Plant biology 2

Question 1

what do amphistomatous and hypostomatous mean?

Answer 1

stomata on the upper AND lower leaf

stomata on just the lower leaf

Question 2

what are stomata sensitive to? (6 things)

Answer 2

light intensity
temperature
water deficit
atmospheric CO2
air pollution
touch

Question 3

who said that stomatal opening was controlled by turgidity of guard cells relative to surrounding subsidiary cells?

Answer 3

von mohl - 1856

Question 4

what does the diffusive capacity of leaves represent?

Answer 4

product of stomatal number and stomatal aperture

Question 5

what is the endogenous circadian rhythm?

Answer 5

stomatal opening and closing over the course of the day under constant environmental conditions

Question 6

what is triggered in soil water deficit?

Answer 6

abscisic acid (ABA)

Question 7

what increases the opening of stomata?

Answer 7

guard cell turgor from active loading of guard cells with K+ (from the walls of surrounding epidermal cells)

K+ uptake also drives the osmotic uptake of water

Question 8

distortion of what what causes stomata to open?

Answer 8

guard cells

Question 9

what 6 reasons make water good for sustaining life?

Answer 9

stable
liquid in a range of temperatures
good solvent
transparent to visible light
generates pressure (turgor)
molecules show mutual attraction and are attracted to surfaces

Question 10

what is the most active region of a plant?

Answer 10

root hair zone

Question 11

what blocks the apoplast pathway?

Answer 11

casparian strip

Question 12

how does water move through the symplast pathway?

Answer 12

between cytoplasm/vacuoles of adjacent cells

Question 13

what are the two types of tracheary elements and which one is longer?

Answer 13

tracheids are < 3mm long

vessel elements are 4 - 300cm in length

Question 14

what is the direction of water movement determined by?

Answer 14

the value of water potential in the adjacent cell

Question 15

which direction will water move?

Answer 15

to the area of decreasing water potential

Question 16

what does it mean by cohesion and tension?

Answer 16

water molecules exhibit strong mutual attraction from hydrogen bonding leading to cohesion between molecules, this creates tension that pulls water in a column up the xylem

Question 17

what 2 methods help pull water up the xylem?

Answer 17

capillary action

root pressure - movement of water through root ‘pushes’ water up xylem aiding ‘pull’ created by cohesion-tension

Question 18

what is cavitation?

Answer 18

tension on water column in xylem causes dissolved gases to come out of solution creating microscopic bubbles that coalesce and fill conduit

Question 19

what is embolism?

Answer 19

cavitation bubbles obstruct passage of water in affected tracheids and vessels

Question 20

when do stomata close to protect leaf against desiccation?

Answer 20

water stress

Question 21

who said that ‘plants obtain a portion of their nutrition from the air when light is involved’?

Answer 21

stephen hales

Question 22

what did julius mayer deduce?

Answer 22

that energy used by green plant tissue was derived form the sun and that plants were capable of of transforming radiant energy to chemical form

Question 23

where does the light dependent reaction of photosynthesis take place and what are the products?

Answer 23

thylakoid membranes

ATP and NADPH

Question 24

where does the reactions of the calvin cycle take place?

Answer 24

in the stroma

Question 25

what were the earliest forms of photosynthetic organisms called?

Answer 25

stromatolites

Question 26

when did photosynthetic diversity evolve?

Answer 26

carboniferous era, 300mya

Question 27

what enzymes catalyse the C4 pathways?

Answer 27

PPDK, PEPC

Question 28

what is the difference in structure of C3 and C4 plants?

Answer 28

C4 leaves have kranz anatomy - spongy mesophyll cells clustered in a ring around the leaf veins outside bundle sheath cells

Question 29

what percentage of plants are CAM plants?

Answer 29

7%

Question 30

what percentage of plants are C4 plants?

Answer 30

2%

Question 31

what are features of CAM plants?

Answer 31

overnight accumulation of acids in vacuole inverted stomatal rhythm adaptation to drought

Question 32

what pigments are in higher plants?

Answer 32

a + b

Question 33

what pigment is in diatoms?

Answer 33

c

Question 34

what pigments are in red algae?

Answer 34

d

Question 35

chlorophyll a + b are only specific to certain wavelengths, what fills the gap?

Answer 35

carotenoids

Question 36

what adaptations do sun leaves have? (4 things)

Answer 36

many cell layers tightly packed cells less grana stacking orientated away from sun

Question 37

what adaptations do shade leaves have?

Answer 37

few cell layers lots of air space more granal stacking orientated towards sun

Question 38

what are the temperature ranges do psychrophiles, mesophiles and thermophiles have?

Answer 38

psychrophiles - 0 - 10 degrees mesophiles - 10 - 30 degrees thermophiles - 30 - 65 degrees

Question 39

what is the definition of stress?

Answer 39

an adverse force/influence that tends to inhibit 'normal' systems from functioning

Question 40

what is the difference between adaptation and acclimatisation?

Answer 40

adaptation is heritable, acclimatisation is not

Question 41

what are the symptoms of chill injury?

Answer 41

reduced photosynthesis and protein synthesis damage to cell membranes impaired protoplasmic streaming

Question 42

which fatty acids exhibit lower transition temperatures?

Answer 42

unsaturated fatty acids

Question 43

freezing stress causes what?

Answer 43

ice damages to membranes

Question 44

what does it mean when water vitrifies?

Answer 44

solidifies without forming ice crystals - does not damage the membrane

Question 45

what adaptations do plants have to avoid high temperature stress? (3 things)

Answer 45

leaf rolling leaf hairs increased wax on leaf surface to reflect light

Question 46

what is the definition of water potential of a solution?

Answer 46

the difference in free energy level between that of pure water and that of a solution

Question 47

what is water potential measured in?

Answer 47

mPa

Question 48

what are xerophytes?

Answer 48

plants adapted to dry conditions

Question 49

what adaptations of xerophytes have? (5 things)

Answer 49

``` stomatal crypts CAM photosynthesis spines not leaves succulence extensive but shallow root systems ```

Question 50

what controls flux of water vapour from leaf to atmosphere

Answer 50

stomatal conductance

Question 51

what is vapour pressure deficit? (VPD)

Answer 51

difference between vapour pressure of bulk air and saturated vapour pressure in in sub stomatal cavity

Question 52

if the VPD is high what does this mean?

Answer 52

the more drought stressed the plant is

Question 53

what is the current CO2 level in the atmosphere?

Answer 53

408ppm

Question 54

what is the current O3 level in the atmosphere?

Answer 54

40ppb

Question 55

what does ozone trigger in a plant?

Answer 55

ethylene production which reduces stomatal sensitivity to abscisic acid therefore affecting a plants capacity to regulate its water balance

Question 56

how much is the Quelccaya glacier shrinking?

Answer 56

600ft per year

Question 57

at what temperature does coral bleaching occur?

Answer 57

above 85F

Question 58

what will melting permafrost release?

Answer 58

methane