• Control and Coordination

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10th Class - Science
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NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination

Question1.
What is the difference between a reflex action and walking?

Answer:A reflex is an involuntary, rapid response to a stimulus. It does not involve any thinking. For example, we pull back our hand on touching any hot surface. It is an instant reaction. We do not have any control over the movement. On the other hand, walking is a voluntary action. It is a part of our routine and we have a full control over walking

Question2.
What happens at the synapse between two neurons?

Answer:The gap between the two neurons is called synapse. At the synapse, the nerve impulse from one neuron gets transmitted to the other neuron. This takes place by the virtue of special neurotransmitters released by the axon terminal of a neuron. These neurotransmitters travel through the synapse to reach the dendrites of the adjacent neuron. The nerve impulses travel along with these neurotransmitters

Question3.
Which part of the brain maintains posture and equilibrium of the body?

Answer:Cerebellum

Question4.
How do we detect the smell of an agarbatti (incense stick)?

ans:We have some olfactory receptors in our nose. These receptors are specialised to pick up the smell. Once they detect any smell, they send the message to the brain. The brain interprets and analyses those signals and tells the body that it is the smell of an incense stick

Question5.
What is the role of the brain in reflex action?

Answer:Brain does not play any direct role in reflex action. Reflex action is mainly controlled by the spinal cord. The brain function as a relay centre for transferring impulses from sensory to motor neurons in the form of cerebral reflexes Control and Coordination such as closure of eyes on exposure to flash of light and salivation in the mouth at the good smell of food. In spinal reflexes, it acts as a collection centre of information without any direct involvement in reflex action

Question6.
What are plant hormones?

Answer:Plant hormones are the special chemicals which help in the growth of various parts of the plant

Question7.
How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

Answer:The movement of leaves of the sensitive plant exhibits nastic movement. This means that the movement does not depend on the direction of the stimulus. Whereas, the movement of a shoot towards light is an example of tropic movement. This movement is dependent on the direction of the light

Question8.
Give an example of a plant hormone that promotes growth?

Answer:Auxin

Question9.
How do auxins promote the growth of a tendril around a support?

Answer:The concentration of, auxin hormone varies in different parts of the plant. It is more in the part of the tendril which is away from the support. Auxin hormone promotes the cell division. Hence, there is increased cell division in that part compared to the part which is nearer to the support. So, the external part of the tendril grows more than the internal part making the tendril coil around the support

Question10.
Why is the use of iodised salt advisable?

Answer:Iodine is an important constituent required by the body to synthesise thyroxin hormone. The deficiency of iodine leads to a disease called goitre. In this disease, the neck region swells up. Hence, it is advisable to consume iodised salt to prevent chances of goiter

Question11.
Design an experiment to show hydrotropism?

Answer: Procedure

  • Take a big tray which should be able to accommodate a porous pot
  • Fill the tray with sand. Put some seeds in it
  • Make a pit in the sand to insert the pot in it
  • Fill the porous pot with water.
  • Do not disturb the set up for about a week
  • After a week, locate the seeds and observe
Observation When seeds are taken out, you will see that the roots show bending towards the direction from which water is diffusing. This shows the hydrotropic movement in roots.
Question12.
How does chemical coordination take place in animals?

Answer:Chemical coordination in animals involves hormones which are secreted by endocrine glands. These hormones help in regulating different metabolic functions in the body. For example, growth hormone is a hormone which regulates the growth of the body. If this hormone is secreted in excess, it leads to gigantism. If this hormone is secreted in less quantity, it leads to dwarfism

Question13.
How does our body respond when adrenaline is secreted into the blood?

Answer:Adrenaline is commonly known as fight or flight hormone. This is because, the hormone prepares the body for any emergency situation. If there is an increased secretion of this hormone in the blood, it causes increased blood supply to limbs and face. It also increases the heart rate and breathing rate. All of these responses enable the body to deal with any situation-be it a fight or; if need be; a flight from the scene

Question14.
Why are some patients of diabetes treated by giving injections of insulin?

Answer:Insulin controls the sugar levels of the body. In some diabetic patients, insulin hormone level is not normal. Hence, insulin injection is given to such patients to compensate for the reduced insulin hormone secretion. Such cases of diabetes are called Insulin Dependent Diabetes Mellitus (IDDM). such as closure of eyes on exposure to flash of light and salivation in the mouth at the good smell of food. In spinal reflexes, it acts as a collection centre of information without any direct involvement in reflex action

Chapter End Questions

Question1.
Which of the following is a plant hormone?
  • Insulin
  • Thyroxin
  • Oestrogen
  • Cytokinin

Answer:

  • Cytokinin
Question2.
The gap between two neurons is called a?
  • dendrite
  • synapse
  • axon
  • impulse

Answer:

  • synapse
Question3.
The brain is responsible for?
  • thinking
  • regulating the heartbeat
  • balancing the body
  • all of the above

Answer:

  • all of the above
Question4.
What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

Answer:Receptors are the sensory structures which provide information about the external environment to the body. This helps the brain to instruct a related organ to take the required action. Receptors are very important for our survival. For example, if a person is blind, performing certain ordinary task may be very difficult for him. Since, one of the receptors (eyes) are not functional in his body, he may not be able to see the obstruction in his path or may even fall in a pit

Question5.
Draw the structure of a neuron and explain its function?

Answer: Structure of neuron Function Neuron helps in transmitting the nerve impulses.

Question6.
Which signals will get disrupted in case of a spinal cord injury?

Answer:The spinal cord is a junction where various nerves meet. In case of spinal cord injury, the communication between the spinal nerves and the brain would get disturbed

Question7.
How does phototropism occur in plants?

Answer:The concentration of auxin differs in different parts of the plant in response to the direction of light. For example, in a stem the concentration of auxin is more in the parts which are away from the light. Presence of auxin hormone increases the cell division in that part. This causes the stem to bend towards the light. That is how phototropism occurs in plants

Question8.
How does chemical coordination occur in plants?

Answer:Plant hormones play a very important role in chemical coordination. Most of the plant hormones stimulate growth in certain parts of the plant. For example, hormones auxin and gibberellins stimulate growth. However, hormone abscisic acid inhibits the growth of the plant

Question9.
What is the need for a system of control and coordination in an organism?

Answer:A living organism constantly interacts with its external environment. For example, a deer has to move in search of its food. It also needs to quickly run in case there is some danger. Hence, there is a need for control and coordination in not just deer but any organism

Question10.
How are involuntary actions and reflex actions different from each other?

Answer:Involuntary actions are those reactions which take place during our daily routine activities, e.g. beating of heart, peristaltic movement of intestines, etc. Reflex actions are the reactions which are involuntary in actions that evoked in response to a sudden danger

Compare and contrast nervous and hormonal mechanisms for control and coordination in animals. ans:
Nervous control mechanism Hormonal control mechanism
  • It is a fast mechanism
    		•
  • It is a slow mechanism
    		•
  • The information is conveyed in form of nerve impulses
    		•
  • The information is conveyed in form of chemical messengers
    		•
  • It is facilitated by neurotransmitters
    		•
  • It is facilitated by hormones
    •
    Question.11
    Compare and contrast nervous and hormonal mechanisms for control and coordination in animals?

    Answer:

    Nervous system:

    A nervous system is described as " a system in an organism that receives the stimulus, transfers it to other parts of body and results corresponding effects. The activity of various parts of the body is organized and co-ordinated by the nervous system to control all internal activities. With the help of sense organs attached to them, they make sensations; vision, hearing, taste, smell and pain are so. The nervous system functions in the response to changes in the external environment

    Hormonal system:

    And so hormones will cross the plasma membrane of the target cell and bind to a receptor protein located in there cytoplasm. This binding leads to a series of events which trigger the formation of secondary messengers. Secondary messengers trigger a sequence of molecular interactions that alters the physiological state of a cell. This process is also known as signal transduction

    Question12.
    What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?

    Answer:The movement in a sensitive plant is controlled by hormones which are a part of hormonal mechanism. The movement in our legs is controlled by nervous control mechanism

    Important Question

    Answers to NCERT Class 10 Science Chapter 7 Control and Coordination

    Question1.
    What is the difference between a reflex action and walking?
    Year of Question :(Board Term I, 2016)

    Answer: Reflex actions are the involuntary actions that occur in response to stimuli. They occur without involvement of conscious areas of brain. All the reflex actions are unconscious actions. Reflex action involves the brain and spinal cord of central nervous systems. On the other hand, voluntary actions are those which occur under the control of cerebellum of the brain. Walking is learnt as we grow. Walking is controlled by the brain and is consciously used whenever required

    Question2.
    What happens at the synapse between two neurons?
    Year of Question :(Board Term I, 2016)

    Answer: At the synapse between two neurons, electric signals are converted into chemicals that can easily cross over the gap and pass on the chemical messenger to the next neuron where it is converted back to electrical signal

    Question3.
    Which part of the brain maintains the posture and equilibrium of the body?
    Year of Question :(Board Term I, 2014)

    Answer: Cerebellum, which is a part of the brain, is responsible for controlling the motor functioning. Hence, it is the part engaged in the maintenance of posture and equilibrium of the body

    Question4.
    How do we detect the smell of an agarbatti (incense stick)?
    Year of Question :(Board Term I, 2016)

    Answer: The smell of an agarbatti is detected by the nose. The olfactory receptors present in the nose sends electrical signal to the fore brain. The fore brain interprets this signal as the smell of the incense stick

    Question5.
    What is the role of the brain in reflex action?
    Year of Question :(Board Term I, 2016)

    Answer: Reflex actions are formed instantaneously in response to a stimulus that has no time to think. For instance, the sensory nerves that detect heat are connected to the nerves that move the muscles of the hand. Such a connection of detecting the signal from the nerves (input) and responding to it quickly (output) is known as reflex arc. Reflex action are generated in spinal cord and the information also reaches brain. This helps the brain to record this event and remember it for future use.  Brain helps the person to get awareness of the stimulus and prevent the danger posed by the situation in the future

    Questions Page number 119

    Question1.
    What are plant hormones?
    Year of Question :(Board Term I, 2018)

    Answer: Plant hormones are the organic substances produced at certain sites of a plant and are translocated to other parts based on the requirement. Plant hormones help to coordinate growth, development and responses to the environment. Ex: Auxins Gibberlins, cytokines, abscisic acid and ethylene

    Question2.
    How is the movement of leaves of a sensitive plant different from the movement of a shoot towards light?
    Year of Question :(Board Term I, 2016)

    Answer: Sl. No Movement of leaves of a sensitive plantM Movement of a shoot towards light

  • 1
  • Movement of leaves of a sensitive plant
  • Movement of a shoot towards light
  • 2
  • Nastic movement Tropic movement
    • #
  • 3
  • Touch is the stimulus
    • Light is the stimulus
  • 4
  • Caused by the sudden loss of water from the swellings at the base of leaves
  • Caused by the unequal growth on the two sides of the shoot
  • 5
  • Not a growth movement
  • Growth movement
  • 6
  • Growth movement
  • Occurs slowly
    • Question3.
    Give an example of a plant hormone that promotes growth?
    Year of Question :(Board Term I, 2016)

    Answer: Auxins and Gibberlins are the hormone responsible for the growth of plant. Auxins are responsible for the cell elongation in shoot and also regulate growth. Gibberlin is responsible for stem elongation and germination

    Question4.
    How do auxins promote the growth of a tendril around a support?
    Year of Question :(Board Term I, 2016)

    Answer: Auxins are the plant hormones produced at the tips of shoots and roots. Auxins are present at the tip of tendrils. When tendrils are attached around any support, their growth is slowed down as auxins are sensitive to touch. This makes them move to the other side of the tip to get support; this makes the other side grow faster than the side of tendril in contact with the support and the tendril bends towards the support

    Question5.
    Design an experiment to demonstrate hydrotropism?
    Year of Question :(Board Term I, 2016)

    Answer: To demonstrate hydrotropism in plants. Procedure

    • i. Plant a seedling in a vessel containing soil
    • iii. Adjacent to the seedling put a porous pot containing water
    • iiii. Leave the set up for few days. Observation
    • iiv. On examining the roots, it is observed that the roots bend towards the source of water and do not grow straight. Result : It confirms that plants show hydrotropism as the roots bend towards the porous pot of water. As hydrotropism is a plant-growth response in which the direction of growth is determined by a stimulus of gradient in water concentration

    Questions Page number 125

    Question1.
    How does chemical coordination take place in animals?
    Year of Question :(Board Term I, 2012)

    Answer: Chemical coordination takes place in animals with the help of chemical messengers called hormones. Hormones are the chemicals that are secreted by specific endocrine glands. Hormones regulate the growth, development and homeostasis of the animals

    Question2.
    Why is the use of iodized salt advisable?
    Year of Question :(Board Term I, 2016)

    Answer: Usage of iodized salt is advisable to avoid the deficiency of iodine. If the intake of iodine is low, the release of thyroxine from the thyroid gland will be decreased. This affects fat, carbohydrate and protein metabolism. Thus, a person may have goitre if the intake of iodine is lowered

    Question3.
    How does our body respond when adrenaline is secreted into the blood?
    Year of Question :(Board Term I, 2017)

    Answer: Adrenaline is a hormone secreted when a person is frightened or mentally disturbed. When Adrenaline reaches the heart, heartbeat will increase to increase blood supply to our muscles. Adrenaline also increases the breathing rate because of contraction of diaphragm and the rib muscles. Adrenaline rush also increases blood pressure and allows entry of more glucose into blood. All these occur when our body responds to the secretion of adrenaline into our blood

    Question4.
    Why are some patients of diabetes treated by giving injections of insulin?
    Year of Question :(Board Term I, 2016)

    Answer: Diabetes is a condition where the pancreatic cells of a person stops producing or reduces the production of insulin hormone. Insulin regulates blood glucose by converting extra glucose to glycogen. When insulin is not produced adequately, a persons blood glucose level is affected and this leads to adverse effects. In order to maintain the insulin and blood glucose levels, diabetes patients are treated with injections of insulin.

    Exercise Questions Page number 126

    Question1.
    Which of the following is a plant hormone?
    Year of Question :(Board Term I, 2010)
    • i(a) Insulin
    • i(b) Thyroxin
    • i(c) Oestrogen
    • i(d) Cytokinin

    Answer: Answer is d) cytokinin. Cytokinin is a plant hormone whereas Insulin, Thyroxin, Oestrogen are the hormones produced by animals.

    Question2.
    The gap between two neurons is called a?
    Year of Question :(Board Term I, 2016)
    • i(a) Dendrite
    • i(b) Synapse
    • i(c) Axon
    • i(d) Impulse

    Answer: Answer is (b) Synapse Dendrite is a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body. An axon or nerve fiber is a long, slender projection of a nerve cell or neuron in vertebrates that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. Impulse is an electrical signal that travels along axon

    Question3.
    The brain is responsible for?
    Year of Question :(Board Term I, 2016)
    • i(a) Thinking
    • i(b) Regulating the heartbeat
    • i(c) Balancing the body
    • i(d) all of the above

    Answer: Answer is (d) all the above Brain is responsible for thinking, brain regulates the heartbeat, and it balance the body

    Question4.
    What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
    Year of Question :(Board Term I, 2012)

    Answer: Receptors are present throughout our body - mainly in sense organs. Receptors collect the information about changes that happen around us and send the signal/information to the brain which responds to the change detected. When receptors do not work properly, the environmental stimuli are not able to create nerve impulses and body does not respond

    Question5.
    Draw the structure of a neuron and explain its function?
    Year of Question :(Board Term I, 2016)

    Answer: Neurons are nerve cells which are functional units of the nervous system. Three main parts of neurons are Dendrites, Axons and cell body. Dendrite: Detects information and sends it to cell body Cell Body: Maintains growth of the cell Axon: Conducts messages away from cell body and signal to next neuron

    Question6.
    How does phototropism occur in plants?
    Year of Question :(Board Term I, 2016)

    Answer: Directional movement and growth of plant in response to light is called as phototropism. Phototropism occurs due to increased auxin on the dark side and decreased auxin on the illuminated side. Because of presence of more auxin, a leaf in the darker side grows faster causing it to bend towards the source of light

    Question7.
    Which signals will get disrupted in case of a spinal cord injury?
    Year of Question :(Board Term I, 2013)

    Answer: In case of a spinal cord injury, signals coming from the nerves, as well as the signals coming to the receptors, will be disrupted. Both these signals meet in a bundle in the spinal cord. Hence, both these signals get disrupted

    Question8.
    How does chemical coordination occur in plants?
    Year of Question :(Board Term I, 2016)

    Answer: Plant growth, development and responses to the environment is controlled and coordinated by a special class of chemical substances known as hormones. Hormones are produced in one part of the plant and are transported to all the needy parts of the plant. The five major types of phytohormones are auxins, gibberellins, cytokinins, abscisic acid, and ethylene. These phytohormones are either growth promoters (such as auxins, gibberellins, cytokinins, and ethylene) or growth inhibitors such as abscisic acid

    Question9.
    What is the need for a system of control and coordination in an organism?
    Year of Question :(Board Term I, 2014)

    Answer: There are various organs in an organism. These organs must be carefully controlled and coordinated for the survival of an organism. In the body of an organism, various fluids are secreted from the glands of the endocrine system. These hormones are responsible for the overall growth and development of an organism. All other daily decisions that include voluntary and involuntary actions are controlled by the central nervous system (CNS). Coordination is needed for all human activities we perform. Our nervous system receives information from surroundings which is processed and a response is elicited. The endocrine system (hormonal system) helps in integrating various metabolic activities like reproduction, development, and all reflex actions (cope up with various give up situations). The hormonal system in plants helps in process of photosynthesis; they need carbon dioxide, water and sunlight. The stomatal opening in leaves opens up to allow in carbon dioxide gas, the roots bend towards water, the stem grows towards sunlight, and the tendrils in climbing plants are supported by the hormonal system of the plant body. Thus, we need a control and coordination system in an organism

    Question10.
    How are involuntary actions and reflex actions different from each other?
    Year of Question :(Board Term I, 2015)

    Answer: Reflex action Involuntary actions

  • 1. Rapid automatic responses to a stimulus without the conscious involvement of the brain
  • 1.Occurs without the consciousness of an organism
  • 2. Controlled by spinal cord
  • 2. Controlled by mid brain or medulla oblongata
  • 3. Very quick and instantaneou
  • 3. Relatively slower
  • 4. May involve any muscle or a gland
  • 4. Involves only smooth muscles
  • 5. Can be conditioned
  • 5. Cannot be influenced by external conditioning
    • Question11.
    Compare and contrast nervous and hormonal mechanisms for control and coordination in animals?
    Year of Question :(Board Term I, 2016)

    Answer: Nervous control Hormonal Control

  • 1 It consists of nerve impulses between PNS, CNS and Brain
  • 1 It consists of the endocrine system which secretes hormones directly into blood
  • 2 Here response time is very short
  • 2 Here response time is very long
  • 3 Nerve impulses are not specific in their action
  • 3 Each hormone has specific
  • 4 The flow of information is rapid
  • 4 The flow of information is very slow
    • Question12.
    What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
    Year of Question :(Board Term I, 2016)

    Answer: Sl. No Movement in sensitive plants Movement in our legs

  • 1
  • 1 The movement in a sensitive plant is a response to stimulus (touch) which is an involuntary action
  • 1 Movement in our legs is a voluntary action
  • 2 No special tissue is there for the transfer of information
  • 2 A complete system CNS and PNS is there for the information exchange
  • 3 Plant cells do not have specialized protein for movements
  • 3 Animal cells have specialized protein which help muscles to contract

    • Important Questions and Answers for Chapter 7: Control and Coordination

    Question 1.
    What is a reflex action? Explain with an example.
    Answer:
    Definition of Reflex Action:
    A reflex action is a sudden, automatic response to a stimulus that does not involve the brain.
    It is involuntary and quick.
    Example:
    When you touch a hot object, your hand immediately pulls back without thinking. This is an example of a reflex action.
    Question 2.
    What are the main parts of the human brain? Mention their functions.
    Answer:
    Fore-brain:
    Controls thinking, memory, and voluntary actions.
    Receives and interprets sensory information (e.g., sight, smell).
    Mid-brain:
    Regulates involuntary actions like heart rate and breathing.
    Hind-brain:
    Contains the cerebellum, which maintains balance and posture.
    Controls precision in voluntary actions like walking and cycling.
    Question 3.
    How do plant hormones control growth? Name some important plant hormones.
    Answer:
    Auxin:
    Helps in the growth of shoots by making cells elongate.
    It moves towards the shady side of a plant, causing the shoot to bend towards light (phototropism).
    Gibberellins:
    Help in the growth of the stem.
    Cytokinins:
    Promote cell division, especially in areas like fruits and seeds.
    Abscisic acid:
    Inhibits growth and helps in wilting of leaves.
    Question 4.
    What happens at a synapse between two neurons?
    Answer:
    Definition of Synapse:
    A synapse is the gap between two neurons where signals are transmitted from one neuron to the next.
    Process:
    The electrical signal triggers the release of chemical signals from one neuron.
    These chemicals cross the synapse and start an electrical impulse in the next neuron.
    Question 5.
    What is the difference between reflex actions and voluntary actions?
    Answer:
    Reflex Actions:
    Automatic and involuntary.
    Do not involve thinking.
    Example: Pulling your hand back when you touch a hot object.
    Voluntary Actions:
    Controlled by thinking.
    Involve the brain.
    Example: Deciding to move a chair.
    Question 6.
    How does the nervous system control and coordinate body activities?
    Answer:
    Sensory receptors detect stimuli (e.g., touch, light).
    Information is sent as electrical impulses through neurons to the brain or spinal cord.
    The brain processes the information and sends signals to muscles or glands for an appropriate response.
    Question 7.
    What is the function of adrenaline in the body?
    Answer:
    Adrenaline is a hormone produced by the adrenal glands.
    It prepares the body for a "fight or flight" response in stressful situations.
    Increases heart rate and breathing rate.
    Directs more blood to the muscles.
    Reduces blood flow to skin and the digestive system.
    Question 8.
    What are the different types of tropic movements in plants? Explain with examples.
    Answer:
    Phototropism:
    Movement of plants towards light.
    Example: Shoots grow towards light.
    Geotropism:
    Movement in response to gravity.
    Example: Roots grow downwards, and shoots grow upwards.
    Hydrotropism:
    Movement of plants towards water.
    Example: Roots grow towards areas with more water.
    Chemotropism:
    Movement in response to chemicals.
    Example: Growth of pollen tubes towards the ovules during fertilization.
    Question 9.
    How does the endocrine system work in animals?
    Answer:
    The endocrine system uses hormones to regulate body activities.
    Hormones are secreted by glands like the thyroid, adrenal, and pancreas.
    Hormones travel through the bloodstream to target specific organs and control processes like:
    Growth (by growth hormone).
    Metabolism (by thyroxine).
    Blood sugar regulation (by insulin).
    Question 10.
    What is the role of insulin in the body?
    Answer:
    Insulin is a hormone produced by the pancreas.
    It regulates the blood sugar level by helping cells absorb glucose.
    When insulin is insufficient, blood sugar levels rise, leading to diabetes.

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