afferent neuron, centre, efferent neuron and effector organ. Automatic, quick and innate response to particular stimuli that is mediated by reflex arc is known as reflex action.
Question. 7 Which of the following statements are true about the brain?
(i) The main thinking part of brain is hind brain.
(ii) Centres of hearing, smell, memory, sight, etc., are located in fore brain.
(iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hind brain.
(iv) Cerebellum does not control posture and balance of the body.
(a) (i) and (ii)
(b) (i) (ii) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Answer. (c)
Explanation: Cerebrum is the center for higher thought processes required for learning, memory, language and speech. Medulla is the center for regulation of involuntary actions.
Question. 8 Posture and balance of the body is controlled by
(a) Cerebrum
(b) Cerebellum
(c) Medulla
(d) Pons
Answer. (b)
Explanation: Cerebellum coordinates the voluntary movements of skeletal muscles as well as posture, balance and equilibrium.
Question. 9 Spinal cord originates from
(a) Cerebrum
(b) Medulla
(c) Pons
(d) Cerebellum
Answer. (b)
Explanation: Spinal cord begins in continuation with medulla and extends downwards.
Question. 10 The movement of shoot towards light is
(a) Geotropism
(b) Hydrotropism
(c) Chemotropism
(d) Phototropism
Answer. (d)
Explanation: Growth movement of plants in response to light is called as phototropism.
Question. 11 The main function of abscisic acid in plants is to
(a) Increase the length of cells
(b) Promote cell division
(c) Inhibit growth
(d) Promote growth of stem
Answer. (c)
Explanation: Abscisic acid (ABA) is a growth retardation hormone.
Question. 12 Which of the following is not associated with growth of plant?
(a) Auxin
(b) Gibberellins
(c) Cytokinins
(d) Abscisic acid
Answer. (d)
Explanation: Abscisic acid (ABA) is a growth retardation hormone.
Question. 13 Iodine is necessary for the synthesis of which hormone?
(a) Adrenaline
(b) Thyroxin
(c) Auxin
(d) Insulin
Answer. (b)
Explanation: Hormones of thyroid gland have iodine as their structural component.
Question. 14 Choose the incorrect statement about insulin
(a) It is produced from pancreas.
(b) It regulates growth and development of the body.
(c) It regulates blood sugar level.
(d) Insufficient secretion of insulin will cause diabetes.
Answer. (b)
Explanation: Insulin regulates blood sugar level.
Question. 15 Select the mis-matched pair
(a) Adrenaline—Pituitary gland
(b) Testosterone—Testes
(c) Estrogen—Ovary
(d) Thyroxin—Thyroid gland
Answer. (a)
Explanation: Adrenaline is secreted by the adrenal gland.
Question. 16 The shape of guard cells changes due to change in the
(a) Protein composition of cells
(b) Temperature of cells
(c) Amount of water in cells
(d) Position of nucleus in the cells
Answer. (c)
Explanation: Shape of guard cell is maintained by its turgidity which in turn is regulated by water content of these cells.
Question. 17 The growth of tendril in pea plants is due to
(a) Effect of light
(b) Effect of gravity
(c) Rapid cell divisions in tendrillar cells that are away from the support
(d) Rapid cell divisions in tendrillar cells in contact with the support
Answer. (c)
Explanation: Growth movements in response to touch are known as thigmotropism.
Question. 18 The growth of pollen tubes towards ovules is due to
(a) Hydrotropism
(b) Chemotropism
(c) Geotropism
(d) Phototropism
Answer. (b)
Explanation: Stigma serves as landing platform for pollens as well as secretes chemical substances that attract pollen tube through style towards ovary.
Q. 19 The movement of sunflower in accordance with the path of sun is due to
(a) Phototropism
(b) Geotropism
(c) Chemotropism
(d) Hydrotropism
Answer. (a)
Explanation: Growth movement of plants in response to light is called as phototropism.
Question. 20 The substance that triggers the fall of mature leaves and fruits from plants is due to
(a) Auxin
(b) Gibberellins
(c) abscisic acid
(d) Cytokinin
Answer. (c)
Explanation: Abscisic acid serves to form of layer of abscission.
Question. 21 Which of the following statements about transmission of nerve impulse is incorrect?
(a) Nerve impulse travels from dendritic end towards axonal end
(b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron
(c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron
(d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells
Answer. (b)
Explanation: Neurotransmitters are released from axon of one neuron to dendrite of next neuron.
Question. 22 Involuntary actions in the body are controlled by
(a) Medulla in fore brain
(b) Medulla in mid brain
(c) Medulla in hind brain
(d) Medulla in spinal cord
Answer. (c)
Explanation: Medulla is part of hind brain and controls the involuntary action.
Question. 23 Which of the following is not an involuntary action?
(a) Vomiting
(b) Salivation
(c) Heart beat
(d) Chewing
Answer. (d)
Explanation: The actions that are not under our direct control are called as involuntary actions.
Question. 24 When a person is suffering from severe cold, he or she cannot
(a) Differentiate the taste of an apple from that of an ice cream
(b) Differentiate the smell of a perfume from that of an agarbatti
(c) Differentiate red light from green light
(d) Differentiate a hot object from a cold object.
Answer. (b)
Explanation: Cold thickens the mucus in nasal passages and block passage of odour to olfactory receptor cells.
Question. 25 What is the correct direction of flow of electrical impulses?
Answer. (c)
Explanation: Electrical impulse travel in following direction:
Impulse → Dendrite → Cell body → axon → dendrite of next neuron
Question. 26 Which statement is not true about thyroxin?
(a) Iron is essential for the synthesis of thyroxin
(b) It regulates carbohydrates, protein and fat metabolism in the body
(c) Thyroid gland requires iodine to synthesise thyroxin
(d) Thyroxin is also called thyroid hormone
Answer. (a)
Explanation: Thyroxin contains iodine in its structure.
Question. 27 Dwarfism results due to
(a) Excess secretion of thyroxin
(b) Less secretion of growth hormone
(c) Less secretion of adrenaline
(d) Excess secretion of growth hormone
Answer. (b)
Explanation: Growth hormone regulates normal growth and development of individual.
Question. 28 Dramatic changes of body features associated with puberty are mainly because of secretion of
(a) Oestrogen from testes and testosterone from ovary
(b) Estrogen from adrenal gland and testosterone from pituitary gland
(c) Testosterone from testes and estrogen from ovary
(d) Testosterone from thyroid gland and estrogen from pituitary gland
Answer. (c)
Explanation: Testosterone and estrogen are male and female sex hormones respectively.
Question. 29 A doctor advised a person to take an injection of insulin because
(a) His blood pressure was low
(b) His heart was beating slowly
(c) He was suffering from goitre
(d) His sugar level in blood was high
Answer. (d)
Explanation: Insulin regulates the blood sugar level.
Question. 30 The hormone which increase the fertility in males is called
(a) Oestrogen
(b) Testosterone
(c) Insulin
(d) Growth hormone
Answer. (b)
Explanation: Testosterone is the male sex hormone necessary for sperm production.
Question. 31 Which of the following endocrine glands is unpaired?
(a) Adrenal
(b) Testes
(c) Pituitary
(d) Ovary
Answer. (c)
Explanation: Pituitary gland is unpaired gland.
Question. 32 Junction between two neurons is called
(a) Cell junction
(b) Neuro muscular junction
(c) Neural joint
(d) Synapse
Answer. (d)
Explanation: Synapse is the junction between two neurons.
Question. 33 In humans, the life processes are controlled and regulated by
(a) Reproductive and endocrine systems
(b) Respiratory and nervous systems
(c) Endocrine and digestive systems
(d) Nervous and endocrine systems
Answer. (d)
Explanation: Nervous system and endocrine system work together to maintain homeostasis.
Short Answer Type Questions
Questions. 34 Label the parts (a), (b), (c) and (d) and show the direction of flow ofelectrical signals in given figure.
Answer.
(a) Sensory neuron
(b) Spinal cord (CNS)
(c) Motor neuron
(d) Effector (muscle in arm)
Direction of flow of electric signal is as shown below:
Sensory receptor → sensory neuron → spinal cord (CNS) → motor neuron → effector organ
Questions. 35 Name the plant hormones responsible for the following:
(a) Elongation of cells
(b) Growth of stem
(c) Promotion of cell division
(d) Falling of senescent leaves
Answer.
(a) Elongation of cells: Auxin
(b) Growth of stem: Gibberellin
(c) Promotion of cell division: Cytokinin
(d) Falling of senescent leaves: Abscisic acid
Questions. 36 Label the endocrine gland in figure:
Answer.
(a) Pineal gland
(b) Pituitary gland
(c) Thyroid gland
(d) Thymus gland
Questions. 37 In figure (a), (b) and (c), which appears more accurate and why?
Answer.
Figure (a) is more accurate. Roots of plants are positive geotropic and grow downwards while stem is positive phototropic and grows upward.
Questions. 38 Label the part of a neuron in figure given below.
Answer.
(a) Dendrite
(b) Cell body
(c) Axon
(d) Nerve ending
Questions. 39 Match the terms of Column (A) with those of Column (B)
| Column (A) | Column (B) |
| (a) Olfactory receptors | (i) Tongue |
| (b) Thermo receptors (temperature receptors) | (ii) Eye |
| (c) Gustatoreceptors | (iii) Nose |
| (d) Photoreceptors | (iv) Skin |
Answer.
The matching of the column (A) with column (B) is:
| Column (A) | Column (B) |
| (a) Olfactory receptors | (iii) Nose |
| (b) Thermo receptors (temperature receptors) | (iv) Skin |
| (c) Gustatoreceptors | (i) Tongue |
| (d) Photoreceptors | (ii) Eye |
Questions. 40 What is a tropic movement? Explain with an example.
Answer.
The directional growth movements of plants due to an external stimuli are called tropic movements. It can be either towards the stimulus, or away from it.
Growth of plant in response to light is known as phototropism. For example, shoots and stem of the plant grow upwards hence show positive phototropism.
Growth of of plant in direction of gravity is known as geotropism. For example, roots of plants are grow downwards hence show positive geotropism.
Questions. 41 What will happen if intake of iodine in our diet is low?
Answer.
Thyroid gland produces thyroxine and triiodothyronine. Thyroxine has four iodine atoms, while triiodothyronine has three iodine atoms. The dietary iodine serves as source and thus iodine deficient diet renders the gland unable to synthesize the hormones. Thyroid hormones deficiency inhibits metabolic rate, growth and development.
A person might suffer from goitre in case of iodine deficiency in the body.
Questions. 42 What happens at the synapse between two neurons?
Answer.
Synapse is the junction between two neurons. Electrical impulse at the axonal end stimulates the axon bulb to release chemical (neurotransmitter) which in turn diffuses across the synapse. The chemical serves to stimulate the dendrites of adjacent neuron which in turn send electrical signals to their cell body to be carried along the axon.
Questions. 43 Answer the following:
(a) Which hormone is responsible for the changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?
Answer.
(a) Oestrogen is responsible for development of secondary sexual characters in females at puberty.
(b) Growth hormone promotes growth and development of the body.
(c) Insulin controls blood sugar level by stimulating oxidation of glucose and absorption of glucose by liver and muscle cells.
(d) Iodine is necessary for the synthesis of thyroxine. It is a thyroid hormone that regulates the metabolism in the body.
Questions. 44 Answer the following:
(a) Name the endocrine gland associated with brain?
(b) Which gland secretes digestive enzymes as well as hormones?
(c) Name the endocrine gland associated with kidneys?
(d) Which endocrine gland is present in males but not in females?
Answer.
(a) Pituitary gland located in the groove of sphenoid bone of the skull in the brain.
(b) Pancreas secretes the pancreatic juice and hormones insulin and glucagon.
(c) Adrenal glands are located on the top of two kidneys.
(d) Testes are present only in males which secrete male sex hormone, testosterone.
Long Answer Type Questions
Question. 45 Draw the structure of a neuron and explain its function.
Answer.
Neuron is the structural and functional unit of nervous system. It serves to carry nerve impulse from one part of body to other. It has dendrites, cell body and axon. Dendrite receives signals from sensory receptors or other neurons. The long extension of cell body of nerve cell is called as axon that serves to conduct the nerve impulse away from the cell body. Cell body is the metabolic center of neuron.
Question. 46 What are the major parts of the brain? Mention the function of different parts.
Answer.
Brain is the most important coordinating centre in the body. It has three major parts namely: fore-brain, mid-brain and hind-brain.
1. Fore brain:
| Sub parts | Functions |
| Cerebrum | Learning, memory, language and speech |
| Cerebral hemispheres | Intelligence and voluntary actions |
| Olfactory lobes | Centres of smell |
| Diencephalon (thalamus and hypothalamus) | Thalamus: recognition of pain, temperature and hard touch. Hypothlalamus: involuntary actions |
2. Mid brain:
| Sub parts | Functions |
| Tectum | Responsible for visual and auditory stimuli. |
| Tegmentum | Contains nuclei for pain modulation, motor coordination and movement planning. |
3. Hind brain:
| Sub parts | Functions |
| Pons | Regulate respiration |
| Cerebellum | Coordinates the voluntary movements of skeletal muscles as well as posture, balance and equilibrium. |
| Medulla | Has reflex centres that control heartbeat, blood vessel diameter and rhythm of breathing as well as other vital and involuntary functions. |
Question. 47 What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected?
Answer.
The central nervous system consists of the brain and the spinal cord.
(i) Brain is the main centre of coordination of sensory information in the body. It is located in protective brain box or cranium and is covered by membranous meninges. Cerebrospinal fluid is the clear tissue fluid which makes protective cushion around and within CNS. It is present in central canal of spinal cord and in brain ventricles.
(ii) Spinal cord is a long cylindrical structure that begins from the medulla oblongata and extends downwards. It is enclosed in a protective bony cage vertebral column and is also surrounded by meninges.
Peripheral Nervous System (PNS): It lies outside the central nervous system and consists of somatic and autonomic nervous system.
It includes cranial, spinal and visceral nerves.
(i) Cranial nerves: Thses consist of the 12 pairs that emerge from the brain mostly concerned with head, neck and facial region of the body.
(ii) Spinal nerves: 31 pairs of spinal nerves arise from the spinal cord and spread throughout the body.
(iii) Visceral nerves: These arise from the spinal cord and are connected to the internal organs of the body.
Question. 48 Mention one function for each of these hormones
(a) Thyroxin
(b) Insulin
(c) Adrenaline
(d) Growth hormone
(e) Testosterone
Answer.
| S. No. | Hormone | Function |
| 1. | Thyroxin | It serves to regulate carbohydrate, protein and fat matabolism in the body and thereby affect overall growth and development. |
| 2. | Insulin | Serves to lower down the blood sugar levels. |
| 3. | Adrenaline | Increases heart rate and supply of blood to various organs; prepare body for short term stress responses. |
| 4. | Growth hormone | It regulates growth and development in the body. |
| 5. | Testosterone | Development of secondary sexual characters in males and sperm formation. |
Question. 49 Name various plant hormones. Also give their physiological effects on plant growth and development.
Answer.
| S. No. | Plant Hormone | Physiological Effect |
| 1. | Auxin | • Promotes lengthening and apical dominance.• Promotes cell elongation and division• Stimulates root formation and development of seedless fruit |
| 2. | Gibberellin | • Promotes Stem elongation, breaking seed dormancy• Mobilization of endosperm reserves• Stimilates flower initiation and fruit set |
| 3. | Cytokinins | • Promotes cell division and delay leaf ageing• Stimulate leaf expansion |
| 4. | Abscisic Acid | • Growth retardation hormone• Reverses the effects of auxin and gibberellins on growth and development |
| 5. | Ethylene | • Growth and development of floral organs• Essential for fruit ripening, promotes senescence and abscission of leaves |
Question. 50 What are reflex actions? Give two examples. Explain a reflex arc.
Answer.
Reflex action: A reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus.
For example:
(i) Moving away your hand upon touching a hot object.
(ii) Closing your eyes on sudden exposure to bright light.
Reflecx arc: Reflex arc is a simple nervous pathway and consists of receptors, sensory neurons, interneurons, motor neurons and muscles. The sensory neurons transmit the sensory information from sensory receptors to spinal cord or brain. The interneurons integrate the incoming information and signal is relayed to motor neurons. The motor pathway transmits the signal from motor neurons to the effector organs (usually muscles and glands).
Question. 51 ‘Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify the statement.
Answer.
Nervous system serves to pass the sensory information from receptor to effector organs and thereby generate response. The afferent/sensory neurons transmit the sensory information from sensory receptors to spinal cord or brain. The interneurons integrate the incoming information and signal is relayed to motor/efferent neurons. The efferent/motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc).
The effector organs generate response in terms of secretion of either any activity or secretion of hormones. It can be said that secretion of hormones is under regulation of nervous system. Hormonal system can regulate wise range of target tissues as compared to nervous system. Hence, together, nervous system and hormonal system serve the function of control and coordination.
Question. 52 How does chemical coordination take place in animals?
Answer.
Hormones are the long range chemical messengers that are released into blood by endocrine gland in response to some signal. These hormones exert their effect on the target cells present distantly from their site of release. These hormones serve the function of chemical coordination in animals.
Hormones are released into the blood stream and can reach all cells but they affect only target cells. This is followed by generation of stimulus specific biochemical or physiological activity. In this way, hormones regulate functioning of different organs and tissues. Each hormone is under regulation of feedback mechanism which in turn ensures reliability of the system.
Question. 53 Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?
Answer.
Two neurons are never in physical contact of each other and the junction between two neurons is referred to as synapsis. The synapse serves like a one-way valve as axonal ends of synapse release the chemical substance that diffuse into synapse. This chemical diffuses towards the dendrite end of next neuron and propagates an electrical signal.
Diffusion of chemical from axonal end followed by its diffusion in synapse and fusion with dendrite of next neuron ensures the transmission of electrical signal. Since, the dendritic end of neuron does not release the chemicals; the nerve impulse can go across only in one direction.