Test 1 Flashcards
Plant blindness
“the inability to see or notice the plants in one’s own environment,” which leads “to the inability to recognize the importance of plants in the biosphere and in human affairs”
An “inability to appreciate the aesthetic and unique biological features” of plants
Monoecious
both sexes/parts in one flower/on one plant
MOST PLANTS
mono = one
ecious = house
Dioecious
separate sexed plants
SMALL proportion of plants
di = two
ecious = house
Male flowers release pollen to fertilize female flower parts
Female plants make seeds/fruit
5 very urban tolerant tree species
- Ginkgo biloba = ginkgo (aka “silver apricot”)
- Ulmus americana = american elm
- Zelkova serrata = japanese zelkova
- Gleditsia triacanthos var. inermis = thornless common honeylocust
- Platanus ×acerifolia = london planetree
Ginkgo biloba
silver apricot
DIOECIOUS
Ripe fruit (FEMALES) smells like vomit
SOLUTION: avoid smelly fruit by planting MALE trees
superb yellow fall foliage color
Ulmus americana
american elm
extremely urban tolerant
ideal street tree
opposing vase-shaped trees create cathedral-like ceiling
dutch elm disease (DED)
lethal funcus spread by beetle
NOW WE HAVE DISEASE-RESISTANT TYPES
treatment w fungicide effective in advance of disease/if tree is in early stage of infection
Zelkova serrata
japanese zelkova
vase shape
Gleditsia triacanthos var. inermis
thornless common honeylocust
SOME species have thorns
this is the THORNLESS variety
Platanus ×acerifolia
london planetree
hybrid of 2 species US + Asian
urban tolerant
grow near/in sidewalk
showy, patchy cream-tan-brown bark
Important campus oak species
Quercus macrocarpa = bur oak
Quercus macrocarpa
Bur oak
NOT a typical urban tree species
IN FRONT OF BURRUSS HALL
(we don’t call it Burruss Hall bc of the burr oak)
macro = big
carpa = fruit
bur = rough, prickly case around seeds/nuts
fringe around the nut
Photosynthesis
converting carbon in the air into sugar
Carbon in the air = carbon dioxide (CO₂)
LIGHT/SOLAR ENERGY IS CONVERTED TO CHEMICAL ENERGY (ATP & NADPH)
CHEMICAL ENERGY IS STORED IN THE FORM OF GLUCOSE (sugar)
BASIS OF FOOD CHAIN
Provides virtually all the energy source for all organisms
2 main parts of photosynthesis
- Light reactions
- Dark reactions
calvin cycle
sugar production
air concentrations
Carbon dioxide (CO₂) = 0.04%
420 ppm (parts per million)
Nitrogen (N₂) = 78%
Oxygen (O₂) = 20.9%
where photosynthesis takes place
chloroplasts
thylakoid membrane
contains chlorophyll (photosynthetic pigments)
part 1 of photosynthesis
light reactions
LIGHT/SOLAR ENERGY IS CONVERTED TO CHEMICAL ENERGY (ATP & NADPH)
2 forms of chemical energy (HIGH ENERGY compounds/MOLECULES) formed in light reactions
1. ATP (adenosine triphosphate)
Contains a large amount of energy in third phosphate bond
ADP (adenosine diphosphate) is a LOW energy compound
2. NADPH
NADP⁺ gains electrons & proton → NADPH
NADP⁺ is a LOW energy compound
electromagnetic radiation
light = form of electromagnetic radiation
short waves = high photon energy
long waves = low photon energy
visible light range
wavelengths 400 nm - 700 nm
photosynthetically active radiation (PAR)
peaks in blue & red
leaves are green bc blue & red are absorbed & green is reflected
2 main photosynthetically active pigments
chlorophyll A & chlorophyll b
part 2 of photosynthesis
CHEMICAL ENERGY IS STORED IN THE FORM OF GLUCOSE (sugar)
Calvin cycle - uses energy rich molecules from light reactions (ATP & NADPH) & CO₂ to produce sugars
Chemical energy to fix CO₂ into sugar
Carboxylation (aka carbon fixation) - addition/insertion of CO₂ to an organic molecule
Rubisco - enzyme that incorporates CO₂ into the Calvin cycle
Catalyzes a 5-C (RuBP) + CO₂ reaction
Links 5-C & CO₂ to make 6-C
Responsible for carbon fixation
CATALYST = increases reaction rate
6-C quickly splits into two 3-C molecules
Split by ATP
3-C molecules are STABLE
Photorespiration
RUBISCO ALSO reacts w oxygen (O₂) INSTEAD OF fixing CO₂
THIS IS BAD bc it wastes carbon & energy
Wasted energy from high energy compounds (ATP, NADPH) converted to low energy NADP
Wasted carbon from CO₂ is NOT FIXED → NO GLUCOSE MADE
C-3 plants
The first stable molecules formed after carbon fixation have 3 carbon atoms
Air spaces between cells w chloroplasts CAUSE PHOTORESPIRATION
Mesophyll cells are exposed to oxygen → photorespiration
RUBISCO ALSO reacts w oxygen (O₂) INSTEAD OF fixing CO₂
About 95% of all C-3 species are subject to photorespiration
C-4 plants
Mesophyll cells are arranged in one layer that surrounds the vascular bundle & bundle sheath cells
Mesophyll cells DO HAVE chloroplasts BUT do NOT have calvin cycle
Bundle sheath cells DO HAVE chloroplasts & calvin cycle
Have different anatomy/metabolism to AVOID PHOTORESPIRATION
Bundle sheath cells are NOT exposed to oxygen → calvin cycle NOT exposed to oxygen → NO photorespiration
C-4 photosynthesis cycle
SPATIAL SEPARATION OF STEPS
CO₂ enters mesophyll cell
CO₂ fixed into a 4 carbon molecule in mesophyll cell
4 carbon molecule sent to bundle sheath cell
No O₂ in bundle sheath cell → calvin cycle completed in bundle sheath cell WITHOUT competition w/ oxygen → NO photorespiration
No competition between CO₂ and O₂ for RuBP (5 carbon molecule) & RUBISCO
RUBISCO function in an oxygen-free zone
THEREFORE:
More sugar/glucose production
More biomass/growth
C-4 plants account for…
Only 3-4% of plants are C-4
25-30% of terrestrial CO₂ fixation
30% of global agricultural grain production
importance of C-4 plants
urban areas
green roofs
C-4 plants advantage over C-3 plants
more drought tolerant
more water efficient
Stomates don’t need to open as much as C-3 species
More adapted to warm/hot & dry seasonal conditions
THE SOUTH
Higher percentage of species in warmer regions are C-4 species
More adapted to lower elevations
Lower elevations are warmer/hotter & drier
More conducive to C-4 plants that are more drought tolerant bc they conserve water
CAM plants
TYPE OF PHOTOSYNTHESIS used to CONSERVE WATER
stomates close to conserve water
allows CO₂ to enter w minimal water loss
CAM photosynthesis cycle
TEMPORAL SEPARATION OF STEPS
STOMATES CLOSE DURING DAY
to conserve water
No CO₂ enters leaf
No CO₂ → no Calvin Cycle
No Calvin Cycle → no sugar production
STOMATES OPEN AT NIGHT
Fix carbon at night
Light reactions & Calvin cycle
Light reactions → ATP & NADPH
ATP & NADPH → calvin cycle
Calvin cycle → glucose
water loss
C-3 > C-4 > CAM
water conservation
CAM > C-4 > C-3
Photorespiration
C-3 > C-4 > CAM
CAM plants advantage
More adapted for dry, marginal lands
Lands unsuited for most crop plants
Stomates
Pores on epidermis (leaf surface/outer-layer of leaf)
Stomata open, CO₂ enters leaf/diffuses into leaf through stomata
WHILE SOMATA ARE OPEN, water vapor escapes to air while stomata are open
Transpiration
carbon dioxide in atmosphere
INCREASING TREND over time bc combusting fossil fuels
day vs night
Day: photosynthesis & cellular respiration
Night: ONLY cellular respiration
Respiration occurs 24/7
cellular respiration overall reaction
opposite of photosynthesis reaction
cellular respiration
Glucose/sugar provides energy (ATP) so the plant can grow/develop (via cellular processes)
Most of the energy is contained in the arrangement of electrons (e⁻) in glucose’s H-C chemical bonds
Stepwise oxidation of glucose in respiration
Break bonds → Oxidation (removal of electrons)
Electrons removed from glucose → ATP (high energy molecule) is produced
O₂ accepts final electron
CELLULAR RESPIRATION REQUIRES O₂ BC O₂ IS AN e⁻ ACCEPTOR
ATP generation
Most ATP made in 3rd step of respiration
32 ATP
Step 3: aerobic
transpiration
As stomates open to allow CO₂ to enter leaf, water vapor escapes from stomates
When plants lose water through pores in leaves
vapor pressure deficit (VPD)
difference in degree of wetness between the leaf & the air surrounding the leaf
Difference in vapor pressure on surface & vapor pressure in air
DRIVING FORCE OF TRANSPIRATION & EVAPORATION
VPD impacts tendency of water molecules to escape from the liquid
Depends on difference in wetness between surface & air
Leaf = 100% wet
Air surrounding < 100% wet
Effect of humidity on transpiration:
Low air humidity → high VPD
Water readily exits leaf → MORE transpiration w DRY air
High air humidity → low VPD
Water slowly/doesn’t exit leaf → LESS transpiration w WET/humid air
transpiration has a (heating/cooling) effect on leaves
COOLING
energy reduction in phase change lowers air temp
temp of artificial turf
average surface temp of artificial turf field HIGHER than average surface temp of natural grass field
