Chapter 44, Problem 1U

Which of these is NOT a method by which sensory receptors receive information about the internal or external environment?

a. Changes in pressure

b. Light or heat changes

c. Changes in molecular concentration

d. All of these are used by sensory receptors.

Summary Introduction

Introduction:

The receptors, which provide information about the environment are known as sensory receptors. The two types of sensory receptors are exteroceptors and interoceptors. The exteroceptors are responsible for sensing the stimuli that arise in the external environment and the interoceptors are responsible for sensing the stimuli which arises within the body.

The exteroceptors and interoceptors are further divided as mechanoreceptors, chemoreceptors and electromagnetic receptors.

Answer to Problem 1U

Correct answer:

The sensory receptors are stimulated by pressure, heat, light and chemical changes in the environment. Therefore, option d. is correct.

Explanation of Solution

Reason for the correct statement:

The different types of sensory receptors are mechanoreceptors, chemoreceptors and electromagnetic receptors. The mechanoreceptors are stimulated by mechanical forces such as pressure, the chemoreceptors are stimulated by chemical changes, and the electromagnetic receptors are stimulated by heat and light.

Option d. is given as "all of these are used by sensory receptors".

As, “sensory receptors receive information from the changes in light, heat, pressure and molecular concentration”, is the right answer.

Hence, option d. is correct.

Reasons for the incorrect statements:

Option a. is given as “Changes in pressure”.

The changes in light, heat and molecular concentrations are also detected by the electromagnetic receptors and the chemoreceptors. So, it is a wrong answer.

Option b. is given as “Light or heat changes”

The changes in pressure and changes in molecular concentration are also detected by the type of sensory receptors, mechanoreceptors and the chemoreceptors. So, it is a wrong answer.

Option c. is given as “Changes in molecular concentration”.

The sensory receptors mechanoreceptors and electromagnetic receptors use the information from changes in pressure, light and heat. So, it is a wrong answer.

Hence, options a., b. and c. are incorrect.

Conclusion

The sensory receptors receive information about the internal and external environment by using the information from changes in light, heat, pressure and molecular concentration.