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 the opposite of

Accepted Answer

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

Question 2

You are part of a desert plant research team trying to discover crops that will be productive in arid climates.You discover a plant that produces a hormone under water-deficit conditions that triggers a suite of drought responses.Most likely the hormone is

Accepted Answer

ABA (abscisic acid) is known to be the hormone that triggers drought responses in plants. When a plant experiences water-deficit conditions, it produces an increased amount of ABA, which in turn closes stomata to conserve water, stimulates root growth to increase water uptake, and activates other genes involved in drought tolerance. Therefore, the discovery of a plant that produces a hormone that triggers drought responses suggests that ABA is the most likely candidate.

Question 3

A long-day plant will flower

Accepted Answer

Long-day plants require a photoperiod that is longer than a critical value for flowering to occur. This means that they flower when the night is shorter than a specific amount, typically around 14-16 hours of darkness. They will not flower under artificial light in the summer and require proper fertilization, but these factors alone are not sufficient to induce flowering in long-day plants. Furthermore, long-day plants will not flower regardless of photoperiod imposed, as they specifically require a certain night length to initiate flowering.

Question 4

-Suppose you laid a seedling on its side so that the root was parallel to the ground as shown in the figure above.Several hours after the change in position,where in the root cells (position A,B,or C in the figure above)would you find the amyloplasts?

Accepted Answer

The answer of 
-Suppose you laid a seedling on its...

Question 5

Which of the following is a likely response of plants to cold stress?

Accepted Answer

The answer of Which of the following is a likely...

Question 6

Most scientists agree that global warming is under way; thus,it is important to know how plants respond to heat stress.Which of the following would be a useful line of inquiry to try and improve plant response and survival to heat stress?

Accepted Answer

Increased production of heat-shock proteins is a well-known response of plants to heat stress. These proteins help to protect other proteins from damage caused by heat stress. The other options may also be useful in some way, but increasing HSP production is a proven approach to improving plant survival under heat stress.

Question 7

The rapid leaf movements resulting from a response to touch (thigmotropism)primarily involve

Accepted Answer

Rapid leaf movements resulting from thigmotropism primarily involve potassium channels. When a plant is touched, there is a rapid influx of calcium ions which triggers the activation of potassium channels, leading to depolarization of the plasma membrane and ultimately the rapid leaf movement.

Question 8

-The rapid leaf movements resulting from a response to touch (thigmotropism)primarily involve

Accepted Answer

Rapid leaf movements in response to touch involve the transport of potassium ions across cell membranes, which results in changes in turgor pressure and cell expansion, causing the movement.

Question 9

In extremely cold regions,woody species may survive freezing temperatures by

Accepted Answer

Woody species in extremely cold regions may increase cytoplasmic levels of specific solute concentrations, such as sugars. This is because solutes can lower the freezing point of water and help prevent ice crystal formation, which can damage cell membranes and ultimately kill the plant. The accumulation of sugars also helps to maintain cell turgor pressure, which is essential for plant survival in cold temperatures.

Question 10

Which of the following best explains both the growth of a vine up the trunk of a tree as well as the directional growth of a houseplant toward a window?

Accepted Answer

Both the growth of a vine up a trunk of a tree and directional growth of a houseplant toward a window are examples of tropism response, where the plant growth is in response to a directional stimulus.

Question 11

Which of the following watering regimens will be most effective at keeping a lawn green during the hot,dry summer months?

Accepted Answer

The answer of Which of the following watering regimens will...

Question 12

What do the results of research on gravitropic responses of roots and stems show?

Accepted Answer

The results of research have shown that the effect of a plant hormone, specifically auxin, can depend on the tissue involved in the gravitropic response. Roots and stems both show a gravitropic response, but different mechanisms are involved. In roots, the hormone redistributes to the lower side of the root tip, stimulating cell elongation and bending the root downwards. In stems, the hormone redistributes to the shaded side of the stem, causing those cells to elongate and bending the stem towards the light. Therefore, the same hormone can have different effects on different tissues.

Question 13

In extremely cold regions,woody species may survive freezing temperatures by

Accepted Answer

Woody species in extremely cold regions may survive freezing temperatures by increasing cytoplasmic levels of specific solute concentrations, such as sugars. This strategy is known as cryoprotection, and it helps to prevent the formation of ice crystals, which can damage cells. By increasing the concentration of solutes, the freezing point of the cytoplasm is lowered, allowing the plant to maintain a liquid state even at very low temperatures. This allows the plant to survive freezing temperatures without being damaged by ice formation.

Question 14

If you wanted to genetically engineer a plant to be more resistant to drought,increasing amounts of which of the following hormones might be a good first attempt?

Accepted Answer

Abscisic acid is known for its role in promoting stomatal closure, reducing water loss in plants and helping them conserve water during drought conditions. It also regulates other mechanisms that enable plants to survive under stress caused by water scarcity. Therefore, increasing amounts of abscisic acid would be a good first attempt to genetically engineer drought-resistant plants.

Question 15

Which of the following best describes positive gravitropism exhibited by plant roots?

Accepted Answer

Positive gravitropism in plant roots is mediated by auxin, similar to the phototropism responses in shoots. When a root is placed horizontally, auxin accumulates on the lower side of the root, causing increased cell elongation and growth, which results in downward bending of the root towards the force of gravity.

Question 16

Plant cells begin synthesizing large quantities of heat-shock proteins

Accepted Answer

Heat-shock proteins are produced in response to stress conditions, including high temperatures that negatively impact cellular processes such as photosynthesis. These proteins help protect cells by preventing the aggregation of denatured proteins and assisting in their refolding.

Question 17

Bald cypress and loblolly pine are both gymnosperm trees native to the southern United States.The cypress grows in swamps; the pine grows in sandy soil.How do you think their anatomies differ?

Accepted Answer

The answer of Bald cypress and loblolly pine are both...

Question 18

Trees found at high elevations tend to be short with stocky tree trunks compared to trees growing in more sheltered areas.The term that describes plants' sensitivity to mechanical stress is

Accepted Answer

Thigmomorphogenesis describes the changes in plant growth and development in response to mechanical stress.

Question 19

A botanist discovers a plant that lacks the ability to form starch grains in root cells,yet the roots still grow downward.This evidence refutes the long-standing hypothesis that

Accepted Answer

The discovery that a plant can grow its roots downward without forming starch grains refutes the hypothesis that falling statoliths (which are dense, starch-containing plastids) trigger gravitropism, as it shows that root growth direction can be determined without the presence of starch grains.

Question 20

The initial response of the root cells of a tomato plant watered with sea water would be to

Accepted Answer

The salt in seawater would cause the water potential in the cytoplasm of the root cells to decrease, leading to water being lost from the cells via osmosis. This would cause the cells to plasmolyze as they lose water and shrink away from the cell wall.

Quiz 39: Plant Responses to Internal and External Signals

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 the opposite of

You are part of a desert plant research team trying to discover crops that will be productive in arid climates.You discover a plant that produces a hormone under water-deficit conditions that triggers a suite of drought responses.Most likely the hormone is

A long-day plant will flower

-Suppose you laid a seedling on its side so that the root was parallel to the ground as shown in the figure above.Several hours after the change in position,where in the root cells (position A,B,or C in the figure above) would you find the amyloplasts?

Which of the following is a likely response of plants to cold stress?

Most scientists agree that global warming is under way; thus,it is important to know how plants respond to heat stress.Which of the following would be a useful line of inquiry to try and improve plant response and survival to heat stress?

The rapid leaf movements resulting from a response to touch (thigmotropism) primarily involve

-The rapid leaf movements resulting from a response to touch (thigmotropism) primarily involve

In extremely cold regions,woody species may survive freezing temperatures by

Which of the following best explains both the growth of a vine up the trunk of a tree as well as the directional growth of a houseplant toward a window?

Which of the following watering regimens will be most effective at keeping a lawn green during the hot,dry summer months?

What do the results of research on gravitropic responses of roots and stems show?

In extremely cold regions,woody species may survive freezing temperatures by

If you wanted to genetically engineer a plant to be more resistant to drought,increasing amounts of which of the following hormones might be a good first attempt?

Which of the following best describes positive gravitropism exhibited by plant roots?

Plant cells begin synthesizing large quantities of heat-shock proteins

Bald cypress and loblolly pine are both gymnosperm trees native to the southern United States.The cypress grows in swamps; the pine grows in sandy soil.How do you think their anatomies differ?

Trees found at high elevations tend to be short with stocky tree trunks compared to trees growing in more sheltered areas.The term that describes plants' sensitivity to mechanical stress is

A botanist discovers a plant that lacks the ability to form starch grains in root cells,yet the roots still grow downward.This evidence refutes the long-standing hypothesis that

The initial response of the root cells of a tomato plant watered with sea water would be to