The Nervous System, Senses & Responses — Practice · Grade 7 Science

Chapter: Coordination, Defense & Reproduction

What this practice covers

By the end of The Nervous System, Senses & Responses you should be able to:

8 questions, written answer, multiple choice and numeric, each with a worked explanation.

Vocabulary used: stimulus, receptor, neuron, reflex, response.

Problem 1

Is a receptor alone the whole sensory experience?
Answer and explanation

No. Signals and processing contribute to perception, interpretation, and response.

Problem 2

Does seeing a ball mean the ball travels through a nerve?
Answer and explanation

No. Signals carry information about detected light; the physical ball does not move through the nerve pathway.

Problem 3

Why is “the brain never learns about a reflex” too strong?
Answer and explanation

A reflex can begin without conscious decision, while related information can still reach the brain.

Problem 4

Can one reaction-time score establish overall intelligence?
Answer and explanation

No. It measures one task under particular conditions and can be affected by several non-intelligence factors.

Problem 5

Illustrative timing trials are 0.20, 0.25, and 0.30 seconds for one defined task. A draft labels the mean a complete measure of the person’s intelligence. Calculate mean and range, describe the measured pathway in general, and correct the claim.
Answer and explanation

Mean response time is 0.25 s and numerical range is 0.10 s. A stimulus-response task involves detection, processing, and action plus measurement conditions. These values cannot establish overall intelligence or health; attention, equipment, and task demands also matter. They describe only the supplied fictional trials.

Mean: 0.75/3=0.25 s.

Range: 0.30−0.20=0.10 s.

Separate the task measure from an unsupported personal conclusion.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 6

Why could different task instructions change a response-time comparison?
Answer and explanation

They can change what must be detected, interpreted, or done. Comparable instructions and timing methods are needed before comparing outcomes.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 7

Which is a stimulus in a light-response model?
  1. A change in light
  2. The whole graph caption
  3. A claim of intelligence
  4. The mean alone
Answer and explanation

A change in light

The light change is the input that relevant receptors can detect.

Problem 8

Find the mean of 0.3, 0.4, and 0.5 seconds.
Answer and explanation

0.4 s

(0.3+0.4+0.5)/3=1.2/3=0.4 s.

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