Chapter 22.3, Problem 1NV

Summary Introduction

To determine:

Definition of the terms auxins, gibberellins, ethylene, cytokinin, nastic response, and tropism.

Explanation of Solution

Auxin is a plant hormone that causes the elongation of the cells present in the growing region. This is present in stems, buds and tip of the roots.

Gibberellin is a plant hormone (phytohormone) that stimulates the process of stem elongation, flowering and germination of the seeds.

Ethylene is a plant hormone that is involved in promoting growth fruit ripening, senescence as well as it is involved in the breaking of dormancy.

Cytokinin is a hormone that promotes physiological growth and development in plants. It is also responsible for cell division, differentiation of chloroplast and delay of senescence.

Nastic response is the non-directional movement that can be described as the response of plants towards a stimulus such as light, temperature, etc. The nastic movements are reversible and it does not represent growth in a direction.

Tropism is defined as a biological phenomenon that indicates a directional movement of an organism, especially plants. For example, phototropism is the growth of the plants in the direction of light.