Question 1

Which of the following best explains why water moves from the soil into the roots of a plant?

Accepted Answer

Water moves from areas of high water potential to areas of low water potential, following the water potential gradient.

Question 2

A plant cell has a solute potential ($$\psi_s) of$$ $$-0.5$$ MPa and a pressure potential ($$\psi_p) of$$ $$0.3$$ MPa. What is the total water potential ($$\psi) of $$the cell?

Accepted Answer

$$\psi = -0.2$$ MPa

Question 3

Which structure in the root acts as a selective barrier, forcing water and dissolved minerals to cross a cell membrane before entering the xylem?

Accepted Answer

Casparian strip

Question 4

Why is active transport required for the uptake of mineral ions such as $$\mathrm{NO_3$^-}$$ and $$\mathrm{K^+} in $$plant roots?

Accepted Answer

Mineral ions are often more concentrated inside root cells than in the soil, requiring energy to move them against their gradient.

Question 5

Which of the following best describes the cohesion-tension theory for water transport in tall trees?

Accepted Answer

Transpiration creates tension that pulls water upward through the xylem, with cohesion and adhesion aiding the process.

Question 6

A plant is placed in a solution with a lower water potential than its own cells. What will happen to the plant cells?

Accepted Answer

Water will move out of the cells, causing them to plasmolyze.

Question 7

Which tissue is responsible for conducting water and dissolved minerals from roots to shoots in vascular plants?

Accepted Answer

Xylem

Question 8

What is the main driving force for the movement of water through the xylem during the day?

Accepted Answer

Transpiration from leaves

Question 9

Which of the following adaptations would you expect to find in a plant living in a dry habitat?

Accepted Answer

Reduced leaf surface area and thick cuticle

Question 10

In the pressure-flow hypothesis for phloem transport, what causes phloem sap to flow from source to sink?

Accepted Answer

A pressure gradient created by active loading of sucrose at the source and unloading at the sink

Question 11

If a plant's guard cells lose turgor pressure, what is the most likely immediate effect?

Accepted Answer

Stomata will close, reducing transpiration

Question 12

Which of the following best describes the role of hydrogen bonding in water transport in plants?

Accepted Answer

Hydrogen bonds allow water molecules to adhere to xylem walls and cohere to each other, facilitating upward movement.

Question 13

A plant cell is placed in pure water. Its solute potential ($$\psi_s) is$$ $$-0.7$$ MPa and its pressure potential ($$\psi_p) is$$ $$0.7$$ MPa. What will happen to the cell?

Accepted Answer

Water will move into the cell until equilibrium is reached.

Question 14

Which process is responsible for the movement of sugars from photosynthetic cells into companion cells in the phloem?

Accepted Answer

Cotransport with protons (H+)

Question 15

Why does water not move directly from the soil into the xylem without crossing a cell membrane?

Accepted Answer

The Casparian strip in the endodermis blocks the apoplastic route, forcing water and solutes to cross a membrane for selective uptake.

Question 16

Which of the following would decrease the rate of transpiration in a plant?

Accepted Answer

High humidity around the leaves

Question 17

A plant is growing in salty soil. What adaptation might you expect to find in its root cells?

Accepted Answer

Root cells with a very low solute potential ($$\psi_s) to $$maintain water uptake.

Question 18

Which of the following best explains why phloem sap can move in multiple directions within a plant?

Accepted Answer

Phloem sap moves from sources to sinks, which can be located in various parts of the plant depending on developmental stage and season.

Question 19

Which of the following is a direct result of transpiration in plants?

Accepted Answer

Decrease in water potential in leaf tissues, creating a pull for water from the roots.

Water and Sugar Transport in Plants (Chapter 35 Study Notes)

Study Guide - Practice Questions

Study Guide - Flashcards