What is control and coordination in organisms?

Control and coordination is the ability of organisms to respond to stimuli and maintain internal balance using nervous and hormonal systems.

Why are these notes useful for competitive exams?

These notes cover essential topics for NEET, SSC, Railway, and Police Bharti exams, as well as Class 10 board exams.

Do these notes explain reflex actions and hormones?

Yes, they include detailed explanations of reflex actions, human and plant hormones, and coordination mechanisms.

1. What is control and coordination in organisms?

Control and coordination are processes that allow organisms to respond to internal and external stimuli, maintaining order and homeostasis. They are achieved mainly via thenervousandendocrinesystems.

3. What are the major divisions of the human nervous system?

Two main divisions:Central Nervous System (CNS)— brain and spinal cord;Peripheral Nervous System (PNS)— nerves connecting CNS to organs. PNS includes somatic and autonomic systems.

5. What is a synapse and how do neurons communicate across it?

Asynapseis a small gap between neuron terminals and the next cell. When an impulse arrives, neurotransmitters (chemical messengers, e.g., acetylcholine) are released, cross the gap, and trigger a response in the next cell.

6. How is a nerve impulse conducted along a neuron?

Impulse conduction is an electrical change (action potential) moving along the membrane. In myelinated axons, propagation is faster viasaltatory conduction— impulse jumps between Nodes of Ranvier.

7. What is a reflex action and what are the components of a reflex arc?

A reflex action is an automatic, rapid response to a stimulus (no conscious control). Thereflex arcincludes receptor → sensory neuron → interneuron (in spinal cord) → motor neuron → effector (muscle/gland). Example: knee-jerk reflex.

9. What are the functions of the spinal cord?

Spinal cord conducts impulses between brain and body and serves as a center for many reflexes. It has grey matter (cell bodies) and white matter (nerve fibers) and is protected by meninges and vertebral column.

11. What is the endocrine system and how is it different from the nervous system?

The endocrine system uses hormones (chemical messengers) secreted by glands into the blood. Its effects are generally slower but longer-lasting compared to the fast and short-lived nervous impulses.

12. What are some functions of the pituitary gland?

Pituitary secretes hormones like growth hormone (GH), FSH, LH, TSH and ACTH. It's often called the "master gland" because it regulates other endocrine glands.

13. What does the thyroid gland secrete and why is iodine important?

Thyroid secretes thyroxine which regulates metabolic rate and growth. Iodine is essential for thyroxine synthesis; deficiency can cause goitre and developmental problems (cretinism).

14. What is the role of adrenal glands and adrenaline?

Adrenal glands secrete adrenaline in emergencies — increases heart rate, breathing rate, blood flow to muscles, and mobilizes glucose (fight-or-flight response).

15. How do insulin and glucagon regulate blood sugar?

Insulin (from pancreas) lowers blood sugar by promoting glucose uptake and glycogen formation. Glucagon raises blood sugar by promoting glycogen breakdown. Malfunction can lead to diabetes.

16. Which hormones control secondary sexual characteristics?

In males, testosterone (from testes) controls secondary sexual features; in females, estrogen and progesterone (from ovaries) regulate secondary characteristics and reproductive cycles.

19. What is phototropism and how does auxin mediate it?

Phototropism is growth toward/away from light. Auxin redistributes to the shaded side causing cell elongation there, bending the shoot toward light (Darwin's coleoptile experiments demonstrated this).

21. What is geotropism (gravitropism)? How do roots and shoots respond?

Geotropism is growth in response to gravity. Roots show positive geotropism (grow downward); shoots show negative geotropism (grow upward). Auxin inhibits elongation in roots but promotes it in shoots.

23. How do plants achieve coordination without a nervous system?

Plants use chemical coordination via hormones. Hormones are produced in one part and transported (via phloem/xylem or cell-to-cell) to effectors; responses are usually slower and longer-lasting.

27. How do taste and smell receptors detect chemicals?

Taste receptors (taste buds) detect chemicals dissolved in saliva; olfactory receptors detect volatile chemicals (airborne) in the nasal cavity. Both are chemoreceptors.

30. What is accommodation in the eye?

Accommodation is adjustment of lens shape by ciliary muscles to focus on near or distant objects (lens becomes thicker for near vision, thinner for distant vision).

33. How are taste signals transmitted to the brain?

Taste buds on the tongue detect chemicals and send signals via cranial nerves (VII, IX) to the gustatory cortex in the brain for perception of taste.

34. (High-level) What is the role of spinal reflexes in protection?

Spinal reflexes provide immediate protective responses (withdrawal from pain) without waiting for brain processing, minimising damage.

35. How do hormones act on target cells?

Hormones travel in blood to target cells which have specific receptors. Binding triggers intracellular responses (through direct gene action or second messenger systems) producing physiological effects.

Class 10 Science — Chapter 7: Control & Coordination

By RAAM SETU | NEET, SSC, Railway & Police Bharti Focused Notes 📘

📘 Introduction

This chapter explains Control & Coordination in living organisms, covering the nervous system, hormones, reflex actions and coordination in plants and animals. Essential for NEET, SSC, Railway, and Police Bharti exams and Class 10 boards.

🔹 Key Concepts

Nervous System: Structure and functions of brain, spinal cord, neurons
Hormones: Chemical coordination via glands
Reflex Actions: Automatic responses to stimuli
Coordination in Plants: Tropic movements and plant hormones
Coordination in Animals: Interaction between nervous and endocrine systems

📊 Chapter Summary Table

Topic	Example / Organ	Function
Nervous System	Brain, Spinal Cord	Coordination & rapid response to stimuli
Hormones	Endocrine glands	Chemical regulation of body functions
Reflex Action	Spinal Cord	Automatic quick response to stimuli

🧮 Practice Questions

Define reflex action. ➡ Show Answer
Reflex action is an automatic and rapid response to a stimulus, controlled by the spinal cord without conscious thought.
What is the role of hormones in coordination? ➡ Show Answer
Hormones are chemical messengers secreted by glands to regulate and coordinate body functions across different organs.
Name two plant hormones and their functions. ➡ Show Answer
Auxins promote growth in response to light (phototropism) and roots growth; Gibberellins stimulate stem elongation and seed germination.

Control & Coordination — 50 Q&A

NCERT Class 10. Mobile-first UI — tap to expand answers.

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Nervous System Endocrine System Plant Hormones Reflex Actions

NCERT Class 10 — Control & Coordination

📘 Introduction

🔹 Key Concepts

📊 Chapter Summary Table

🧮 Practice Questions

1. What is control and coordination in organisms?

2. Define stimulus, receptor and effector with quick examples.

3. What are the major divisions of the human nervous system?

4. Describe the structure of a neuron (nerve cell).

5. What is a synapse and how do neurons communicate across it?

6. How is a nerve impulse conducted along a neuron?

7. What is a reflex action and what are the components of a reflex arc?

8. Differentiate voluntary and involuntary actions with examples.

9. What are the functions of the spinal cord?

10. Name major parts of the brain and one function each.

11. What is the endocrine system and how is it different from the nervous system?

12. What are some functions of the pituitary gland?

13. What does the thyroid gland secrete and why is iodine important?

14. What is the role of adrenal glands and adrenaline?

15. How do insulin and glucagon regulate blood sugar?

16. Which hormones control secondary sexual characteristics?

17. Compare nervous and hormonal (endocrine) coordination briefly.

18. Name major plant hormones and one function each.

19. What is phototropism and how does auxin mediate it?

20. Explain apical dominance.

21. What is geotropism (gravitropism)? How do roots and shoots respond?

22. Define tropism and give four types.

23. How do plants achieve coordination without a nervous system?

24. Differentiate tropic and nastic movements with examples.

25. What is homeostasis? Give two examples where control systems maintain it.

26. Name sensory receptors for sight, hearing, taste and smell.

27. How do taste and smell receptors detect chemicals?

28. Why is the myelin sheath important? Name a disease caused by myelin damage.

29. Give a simple explanation of resting and action potential.

30. What is accommodation in the eye?

31. Describe the pupillary reflex in bright light.

32. Give a short account of how sound is detected by the ear.

33. How are taste signals transmitted to the brain?

34. (High-level) What is the role of spinal reflexes in protection?

35. How do hormones act on target cells?

36. Briefly describe diabetes mellitus and its two common types.

37. What is negative feedback? Give an example in hormone regulation.

38. What is positive feedback? Give a biological example.

39. Why are reflex actions faster than voluntary actions?

40. What are some higher functions of the cerebrum?

41. Which vital involuntary functions are controlled by medulla oblongata?

42. Give one example of hormone deficiency and its effects.

43. What causes goitre and how is it prevented?

44. Mention two practical uses of plant hormones (auxins/gibberellins).

45. Name a classical experiment that demonstrated chemical coordination in plants.

46. What are plant growth regulators and how are they used agriculturally?

47. What is signal transduction (simple view)?

48. Name two nervous system disorders and a short cause for each.

49. Quick revision: Key hormones & their source (bullets).

50. High-yield summary: Control & Coordination (one-minute revision).