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Tag: Chapter 6 – Control and Coordiantion

  • Class 10th Science Chapter 6 – Control and Coordination – Exercises

    Q1. Which of the following is a plant hormone?

    (a) Insulin
    (b) Thyroxin
    (c) Oestrogen
    (d) Cytokinin

    Answer: (d) Cytokinin

    Explanation:

    • Insulin, thyroxin and oestrogen are human hormones.

    • Cytokinin is a plant hormone that promotes cell division and growth.

    Q2. The gap between two neurons is called a

    (a) dendrite
    (b) synapse
    (c) axon
    (d) impulse

    Answer: (b) synapse

    Explanation:

    A synapse is a microscopic gap between two neurons through which nerve impulses pass using chemical neurotransmitters.

    Q3. The brain is responsible for

    (a) thinking
    (b) regulating the heartbeat
    (c) balancing the body
    (d) all of the above

    Answer: (d) all of the above

    Explanation:

    • Thinking is controlled by cerebrum

    • Heartbeat is regulated by medulla

    • Balance and posture are controlled by cerebellum
      Therefore, the brain performs all of these functions.

    Q4. 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 special cells present in our sense organs that receive stimuli such as light, sound, smell, taste, pressure, pain, and temperature.
    They send this information to the brain through nerve impulses for interpretation and response.

    If receptors do not work properly:

    • We may not feel pain or danger signals (e.g., touching a hot object)

    • We may lose senses such as hearing, vision, smell, taste, or touch

    • The body may fail to respond correctly to the environment, causing accidents or injuries

    Example:

    A person whose pain receptors are damaged may touch fire without realising and get burnt.

    Q5. Draw the structure of a neuron and explain its function.

    Answer:

    Diagram of a Neuron (rough sketch format for exam)

    Function:

    A neuron is the structural and functional unit of the nervous system.
    Its function is to receive and transmit nerve impulses from one part of the body to another.

    Q6. How does phototropism occur in plants?

    Answer:

    Phototropism is the growth movement of plants in response to light.

    How it occurs:

    • When light falls on one side of the plant shoot, the auxin hormone moves to the shaded side.

    • Cells on the shaded side elongate more than cells on the lighted side.

    • This causes the shoot to bend towards the light.

    Example:

    Bending of a plant stem towards sunlight.

    Q7. Which signals will get disrupted in case of a spinal cord injury?

    Answer:

    If the spinal cord is damaged, the following signals will be disrupted:

    • Reflex actions

    • Communication between brain and body

    • Movement and muscle control

    • Sensory signals from body parts

    • Control of organs below the injury

    Result:

    Paralysis, loss of sensation, and inability to coordinate body movements.

    Q8. How does chemical coordination occur in plants?

    Answer:

    Chemical coordination in plants occurs through plant hormones.
    These hormones are produced in one part of the plant and transported to other parts where they regulate growth and responses.

    Important plant hormones:

    Hormone Function
    Auxin Cell elongation, bending towards light
    Gibberellin

     

    Stem growth and seed germination
    Cytokinin Cell division
    Abscisic acid

     

    Closes stomata, inhibits growth, stress response

    Q9. What is the need for a system of control and coordination in an organism?

    Answer:

    An organism needs a system of control and coordination to:

    • Receive information from the surroundings

    • Process and respond to stimuli correctly

    • Coordinate functions of different organs

    • Maintain balance and homeostasis

    • Ensure survival in changing environments

    Explanation:

    Control and coordination help different body parts work together smoothly, for example:

    • Running away from danger

    • Adjusting body temperature

    • Regulating heartbeat and breathing

    Q10. How are involuntary actions and reflex actions different from each other?

    Involuntary Actions Reflex Actions
    Occur without conscious control Quick, automatic response to a stimulus

     

    Controlled by brain (medulla)

    		 Controlled by spinal cord
    Slow compared to reflex Very fast
    Example: heartbeat, breathing

     

    Example: removing hand from hot object

    Q11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

    Feature Nervous System Hormonal (Endocrine) System
    Mode of transmission Electrical impulses

     

    Chemical hormones in blood
    Speed Very fast Slow
    Duration Short-lived Long-lasting
    Target

     

    Specific organs or tissues

    		 Many organs at once
    Example Touch, reflex action

     

    Growth, puberty, sugar control

    Q12. What is the difference between the manner in which movement takes place in a sensitive plant and movement in our legs?

    Sensitive Plant Movement Movement in Human Legs
    Response to stimuli (touch) Controlled by brain and spinal cord
    Chemical changes in cells cause water to move

     

    Muscle contraction causes movement
    Not growth-based

     

    Requires coordinated muscles & nervous system
    Fast and temporary

     

    Slower and under voluntary control
    Example: Touch-me-not leaf closes Walking, running, jumping

     

     

     

     

     

     

     

     

  • Class 10th Science Chapter 6 – Control and Coordination – In-text Questions

    PAGE 105 – QUESTIONS & ANSWERS

    Q1. What is the difference between a reflex action and walking?

    Answer:

    Reflex Action Walking
    Automatic, rapid, involuntary action Slow, voluntary, controlled action
    Does not involve thinking

    Requires thinking and decision
    Controlled by spinal cord

    Controlled by brain (cerebellum)
    Example: Pulling hand away from flame Example: Walking, running

    Q2. What happens at the synapse between two neurons?

    Answer:

    At the synapse, the electrical impulse arriving at the end of one neuron triggers the release of chemical neurotransmitters into the gap.
    These chemicals cross the synapse and start a new electrical impulse in the next neuron.

    Q3. Which part of the brain maintains posture and equilibrium of the body?

    Answer:

    The cerebellum, located in the hindbrain, maintains balance, posture and precision of voluntary movements.

    Q4. How do we detect the smell of an agarbatti (incense stick)?

    Answer:

    Odour molecules from agarbatti are detected by olfactory receptors in the nose.
    These receptors send information to the forebrain, which interprets it as smell.

    Q5. What is the role of the brain in reflex action?

    Answer:

    The reflex action is coordinated by the spinal cord, but signals also reach the brain, which interprets the situation and allows us to become aware of what happened after the action has already occurred.

    Q1. What are plant hormones?

    Answer:

    Plant hormones are chemical substances produced in plants that regulate growth and responses to stimuli.
    Example: Auxin, Cytokinin, Gibberellin, Abscisic acid

    Q2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

    Answer:

    Sensitive plant movement Shoot bending towards light
    Very quick response Slow response
    Not dependent on growth Depends on growth
    Due to change in water content in cells

    Due to uneven auxin distribution

    Q3. Give an example of a plant hormone that promotes growth.

    Answer:

    Auxin – promotes cell elongation.

    Q4. How do auxins promote the growth of a tendril around a support?

    Answer:

    When a tendril touches support, auxin collects on the opposite side, causing cells on that side to grow longer.
    This unequal growth causes the tendril to curve around the support.

    Q5. Design an experiment to demonstrate hydrotropism.

    Answer:

    Experiment:

    • Take a pot divided into two sections.

    • Fill both sides with soil.

    • Place seeds on both sides.

    • Pour water only on one side.

    • Cover pot for a few days.

    Observation:

    Roots bend towards the side containing water.

    Conclusion:

    Roots show positive hydrotropism.

    PAGE 111 – QUESTIONS & ANSWERS

    Q1. How does chemical coordination take place in animals?

    Answer:

    Animals use hormones, secreted by endocrine glands, which are released into the bloodstream and reach target organs, regulating growth, metabolism, reproduction, and emergency responses.

    Q2. Why is the use of iodised salt advisable?

    Answer:

    Because iodine is necessary for the thyroid gland to produce thyroxin hormone.
    Its deficiency causes goitre (swelling of the neck).

    Q3. How does our body respond when adrenaline is secreted into the blood?

    Answer:

    Adrenaline prepares the body for fight or flight:

    • Faster heartbeat

    • Increased breathing rate

    • Increased blood flow to muscles

    • More oxygen supply

    • Energy release increases

    Q4. Why are some patients of diabetes treated by giving injections of insulin?

    Answer:

    Diabetes occurs because the pancreas does not produce enough insulin, so blood sugar rises.
    Injected insulin helps to control blood sugar levels.