Chapter 36

Question 1

Early nonvascular land plants

Answer 1

lived in shallow water and had aerial roots

Question 2

What is the tradeoff in plants?

Answer 2

Enhancing photosynthesis

Minimizing water loss

Question 3

Phyllotaxy

Answer 3

the arrangement of leaves on a stem

important for light capture

Question 4

As water availability increases,

Answer 4

Leaf size normally increases

Question 5

Self-pruning

Answer 5

shedding of lower shaded leaves

they loose more than they gain through photosynthesis, so they are removed

Question 6

Horizontal leaves

Answer 6

Better in low-light conditions since they capture more sunlight

Question 7

Vertical leaves

Answer 7

Better in sunny conditions because they are less damaged by sun and allow light to reach lower leaves

Question 8

Mycorrhizae

Answer 8

Roots and hyphae of soil fungi form mutualistic associations

Increases surface area

Helps plants colonize land

Question 9

Apoplast

Answer 9

refers to transport outside of the plasma membrane (not cell wall)

Question 10

Symplast

Answer 10

refers to transport within the cytosol and plasmodesmata

Question 11

The Apoplastic Route

Answer 11

through cell walls and extracellular spaces

Question 12

The Symplastic Route

Answer 12

through the cytosol and plasmodesmata

Question 13

The Transmembrane Route

Answer 13

Across cell walls

Question 14

How is membrane potential established?

Answer 14

Pumping hydrogen ions by proton pumps

this establishes a concentration gradient

Question 15

Water potential

Answer 15

a measurement that combines the effects of solute concentration and pressure

Question 16

Which way does water potential flow?

Answer 16

From regions of higher water potential to regions of lower water potential

Question 17

Solute potential

Answer 17

always negative. lowers the water potential

Question 18

Pressure potential

Answer 18

physical pressure on a solution, like from a cell wall

Question 19

Turgor pressure

Answer 19

the pressure exerted by the plasma membrane against the cell wall and protoplast

Question 20

Protoplast

Answer 20

living part of the cell, which also includes the membrane

Question 21

What will happen to a flaccid cell?

Answer 21

Plasmolysis

If placed in a salty surrounding environment

Question 22

Plasmolysis

Answer 22

occurs when the protoplast shrinks and pulls away from the cell wall

Question 23

Turgid

Answer 23

cell gains water

flaccid cell placed in lower solute concentration outside the cell

Question 24

Aquaporins

Answer 24

transport proteins in the cell membrane that facilitate the passage of water

affect the rate of water movement across the membrane

Question 25

Endodermis

Answer 25

intermost layer of cells in root cortex last checkpoint for selective passage into vascular tissue

Question 26

Casparian strip

Answer 26

blocks apoplectic transfer of minerals from the cortex to vascular tissue water and minerals forced to cross a plasma membrane

Question 27

Xylem sap

Answer 27

water and dissolved minerals now in the vascular system

Question 28

Transpiration

Answer 28

the evaporation of water from a plant's surgace

Question 29

How does transpiration pull water?

Answer 29

When it evaporates, it needs more water to replace it Creates negative pressure

Question 30

Root pressure

Answer 30

the water potential is low in the xylem, so it flows there push of xylem sap minor mechanism

Question 31

Guttation

Answer 31

effect of root pressure exudation of water droplets on tips of leaves

Question 32

Adhesion

Answer 32

water molecules are attracted to cellulose in xylem cells offsets the force of gravity

Question 33

Cohesion

Answer 33

water molecules are attractched to eachother

Question 34

Does bulk flow require energy?

Answer 34

No. Largely driven by transpiration which relies on sunlight to open and close stomata

Question 35

Bulk flow versus diffusion

Answer 35

Driven by differences in pressure potential, not solute potential occurs in dead and alive cells moves the entire solution faster

Question 36

What opens and closes stomata

Answer 36

Changes in turgid pressure When turgid, guard cells bow outward and the pore opens When flaccid, guard cells are less bowed and the pore closes Results from K+ solute potential

Question 37

Stomatal opening at dawn is triggered by

Answer 37

Light CO2 depletion Circadian rhythms

Question 38

Abscisic acid

Answer 38

hormone produced in response to water deficiency and causes closure of stomata

Question 39

How does sugar move?

Answer 39

From source to sink through the phloem, specifically sieve tube often requires active transport

Question 40

What else does the phloem transfer

Answer 40

Viruses, information, electrical signals

Question 41

The symplast does NOT transport

Answer 41

DNA

Question 42

Active transport at the cellular level does not require

Answer 42

Xylem membranes

Question 43

Which of the following would not normally function as a sink?

Answer 43

Mature leaf

Question 44

What process is not affected by proton gradients?

Answer 44

Xylem transport

Question 45

Which of the following experimental procedures would most likely reduce transpiration while allowing the normal growth of a plant?

Answer 45

Increasing the level of carbon dioxide around the plant

Question 46

If the guard cells and surrounding epidermal cells in a plant are deficient in potassium ions, all of the following would occur except

Answer 46

Leaf temperatures would decrease

Question 47

What drives water through the xylem?

Answer 47

Evaporation in leaves

Question 48

What does bulk flow not depend on?

Answer 48

Force of gravity

Question 49

Which is false of phloem cells?

Answer 49

Companion cells control the rate and direction of movement of phloem sap.

Question 50

One would expect to find the highest density of aquaporins in which of the following

Answer 50

the plasma membrane of guard cells

Question 51

CAM plants

Answer 51

Keep stomatas open at night for CO2 Keep stomatas closed during day to prevent transpiration

Question 52

What causes cohesion

Answer 52

Hydrogen bonds between oxygen atom of one water molecule and hydrogen atom of another water molecule

Question 53

Sugar movement in phloem

Answer 53

Can go upwards and downwards primarily goes downwards

Question 54

Tomato problem

Answer 54

Stomata apertures

Question 55

All of the following involve active transport across membranes except

Answer 55

the movement of sugar from one sieve-tube element to the next