Question 1

Vines in tropical rain forests must grow toward large trees before being able to grow toward the sun. To reach a large tree, the most useful kind of growth movement for a tropical vine presumably would be ________.

Accepted Answer

The answer of Vines in tropical rain forests must grow...

Question 2

Upon exposure to blue light, plants not only begin to grow toward the light, but move their chloroplasts to the sunny side of each cell. The adaptive advantage of moving chloroplasts to the sunny side of each cell ________.

Accepted Answer

Moving chloroplasts to the sunny side of each cell maximizes light absorption by the chloroplasts for photosynthesis, resulting in increased energy production for the plant.

Question 3

Phytochrome plays a critical role in seed germination. Which of the colors maximizes the seed germination?

Accepted Answer

Phytochrome absorbs red light, which promotes seed germination. Other colors may also have an effect on seed germination, but red is the most effective.

Question 4

________ prevents seeds from germinating until conditions are favorable for the growth of the plant.

Accepted Answer

Abscisic acid (ABA) is a plant hormone that inhibits germination and growth during unfavorable environmental conditions, such as drought or high salinity. It prevents the breakdown of seed storage compounds and the activation of enzymes needed for germination, until conditions become favorable for growth.

Question 5

As cytokinins are primarily produced in roots, what route would they travel to influence lateral shoot formation in a recently topped tree?

Accepted Answer

The answer of As cytokinins are primarily produced in roots,...

Question 6

Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only 1/4 inch of soil is that the ________.

Accepted Answer

Seeds that require light to germinate should only be covered with a thin layer of soil or not covered at all, as they need exposure to light to trigger their germination response.

Question 7

Many plants flower in response to day-length cues. Which of the following statements best summarizes this phenomenon?

Accepted Answer

The answer of Many plants flower in response to day-length...

Question 8

Mammalian eyes sense light because the photoreceptor cells have molecules called opsins, which change structure when exposed to light. Which of the following plant molecules would be analogous to mammalian opsins in their light-sensing ability?

Accepted Answer

Phytochrome is a plant protein that undergoes a conformational change when exposed to red light and regulates many plant processes, including seed germination and photoperiodism. Pfᵣ (cryptochrome) is also a plant protein involved in regulating circadian rhythms and responses to blue light. Both of these molecules are analogous to mammalian opsins in their light-sensing ability. Auxin and cytokinins are plant hormones, and phototropins are another class of plant photoreceptors, but they do not have the same light-sensing abilities as opsins or the plant proteins involved in light regulation.

Question 9

Which type of mutant would be most likely to produce a bushier phenotype?

Accepted Answer

The answer of Which type of mutant would be most...

Question 10

A gardener in Canada wants to surprise his mother on her birthday and make her favorite hibiscus bush flower in May instead of at the end of June. The bush is growing in the greenhouse. Which of the following might make the hibiscus bush flower early?

Accepted Answer

The answer of A gardener in Canada wants to surprise...

Question 11

The biological clock controlling circadian rhythms must ultimately ________.

Accepted Answer

The biological clock controlling circadian rhythms is driven by gene expression in a feedback loop of transcription and protein degradation. Therefore, it must affect gene transcription.

Question 12

Suppose a plant had a photosynthetic pigment that absorbed far-red wavelengths of light. In which of the following environments could that plant thrive?

Accepted Answer

A plant with a photosynthetic pigment that absorbs far-red wavelengths of light would be adapted to low-light environments, such as the forest floor beneath a canopy of taller plants. The other options do not provide the appropriate low-light environment for this type of pigment.

Question 13

If you were shipping green bananas to a supermarket thousands of miles away, which of the following chemicals would you want to eliminate from the plants' environment?

Accepted Answer

Ethylene is a natural plant hormone that accelerates the ripening process, and it is produced by ripening fruits, including bananas. If green bananas are exposed to ethylene, they will begin to ripen too quickly and will not be in saleable condition by the time they reach the supermarket. Therefore, to ensure a longer shelf life for the green bananas, the plants' environment should be free of ethylene.

Question 14

In the fall, the leaves of some trees change color. This happens because chlorophyll breaks down and the accessory pigments become visible. What hormone is responsible for this?

Accepted Answer

The answer of In the fall, the leaves of some...

Question 15

Plants often use changes in day length (photoperiod)to trigger events such as dormancy and flowering. It is logical that plants have evolved this mechanism because photoperiod changes ________.

Accepted Answer

Photoperiod changes are more predictable than air temperature changes, making it an advantageous mechanism for plants to use to trigger events like dormancy and flowering.

Question 16

Who might be interested in using cytokinins?

Accepted Answer

The answer of Who might be interested in using cytokinins?
...

Question 17

Which of the colors of visible light induces curvature in coleoptile most effectively?

Accepted Answer

Blue light induces curvature in coleoptile most effectively. This phenomenon is known as phototropism, where plants bend towards the direction of light. The photoreceptor responsible for this response is called phototropin, which is most sensitive to blue light.

Question 18

A population of plants experiences several years of severe drought. Much of the population dies due to lack of water, but a few individuals survive. You set out to discover the physiological basis for their adaptation to such an extreme environmental change. You hypothesize that the survivors have the ability to synthesize higher levels of ________ than their siblings do.

Accepted Answer

Abscisic acid is a plant hormone that plays an important role in regulating water balance and stomatal closure in response to drought stress. Therefore, it is likely that the survivors have the ability to synthesize higher levels of abscisic acid to adapt to the extreme environmental change of severe drought.

Question 19

Which of the following environmental factors can be sensed by plants?
I gravity
II pathogens
III wind
IV light

Accepted Answer

Plants have the ability to sense a variety of environmental factors including gravity (which influences their direction of growth), pathogens (triggering immune responses), wind (affecting growth patterns and physical strength), and light (guiding photosynthesis and growth direction).

Question 20

If a farmer wanted more loosely packed clusters of grapes, he would most likely spray the immature bunches with ________.

Accepted Answer

Gibberellins promote cell elongation and division, which can lead to looser clusters of grapes.

Quiz 39: Plant Responses to Internal and External Signals