BOT 3015 Ch. 9 HW

Water potential is calculated as Ψw=Ψs+Ψp. A cell has a solute potential (Ψs) of -0.5 MPa and a pressure potential (Ψp) of 0.2 MPa. What is the water potential of this cell?

-0.3 MPa

Which of these are needed for pressure-flow to drive movement of substances in the phloem?

-A high-concentration of food substances at a source. -A low-concentration of food at an area where food is being utilized, creating a sink. -A concentration gradient between source (high concentration) and sink (low concentration).

Which of these statements are true of active transport?

-Energy is expended. -Something is moved across a membrane. -A transport protein is needed. -A proton pump is helping to move the molecules.

True or false: Water moves from the soil into the plant only if the water potential of the soil is less than the root.

-False. -Water moves from the soil into the plant only if the water potential of the soil is greater than in the root.

Which of these are part of the pathway water takes through a plant?

-Movement across a membrane at the endodermis. -Movement up the stem and into the leaves in the xylem. -Evaporation from leaf tissues and transpiration into the atmosphere. -Movement from soil to roots through osmosis

How much of the weight of young plant cells is made up of water?

90%

In the pressure-flow hypothesis, what is the main factor driving the movement of dissolved organic solutes? Multiple choice question.

A concentration gradient between source and sink

What is it called when plants expend energy to move substances across a membrane?

Active transport

Some large molecules develop electrical charges when they get wet. Water molecules have their own electrical charges which causes them to __________ to the large particles.

Adhere

Even in water that is not being stirred, there is constant motion of the molecules. This _____________ movement of molecules can be observed by releasing a small droplet of dye into a water bath and observing the distribution of pigment particles over time.

Brownian

Water moves through fine roots largely in the spaces between cells and cellulose fibers in the cell wall. When water moving through roots reaches the endodermis, what feature forces the water to diffuse across a semipermeable membrane, therefore filtering the dissolved solutes?

Casparian strips

During photosynthesis, what is happening in guard cells that brings about a change in water potential?

Cells expend energy to get potassium from epidermal cells. This lowers the water potential and increases turgor pressure.

Some desert plants have their stomata sunken into stomatal _______, which help reduce water loss.

Crypts

What do we call the movement of molecules from a region of higher concentration to one of lower concentration?

Diffusion

Cellulose develops ________ charges when wet, which attract water molecules. The water molecules are said to adhere to the charged cellulose.

Electrical

Stomata are openings on a leaf that allow the uptake of carbon dioxide and the release of water vapor. Which of these are components of a stomatal apparatus?

Guard cells Stoma

Select all true statements about transpiration.

It is driven by evaporation. It creates tension in the xylem.

Where does translocation of food substances occur in plants?

Phloem

Plasmolysis would occur when a cell is ______.

Placed in a very concentrated solution.

If a cell loses water, the cell membrane pulls away from the wall in a process called

Plasmolysis

In the water potential formula (Ψw=Ψs+Ψp), the term Ψp is referred to as __________ potential.

Pressure

In addition to the carbon and oxygen plants get from CO2 and the hydrogen they get from H2O, there are several other minerals necessary for normal plant growth. Where do those come from?

Soil

Which of these are features of CAM photosynthesis?

Stomata are open at night. Plants convert CO2 to organic acids. Water loss is kept to a bare minimum.

What is Brownian movement? Multiple choice question. The movement of brown dye The movement of water from areas of high pressure to low pressure The constant motion of molecules The motion of water molecules as they move from the brown soil to the root

The constant motion of molecules

What is diffusion? Multiple choice question. The movement of molecules through a permeable barrier, regardless of their concentration on either side of the barrier The movement of molecules from an area of lower concentration to an area of higher concentration The movement of molecules from an area of higher concentration to an area of lower concentration

The movement of molecules from an area of higher concentration to an area of lower concentration

What are the advantages of sunken stomata for plants living in arid environments?

They reduce water loss. They can be filled with epidermal hairs that further reduce water loss.

Water helps to move dissolved sugars during a process called ________ carried out by the phloem.

Translocation

Water transport in xylem is driven by evaporation from leaves, a process called

Transpiration

What is the name of the process in which water vapor is lost from the internal leaf atmosphere?

Transpiration

The pressure that builds as water enters plant cells, called _________ , Incorrect Unavailable pressure, is what makes plant cells rigid. If that pressure is lost, plants wilt.

Turgor

Turgor pressure requires cell ______ the expansion of cells as they take up water.

Walls to constrain

What type of gradient enables transport from roots to shoots in the xylem?

Water potential

Guard cells open and close the stomata as their turgor changes in response to several environmental factors such as light intensity, CO2 concentration, and water availability. Under which condition do guard cells open the stomata?

When the turgor pressure in the guard cell is high

Casparian

______ strips the walls of endodermal cells force water to cross the cell membrane before reaching the xylem.

Evaporation of water in a leaf creates negative pressure in the xylem. This causes water to ______ the roots.

be pulled up the stem from

The elements that are most abundant in plants are called _______,whereas the rest of the elements present in lower quantities are called _______.

macronutrients; micronutrients