Chapter 28, Problem 1CP

Summary Introduction

To determine: The term tropism.

Introduction: The plants have the ability to react to and to produce adjustments to a increased variety of changes in their surrounding environment.

Explanation of Solution

A growth response by a plant involving curving or bending in response to a unidirectional stimulus that determines the direction of movement is called as tropism.

Summary Introduction

To determine: The mechanism by which the plants respond to light.

Introduction: The ability of the plants to respond to their external environment is expressed primarily in changing patterns of growth.

Explanation of Solution

Phototropism: It involves the growth of shoot, petiole, or coleoptile of leaf toward the light. Lateral redistribution of auxin caused by the light to the shaded side of the structure. Auxin promotes the cell elongation on the shaded side of the plant.

Summary Introduction

To determine: The mechanism by which the plants respond to gravity.

Introduction: The plant responds to a great variety of stimuli such as light, gravity, temperature and moisture gradient. The response to stimuli is varied among the different plants.

Explanation of Solution

Gravitropism: It involves the upward growth of shoots and downward growth of roots. Auxin redistribution to the lower side of the root and stem of plant is caused by the auxin. Increased concentration of auxin stimulates the cell elongation in stem and inhibits cell elongation in root.

Summary Introduction

To determine: The mechanism by which the plants respond to a moisture gradient.

Introduction: The capacity of roots to obtain nutrients and water serves as a major factor in determining the survival of the terrestrial plants. The growth of root is influenced by the various environmental stimuli.

Explanation of Solution

Hydrotropism: In response to the moisture gradient, it involves the directed growth of roots. Auxin has a role and the mechanism is perceived in the rootcap.