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Test your knowledge of the five major classes of plant hormones (auxins, cytokinins, gibberellins, abscisic acid, ethylene) by matching one hormone to each lettered box. (Note that some hormones will match up to more than one box.)
To complete: The given map of the five major classes of plant hormones.
Concept introduction:
Plant hormones are chemical messengers that are produced in trace amounts, but profoundly affect the growth and development of a plant. These include auxins, cytokinins, gibberellins, abscisic acid and ethylene.
The plant hormones perform various functions such as promoting growth, breaking dormancy, mediating fruit ripening and providing tolerance to stress.
Explanation of Solution
Pictorial representation: Fig.1 shows the completed map representing the five major classes of plant hormones.
Fig.1: The five major classes of plant hormones.
(a)
Correct answer: Auxin.
Explanation: Auxins are a group of plant hormones that promotes cell elongation. They are produced by the apical meristems of shoot and root. They promote the growth of root and shoot of the plant. Hence the correct answer is auxin.
(b)
Correct answer: Gibberellins.
Explanation: The gibberellins are a group of plant hormones that stimulate the elongation of stem by promoting cell elongation. Hence the correct answer is gibberellins.
(c)
Correct answer: Auxin.
Explanation: Auxin is produced by the apical bud of the shoot and functions to inhibit the growth of axillary buds, a phenomenon called apical dominance. Hence, the correct answer is auxin.
(d)
Correct answer: cytokinin.
Explanation: The cytokinins are a group of plant hormones that stimulate rapid cell division in roots and shoots of the plant. It also promotes the growth of lateral buds, thereby nullifying the effects of auxin. Hence, the correct answer is cytokinin.
(e)
Correct answer: Auxin.
Explanation: In addition to cell elongation, the auxins also function to retard the abscission of leaves. It also plays a crucial role in nullifying the effects of ethylene. Hence, the correct answer is auxin.
(f)
Correct answer: Ethylene.
Explanation: Ethylene is a gaseous hormone that promotes ripening of fruit and abscission of leaves from trees. Hence, the correct answer is ethylene.
(g)
Correct answer: Gibberellin.
Explanation: The gibberellin is a plant hormone that promotes the germination of seed. It inhibits seed dormancy by nullifying the effects of abscisic acid. Hence the correct answer is gibberellin.
(h)
Correct answer: Abscisic acid.
Explanation: The abscisic acid is a plant hormone that is involved in the stress responses. It inhibits growth, promotes seed dormancy during winter or periods of drought. Hence, the correct answer is abscisic acid.
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Chapter 33 Solutions
CAMPBEL BIOLOGY:CONCEPTS & CONNECTIONS
- List several ways that each of these hormones affects plant growth and development: auxins, gibberellins, cytokinins, ethylene, abscisic acid, and brassinosteroids.arrow_forwardDefine what a plant hormone is. Also, explain, using an example for each, of how hormones can both work together and work against each other when they are received by a particular part of a plant.arrow_forwardWhat are the effects brought by cytokinin in plants? Explain the partnerships between cytokinin with auxin and hormone mentioned in Question 3 a). (i) (ii) Write an account on interactions between gibberellins, indole acetic acid and abscisic acid in plant growth promotion and seed germination.arrow_forward
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- Greenhouse-grown tomato seedlings are often brushed by hand to simulate wind. This causes seedlings to grow slower, thicken stems, & resist mechanical wind damage when planted in the field. Which hormone is responsible? Auxin Salicylic acid Gibberellin Abscisic acid cytokinin Ethylenearrow_forwardHormones and signal pathways Complete the following paragraph to describe signal transduction as it occurs within plants. Choices may be used more than once or not at all. Chemical signals called play an important role in a plant's ability to respond to a stimulus. These signals bind to receptors, the first step in a cellular response called a may be located in the plasma membrane, the cytoplasm, the nucleus, or the endoplasmic reticulum. The series of relay proteins or enzymes activated by the hormone binding the receptor make up the Some responses are immediate, while others require a like Ca*, to initiate a cellular response. The result of the transduction pathway is a which is often the transcription of specific genes, resulting in some measurable change. hormones reflex arc signal transduction pathway Signal transducers second messenger response Receptor proteins first messengerarrow_forwardPlant cells communicate in a variety of ways to elicit cellular responses. In the figure below the plant is responding the presence of light with the release of auxin. Auxin was first discovered for its ability to promote growth in plants. It is a plant hormone that inhibits the lengthening and stimulate the formation of lateral roots and root hairs. a) Describe the plant’s response to the presence of light. (refer to picture)arrow_forward
Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning