🧠 UNIT – 6: CONTROL AND COORDINATION

🧠 UNIT – 6: CONTROL AND COORDINATION

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Learning Objectives

• Nervous system in animals

• Reflex action and reflex arc

• Coordination in plants

• Hormones in plants and their functions

• Hormones in animals and their functions

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I. Multiple Choice Questions (1 Mark each)

1. The brain is responsible for
   A. Thinking B. Regulating heartbeat C. Balancing the body D. All of the above

2. The incorrect statement about thyroxine is
   A. It regulates fat metabolism
   B. Its deficiency leads to goitre
   C. It is secreted by parathyroid gland
   D. Iodine is essential for its production

3. The gap between two neurons is called
   A. Dendrite B. Axon C. Synapse D. Cell body

4. Example of reflex action:
   A. Folding a chair B. Pulling hand back after touching a sharp object
   C. Tasting food D. Clapping at a programme

5. The centre of reflex action is
   A. Cerebrum B. Spinal cord C. Cerebellum D. Hypothalamus

6. Hormone that regulates carbohydrate, protein, and fat metabolism:
   A. Testosterone B. Adrenaline C. Thyroxine D. Insulin

7. If plant roots grow towards nitrate concentration, this is
   A. Phototropism B. Hydrotropism C. Thigmotropism D. Chemotropism

8. Mismatched pair:
   A. Adrenaline – Pituitary gland B. Testosterone – Testis C. Insulin – Pancreas D. Thyroxine – Thyroid gland

9. Correct path of transmission in a neuron:
   A. Dendrite → Axon → Cell body → Nerve ending
   B. Dendrite → Cell body → Axon → Nerve ending
   C. Dendrite → Nerve ending → Cell body → Axon

10. Correct path of reflex arc in figure: C → A → B → E → D

11. Growth of roots deep into soil shows
    A. Negative phototropism B. Positive geotropism

12. Part of brain controlling balance: Cerebellum

13. Type of movement in plant stem towards light: Phototropism

14. Path of reflex action:
    Receptor → Sensory neuron → Spinal cord → Relay neuron → Motor neuron → Effector

15. Disorder caused by under-secretion of thyroxine: Goitre

16. Hormone regulating blood sugar: Insulin

17. Plant hormone promoting cell division: Cytokinin

18. Correct order of events in reflex arc diagram: D → P → R → S → Q

19. Part of brain maintaining posture: Cerebellum

20. Part of brain controlling involuntary actions: Medulla

21. Movement of pollen grains towards ovary: Chemotropism

22. Plant hormone responsible for phototropism: Auxin

23. Transmission of information by: Electrical signals

24. Upward growth of shoot shows: Negative geotropism and positive phototropism

25. Correct statement: Abscisic acid inhibits plant growth

26. Movement pattern of roots: Undirected and positive geotropism

27. Response that is not growth-based: Leaves tingle when touched

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II. One Mark Questions

28. What are the tropic movements necessary for growth in roots and shoots of plants?

29. What is geotropism?

30. What is a neuron?

31. Which hormone inhibits plant growth?

32. What is reflex action? Give one example.

33. How does chemical coordination occur in plants?

34. Name the mineral essential for production of thyroxine.

35. What is the role of abscisic acid in plants?

36. What is the function of pancreas as an endocrine gland?

37. How do muscle cells respond to nerve impulses?

38. What is voluntary action?

39. What is involuntary action?

40. Name the parts of brain controlling voluntary and involuntary actions.

41. What is the role of receptors in our body?

42. Name the plant hormones that promote growth.

43. Differentiate between reflex action and walking.

44. Why is folding of sensitive plant leaves not a tropism?

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III. Two Mark Questions

45. A doctor advises an elderly person to consume less sugar. What disorder is this? Name the hormone responsible.

46. How is thyroid gland helpful in balanced body growth?

47. How does adrenaline help in situations of fear or stress?

48. How does chemical coordination take place in animals?

49. Write two differences between nervous system and hormonal coordination.

50. Write the functions of medulla and cerebellum in human brain.

51. In neuron, mention the direction of nerve impulse:
     a) Towards the cell b) Away from the cell.

52. How does adrenaline help an athlete prepare for a race?

53. How do leaves of the sensitive plant move when touched?

54. Why is phototropism beneficial for plants?

55. What causes mouth watering when seeing delicious food? Which part of brain controls this?

56. Why does a person lose control after consuming excess alcohol?

57. What causes stem to grow towards light and roots downward?

58. Which figure shows correct tropic movement? Why?

59. Write two differences between central and peripheral nervous systems.

60. Write two differences between endocrine glands and nervous system.

61. Mention function of plant hormones: i) Auxin ii) Cytokinin.

62. How do auxins promote growth of tendrils?

63. How does body respond when adrenaline is secreted into blood?

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IV. Three Mark Questions

64. “Reflex action is more effective than thinking process of brain.” Justify.

65. Give reason: Chemical coordination is more stable and continuous than electrical coordination.

66. Explain how phototropism, thigmotropism and chemotropism work together in creepers.

67. Identify the given structure. Write its common function and function of parts A & C.

68. Draw the diagram of human brain and label parts.

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V. Four Mark Questions

69. Name hormones controlling these activities in humans:
     a) Blood sugar level b) Menstrual cycle c) Emergency situations d) Metabolism

70. Name the structural and functional unit of nervous tissue and explain impulse transmission.

71. What is reflex arc? Trace events when bright light is focused on eyes.

72. Differentiate between movement of leaves in Mimosa pudica and shoot bending towards light.

73. Name the structure (neuron/reflex arc). Write functions of parts A & B and explain its quick response.

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VI. Five Mark Question

74. a) How do climbing plants show directional movement?
     b) Mention the functions of thyroxine and adrenaline hormones in humans.

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🧠 UNIT – 6 : CONTROL AND COORDINATION – KEY ANSWERS

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I. Multiple Choice Questions (1 mark each)

No	Correct Answer	Explanation
1	✅ D. All of the above	Brain controls thinking, heartbeat, balance
2	✅ C. It is secreted by parathyroid gland	Incorrect – thyroxine is secreted by thyroid gland
3	✅ C. Synapse	Gap between two neurons for impulse transfer
4	✅ B. Pulling hand back after touching a sharp object	Reflex action
5	✅ B. Spinal cord	Reflex center
6	✅ C. Thyroxine	Controls carbohydrate, fat, and protein metabolism
7	✅ D. Chemotropism	Growth toward chemical stimulus
8	✅ A. Adrenaline – Pituitary gland	Incorrect pair; adrenaline is secreted by adrenal gland
9	✅ B. Dendrite → Cell body → Axon → Nerve ending	Correct impulse path
10	✅ C → A → B → E → D	Correct reflex arc path
11	✅ B. Positive geotropism	Roots grow toward gravity
12	✅ Cerebellum	Maintains posture and balance
13	✅ Phototropism	Stem grows toward light
14	✅ Receptor → Sensory → Spinal cord → Relay → Motor → Effector	Reflex path
15	✅ Goitre	Caused by thyroxine deficiency
16	✅ Insulin	Controls blood sugar level
17	✅ Cytokinin	Promotes cell division
18	✅ D → P → R → S → Q	Sequence of reflex arc
19	✅ Cerebellum	Balances body
20	✅ Medulla	Controls involuntary actions
21	✅ Chemotropism	Pollen tube grows toward ovary
22	✅ Auxin	Causes bending toward light
23	✅ Electrical signals	Nerves transmit impulses electrically
24	✅ Negative geotropism, Positive phototropism	Shoots grow up and toward light
25	✅ Abscisic acid inhibits plant growth	Growth-inhibiting hormone
26	✅ Positive geotropism	Roots grow downwards
27	✅ Touch response	Non-growth movement (nastic)

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II. One Mark Answers

28. Tropic movements:
    Roots → Positive geotropism; Shoots → Positive phototropism.

29. Geotropism: Growth movement in response to gravity.

30. Neuron: Structural and functional unit of nervous system.

31. Hormone inhibiting growth: Abscisic acid.

32. Reflex action: Sudden involuntary response (e.g., withdrawing hand from hot object).

33. Chemical coordination in plants: Through plant hormones.

34. Mineral for thyroxine: Iodine.

35. Abscisic acid: Inhibits growth and induces dormancy.

36. Endocrine function of pancreas: Secretes insulin to regulate blood sugar.

37. Muscle cells: Contract in response to nerve impulse.

38. Voluntary action: Controlled by will (e.g., writing).

39. Involuntary action: Not under control (e.g., heartbeat).

40. Brain parts:
    Voluntary – Cerebrum; Involuntary – Medulla.

41. Receptors: Detect external and internal stimuli.

42. Growth-promoting hormones: Auxins and Cytokinins.

43. Difference:
    Reflex – Involuntary; Walking – Voluntary.

44. Mimosa movement: Nastic movement, not tropism (not growth-based).

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III. Two Mark Answers

45. Disorder: Diabetes; Hormone: Insulin (from pancreas).

46. Thyroid gland: Secretes thyroxine – maintains metabolism and body growth.

47. Adrenaline: Increases heartbeat, breathing rate, blood flow to muscles during stress/fear.

48. Chemical coordination in animals: By endocrine glands secreting hormones into blood.

49. Differences – Nervous vs Hormonal Coordination:
    | Nervous | Hormonal |
    |----------|-----------|
    | Fast, short-lived | Slow, long-lasting |
    | Electric impulses | Chemical messengers |

50. Functions:
    Medulla – controls involuntary actions (heartbeat, breathing);
    Cerebellum – coordinates movement and balance.

51. Direction of impulse:
    a) Toward cell – Dendrites b) Away – Axon.

52. Adrenaline in athletes: Increases heartbeat, breathing, energy — prepares body for action.

53. Mimosa movement: Cells lose water → turgor change → leaves fold.

54. Phototropism benefit: Ensures maximum sunlight for photosynthesis.

55. Mouth watering: Reflex from cerebrum (thinking) to salivary glands.

56. Alcohol effect: Affects cerebellum – loss of coordination and balance.

57. Reason for movement:
    Auxin accumulates in shaded part of shoot – bends toward light; roots grow downward due to gravity.

58. Correct figure: B – shows bending toward light (positive phototropism).

59. CNS vs PNS:
    | Central NS | Peripheral NS |
    |-------------|---------------|
    | Brain & spinal cord | Nerves connecting body parts |
    | Control center | Carries impulses |

60. Endocrine vs Nervous System:
    | Endocrine | Nervous |
    |------------|----------|
    | Chemical messengers (hormones) | Electrical impulses |
    | Slow & long-lasting | Fast & short-term |

61. Functions:
    Auxin – cell elongation;
    Cytokinin – cell division.

62. Tendrils: Auxin accumulates on shaded side → faster growth → curling.

63. Adrenaline effect: Increases heart rate, blood pressure, and oxygen supply — “fight or flight” response.

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IV. Three Mark Answers

64. Reflex action vs brain thinking:
    Reflex is faster and protective; involves spinal cord, not brain.

65. Chemical coordination stability:
    Hormones stay longer in blood; nervous signals short-lived.

66. Coordination in creepers:
    Phototropism – stem to light;
    Thigmotropism – coil around support;
    Chemotropism – roots toward nutrients.

67. Structure: Neuron – transmits impulses;
    Part A – Dendrite (receives impulses), Part C – Axon (sends impulses).

68. Human brain diagram:
    Label – Cerebrum, Cerebellum, Medulla, Spinal cord, Pons.

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V. Four Mark Answers

Function	Hormone	Gland
a) Blood sugar	Insulin	Pancreas
b) Menstrual cycle	Oestrogen/Progesterone	Ovary
c) Emergency	Adrenaline	Adrenal gland
d) Metabolism	Thyroxine	Thyroid gland

70. Neuron impulse transmission:
    Impulse → Dendrite → Cell body → Axon → Synapse → Next neuron.
    Neurotransmitters carry impulses chemically across synapse.

71. Reflex arc (eye light):
    Receptor (retina) → Sensory neuron → Spinal cord → Motor neuron → Eye muscle (pupil contracts).

72. Mimosa vs Tropism:
    | Mimosa | Phototropism |
    |---------|---------------|
    | Nastic (non-directional) | Directional (toward stimulus) |
    | Touch response | Light response |
    | Temporary | Growth-based |

73. Neuron functions:
    A – Dendrite receives impulse,
    B – Axon transmits impulse;
    Reflex action is quick as it bypasses brain, using spinal cord.

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VI. Five Mark Answer

74. a) Climbing plants:
    Thigmotropism – tendrils coil around support; Phototropism – stem grows toward light.

b) Hormone functions:

• Thyroxine: Controls metabolism, growth, and energy balance.

• Adrenaline: “Fight or flight” hormone; increases heart rate, breathing, alertness.