📚 CBSE Grade-10 Study Guide
HomeScience (086) (AI practice)

Science (086) — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] medium exam-ready
Assertion (A): Reflex actions are carried out without conscious thought. Reason (R): In a reflex action, the nerve signal travels from the receptor to the brain before reaching the effector muscle.
  1. A Both A and R are true, and R is the correct explanation of A.
  2. B Both A and R are true, but R is NOT the correct explanation of A.
  3. C A is true but R is false.
  4. D A is false but R is true.
Generated by claude-sonnet-4-6 · 2026-06-26 01:00 · grounding rag
Model Answer

Answer: C

Assertion (A) is true — reflex actions occur without conscious thought. Reason (R) is false — in a reflex arc, the nerve signal travels from receptor → spinal cord → effector muscle, bypassing the brain for the response.

Explanation

The key error in R is the claim that the signal travels to the brain before reaching the effector. The textbook clearly states that reflex arcs are formed in the spinal cord itself, allowing a quick response without waiting for the brain. Information does reach the brain, but only after (or simultaneously with) the reflex response — the brain is not in the reflex arc pathway. That is precisely why reflexes are fast and unconscious (A is true), but R gives the wrong mechanism, making it false.

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.