Plant Adaptations to the Environment Flashcards
1
Q
all life on earth is __
A
carbon-based
2
Q
- complex sequence of metabolic reactions
- can be separated into two processes: light dependent, light-independent reactions
A
photosynthesis
3
Q
two process of photosynthesis
A
- light dependent reaction
- light independent reaction
4
Q
Process of photosynthesis (formula)
A
6CO2 + 12H20 –> C6H1206 + 602 + 6H20
5
Q
rates of photosynthesis and respiration, and therefore net photosynthesis, aer typially measured in what
A
mole CO2 per unit leaf area (or mass) per unit time
(µmol/m^2/s)
6
Q
the harvesting of energy from the chemical breakdown of simple sugars and other carbohydrates
A
cellular respiration
6
Q
net photosynthesis formula
A
photosynthesis - repiration
7
Q
where does the process of cellular respiration occur
A
mitochondria
8
Q
other term for cellular respiration
A
aerobic respiration
9
Q
what does the cellular respiration involve
A
oxidation of carbohydrates to generate energy (ATP)
10
Q
cellular respiration formula
A
C6H12O6 + 6O2 –> GCO2 + 6H20 + ATP
11
Q
where does the process of photosynthessis occur
A
chloroplast in mesophyll cells
12
Q
three main types of photosynthesis
A
- C3 photosynthetic pathway
- C4 photosynthetic pathway
- CAM (crassulacean acid metabolism)
13
Q
other term for C3 photosynthetic pathway
A
Calvin cycle
14
Q
products of light dependent reactions
A
- ATP
- NADPH
15
Q
what is ATP and NADPH used for
A
- synthesize energy-rich sugar G3P
- regenerate RuBP (light-independent reaction)
16
Q
obligatory component of energy-producing reactions including glycolysis and glycerolipid biosynthesis
A
Glycerol-3-phosphate (G3P)
17
Q
molecule that starts the cycle, is regenerated so that the cycle can continue
A
ribulose 1,5-bisphosphate (RuBP)
18
Q
catalyzes a reaction between CO2 and RuBP
A
Ribulose-1,5-bisphosphate Carboxylase-Oxygenase (RuBisCO)
19
Q
- light of wavelengths 400-700 nm
- portion of light spectrum utilised by plants for photosynthesis
A
Photosynthetically active radiation (PAR)
20
Q
provides energy required to convert co2 into simple sugars
A
solar radiation
21
Q
what directly influence rate of photosynthesis
A
availability of light (PAR)
22
Q
what happens at night in the absence of PAR
A
- respiration
- net uptake of CO2 is negative
23
Q
what does rate of CO2 loss when value of PAR is zero provide
A
estimate of rate of respiration
24
what happens when the value of PAR increases
rate of photosynthesis also increases
25
Rate of net photosynthesis is zero
CO2 uptake in photosynthesis = CO2 loss in respiration
26
- light level at which rate of CO2 uptake for photosynthesis = loss of CO2 in respiration
- value of PAR at which
O2 produced by photosynthesis = O2 consumed by respiration
light compensation point
27
- light intensity at which a plant reaches the maximum photosynthesis rate
- about 10% of full sunlight for shade plants
- 50-70% of full sunlight for C3 sun plants
- 200% for C4 sunplants
light saturation point
28
value of net CO2 exchange at PAR = 0 provides an estimate of what
rate of respiration
29
where CO2 enters leaf in terrestrial plants
stomata
30
how does CO2 enter in stomata
diffusion
31
where does water move
region of high to low (more negative) water potential
32
difference between aquatic and terrestrial plants in their leaves
lack of stomata in aquatic autotrophs
33
examples of aquatic autotrophs
- submerged plants
- algae
- phytoplankton
34
difference between terrestrial and aquatic autotrophs in terms of carbon source
some aquatic species use bicarbonate
35
used to convert bicarbonate into CO2
carbonic anhydrase
36
two ways of conversion of bicarbonate into CO2
1. active transport of bicarbonate into cell followed by conversion to CO2
2. excretion of enzyme to adjacent waters and subsequent uptake of converted CO2 across membrane
37
both photosynthesis and respiration respond directly to variations in what
temperature
38
temperature that controls the rate of photosynthesis and respiration
temperature of leaf
39
where does temperature of leaf depend
exchange of thermal energy between leaf and surrounding environment
40
where is the relative importance of evaporation and convection to the maintenance of leaf temperature dependent
physical environment
41
heat dissipation in location where water is available
transpiration
42
heat dissipation in location with drier conditions
convection
43
harness energy of the SUn to fuel conversion of CO2 into glucose in process of photosynthesis
autotrophs
44
temperature decrease from __ to __ of leaf surface
center to edge
45
to survive, grow, and reproduce, what must plants maintain
positive carbon balance (photosynthesis > respiration)
46
examples of many features of physical environment that directly influence plant processes
1. light
2. temperature
3. moisture
47
most important of trade-offs in the ability of plants to adapt to limitations
acquisition of ABOVE and BELOW ground sources
48
allocating carbon to production of leaves and stems
decrease allocation of carbon to production of roots
49
allocating carbon to production of roots
decrease allocation of carbon to production of leaves
50
where does the amount of solar radiation reaching the Earth's surface vary
- diurnally
- seasonally
- geographically
51
major factor influencing amount of light a plant receives
shade
52
Two light environments where plants live
1. sun
2. shade
53
species adapted to high-light environments
- shade-intolerant species or
- sun-adapted species
54
species adapted to low-light environments
shade-tolerant plants
55
shade-tolerant plants tend to have what
- lower light saturation point
- lower maximum rate of photosynthesis
56
why do shade-tolerant plants have lower light saturation point and lower maximum rate of photosynthesis
lower concentrations of photosynthetic enzyme RuBisCo
57
low concentrations of producing rubisco and other compounds involved in photosyntheis result in what
lower rate of leaf respiration
58
where are the variations in photosynthesis, respiration and growth rate that characterize plant species adapted to different light environments illustrated
work of plant ecologist
Peter Reich & colleagues at University of Minnesota
59
Results of Peter Reicha nd colleagues about species adapted to lower light environments
lower maximum rates of net photosynthesis and leaf respiration
60
plants adaptation have evolved to respond variations in what
- precipitation
- soil moisture
- demand for water linked to temperature
61
as air temperature rises, what increases
saturation vapor pressure
62
amount of water required by plant to offset losses from transpiration will increase with __
temperature
63
what causes the decline in leaf area due to decreasing water availability
reduced allocation of carbon to production of leaves
64
capture light energy and transform CO2 into sugars in mesophyll cells
C3 plants
65
divide photosynthesis between mesohpyll and bundle sheath cells
C4 plants
66
C4 plants two distinct types of photosynthetic cells
- mesophyll cells
- bundle sheath cells
67
C4 plants are mostly what
- grasses (native to tropical and subtropical regions)
- shrubs (arid and saline environments)
68
pathway used by small group desert plants in hot deserts
CAM pathway
69
Two advantages of C4 plants over C3 plants
1. PEP does not react with oxygen
2. conversion of malic and aspartic acids into CO2 with bundle sheath increase efficiency of reaction
70
C4 plants have a __ __ __ of photosynthesis than C3 plants
higher maximum rate
71
PEP
Phosphoenolpyruvate
72
CAM plants open their stomata at night to take up CO2 and convert it to __ using __
- malic acid
- PEP
73
although CAM pathway is slow and inefficient, what is its advantages?
- reduce water loss through transpiration
- increase water-use efficiency
74
what causes the different temperature responses of different species from different thermal habitats
process of acclimation reversible phenotypic changes
75
- plants acquire this through the formation or addition of protective compounds in the cells, which act as antifreeze and lower the temperature at which freezing occurs
- genetically controlled characteristic
frost hardening
76
happens when plants shed their leaves before the colds season start
winter deciduous
77
amount of light reaching a plant influences what
photosynthetic rate
78
two key physical processes of photosynthesis
1. diffusion
2. transpiration
79
where does the amount of water loss depend
humidity
80
where does plant draw water, and release to
- draw from soil (highest water potential)
- release to atmosphere (lowest water potential)
81
what problems are created during transpiration
moisture conservation problems
82
how are stomata used
- open to take CO2
- closed to conserve water
83
affect both photosynthesis and respiration
leaf temperature
84
what increases with temperature
respiration
85
difference between the absorption and release of longwave and shortwave radiation by plants
plant's net radiation balance
86
response to different light environments by plants
- adaptations
- phenotypic plasticity
87
have low photosynthetic, respiratory, metabolic, and growth rates
shade-adapted (shade-tolerant) plants
88
- have higher photosynthetic, respiratory, and growth rates
- lower survival rates under shaded conditions
sunplants (shade-intolerant)
89
where does C4 plants fix CO2
- malate
- aspartate
mesophyll cells
90
the amount of carbon fixed per unit of water transpired
water-use efficiency
91
CAM plants convert CO2 to what
malate
92
ability to tolerate high air teperatures is related to what
plant moisture balance
93
directly affects a plant's survival, growth, and reproduction
availability of nutrients
