Question 1

Most plants absorb water and minerals from the _______ and transport them through the _______.

Accepted Answer

Plants absorb water and minerals from the soil through their roots and transport them using xylem tissue to the rest of the plant. The atmosphere is not a significant source of water and minerals for most plants, and phloem tissue is responsible for transporting carbohydrates and other organic compounds. Therefore, the correct answer is D) soil;xylem.

Question 2

One difference between sieve-tube cells and vessels is that sieve-tube cells are _______,but vessels are dead.

Accepted Answer

Sieve-tube cells are part of the phloem in plants and are alive to facilitate the transport of sugars and other nutrients. In contrast, vessels, which are part of the xylem, are dead and serve primarily to transport water and minerals.

Question 3

FITC-boronic acid is a dye that stains cell walls and intracellular spaces.This dye is probably transported via:

Accepted Answer

FITC-boronic acid stains cell walls and intracellular spaces, indicating it moves outside the plasma membrane, through the apoplast, which includes cell walls and intercellular spaces. This is characteristic of apoplastic transport.

Question 4

Which of the following would you expect to be happening if a plant is showing water stress?

Accepted Answer

Abscisic acid (ABA) is a plant hormone that plays a crucial role in the response to water stress. When a plant is dehydrated or experiencing water stress, ABA is produced in the leaves and is transported to the guard cells, which are responsible for opening and closing the stomata. The presence of ABA signals the guard cells to close the stomata, reducing water loss through transpiration and helping the plant conserve water.

Question 5

You want to calculate the relative water content of a sapling.You measure the fresh weight to be 11.95g,the turgid weight to be 12.5g,and the dry weight to be 11.5g.What is the RWC of this plant,and is it likely to live or die?

Accepted Answer

Relative Water Content (RWC) is calculated using the formula: RWC = [(Fresh Weight - Dry Weight) / (Turgid Weight - Dry Weight)] * 100. Plugging in the values: RWC = [(11.95 - 11.5) / (12.5 - 11.5)] * 100 = 45%. A RWC of 45% is quite low, indicating the plant is likely to die.

Question 6

One function of cell walls in plants is to prevent the continual increase in the expansion of the cell membrane.

Accepted Answer

Cell walls provide structural support to plant cells and prevent them from bursting due to osmotic pressure. This prevents the cell membrane from excessive expansion.

Question 7

Which of the following plant hormones stimulates development of an abscission zone in the leaf petiole?

Accepted Answer

Ethylene is the plant hormone that stimulates the development of an abscission zone in the leaf petiole. The abscission zone is a region of cell separation that allows the leaf to detach from the plant when it is ready to fall off. Ethylene also plays a role in the ripening of fruit and is produced in response to stress, such as drought or damage.

Question 8

Transpiration water loss occurs mostly through which of the following structures?

Accepted Answer

Transpiration water loss occurs mostly through stomata, which are specialized openings on the surface of leaves and stems that regulate gas exchange and water loss. Pores (A) is a generic term that does not specifically describe the structures through which transpiration occurs. Epidermal cells (C) are the outermost layer of cells that protect the plant and do not play a direct role in water loss. Guard cells (D) are specialized cells that surround stomata and control their opening and closing but do not contribute to water loss. Vessels (E) are specialized structures in the xylem that transport water and minerals but do not play a direct role in water loss through transpiration.

Question 9

Mutant plants that wilt easily under strong sunlight and high temperatures have been isolated.The stomata in these plants are functional,but do not respond to ABA.What protein may be missing from these plants?

Accepted Answer

ABA is a hormone that regulates stomata closure under stressful conditions such as high temperature and strong sunlight. The fact that the stomata in these mutant plants are functional but do not respond to ABA suggests that there may be a defect in the ABA receptor. The other options, aquaporin, H⁺-ATPase proton pump, and P proteins, are not directly involved in ABA signaling and therefore are unlikely to be missing from these mutant plants.

Question 10

Most plants transport sucrose over long distances through the xylem.

Accepted Answer

Most plants actually transport sucrose through the phloem, not the xylem. The xylem is responsible for transporting water and minerals from the roots to the rest of the plant.

Question 11

What will happen if you place a turgid cell in a hypertonic solution? A hypotonic solution?

Accepted Answer

When a turgid cell is placed in a hypertonic solution, it will lose water due to osmosis. The water will move from the cell to the solution in order to equalize the concentration of solutes on both sides of the cell membrane.

Question 12

Active transport in plants works against a concentration gradient and this allows for substances to pass through plant cells without an energy input.

Accepted Answer

Active transport in plants requires an input of energy (usually from ATP) and works to transport substances against their concentration gradient, from an area of low concentration to an area of high concentration. This allows plants to selectively accumulate certain ions and nutrients, such as potassium and nitrate, in their cells.

Question 13

The Casparian strip prevents apoplastic movement through epidermal cells.

Accepted Answer

The Casparian strip prevents apoplastic movement through the endodermal cells, not the epidermal cells, ensuring that substances must pass through cell membranes to enter the vascular system.

Question 14

Liquids move faster in plant cells by bulk flow than by diffusion.

Accepted Answer

Bulk flow is the movement of fluids in response to a pressure gradient, which can rapidly move liquids through plant cells. Diffusion, on the other hand, is a slower process where molecules move from an area of higher concentration to an area of lower concentration.

Question 15

When guard cells are ________ a stomatal pore opens between them.

Accepted Answer

When guard cells are turgid, meaning they have taken up water and become swollen, they create an opening between them and the stomatal pore opens. This allows gas exchange to occur through the pore.

Question 16

Arabidopsis plants that have mutant AtSUC2 alleles accumulate sugar and starch in their mature leaves.What process might these plants be unable to carry out?

Accepted Answer

AtSUC2 is a sucrose transporter protein that plays a critical role in phloem loading. Without functional AtSUC2 alleles, the plant is unable to properly transport sucrose from source tissues (e.g. mature leaves) to sink tissues (e.g. roots, developing fruits), resulting in accumulation of sugar and starch in the mature leaves. The other processes listed are not directly related to sugar transport and are therefore not affected by mutations in AtSUC2.

Question 17

The plant cell can move substances into cells using proton pumps that work against a gradient.

Accepted Answer

The proton pumps in the plant cell work against a gradient to move substances into the cell. This process is called active transport.

Question 18

If scientists want to develop plants that can withstand cold conditions they would breed for the ability of the plant to increase solutes in cells.

Accepted Answer

Increasing solutes in cells, such as sugars and amino acids, can help plants better tolerate freezing temperatures by reducing the formation of ice crystals which can damage cells. Therefore, breeding for this trait can help develop plants that can withstand cold conditions.

Question 19

Which of the following is the advantage that plants in arid habitats experience when they keep their stoma closed during hot daytime hours?

Accepted Answer

Keeping stomata closed during hot daytime hours helps plants in arid habitats conserve water. This is because water is lost through the stomata during transpiration, and keeping the stomata closed reduces the rate of water loss.

Question 20

Bulk flow in the phloem tissue is mostly downward whereas bulk flow in xylem is mostly:

Accepted Answer

Bulk flow in xylem is mostly upward as it is responsible for the transportation of water and minerals from roots to the aerial parts of plants. This upward flow is facilitated by transpiration, which creates a negative pressure gradient that pulls the water up through the xylem.

Quiz 29: Flowering Plants: Nutrition and Transport

Most plants absorb water and minerals from the _ and transport them through the _.