These go beyond the standard 12 exercise questions into genuine HOTS territory — an assertion-reason question on reflex speed, a conceptual comparison of plant vs animal response speed, a step-by-step reflex-arc application question, a geotropism-vs-phototropism hormone comparison, a brain-damage diagnostic question, and a fight-or-flight physiology question. See the standard-level Chapter 6 Solutions first if you haven’t already.
Extra Questions (HOTS Level): Control and Coordination (Class 10 Science Chapter 6)
Q1. (Assertion-Reason) Assertion (A): Reflex actions occur faster than voluntary actions that require conscious thought. Reason (R): A reflex arc is completed mainly at the level of the spinal cord, without waiting for the signal to reach and be processed by the brain.
Reflexes bypass the slower path of full brain-level processing (sensing → brain → decision → action), instead routing the response through the spinal cord’s relay neuron directly to a motor neuron. Both A and R are true, and R correctly explains why A is true.
Q2. (Conceptual) Explain why plant responses to stimuli are generally much slower than an animal’s nervous responses, in terms of the underlying mechanism.
Plants have no nervous system, so they coordinate entirely through chemical hormones that must be produced and then diffuse cell-to-cell or through tissue to reach their target — a relatively slow process. Animals additionally have a nervous system that transmits information as fast electrical impulses along neurons, reaching target muscles almost instantly. This structural difference (diffusion-based chemical signalling vs. wired electrical signalling) is why a plant’s response (e.g. bending towards light over hours) is far slower than an animal reflex (e.g. withdrawing a hand in a fraction of a second).
Q3. (Applied, step-by-step) A person accidentally touches a hot iron and withdraws their hand before consciously feeling the pain. Trace the exact path of the signal, naming every component involved.
Receptor (heat/pain receptors in the skin) detects the stimulus → sensory neuron carries the impulse to the relay (connector) neuron in the spinal cord → the relay neuron immediately passes the signal to a motor neuron → the motor neuron carries the impulse to the effector (the arm/hand muscle), causing it to contract and withdraw the hand. Conscious awareness of pain reaches the brain via a separate, slightly slower signal pathway running in parallel — which is why the hand is already withdrawn before the pain is consciously felt.
Q4. (Hormone comparison) Explain why a plant shoot bends towards light (phototropism) while its root bends away from light and towards gravity (geotropism), even though both responses are controlled by the same hormone, auxin.
Auxin promotes cell elongation in shoots, so it accumulates on the shaded/lower side, making that side grow faster and bend the shoot towards light or away from gravity. In roots, however, auxin is far more sensitive and actually inhibits elongation at the same concentration that promotes it in shoots — so the side of the root with more auxin (the lower side, under gravity) grows slower, causing the root to bend down towards gravity. The same hormone therefore produces opposite bending directions in shoots and roots because roots and shoots respond differently to the same auxin concentration.
Q5. (Diagnostic) A patient has trouble maintaining balance and performing precise, coordinated movements (like touching their nose with a finger), but their thinking, memory and sensory perception are completely normal. Which part of the brain is most likely affected, and why?
The cerebellum (part of the hindbrain) is most likely affected — it is specifically responsible for maintaining posture, balance, and the precision/coordination of voluntary muscular movements, but is not involved in thinking or memory (that is the cerebrum’s role) or basic involuntary functions like heartbeat (that is the medulla’s role).
Q6. (Applied physiology) During a sudden fright, a hormone is released that prepares the body for "fight or flight." Name the hormone, its source gland, and describe at least three physiological changes it causes.
Adrenaline, released by the adrenal glands. It causes: (i) increased heart rate, pumping more blood; (ii) faster breathing rate, supplying more oxygen; (iii) diversion of blood flow away from the digestion system and towards skeletal muscles, preparing the body for rapid physical action.
See also: Revision Notes | Formulas Handbook
