Ch. 33 Control Systems in Plants

Taylor - Campbell Biology: Concepts & Connections 10th Edition

Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783Not the one you use?Change textbook

Taylor, Simon, Dickey, Hogan 10th Edition

Ch. 33 Control Systems in Plants

Problem 18

Chapter 33, Problem 18

A plant nursery manager tells the new night security guard to stay out of a room where chrysanthemums (which are short-day plants) are about to flower. Around midnight, the guard accidentally opens the door to the chrysanthemum room and turns on the lights for a moment. How might this affect the chrysanthemums? How could the guard correct the mistake?

Verified step by step guidance

Understand the concept of photoperiodism: Photoperiodism is the response of plants to the lengths of light and dark periods. Chrysanthemums are short-day plants, meaning they require long periods of darkness to initiate and sustain flowering.

Recognize the impact of light interruption: Turning on the lights, even briefly, during the critical dark period can interrupt the flowering process of short-day plants like chrysanthemums. This exposure to light might reset the plant's internal clock and delay flowering.

Identify the critical dark period: Research or inquire about the specific critical dark period for chrysanthemums, which is the minimum uninterrupted darkness required for flowering.

Consider corrective actions: To correct the mistake, the guard could ensure that the lights are not turned on again during the critical dark period in subsequent nights. Consistency in maintaining the required dark period is crucial for the flowering process.

Implement long-term solutions: The nursery manager could install safety measures such as automatic timers or motion sensors that prevent lights from being turned on during critical dark periods, or use blackout curtains to shield the plants from accidental light exposure.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Photoperiodism

Photoperiodism is the physiological reaction of organisms to the length of day or night. In plants, it determines flowering and growth patterns based on light exposure. Short-day plants, like chrysanthemums, require longer nights to trigger flowering, meaning any interruption of darkness can disrupt their blooming process.

Chrysanthemum Flowering Requirements

Chrysanthemums are classified as short-day plants, meaning they typically flower when the day length is shorter than a critical threshold, usually requiring at least 12-14 hours of uninterrupted darkness. Exposure to light during their dark period can inhibit flowering, causing stress and potentially delaying or preventing the blooming process.

Light Interruption and Correction

If the guard accidentally turns on the lights in the chrysanthemum room, it can disrupt the plants' flowering cycle. To correct this mistake, the guard should ensure that the plants receive the necessary uninterrupted dark period following the light exposure. This may involve keeping the lights off for the remainder of the night and ensuring that future light exposure is minimized.

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Textbook Question

A certain short-day plant flowers only when days are less than 12 hours long. Which of the following would cause it to flower?a. a 9-hour night and 15-hour day with 1 minute of darkness after 7 hoursb. an 8-hour day and 16-hour night with a flash of white light after 8 hoursc. a 13-hour night and 11-hour day with 1 minute of darkness after 6 hoursd. a 12-hour day and 12-hour night with a flash of red light after 6 hours

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If apples are to be stored for long periods, it is best to keep them in a place with good air circulation. Explain why.

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Write a short paragraph explaining why a houseplant becomes bushier if you pinch off its terminal buds.

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Textbook Question

A plant biologist observed a peculiar pattern when a tropical shrub was attacked by caterpillars. After a caterpillar ate a leaf, it would skip over nearby leaves and attack a leaf some distance away. Simply removing a leaf did not trigger the same change nearby. The biologist suspected that a damaged leaf sent out a chemical that signaled other leaves. How could this hypothesis be tested?

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Textbook Question

Imagine the following scenario: A plant biologist has developed a synthetic chemical that mimics the effects of a plant hormone. The chemical can be sprayed on apples before harvest to prevent flaking of the natural wax that is formed on the skin. This makes the apples shinier and gives them a deeper red color. What kinds of questions do you think should be answered before farmers start using this chemical on apples? How might the scientist go about finding answers to these questions?

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Textbook Question

The discovery of auxin is a good example of how scientists build upon each other's work. For each of the three sets of researchers discussed in the chapter (the Darwins, Boyle-Jensen, and Went), write a one-sentence summary of what they discovered. If you were going to credit one person as being the 'discoverer' of auxin, who would it be?

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