Chapter 9 Water In Plants

Question 1

solvent

Answer 1

(sol′vent) a substance (usually liquid) capable of dissolving another substance

Question 2

semipermeable membrane

Answer 2

(sem-ee-pur′me-uh-bil mem′brane) a membrane that allows some molecules to pass through it but not others; see differentially permeable membrane

Question 3

osmosis

Answer 3

(oz-moh′sis) the diffusion of water or other solvents through a differentially permeable membrane from a region of higher concentration to a region of lower concentration

Question 4

osmotic potential

Answer 4

(oz-mot′ik puh-ten′shil) a measure of the potential of water to move from one cell to another as influenced by solute concentration

Question 5

turgid

Answer 5

(tur′jid) firm or swollen because of internal water pressures resulting from osmosis

Question 6

turgor pressure

Answer 6

(tur′gur presh′ur) pressure within a cell resulting from the uptake of water

Question 7

pressure potential

Answer 7

(presh′er puh-ten′shuhl) turgor that builds up against the cell wall as a result of water entering the vacuole

Question 8

water potential

Answer 8

(waw′tuhr puh-ten′shil) the potential of water to move from one location to another as influenced by osmotic, pressure, and other influences

Question 9

plasmolysis

Answer 9

(plaz-mol′uh-sis) the shrinking in volume of the protoplasm of a cell and the separation of the protoplasm from the cell wall due to loss of water via osmosis

Question 10

imbibition

Answer 10

(im-buh-bish′un) adsorption of water and subsequent swelling of organic materials because of the adhesion of the water molecules to the internal surfaces

Question 11

active transport

Answer 11

(ak′tiv trans′port) the expenditure of energy by a cell in moving a substance across a plasma membrane against a diffusion gradient

Question 12

The Cohesion-Tension Theory

Answer 12

The cohesion-tension theory (C-T theory) by Boehm (1893) and Dixon and Joly (1894) postulates that the water ascent in trees is exclusively due to the transpirational pull from continuous water columns in the xylem conduit running from the roots to the leafs.

Question 13

hydathode

Answer 13

(hy′duh-thohde) structure at the tip of a leaf vein through which water is forced by root pressures

Question 14

guttation

Answer 14

(guh-tay′shun) the exudation from leaves of water in liquid form due to root pressure

Question 15

pressure-flow hypothesis

Answer 15

(presh′ur floh hy-poth′uh-sis) the theory that food substances in solution in plants flow along concentration gradients between the sources of the food and sinks (places where the food is utilized)

Question 16

hydroponics

Answer 16

(hahy-druh-pon′iks) technique used to grow plants using mineral nutrient solutions without soil

Question 17

Osmotic potential

Answer 17

is a measure of the potential of water to move from one cell to another as influenced by solute concentration. The pressure that develops in a cell as a result of water entering it is called turgor. Water moves from a region of higher water potential (osmotic potential and pressure potential combined) to a region of lower water potential when osmosis is occurring. Osmosis is the primary means by which plants obtain water from their environment..

Question 18

Plasmolysis

Answer 18

Plasmolysis is the process in which cells lose water in a hypertonic solution. The reverse process, deplasmolysis or cytolysis, can occur if the cell is in a hypotonic solution resulting in a lower external osmotic pressure and a net flow of water into the cell.

Question 19

What is Brownian movement?

Answer 19

The constant motion of molecules

Question 20

plasmodesmata.

Answer 20

Plasmodesmata are intercellular pores connecting adjacent plant cells allowing membrane and cytoplasmic continuity and are essential routes for intercellular trafficking, communication and signaling in plant development and defense

Question 21

Brownian motion

Answer 21

Brownian movement also called Brownian motion is defined as the uncontrolled or erratic movement of particles in a fluid due to their constant collision with other fast-moving molecules.

Question 22

Brownian motion

Answer 22

Brownian movement also called Brownian motion is defined as the uncontrolled or erratic movement of particles in a fluid due to their constant collision with other fast-moving molecules.

Question 23

Water potential

Answer 23

Water potential is the potential energy of water per unit volume relative to pure water in reference conditions. Water potential quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure and matrix effects such as capillary action.

Question 24

Turgor pressure

Answer 24

Turgor pressure is the hydrostatic pressure in excess of ambient atmospheric pressure which can build up in living, walled cells. Turgor is generated through osmotically driven inflow of water into cells across a selectively permeable membrane; this membrane is typically the plasma membrane

Question 25

When does water move from the soil into the plant

Answer 25

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

Question 26

sequence of events as water moves through a plant

Answer 26

1. Water enters the roots from the soil via osmosis
2. water crosses a semipermeable membrane at the endodermis as it enters the central root system of the plant
3. Water is transported up the stem and into the leaves through the xylem
4. water evaporates from the leaves, leaving through the stomata

Question 27

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

Answer 27

plasmolysis

Question 28

plasmolysis

Answer 28

contraction of the protoplast of a plant cell as a result of loss of water from the cell.

Question 29

Ψp

Answer 29

Pressure potential

Question 30

Ψs

Answer 30

Solute potential

Question 31

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

Answer 31

electrical

Question 32

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

Answer 32

walls to constrain

Question 33

Active transport

Answer 33

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

Question 34

Proton pump

Answer 34

Proton pump is a membrane-integrated enzymatic complex which is able to mobilize protons to generate a proton gradient across the membrane. This proton gradient constitutes a fundamental energy reservoir. The proton pump plays an important role in cell respiration and photosynthesis.

Question 35

Which of these statements are true of active transport?

Answer 35

A proton pump is helping to move the molecules.

A transport protein is needed.

Energy is expended.

Something is moved across a membrane.

Question 36

Parts of the pathway water takes through a plant?

Answer 36

Movement across a membrane at the endodermis

Movement up the stem and into the leaves in the xylem

Movement from soil to roots through osmosis

Evaporation from leaf tissues and transpiration into the atmosphere

Question 37

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

Answer 37

transpiration

Question 37

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

Answer 37

transpiration

Question 38

About how much water does a hardwood tree need to produce one pound of wood?

Answer 38

120 gallons

Question 39

Root pressure

Answer 39

root pressure, in plants, force that helps to drive fluids upward into the water-conducting vessels (xylem). It is primarily generated by osmotic pressure in the cells of the roots and can be demonstrated by exudation of fluid when the stem is cut off just aboveground.

Question 40

polar molecule

Answer 40

A polar molecule is a molecule in which one end of the molecule is slightly positive, while the other end is slightly negative

Question 41

What does it mean when we say water is a polar molecule?

Answer 41

Each molecule is attracted to other water molecules.

It has one end with a weak positive charge and an opposite end with a weak negative charge.

Question 42

hydrophilic

Answer 42

having a tendency to mix with, dissolve in, or be wetted by water.

Question 43

Because polar water molecules attract each other, water is said to be ______

Answer 43

cohesive

Question 44

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

Answer 44

be pulled up the stem from

Question 45

When some plants are pruned in the spring, water will exude from the cut ends. What causes this?

Answer 45

Root pressure

Question 46

Casparian strips

Answer 46

Casparian strips are ring-like cell-wall modifications in the root endodermis of vascular plants

Question 47

_____ strips in root endodermal cells contain suberin to limit the movement of minerals and water.

Answer 47

Casparian

Question 48

Cohesion.

Answer 48

the sticking together of particles of the same substance.

Question 49

true statements about transpiration.

Answer 49

It creates tension in the xylem.

It is driven by evaporation.

Question 50

Guard cells

Answer 50

Guard cells are pairs of epidermal cells that control gas diffusion by regulating the opening and closure of stomatal pores

Question 51

When plants cannot access water to keep up with the demands of transpiration, they experience water stress. If this happens, _____ will close in response to the stress.

Answer 51

Stoma

Question 52

CAM photosynthesis

Answer 52

Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night.

Question 53

c4 photosynthesis

Answer 53

C4 photosynthesis is a CO2-concentrating mechanism that increases the carboxylation rate of Rubisco while simultaneously minimizing oxygenase activity and the inhibitory effects of photorespiration

Question 54

C3 Photosynthesis

Answer 54

Plants which use only the Calvin cycle for fixing the carbon dioxide from the air are known as C3 plants.

Question 55

Photorespiration

Answer 55

Photorespiration is a wasteful pathway that competes with the Calvin cycle. It begins when rubisco acts on oxygen instead of carbon dioxide.

Question 56

rubisco

Answer 56

A plant enzyme which catalyzes both the fixing of atmospheric carbon dioxide during photosynthesis and the reverse process of photorespiration.

Question 57

Calvin cycle

Answer 57

The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose

Question 58

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

Answer 58

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

Question 59

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

Answer 59

crypts

Question 60

features of CAM photosynthesis?

Answer 60

Water loss is kept to a bare minimum.

Plants convert CO2 to organic acids.

Stomata are open at night.

Question 61

environmental factors affects stomatal opening and closing and therefore transpiration rates

Answer 61

CO2 concentration

Humidity

Light intensity

Temperature

Question 62

Guttation

Answer 62

Guttation is the process of secretion of water droplets from the pores of some vascular plants like grass

Question 63

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

Answer 63

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)

Question 64

stomatal crypts

Answer 64

In some plants, stomata are exclusively located in epidermal depressions called crypts. It has been argued that crypts function to reduce transpiration; however, the occurrence of crypts in species from both arid and wet environments suggests that crypts may play another role.