Lecture 11:Physiology II

Question 1

Types of water potential are

Answer 1

additive

Question 2

Water flows along water ____

Answer 2

water potential gradients: water will move from higher water potential to lower water potential
-ve attracting, +ve repelling
pure water= 0 Mpa dry air=-100 Mpa
water will move from pure water to air

Question 3

Gravimetric water potential (gravitational)

Answer 3

height increases water potential

Ex. height increases water potential and water will move back down to lower water potentials

Question 4

Osmotic water potential

Answer 4

increasing salinity decreases water potential

saltier means you have lower water potential and water will want to move in to decrease the salinity

Question 5

Matric water potential

Answer 5

energy associated with attractive forces on surfaces of large molecules inside cells or on surfaces of soil particles
Increasing matric forces decreases water potential

Question 6

Hydrostatic water potential (hydrostatic pressure, pressure potential, turgor potential)

Answer 6

High pressure increases water potential

water inside cell has strength for pressure and makes water want to move out

Question 7

Photosynthesis for water balance in plants

Answer 7

Open stomata for CO2 to come in and make sugars for the start of photosynthesis
Water beings evaporating out of these cells
As losing water, creates water potential gradient for water to move from soil to air

Question 8

Water moves toward

Answer 8

lower water potentials

Question 9

When soil is dry,

Answer 9

water potentials decrease in plants and may cause damage
stomata can shut to stop losing water
damage can sometimes be repaired

since water potentials decrease, harder for water to move through water potential as plant has to be even more negative to get water to move through

Question 10

Critical water potential: plants shut stomata when no rain causes

Answer 10

decreases transpiration and sacrifice photosynthesis to protect the xylem

Question 11

Adaptations of terrestrial plants to dry soils (water relations)

Answer 11

Try to get more water out of the soil
Higher concentration of organic solutes to try to pull more water out of the soil
More root hairs to forage better within the soil to pull water out
Protecting roots: shed small roots during drought
deep roots: searching for other water sources:
Grow only in wet season
Close stomata
Store water (succulents)
Small leaves have less boundary layer and would be cooler, so evaporation is slower OR thick boundary layer so air next to plant is more humid

Question 12

Water balance in microorganisms

Answer 12

Mostly iso-osmotic (similar water potential) to environment

Question 13

Challenges environments for water balance in microorganisms

Answer 13

Estuaries, tide pools, saline lakes are constantly changing in salinity; cause a lot of change in the organisms –> spend energy on osmotic adjustment and changing solute concentration

Question 14

Very dry environments for microorganisms

Answer 14

Difficult for microbes as much of terrestrial microbial activity is enhanced by water availability

Question 15

Water balance in animals

Answer 15

movement, eating, drinking —-> greater control

Question 16

Fish (teleosts): marine fish environment

Answer 16

Marine fish are hypoosmotic to (less salty than) the environment

Question 17

Fish (teleosts): freshwater fish environment

Answer 17

Freshwater fish are hyperosmotic to (more salty than) the environment

Question 18

Fish want to maintain their

Answer 18

salinity
less salty than the water in marine environments
more salty than water in fresh water

Question 19

Fish have adapted behaviors and physiologies that help them slow the

Answer 19

natural movement of water
into their bodies (in fresh water)
out of their bodies (in salt water)

Question 20

Terrestrial animals use skin as

Answer 20

barrier to water loss but prevents gas exchange with environment

Question 21

Amphibians rely on

Answer 21

stable water supplies

Question 22

Some organisms are desiccation tolerant meaning

Answer 22

ability of organism to survive and regain function after losing almost all of its water and drying out

Question 23

What are the categories of energy in photosynthesis in terrestrial plants

Answer 23

C3 photosynthesis: most plants
C4 photosynthesis: corn, sugar cane, other warm climate grasses, few forbs, very few woody plants)
CAM (many succulents)

Question 24

C3, C4, CAM are named for their difference in

Answer 24

first C compound made from CO2 and more important differences in timing/location of CO2 uptake from atmosphere and Calvin cycle

C3 photosynthesis: 3PG (phosphoglycerate 3C’s)
C4 photosynthesis: OAA (oxaloacetic acid: 4C’s)
CAM photosynthesis: malic acid and OAA

Question 25

Rubisco

Answer 25

enzyme that is apart of productive Calvin cycle in taking CO2 to produce O2 and unproductive Photorespiration cycle in take in O2 and produce CO2

Low temperatures, Rubisco and photosynthesis more
High temperatures, Rubisco does Photorespiration

Question 26

Photorespiration

Answer 26

inefficiency of photosynthesis with Rubisco

unproductive breakdown of things we are trying to build within the cell

process where rubisco uses oxygen instead of carbon dioxide during photosynthesis, leading to release of carbon dioxide and loss of fixed carbon

Question 27

Photorespiration dependent on

Answer 27

relative percent of O2 vs. CO2
Higher CO2 concentration decreases photorespiration
(Lower O2 concentration increases photorespiration)
Lower CO2 increases photorespiration
(Higher O2 increases photorespiration)
Higher temperatures increase efficiency of O2 uptake and increase photorespiration

Question 28

Is C4 or C3 better at high temperatures?

Answer 28

C4

Question 29

Carbon moves through:

Answer 29

stomata –> mesophyll cells –> bundle sheath cells –> phloem

Question 30

C3 photosynthesis

Answer 30

mesophyll cells have Calvin Cycle
Photosynthesis directly with CO2

Question 31

C4 photosynthesis

Answer 31

bundle sheath cells (across waxy boundary) have Calvin cycle
builds up C concentrations before starting Calvin cycle

brings in CO2 into mesophyll cell and packs carbon into C4 which is broken back into CO2 to then run Calvin Cycle

Question 32

C3 plants include

Answer 32

most northern grasses, most trees, shrubs
Ex. rice, wheat, cheatgrass

Question 33

C4 plants include

Answer 33

mostly tropical and subtropical grasses, including most central TX grasses
Ex. corn, sugarcane, little bluestem

Question 34

C4 photosynthesis decreases

Answer 34

photorespiration dramatically

Calvin cycle is moved to different cell and not exposing Rubisco directly to raw air with lots of oxygen compared to C3

Question 35

Costs of C4 photosynthesis

Answer 35

Costs additional ATP
C4 not as beneficial at low temp and low light levels
Would be costly to switch back and forth: different cells have Calvin cycle so plants are either C4 OR C3 entirely

Question 36

If C4 benefits do not outweigh the costs over whole year, becomes

Answer 36

unfavored (in comparison to C3)

Question 37

We can infer ___ from ____ ratios of C3 and C4 plants

Answer 37

diets
isotope

Question 38

Which has less 13C: C3 or C4

Answer 38

C3 (more negative %)

Question 39

δ13C of tissues of a terrestrial animal tells us about

Answer 39

ratio of C3:C4 plants in diet

Question 40

Question: what does δ13C of modern US: -16.4 and modern UK: -21.7 tell us about diet?

Answer 40

UK has more negative % so UK eat more C3 plants
USA has more positive % so US eat more C4 plants

Question 41

How do C3 and C4 vs. CAM photosynthesis differ

Answer 41

Timing of CO2 uptake
C3 and C4 photosynthesis open stomata during day
Cam photosynthesis: open stomata at night and store carbon dioxide at night and fix during day

Question 42

CAM photosynthesis (crassulacean acid metabolism)

Answer 42

Strategy for water conservation
Open stomata at night to lose less water- when air is humid
Run Calvin cycle during day
Common in arid/dry environments
Seen in tropical epiphytes (plants growing on plants)
Ex. Prickly pear, Agave, Pineapple

Question 43

Plants can switch between C4 and CAM why?

Answer 43

Plants can be facultative in switching between the two when favorable

Question 44

How do you think climate change (increasing CO2 and temperature) might influence the abundance of C3, C4, and CAM plants

Note that greater CO2 and lower temperatures decrease water limitation

Photosynthesis Type C3:
Better in __ CO2 concentrations
Better in ___ temperatures

Photosynthesis Type C4
Better in __ CO2 concentrations
Better in __ temperatures

Photosynthesis Type CAM
Better in __ CO2 concentrations
Better in __ temperatures

Answer 44

C3: Average, Average
C4: lower (build up Carbon concentration before Calvin cycle) , higher (lower photorespiration)
CAM: lower (since able to store in CO2 in stomata during night), higher

Question 45

Heterotrophs

Answer 45

Organism that consumes other plants and animals for energy and nutrients
Does not make energy themselves

Question 46

Tradeoffs for heterotrophs

Answer 46

Detritus abundant but low in useful compounds and nutrients
Living prey difficult to find and catch, but great to eat
Plants easy to find but less energy rich –> herbivores generally have to eat more volume than carnivores

Question 47

Heterotrophs have many adaptations to

Answer 47

particular food sources
Ex. beaks for cracking seeds, humming birds with long flower tubes to access nectar, mosquito with straw mouth to pierce skin and suck blood, skimmers pick up fish with beak shape

Question 48

Herbivores have much longer digestive tracts due to

Answer 48

They eat food low in nutrients and need lots of time to try to get those nutrients unlocked and broken down from the power quality food

Question 49

Examples of how heterotrophs use tools for their benefit

Answer 49

Dolphin picks up a sponge from the environment protect their noses (rosta) while they poke at the floor to find fish