Chapter 6 Plant Adaptations

Question 1

Autotroph-

Answer 1

organism that obtains carbon without consuming other organisms… take co2 then converts it into organic compounds. also known as primary producers

Question 2

Heterotroph

Answer 2

obtains carbon by eating other organisms or their by products

Question 3

Photosynthesis

Answer 3

incorporation of co2 into organic compounds through the use of light energy

Question 4

Assimilation

Answer 4

uptake of CO2 from atmosphere

Question 5

Two steps of photosynthesis

Answer 5

light dependent and light independent

Question 6

C3 Light dependent stage of photosynthesis description and steps

Answer 6

-initial photochemical reaction that traps light energy inside chlorophyll, producing NADPH (a reductant), ATP, and O2

Steps: solar radiation and H20 produce NADPH which moves around in a cycle until ATP and NADPH is produced!

Question 7

C3 Light independent stage of photosynthesis description and steps

Answer 7

Independent calvin!!
CO2 is reduced by NADPH and created into carbohydrates (C6H12O6)

Steps: NADPH and ATP convert to some different compounds until eventually chemically reacting with Co2 with the help of the enzyme rubisco creating phosphoglyceric acid, which then moves to become glucose and other compounds

Question 8

Photorespiration

Answer 8

Oxidation of organic acids, using O2 and releasing CO2 - Reduces net photosynthesis by 30-50% in C3 plants - Occurs only in photosynthetic cells in the light, ends up producting PGA3 which can be be created into sugars, but is much less efficient compared to carboxylation.

Question 9

Dark respiration

Answer 9

Takes place exclusively in mitochondria, oxidizing carbohydrates (e.g., glucose) to generate energy in the form of ATP

Dark respiration can occur in all cells in the dark or light. It probably continues in photosynthetic cells in the light at 5 -15% the rate of net photosynthesis

Question 10

Stomatal Conductance

Answer 10

the measure of the rate of passage of carbon dioxide (CO2) entering, or water vapor exiting through the stomata of a leaf…. co2 in, water out when stoma opens/higher conductance

Question 11

Transpiration

Answer 11

• loss of water from the inside of the leaf through the stomata… function of gs (stomatal conductance) and diffusion gradient of water inside and outside of plant

Question 12

Vapor pressure deficit

Answer 12

sat-actual

helps us see gradient for water loss in traspiration

Question 13

Relative humidity

Answer 13

actual/saturated * 100….helps us see gradient . for water loss in transpiration

Question 14

Water potential

Answer 14

idea that for water to move through plant, there must remain a gradient from the roots, to the stem, to the leaves, and to the atmosphere

Question 15

Water-use efficiency

Answer 15

use of water to fix carbon, when stomata closes up when less relatively humid, efficiency increases as this process decreases water loss even though carbon dioxide increases will also stop

Question 16

CO2 uptake by aquatic autotrophs

Answer 16

co2 difuses directly across the leaf surface into the leaf interiors or some can utilize Bicarbonate but it must first be transformed into CO2… NO STOMATA

Question 17

Respiration two types and descriptions

Answer 17

light respiration (photorespiration… respiration that only occurs in photosynthetic cells in light)

and dark respiration (“true respiration”… creates ATP by oxidizing carbohydrates.. can occur in ANY CELLS)

Question 18

Whole plant net carbon gain

Answer 18

all living tissues of plant go through respiration… only leave can photosynthesize… carbon balances of whole plant

Question 19

In terrestial plants, the flow of Co2 into the leaf is a function of

Answer 19

the diffusion gradient of CO2… if its higher concentration outside, then the stoma will remain open

Question 20

Link between light and dark reactions of photosynthesis

Answer 20

Light dependent produces ATP and NADPH which in dark reactions helps to produce glucose using rubisco

Question 21

Role of rubisco?

Answer 21

catalyzes the reaction between CO2 and RuBP which is called carboxylation

Question 22

Role of chlorophyll

Answer 22

traps light energy to start the process

Question 23

What are the components of stomatal conductance, and which one(s) are under the active control of the plant?

Answer 23

Based on number of stoma per unit leaf area and aperture (size of stomatal openings)

APERTURE IS UNDER PLANT CONTROL

Question 24

Describe photosynthesis as a diffusion process (A = (Ca-Ci)*gs).

Answer 24

carbon dioxide moves into plant due to diffusion gradient

Question 25

What is the relationship between temperature and relative humidity (and vapor pressure deficit - VPD)?

Answer 25

temp increase, relative humidity decreases, VPD increases (think of it as a higher deficit between actual and saturated)

Question 26

Controls on transpiration (E = VPD*gs): how is transpiration controlled by the external physical environment; by the plant?

Answer 26

• diffusion gradient of water is a major influence by the environment on the process of transpiration
• stomatal conduction is done by plant to control transpiration

Question 27

How does stomatal conductance respond to changes in relative humidity (VPD)?

Answer 27

AS RELATIVE HUMIDITY DECREASES, STOMATA CONDUCTANCE DECREASES.. AS TEMP GOES UP, RElATIVE HUMIDITY GOES DOWN, STOMATA CONDUNCTANCE GOES DOWN, TRANSPIRATION LESSENS to become more water efficient in heat

Question 28

What conditions must hold to maintain the flow of water through the soil-plant-atmosphere continuum?

Answer 28

Gradient must be maintained, when soil dry, roots must be dryer than soil, atmosphere must be even more dry than plant

Question 29

How do patterns of carbon allocation influence net carbon uptake and plant growth?

Answer 29

Where carbon is in the plant influences whether carbon dioxide will increase (if its in the leaves which can photosynthesize) or decrease (in the stem or roots that only respire)…check this tho

Question 30

Photosynthetically active radiation (PAR)

Answer 30

radiation that is able to be used in photosynthesis (0 PAR is total darkness) on the light spectrum

Question 31

At 0 PAr, how does the rate of respiration lead to the net carbon loss?

Answer 31

Only respiration is occurring not photosynthesis so net carbon is decreasing!

Question 32

Light compensation point

Answer 32

point where there’s enough light and photosynthesis to offset respiration of the plant… depends on biochem of species

Question 33

Light saturation point

Answer 33

point where more light won’t increase the rate of photosynthesis, this point depends on species biochemistry

Question 34

How do patterns of carbon allocation respond to the availability of above-ground resources (light) during growth and development?

Answer 34

They adapt to be shade tolerant and intolerant and often have different shapes of leaves and tree structures… reduced light means increase in leaf area by allocating carbon to leaf production instead of stem/roots

Question 35

(shade tolerant or intolerant) higher respiration rate?

Answer 35

shade intolerant… think of more growth/more ATP/more respiration

Question 36

(shade tolerant or intolerant) higher light compensation point?

Answer 36

shade intolerant

Question 37

(shade tolerant or intolerant) lower saturation point

Answer 37

shade tolerant

Question 38

(shade tolerant or intolerant) fatter leaves

Answer 38

shade intolerant

Question 39

Consequences of light adaptations on patterns of survival in sun and shade environments

Answer 39

– shade environment adaptations allow for growth in more range of PAR whereas sun can only function in a smaller range
-plants with sun adaptions are able to photosynthesize and allocate carbon to higher rates of growth, while shade adaptation plants can’t keep up

Question 40

How do patterns of carbon allocation respond to the availability of below-ground resources (water and nutrients) during growth and development?

Answer 40

More dry environments will have plants allocate more carbon to root production and lessens allocation to leaves… this allows the plant a greater access to water in the soil, while decreasing water loss through transpiration by having less leaves

Question 41

(mesic or xeric) thinner WIDER leaves

Answer 41

mesic, because this allows them to uptake more carbon and still retain high amounts, even though transpiration is high, from the environment

Question 42

(mesic or xeric) more roots than shoots

Answer 42

xeric because of nutrient availability below ground

Question 43

(mesic or xeric) more water use efficient

Answer 43

xeric because not much water so you gotta HOARD

Question 44

Mesic and xeric meaning

Answer 44

mesic means wet (“me always wet” -aubrey)

xeric means dry (eric always dry)

Question 45

Differences between C3/C4/CAM

Answer 45

C3: Uses only mesopyhll cells, uses less energy than C4, but is less efficient in carbon gains due to photorespiration caused by rubsico

C4: takes place in 2 cells (bundle sheath and mesophyll), more energy to photosynthesize but more water use efficient as it AVOIDS photorespiration… lower stomatal conductance needed

CAM: same as C4 except in one cell during different times of day. Stomata only open at night which reduces water loss heavily… high energy cost though… low net carbon gain

Question 46

General patterns of net photosynthesis response to leaf temperature

Answer 46

net photosynthesis increases until temperature is high enough to increase respiration a lot, then net photosynthesis goes down… shape of a upside down parabola

Question 47

How does photosynthesis differ in response to temperature comparing C3 and c4 species?

Answer 47

c3 can net photosynthesize for longer ranges but lower amounts of net carbon gain, c4 can net photosynthesize for higher temperatures but for a short ranges of temperature

Question 48

Plant net radiation balance

Answer 48

the balance of rays absorbed by the canopy (dominated by shortwave radiation coming in)

Question 49

Dissipation of thermal energy (heat)

Answer 49

for a leaf to maintain a temperature, the net energy absorbed must be offset by energy lost

Question 50

Boundary layer

Answer 50

boundary layer between leaf and atmosphere that most directly influenced the plants temperature

Question 51

Influence of leaf morphology on thermal balance

Answer 51

wider leaves have lower boundary layer conductance… skinnier leaves have higher boundary layer conductance…. More SA, lower conductance of boundary layer

Question 52

Micro- and macronutrients

Answer 52

doesn’t relate to importance, only quantity of which they are required… you need MORE carbon (macro) then micro!

Macro nutrients cause more photosynthesis and higher rates of metabolic processes!

Question 53

Nutrient uptake and leaf nutrient concentrations

Answer 53

increase soil concentrations increase rate of uptake… increasing nitrogen uptake causes more leaf nutrients

Question 54

Leaf nitrogen concentrations and maximum rates of net photosynthesis

Answer 54

leaf nitrogen increases with maximum rates of net photosynthesis!

Question 55

Adaptations to low nutrient environments

Answer 55

Depends on species how much macronutrients affect growth… species adapt to different amounts of nutrients in soils, so if they have more nutrients, sometimes this can cause decreased growth as this isn’t an ideal environment for the plant!

Question 56

What feature(s) of the physical environment limit a plants ability to dissipate heat (energy) via convection? Evaporation?

Answer 56

Evaporation- the relative humitdity/VPD between air and leaf

Convection - atomspheric temperature of the environment/ thats influence on the boundary layer which conducts to the leaf

Question 57

What characteristic(s) of a plant limit its ability to dissipate heat (energy) via convection? Evaporation?

Answer 57

Evaporation - stomatal conductance and the amount of water in the plant

Convection- leaf size and shape influence some characteristics of the boundary layer such as its size… when in turn affect the ability to dissipate heat via convection

Question 58

Why is leaf longevity considered a possible adaptation for survival and growth in low nutrient environments?

Answer 58

lower nitrogen leads to longer leaf life span, longer life span is more new photosynthesis… natural selection pushes longer leaf life spans for lower nitrogen because it would need more carbon to continually grow leaves rather than sustain the same leaves

Question 59

Rizhobium bacteria

Answer 59

infects the roots and gains carbon from the plant… but its mutualistic, but this bacteria fixes N2 gas for the plant!…. give and take btwn N2 and Carbon!

Question 60

Legumes

Answer 60

are responsible for 90% of nitrogen in soil!

Question 61

Mycorrhizal fungi

Answer 61

fungi are the dominant decomposers of organic matter that infects roots but increases the surface area of roots by attaching to the roots and taking carbon from the plant, but providing it with uptake of other nutrients and water

Question 62

What is the general tradeoff between the ability to tolerate low resource availability and the maximum rates of photosynthesis and growth under conditions of high resource availability

Answer 62

species adapted to high nutrient environments (intolerant plants, high growth, high photosynthesis), but limit its ability to persist under low nutrient ability

low species environemt plants (tolerant plants), in more environments of low and high resources, however, under high resources, they aren’t able to grow as fast as intolerant plants!