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Flashcards in Class 2 Deck (133)
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1

water makes up most of the -- of plant cells

mass

2

water makes the bulk of the content of -- and --

vacuole and tissues

3

plant must maintain its hydration within -- or growth will cease and tissue becomes stressed, and plant may wilt or die

narrow limits

4

In lettuce, water may = --% of plant fresh mass

95

5

In wood, water may = --%

35-75

6

seed are --% water

5-15

7

because water content fluctuates diurnally, seasonally, and ontogenetically, plant growth is typically measured in -- mass

dry

8

as plants lose water, their final defense system/active response leads to the production of stress hormones

abscisic acid and solute accumulation

9

1st process that tapers off as water is lost

cell expansion

10

decrease in cell expansion is followed by a decrease in --

wall and protein synthesis

11

water is lost, stomata closes, then -- stops

photosynthesis

12

-- water potential = dehydration

negative

13

potential of pure water

-0

14

Why do plants need so much water? Water is lost as a side-effect of photosynthesis

transpirational cost

15

1 mol CO2 --> lose -- molecules of water

100

16

Opening up stomata to get CO2 for photosynthesis exposes the moist plant interior to the drying air, creating a huge driving force for water to -- out of leaf (transpiration)

evaporate

17

transpiration can cool the leaf several degrees below --

air temperature

18

Transpiration takes a huge amount of water, when transpiring under full sun, a leaf can exchange its total water content in -- minutes

20

19

a small fraction of the water taken up is used for -- and --

photosynthesis and tissue expansion

20

On a warm, dry, sunny, day a leaf will exchange up to 100 % of its water in

an hour

21

evaporation of water during transpiration -- heat energy, keeping plants under bright sunlight up to a few degrees cooler than air

dissipates

22

transpiration is a form of -- cooling because it is cost free

passive

23

animal sweating is a form of -- cooling

active

24

water is a limiting yet -- resource for growth

required

25

no water > -- closes > no photosynthesis > plant overheats

stomata

26

T/F: water is the most limiting resource for agricultural and ecosystem productivity

true

27

photosynthetic rate -- once T. optimum is reached

quickly tapers off

28

photosynthesis is -- dependent

temperature

29

respiration -- as temperature increases to increase metabolism

increases exponentially

30

net carbon =

photosynthesis - respiration