Q7
1 markMCQSection A

The correct sequence of events when someone's hand touches a hot object unconsciously :

Control and Coordination
Reflex Action and Reflex Arc

Options

(A)Receptors in skin →\rightarrow Motor neuron →\rightarrow Relay neuron →\rightarrow Sensory neuron →\rightarrow Effector muscle in arm
(B)Receptors in skin →\rightarrow Relay neuron →\rightarrow Sensory neuron →\rightarrow Motor neuron →\rightarrow Effector muscle in arm
(C)Receptors in skin →\rightarrow Sensory neuron →\rightarrow Relay neuron →\rightarrow Motor neuron →\rightarrow Effector muscle in arm
(D)Receptors in skin →\rightarrow Sensory neuron →\rightarrow Effector muscle in arm →\rightarrow Motor neuron →\rightarrow Relay neuron
Official Answer

The correct sequence of events when a hand touches a hot object is: Receptors in skin →\rightarrow Sensory neuron →\rightarrow Relay neuron →\rightarrow Motor neuron →\rightarrow Effector muscle in arm.

ReceptorsSensory neuronRelay neuronMotor neuronEffector muscle

Marking Scheme

  • 11 mark for identifying the correct sequence: Receptors in skin →\rightarrow Sensory neuron →\rightarrow Relay neuron →\rightarrow Motor neuron →\rightarrow Effector muscle in arm.

Hint

Recall the pathway of a reflex arc: it starts with a receptor detecting the stimulus, travels to the spinal cord via a sensory pathway, and returns to the muscle via a motor pathway.

Quick Oral Answer

The pathway of a reflex arc is: Receptor in skin →\rightarrow Sensory Neuron →\rightarrow Relay Neuron (in spinal cord) →\rightarrow Motor Neuron →\rightarrow Effector Muscle.

Analysis & Explanation

In a reflex action, the stimulus (heat/pain) is detected by specialized receptors in the skin. This triggers an electrical impulse that travels along a sensory neuron to the spinal cord. In the spinal cord, the impulse is transmitted via a relay neuron to a motor neuron. The motor neuron then carries the signal to the effector (muscle in the arm), which contracts to pull the hand away. Therefore, Option C represents the correct pathway of a reflex arc. Options A and B are incorrect because they place the motor neuron or relay neuron before the sensory neuron. Option D is incorrect because it places the effector muscle before the motor neuron.

Common Mistakes

  1. 1Confusing the direction of sensory and motor neurons.
  2. 2Placing the relay neuron before the sensory neuron in the pathway.

Interesting Facts

Reflex arcs have evolved in animals because the thinking process of the brain is not fast enough to prevent immediate injury in dangerous situations.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2024?

This question carries 1 mark in the CBSE Class 10 Science 2024 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Control and Coordination" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Reflex Action and Reflex Arc" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2024 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2024 paper.