Chapter 22.3, Problem 4MI

Summary Introduction

To classify:

Each of the following as an example of tropism or nastic movement.

Introduction:

The term tropism is phenomenon when a plant responses to an environmental stimuli. The plant may turn towards or away from the stimuli in tropism. If a plant turns towards the stimuli, then it is positive tropism, if the plant turns away from the stimuli, then it is negative tropism.

Answer to Problem 4MI

Venus flytrap closes on an insect − Nastic movement

Sweet pea tendrils climb a fence − Tropism

Plant grows towards a lamp − Tropism

Mimosa pudica leaflets become limp when touched − Nastic movement

Plant roots grow into the soil − Tropism.

Explanation of Solution

Nastic movements cause movement in plant in response to some environmental stimuli, but unlike tropism, in nastic movement, plant movement does not depend on stimuli direction.

When an insect comes near venus flytrap, then it immediately captures it and closes. This is nastic movement.

Sweet pea tendrils grow against gravity. It is an example of negative gravitropism. So, this is tropism.

Plant growing towards the direction of lamp light is the example of positive phototropism. So, this is tropism.

When anyone touches mimosa pudica leaflets, then the leaflets become limp. This is nastic movement.

Plants root growing in the soil is the example of positive gravitropism. So, this is tropism.