Control and Coordination · Class 10 Science: 162 MCQs with answers

Q1. Describe the structure of a neuron and the path an impulse takes through it.

Q2. What happens at the synapse between two neurons?

Q3. What is a reflex action? Why is it advantageous?

Q4. Differentiate between the functions of the cerebellum and the medulla.

Q5. How are the brain and spinal cord protected in our body?

Q6. How does the touch-me-not plant close its leaves on being touched, without any muscles?

Q7. Define tropic movements and classify them as positive or negative with one example each.

Q8. Describe how a tendril coils around a support.

Q9. Give an example of chemotropism and explain what happens.

Q10. Name the five major plant hormones and one function of each.

Q11. Why is abscisic acid called a stress hormone or growth inhibitor?

Q12. Iodine deficiency causes:

Q13. Childhood deficiency of growth hormone causes:

Q14. Deficiency of insulin causes:

Q15. Iodised salt is promoted to prevent:

Q16. What are hormones? List their three key characteristics.

Q17. What changes does the body go through once adrenaline reaches the blood?

Q18. Why is the use of iodised salt advisable?

Q19. What is the function of thyroxine, and what happens when it cannot be made?

Q20. What are the effects of abnormal growth hormone secretion?

Q21. Name the hormones responsible for the changes at puberty and their sources.

Q22. Four kinds of receptor detect four kinds of stimulus. Photoreceptors, phonoreceptors, olfactory receptors and gustatory receptors are found respectively in the:

Q23. The correct order within one neuron is:

Q24. Pain from a burn is felt:

Q25. Which brain part smooths a gymnast's landing?

Q26. Salivation on smelling food is coordinated via the:

Q27. Pupil narrowing in bright light is managed by the:

Q28. The fluid around the brain serves to:

Q29. Hunger is registered in a centre of the:

Q30. Muscle contraction at the molecular level involves:

Q31. Which sequence describes signal types along a two-neuron path?

Q32. Sneezing at dust is:

Q33. A key reason reflex arcs evolved is that:

Q34. Which pair is matched correctly?

Q35. Trace the reflex arc when you step on a sharp object.

Q36. List the functions of the fore-brain.

Q37. How does nervous tissue cause action in a muscle?

Q38. Name the receptors for taste and smell, and state what happens when receptors fail to work.

Q39. Why is a second (hormonal) system of control needed in addition to nerves?

Q40. A tendril coils because its touching side grows:

Q41. The touch-me-not's fold is NOT a tropism because it:

Q42. Touching ONE leaflet of Mimosa folds distant leaflets too, proving:

Q43. A seedling turned horizontal will show, in days:

Q44. Seed dormancy through a harsh season is enforced by:

Q45. Which is a growth-mediated movement?

Q46. The tendril and the touch-me-not both respond to touch, but differ in:

Q47. Why doesn't the root tip bend toward light in a window-side pot?

Q48. Which of these plant movements is the FASTEST?

Q49. Explain phototropism in shoots using the role of auxin.

Q50. What are the differences between the movement of the touch-me-not's leaves and the movement of a shoot toward light?

Q51. How is information communicated within a plant that has no nervous tissue?

Q52. Design a simple experiment to demonstrate geotropism.

Q53. Testosterone and oestrogen are secreted respectively by the:

Q54. As blood sugar returns to normal, insulin secretion:

Q55. Hormonal responses differ from reflexes by being:

Q56. Only certain cells respond to a hormone because they alone possess:

Q57. 'Butterflies in the stomach' before an exam are caused by:

Q58. Childhood EXCESS of growth hormone causes:

Q59. Which hormone's synthesis directly depends on a dietary mineral?

Q60. Consider these gland-and-hormone pairs. I. Thyroid and thyroxine. II. Pancreas and insulin. III. Adrenal gland and adrenaline. IV. Pituitary and oestrogen. Which pairs are correct?

Q61. Why do diabetic patients take insulin injections?

Q62. How is the timing and amount of hormone release regulated? Explain with insulin.

Q63. Compare nervous and hormonal mechanisms of control (four points).

Q64. How do specific tissues respond to a hormone that the blood delivers everywhere?

Q65. Consider these statements about the neuron. I. Dendrites receive information. II. The cell body processes it. III. The axon conducts the impulse away. IV. The impulse travels as a chemical along the whole length of the neuron. Which statements are correct?

Q66. Which of these best explains why a nerve impulse changes from electrical to chemical and back again as it passes from one neuron to the next?

Q67. Assertion (A): A nerve impulse travels in one direction only, from dendrite to axon end. Reason (R): The chemical that crosses the synapse is released on one side of the gap only and detected on the other.

Q68. What is the best explanation of why nervous coordination is fast but short-lived, while hormonal coordination is slow but sustained?

Q69. Which is the correct explanation of why food seems tasteless when a person has a heavy cold?

Q70. Which statement best explains why the reflex that pulls a hand off a hot object does not pause for the brain?

Q71. A person touches a hot pan, jerks the hand back, and only then feels the pain. This order of events shows that:

Q72. Consider these statements about the reflex arc. I. It runs receptor, sensory neuron, spinal cord, motor neuron, effector. II. The effector is a muscle or a gland. III. Sneezing and blinking are reflex actions. IV. Writing an examination answer is a reflex action. Which statements are correct?

Q73. Three parts of the brain do three different jobs: thinking and voluntary action, balance and precision of movement, and the control of blood pressure and vomiting. They are respectively the:

Q74. Which of these best explains why a person with cerebellar damage can still move their limbs but cannot walk a straight line or pick up a glass smoothly?

Q75. An injury to the brain stem is far more likely to be fatal than an injury of the same size to the cerebrum. The reason is that the brain stem:

Q76. Consider these statements about the protection of the central nervous system. I. The brain is enclosed in the bony skull. II. It floats in a fluid that absorbs shocks. III. The spinal cord runs through the vertebral column. IV. The fluid also supplies the brain with oxygen instead of blood. Which statements are correct?

Q77. What is the best explanation of why the brain is described as floating in fluid rather than resting on bone?

Q78. If the MOTOR neuron of a reflex arc is damaged but the sensory neuron is intact, the person will:

Q79. Which statement correctly distinguishes voluntary, involuntary and reflex actions?

Q80. Which of these is NOT part of a reflex arc?

Q81. Assertion (A): Salivation at the smell of food and the narrowing of the pupil in bright light are both involuntary. Reason (R): Both are decided by the fore-brain, which is where thinking takes place.

Q82. Which is the correct explanation of why reflex arcs evolved in animals whose brains were already capable of directing movement?

Q83. Which statement best explains why muscle contraction is described as a change of shape in the muscle cells themselves?

Q84. Nerve impulses cannot serve ALL body cells because:

Q85. Neurons cannot fire continuously because:

Q86. Assertion: The hand withdraws from a flame before pain is felt. Reason: The reflex arc through the spinal cord acts faster than the sensory report reaches the brain.

Q87. Assertion: A drunk person walks unsteadily. Reason: Alcohol affects the cerebellum's coordination function.

Q88. If the sensory neuron of a reflex arc is cut, the response to the stimulus will:

Q89. Which of these best explains why the centre that registers hunger lies in the fore-brain rather than in the spinal cord?

Q90. A boxer's 'duck' on seeing a punch differs from an eyeblink reflex because the duck:

Q91. Which failure best explains uncontrolled blood-pressure regulation after a brain-stem injury?

Q92. Explain the journey of a nerve impulse from stimulus to response: reception at a receptor, conduction through neurons, the events at each synapse, and the final action at a muscle — with the electrical/chemical distinction made clear at every stage.

Q93. Define reflex action and reflex arc. Trace the complete arc for touching a hot object, explain why the pathway bypasses the brain, discuss when the brain does get involved, and give two more examples of reflexes with their survival value.

Q94. Describe the human brain's organisation: the three divisions and every major function of each, the distinction between voluntary and involuntary actions with their controlling regions, and the protective arrangements for the brain and spinal cord.

Q95. Compare nervous coordination with the situations it cannot handle: analyse the two structural limits of neurons, show with examples why growth and sustained regulation need a different mechanism, and outline how the chemical (hormonal) system complements the wiring — ending with one process where both systems visibly cooperate.

Q96. Which statement best explains how a plant coordinates its activities without nerves or muscles?

Q97. Consider these statements about the touch-me-not plant. I. Its leaves fold within seconds of being touched. II. The folding is caused by cells changing their water content. III. The movement is not a growth movement. IV. The point touched and the point that moves are the same. Which statements are correct?

Q98. What is the best explanation of why the touch-me-not folds in seconds while a shoot takes days to bend towards light?

Q99. Four tropisms are named after four stimuli. A shoot bending to light, a root growing down, a root growing towards moisture, and a pollen tube growing towards the ovule are respectively:

Q100. Assertion (A): A shoot shows positive phototropism while a root shows negative phototropism. Reason (R): The same hormone that makes shoot cells elongate inhibits elongation in root cells.

Q101. A seedling growing upright in a pot is laid on its side and left in the dark for two days. What will be seen?

Q102. Roots are often found growing into a cracked underground drainpipe. This best demonstrates:

Q103. Which statement best explains what a plant gains from tropic growth movements?

Q104. A tendril touching a support curls around it. The mechanism is that:

Q105. In one-sided light, a shoot bends towards the light because auxin:

Q106. Consider these plant hormones and what they do. I. Auxin causes cells to elongate. II. Gibberellin promotes stem growth. III. Cytokinin promotes cell division. IV. Abscisic acid promotes growth. Which statements are correct?

Q107. Fruits and developing seeds are rich in cytokinin. The reason is that these are sites of:

Q108. Which is the correct explanation of why a seed that could germinate at once may instead lie dormant through a dry or cold season?

Q109. Traders ripen green bananas artificially by exposing them to a gas. That gas and its role are:

Q110. Which statement best explains why a plant can manage with hormones that travel only by diffusion, when an animal needs a bloodstream?

Q111. Which pairing of a plant hormone with its effect is WRONG?

Q112. Which experiment demonstrates geotropism most convincingly?

Q113. A pot on a windowsill has light coming from one side only. The shoot bends towards the window, but the root does not bend away from it. The best reason is:

Q114. A shoot tip is cut off and one-sided light is then shone on the stump. The shoot will:

Q115. If auxin were applied evenly to ALL sides of a shoot receiving one-sided light, the shoot would:

Q116. Consider these statements about movement in plants. I. Some movements are caused by growth and are permanent. II. Some are caused by changes in the water content of cells and are reversible. III. Growth movements are directional, towards or away from a stimulus. IV. All plant movements are caused by growth. Which statements are correct?

Q117. Consider these statements comparing plant and animal coordination. I. Plants have no specialised conducting tissue for signals. II. Plant responses are slower than animal responses. III. Plant coordination is chemical and hydraulic rather than electrical. IV. Plants can therefore not respond to their surroundings at all. Which statements are correct?

Q118. Which of these best explains why one very ripe fruit left in a basket hastens the ripening of the others?

Q119. Which statement best explains what a plant gains by having hormones that inhibit growth as well as hormones that promote it?

Q120. Assertion: One overripe mango hastens ripening of the basket. Reason: Ethylene is gaseous and diffuses to neighbouring fruits.

Q121. Assertion: The touch-me-not's response involves no hormones acting over days. Reason: Its movement is an immediate turgor change, not growth.

Q122. Touching a single leaflet of a touch-me-not causes leaflets some distance away to fold as well. This proves that:

Q123. What is the best explanation of why the same hormone, auxin, can make a shoot bend towards light and a root bend away from it?

Q124. A creeper climbing a wire fence uses which hormone-mediated behaviour?

Q125. A creeper growing along a wall sends out tendrils that find and grip a wire fence. This behaviour depends on:

Q126. Plant coordination is fully chemical/hydraulic. The trade-off versus animal wiring is:

Q127. Compare and contrast the two types of movement in plants — immediate turgor-driven movements and growth-dependent tropic movements — describing the mechanism of each with the touch-me-not and the light-seeking shoot as case studies, and stating why both are needed.

Q128. Describe all five classes of tropism with definitions, examples and the adaptive advantage of each — and explain the mechanism of thigmotropism in tendrils in detail.

Q129. Write a complete account of plant hormones: the five classes with sources/roles, how they move, the auxin phototropism experiment logic (tip removal), the commercial uses of ethylene, and the special position of abscisic acid.

Q130. Compare coordination in plants and animals across: speed, messengers, specialised tissues, nature of response, and energy economics — then argue why each system fits its owner's lifestyle, using the touch-me-not and the human reflex arc as the closing pair of examples.

Q131. Consider these statements about endocrine glands. I. They have no ducts and secrete directly into the blood. II. The blood carries the hormone to every part of the body. III. Only cells with the matching receptor respond to it. IV. The hormone is therefore delivered straight to its target alone. Which statements are correct?

Q132. Which is the correct explanation of why the changes produced by adrenaline — a faster heart, deeper breathing and blood diverted to the muscles — make sense together?

Q133. Which statement best explains the fluttering feeling in the stomach that many students notice before an examination?

Q134. Which statement best explains why a person whose thyroid makes too little thyroxine tends to feel cold and tired?

Q135. Assertion (A): Iodised salt is promoted by public health programmes across India. Reason (R): Thyroxine regulates carbohydrate, protein and fat metabolism in the body.

Q136. Which of these best explains why the pituitary is called the MASTER gland?

Q137. What is the best explanation of why the pancreas is unusual among the glands of the body?

Q138. Which sequence correctly describes the insulin feedback loop after a sugary meal?

Q139. Which is the correct explanation of why hormone amounts must be precisely timed and dosed?

Q140. Which change is NOT part of the body's adrenaline response?

Q141. Which statement best explains why insulin is given by injection rather than as a tablet?

Q142. Consider these statements comparing nervous and hormonal control. I. Nervous signals are electrical, fast and short-lived. II. Hormonal signals are chemical, slower and longer-lasting. III. A nerve reaches one target; a hormone reaches many. IV. The two systems work independently and never interact. Which statements are correct?

Q143. Which of these best explains why a person with diabetes is advised to control diet and take exercise as well as use insulin?

Q144. What is the best explanation of why only certain cells in the body respond to a given hormone, though the blood carries it everywhere?

Q145. A person living where the soil is poor in iodine develops a swelling at the front of the neck. The swelling is:

Q146. Which is the correct explanation of why a person whose adrenaline could not be switched off would be seriously ill?

Q147. Assertion (A): A diabetic patient may show sugar in the urine. Reason (R): A diabetic patient's kidney tubules lose the ability to reabsorb any sugar at all.

Q148. If the pancreas went on secreting insulin at its peak rate even after the blood sugar had returned to normal, the result would be:

Q149. Which statement best explains why several hormone disorders can be treated by giving the missing hormone from outside the body?

Q150. Assertion (A): Adrenaline produces its effects within seconds, although hormones are described as slower than nerves. Reason (R): It is released straight into the blood at a moment when the heart is already pumping hard, and the tissues it acts on are richly supplied with blood.

Q151. Which of these best explains why the changes of puberty appear over several years rather than suddenly?

Q152. Assertion: A frightened deer's muscles receive extra blood. Reason: Adrenaline contracts the small arteries of the digestive system and skin, diverting flow.

Q153. Assertion: Diabetes patients may show sugar in urine. Reason: When blood sugar exceeds the kidney's reabsorption capacity, glucose escapes into urine.

Q154. A population in a mountain region with iodine-poor soil will most likely show increased:

Q155. If adrenaline secretion could not switch off, the person would suffer:

Q156. Insulin injections rather than tablets are used because insulin:

Q157. Which scenario needs HORMONAL rather than nervous control?

Q158. The insulin feedback loop is best described as:

Q159. Describe the full adrenaline response: the trigger, the gland, every bodily effect and its purpose, the nervous-hormonal cooperation involved, and why the response must be temporary.

Q160. Write a complete account of the major endocrine glands: for pituitary, thyroid, pancreas, adrenal, testes and ovaries — the hormone, its function, and the disorder caused by its imbalance where applicable; end with why such a chemical system complements the nervous system.

Q161. Explain feedback regulation of hormones in depth: why precision matters, the insulin loop step by step, what failure of the loop produces, a second illustration of regulation (thyroxine/iodine), and the design principle feedback represents.

Q162. A doctor sees three patients: a child far shorter than peers, an adult with a swollen neck from an iodine-poor region, and a middle-aged patient with constant thirst, frequent urination and sugar in urine. Diagnose each, name the gland-hormone axis involved, explain the mechanism of each disorder, and state the treatment or prevention.