chapter 6 plant adaptations

Question 1

Sunlight

Answer 1

Primary Energy Source
Exception in Deep Sea Hydrothermal Vents
Energy from Oxidation of Hydrogen Sulfide

Question 2

PAR

range of

Answer 2

photosynthetic active radiation

-range of visible spectrum of light

Question 3

Spectrum of Light

Answer 3

Energy Varies on Wavelength
Ultraviolet (< 400 nm)
Visible Spectrum (400 – 700 nm) range of PAR for plants for photosynthesis
Infrared (>700 nm)

Question 4

Pigments Absorb Energy

Answer 4

Chlorophyll-reflect green, absorb Red and blue
Carotenoids-absorb green, reflect red, yellow, autumn leaves
Phycobilins-bacteria, absorbs wider range, blue green color

Question 5

Water & Light

• long vs. short
• what light at depth
• what light at surface

Answer 5

Water Limits Energy from Light
Absorbs Light quickly
-----Longer Wavelengths – Infrared Light 
Scatters Light
------Short Wavelengths Most
Green Light Predominates at Depths
white light  at surface

Question 6

Adaptations to Light In Water

Answer 6

Deeper Plants must Harness Different Range of Light
Ulva absorbs Red & Blue-mirror chlorophyll
—–Shallow
—-Green Alga
—-Similar to Terrestrial
Porphyra absorbs green-mirrors carotenoids
——deep
——Red Alga

Question 7

Photosynthesis

Answer 7

6 CO2 + 6 H2O → (CH2O)6 + 6O2

-uses sun, carbon, water-> produces sugar and oxygen

Question 8

Respiration

Answer 8

(CH2O)6 + 6O2 → 6 CO2 + 6 H2O
uses sugar and oxygen-> to produce carbon and water
Gives off Heat
Converts ADP to ATP

Question 9

Light Dependent

Answer 9

Uses light energy to Chemical Bond energy (ATP)

Question 10

Light Independent

Answer 10

Uses ATP to convert CO2 into simple sugars
Does not require sunlight, BUT
Limited by ATP availability from Light Reactions

Question 11

C3 Photosynthesis
catalyzed by
Net Photosynthesis=

Answer 11

CO2 + ribulose bisphosphate (5 carbon sugar)
Produces phosphoglyceric acid (3 carbon acid)
Catalyzed by Rubisco
Net photosynthesis
Photosynthesis − Respiration
Usually measured in moles CO2 per leaf area (or mass) per unit time

Question 12

C3 pathway has one major drawback
rubisco is also an
and results in
reduces what

Answer 12

Rubisco is also an oxygenase
Can catalyze reaction between O2 and RuBP
Results in photorespiration – the release of CO2
Occurs when Internal CO2 levels low
Reduces the efficiency of C3 photosynthesis by as much as 25%

Question 13

Photosynthesis related to light availability

Answer 13

Rate increases quickly at low light
Slows as intensity increases
-as light increases photosynthesis increase, continues to increase, photosynthesis decreases

Question 14

Light compensation point (LCP)

Answer 14

Light level (PAR) at which:
Net photosynthesis = 0
CO2 uptake = CO2 loss 
photosynthesis = respiration
-all equal all balanced out

Question 15

Light saturation point

Answer 15

value of PAR above which photosynthesis does not increase

Question 16

Photoinhibition

Answer 16

Rate of photosynthesis declines as PAR exceeds saturation point
Seen in some shade-adapted plants

Question 17

Reactions of photosynthesis take place in

Answer 17

mesophyll cells

Question 18

Stomata
driven by
determined by

Answer 18

Openings on the leaf surface 
Allow CO2 to enter
-Driven by Diffusion/Gradients
-determined by
------stomatal density
number per unit leaf surface area
------Aperture
size of stomatal openings

Question 19

Stomatal Aperture

• open when
• close when

Answer 19

Controlled by Plant
Open when:
CO2 concentration outside > inside leaf 
Closed when:
Photosynthesis reduced
Demand for CO2 reduced
Often based on Water Availability

Question 20

Wip= Wr + Wa - Wt - Ws

Answer 20

Wip= Plant’s internal water
Wr = Roots
Wa = Air
Wt = Transpiration
Ws = Secretions

Question 21

plants must move water, movement against, and ____size

Answer 21

from soil to roots-from soil to roots, from roots to uppermost parts-friction

and limits size

Question 22

Extent of plant root development
Reflects differences in:
deeper roots help plants that live in

Answer 22

Evolutionary History
Water availability.
Deeper roots
Help plants in dry environments extract water from deep within the soil profile.

Question 23

Turgor pressure

plants function best when

Answer 23

Force exerted outward on a cell wall by the water inside the cell
plants function best when their cells are fully hydrated (at maximum turgor)

Question 24

Vascular Plants

Answer 24

Plants with internal structure for fluid movement
Xylem
Water Movement
Tracheids 
-------Structural & Movement
Vessel Elements
-------Mainly Movement

Question 25

Water Transport occurs because of

Answer 25

Transpiration | Cohesive Properties of Water

Question 26

Transpiration water moves to Transpirational Pull acts as

Answer 26

``` Transpiration Water Vapor Lost from Leaves Water moves to Equalize Osmotic Pressure Transpirational Pull Force or tension in leaves due to transpiration Affects Water Column in Xylem Acts as Lower Atmospheric Pressure ```

Question 27

Cohesive Properties of Water | as it gets smaller=

Answer 27

Cohesion of Water | Capillary Action-as it gets smaller, more capillary action

Question 28

``` Water Movement Between Soils and Plants flows down a water potential symbol is pure water has a water potential of water potential in nature generally ```

Answer 28

``` Water moving between soil and plants flows down a water potential gradient. Water potential (ψ) The capacity to perform work. Dependent on free energy content. Pure Water ψ = 0. ψ in nature generally negative. ```

Question 29

ψ plant = ψ π + ψ m + ψ p | as long as what, water flows from soil to plant

Answer 29

ψ π Reduction in ψ due to dissolved substances. ψ m Reduction in ψ due to Matric Forces Tendency to adhere to container walls ψ p Reduction in ψ due to negative pressure created by Transpiration & changes in Turgor pressure As long as ψ plant < ψ soil, water flows from the soil to the plant.

Question 30

water movements in plants go from areas of ____ water potential to ____ water potential As water moves from soil to root to leaf to atmosphere: Stomata close at night and ψleaf becomes

Answer 30

Movement goes from areas of higher water potential to lower potential Depends on increasingly negative water potential As water moves from soil to root to leaf to atmosphere: ψatm < ψleaf < ψroot < ψsoil There is daily variation in ψleaf and ψroot Stomata close at night and ψleaf Less negative because water is not being lost

Question 31

Water loss through transpiration will continue as long as: | roots are able to maintain more ____ water potential than soil

Answer 31

light energy striking the leaf supplies enough heat for evaporation moisture is available in the soil Roots are able to maintain more negative water potential than soil

Question 32

at field capacity water is water potential of soils is close or at clay soils have a more ____ water potential than sandy soils

Answer 32

``` At field capacity water is freely available ψsoil is at or close to zero As water is taken from the soil ψsoil becomes more negative water holds more tightly to the soil ψm becomes more negative Strongly affected by soil type clays soils have a higher surface area so have more negativeψm than sandy soils ```

Question 33

soil and water -wilting coefficient less water= ____ hold by soil particles

Answer 33

``` Availability of Water to Plants: Amount of water present Ability of Soils to Hold water Wilting Coefficient Minimum water content of uptake Less Water-> Tight hold by soil particles ```

Question 34

Water & Wilting water uptake dependent on -modify ____ concentration -ability of plants to survive depend on ______

Answer 34

Water Uptake Dependent on Osmotic Pressure Modify Solute Concentration Ability of Plants to Survive Depend on Evolution Desert Plants Changing Environments

Question 35

Water & Photosynthesis -as soil dries water potential of root and leaf must also become more ____ in order to maintain water potential gradient when gradient is lost stomatas photosynthesis

Answer 35

``` As soil dries: ψroot and ψleaf must also become more negative to maintain the water potential gradient When Gradient is lost Stomatas must close Photosynthesis Ceases Varies among plants ```

Question 36

Rate of transpiration 
 varies depending on what factors controlling the stomata is the plants most important way to regulate what water use efficiency higher ratio= lower ratio=

Answer 36

Varies daily depending on: Environmental conditions Characteristics of an individual plant Controlling the stomata Plant’s most important way to regulate water loss leads to a trade-off Taking in CO2 for photosynthesis Losing water that it requires to live Water use efficiency Ratio of carbon fixed per unit of water lost higher ratio=arid climate lower ratio= moist climate

Question 37

``` Aquatic Autotrophs CO2 diffuse water across no uses enzyme what layer is important it is an area of ```

Answer 37

``` no cell wall CO2 diffuses water across cell membrane Some can use bicarbonate as a carbon source convert HCO3− to CO2 Using the enzyme carbonic anhydrase Boundary Layer Important Area of unstirred water May become deprived of CO2 ```

Question 38

temp in photosynthesis vs respiration

Answer 38

Temperature important Both for respiration & photosynthesis Maximum temperature for reactions *Photosynthesis lower than cellular respiration

Question 39

Most solar radiation not used for photosynthesis | what is the main avenue for heat loss

Answer 39

Most solar radiation not used for photosynthesis Potential for heating (or overheating) plants Evaporation Main avenue for heat loss in terrestrial plants Part of Transpiration

Question 40

Balancing Heat Gain Against Heat Loss

Answer 40

HS = Hm ± Hcd ± Hcv ± Hr - He ``` HS = Total heat stored in an organism Hm = Gained via metabolism Hcd = Gained / lost via conduction Hcv = Gained / lost via convection Hr = Gained / lost via electromag. radiation He = Lost via evaporation ```

Question 41

Temperature Regulation by Desert Plants

Answer 41

``` Desert Plants: Must reduce heat storage. Hs = Hcd + Hcv + Hr To avoid heating, plants have (3) options: Decrease heating via conduction (Hcd). Increase convective cooling (Hcv). Reduce radiative heating (Hr). Missing Hm + He ? ```

Question 42

Temperature Regulation by Arctic Plants

Answer 42

Arctic and Alpine Plants Two main options to stay warm: Increase radiative heating (Hr). Decrease Convective Cooling (Hcv).

Question 43

Plants Adapt to Their Environments | allocate carbon more to

Answer 43

Conditions can lead to trade-offs adaptations for one may not be as effective in a different environment Results in differing suitability Carbon Distribution Allocating more to leaves & stems increases access to light & CO2 Reduces carbon available to produce roots Decreases access to water & soil nutrients

Question 44

Shade intolerant plants

Answer 44

adapted to high-light environments

Question 45

Shade tolerant plants adapted to limited to

Answer 45

``` adapted to low-light environments Produce less rubisco Require less energy Leaf respiration lower light saturation point is lower Limited in High Light Environments ```

Question 46

shade tolerant and intolerant leaf size and thiness Surface leaf area

Answer 46

Shade-tolerant and shade-intolerant species also show differences in leaf morphology Specific Leaf Area (SLA) ratio of surface area weight (cm2 : g) Surface area of leaf produced per gram of biomass allocated to leaf production shade tolerant- leaves thinner, greater SLA, larger leaves Shade intolerant-leaves thicker, smaller SLA, smaller leaves

Question 47

C3 Photosynthesis

Answer 47

Used by most plants and algae. CO2 + ribulose bisphosphate (5 carbon sugar) = phosphoglyceric acid (3 carbon acid) To fix carbon, plants must open stomata to let in CO2 . Water gradient may allow water to escape. Photorespiration can become a problem

Question 48

``` C4 Photosynthesis need fewer what reduce what increase rate of what diffuse to specialized cells surrounding ```

Answer 48

``` Reduce internal CO2 concentrations. Increases rate of CO2 diffusion inward. Need fewer stomata open. Conserving water Acids produced during carbon fixation diffuse to specialized cells surrounding bundle sheath. ```

Question 49

CAM Photosynthesis ____ rates of photosynthesis _____rates of water use efficiency

Answer 49

(Crassulacean Acid Metabolism) Limited to succulent plants in arid and semi-arid environments. Carbon fixation takes place at night. Reduced water loss. Low rates of photosynthesis. Extremely high rates of water use efficiency.

Question 50

``` C3 Photosynthesis adaptations assimilate in ___ biochemical process mostly ____ environment requires opening of ___ lead to ____ ```

Answer 50

Assimilate Carbon in single biochemical process Calvin-Benson Cycle Mostly Mesic Environments CO2 availability Limiting Factor for photosynthesis Requires Opening of Stomata Leads to Water Loss

Question 51

``` C4 Photosynthesis adaptations ____ separates initial c assimilation where Calvin benson cycle where what kind of environments what kind of plants ```

Answer 51

Assimilate Carbon in 2 biochemical processes Spatially Separates: Initial C assimilation (4-carbon acid) – Mesophyll Calvin-Benson Cycle (C3 Process) – Bundle Sheath CO2 availability Limiting Not as much as C3 Can Concentrate in Bundle Sheath Cells Increases Stomatal Resistance Reduces Water Loss Mostly Xeric Environments Grasses

Question 52

``` CAM adaptations ______ separates initial assimilation- Calvin benson cycle open stomata during ___ environments ```

Answer 52

``` CAM Photosynthesis Crassulacean acid metabolism Assimilate Carbon in 2 biochemical processes Temporally Separates: Initial assimilation (night) Calvin-Benson Cycle Temporally (Day) Only open stomata during night Mostly xeric Environments Desert Succulents ```

Question 53

tradeoffs of diff photosynthesis c3 c4 photosynthesis at what temperatures which is more efficient high levels of CO2

Answer 53

c3 high photo at low temps-loose photosynthesis at not that nigh temps compared to c4 c4 high photo at high temps c3 efficient at high levels of co2

Question 54

C3, C4, CAM plants | which one will predominate

Answer 54

``` Tell story of Historic Temperature Changes C3 more adapted to cool environments C4 more adapted to warm environments Presently Increasing Temperatures Increasing CO2 Which One will Predominate? C3 ```

Question 55

Photosynthesis & Climate Change

Answer 55

``` Greenhouse Gasses Trap Heat Maintain Physiological Temperature Human Activities Increase Effect Effects Distribution of C3 & C4 plants Increase Efficiency of C3 C4 plants expanded during low CO2 Question: How Does Temperature Play? ```

Question 56

Aquatic Plants utilize what kind of photosynthesis

Answer 56

Many Utilize C4 & CAM mechanisms Balance CO2 an O2 levels Time Photosynthesis to Coincide with Availability of C02

Question 57

``` Water, Temperature & Plants for dry environments fewer smaller increases ____ efficiency greater allocation to ```

Answer 57

``` Water & Temperature are central to plant Adaptations Often a trade-off is required. Dry Environments Fewer, smaller stomatas Increased water-use efficiency Decreased photosynthic rates Greater Allocation to roots ```

Question 58

Water, Temperature & Plants adaptations to seasonal variations, dry environments drought deciduous

Answer 58

Adaptations to Seasonal Variations Drought Deciduous Grow new leaves before rainy season May drop leaves during hot, dry times

Question 59

Adaptations to Seasonal Variations cold tolerant plant -frost Harding winter deciduous

Answer 59

``` Cold-tolerant plants Frost hardening Genetic ability to tolerate extreme cold variable within and among species Produce compounds allowing leaves to survive freezing temperatures needle leaf evergreens – pine and spruce Winter deciduous Shed leaves before beginning of the cold season ```

Question 60

Macronutrients | needed in

Answer 60

Needed in large amounts carbon, hydrogen, oxygen derived from CO2 and H2O nitrogen, phosphorus, potassium, calcium, magnesium, sulfur terrestrial plants acquire from the soil aquatic autotrophs acquire from the substrate or water

Question 61

Micronutrients (trace elements)

Answer 61

Needed in smaller amounts

Question 62

``` plants and nutrients in low nutrient environment -absorb ___ nutrients in fertile soils ____ levels when nutrients are limited ____ root to shoot ratio ______ leaf longevity ```

Answer 62

``` Plants in low-nutrient environments Possess a number of adaptations Low absorption rate Absorb fewer nutrients in fertile soils, but Higher levels when nutrients are limited Higher ratio of roots to shoots Lower growth rate Increased leaf longevity ```