Question 1

What happens when coleoptiles are illuminated with directional light from the side instead of from directly overhead?

Accepted Answer

When coleoptiles are illuminated with directional light from the side, auxin, a plant growth hormone, is transported away from the lighted side. This differential distribution of auxin causes the cells on the darker side to elongate more than those on the lighted side, leading to the bending of the coleoptile toward the light source.

Question 2

Before ARF transcription factors can trigger auxin-induced gene expression,what must happen?

Accepted Answer

The answer of Before ARF transcription factors can trigger auxin-induced...

Question 3

Abscisic acid synthesized in the root travels to different parts of the shoot where it regulates transpirational water loss.What is the most likely way that ABA travels from the root to the various locations within the shoot?

Accepted Answer

Abscisic acid is transported through the xylem, which includes vessels and tracheids, from the roots up to the various locations within the shoot.

Question 4

A plant physiologist treats a leaf with abscisic acid and observes that the stomata close.What happened inside the guard cells during the experiment?

Accepted Answer

Abscisic acid influences the movement of potassium ions out of the guard cells, leading to water loss and closure of the stomata. This mechanism helps the plant to conserve water during times of drought or stress.

Question 5

The acid growth hypothesis links

Accepted Answer

The acid growth hypothesis states that auxin induces cell wall acidification, which activates enzymes that loosen the cell wall, allowing for cell expansion to occur.

Question 6

A scientist is investigating a hormone response in rose bush stems by removing the apical meristems of the main stems.What is the most likely result of this experiment and what hormone is responsible?

Accepted Answer

Removing the apical meristem reduces auxin levels, which normally inhibit lateral bud growth. This allows cytokinin to promote the development of lateral buds.

Question 7

Red light and phytochrome are involved in which of the following plant growth responses? Check all that apply.

Accepted Answer

The answer of Red light and phytochrome are involved in...

Question 8

Several scientists,including Charles and Francis Darwin,Frits Went and others,demonstrated that auxins caused stems to bend toward light in a series of elaborate experiments.Went was the researcher who finally determined that bending of the stem toward light was a result of which mechanism?

Accepted Answer

Frits Went determined that the transport of auxin to the shaded side of the plant stem stimulated stem elongation and a bending in the direction of the light. This is known as phototropism, whereby light is the stimulus that causes the plant to grow towards it.

Question 9

In some genetically engineered tomatoes,fruit ripening was delayed by crippling the gene that produces which hormone?

Accepted Answer

Ethylene is the hormone responsible for fruit ripening. Crippling the gene that produces ethylene would delay the ripening process.

Question 10

The directional growth response of plants to touch is called

Accepted Answer

Thigmotropism is the directional growth response of plants to touch. Phototropism is the directional growth response to light, gravitropism is the directional growth response to gravity, photoperiodism is the response of plants to changes in day and night length, and thermotropism is the response of plants to temperature.

Question 11

What endogenous process helps plants to keep their movements and other responses synchronized with the environment?

Accepted Answer

A circadian clock helps plants to keep their movements and responses synchronized with the environment by controlling physiological processes such as photosynthesis, hormone production, and cell division based on the time of day.

Question 12

During a viticulturist's presentation on growing and managing grapes,why did he state that it is imperative to encourage the grapevine's natural tendency for positive thigmotropism?

Accepted Answer

Positive thigmotropism is the tendency of a plant to grow towards and wrap around a solid object for support. In the case of grapevines, this is important because it allows the twining stems to wrap around the supporting wires and helps to keep the plant upright as it grows.

Question 13

A viticulturist wants to grow larger grapes.Which specific hormone would a viticulturist apply to the plants?

Accepted Answer

Gibberellin is the hormone responsible for promoting cell division and elongation in plants. This hormone can increase the size of grapes, making them larger and more desirable for sale.

Question 14

Which of the following are true statements about gibberellins? Check all that apply.

Accepted Answer

Gibberellins are plant hormones that can restore growth in dwarf mutants, are produced in apical regions, promote internode elongation, and hasten seed germination. They do not inhibit amylase; instead, they stimulate its production.

Question 15

Which naturally-occurring plant hormone has a major role in the phototropic response of plants?

Accepted Answer

Auxin, specifically the auxin molecule indole-3-acetic acid (IAA), has been identified as the primary hormone responsible for the phototropic response in plants. Auxin is transported to the shaded side of the plant, promoting cell elongation and causing the plant to bend towards the light source.

Question 16

In Arabidopsis plants,about 7% of its genome is devoted to processes tied to which molecule?

Accepted Answer

The answer of In Arabidopsis plants,about 7% of its genome...

Question 17

How do nastic movements differ from tropisms?

Accepted Answer

Tropisms are directional responses to directional stimuli, meaning that the direction of the stimulus affects the direction of the response. For example, in phototropism, the plant bends towards the source of light. In contrast, nastic movements are non-directional responses to stimuli, meaning that the direction of the stimulus does not affect the direction of the response. For example, the leaves of the Venus flytrap close in response to touch, regardless of the direction of the touch stimulus.

Question 18

While flipping through an agriculture products catalog,you come across the following advertisement,"The Centralized Ripening System-makes large scale hormone distribution even easier!".What hormone does this product distribute?

Accepted Answer

The advertisement mentions "ripening" and "hormone distribution", which suggests that the product is meant for ethylene distribution. Ethylene is a plant hormone that plays a key role in fruit ripening.

Question 19

Directional,light-triggered plant development is known as

Accepted Answer

The answer of Directional,light-triggered plant development is known as
...

Question 20

When one plant is shaded by another,why is the ratio of far-red to red light increased compared to an unshaded plant?

Accepted Answer

EWhen light passes through or is reflected off the leaves of plants, most of the red light, which is crucial for photosynthesis, is absorbed by chlorophyll. This leaves a higher proportion of far-red light in the shaded areas. Additionally, shaded environments are naturally enriched in far-red wavelengths because of this selective absorption by chlorophyll in the leaves of the shading plants. This is why plants in shaded conditions experience an increased ratio of far-red to red light.

Quiz 39: Sensory Systems in Plants