ASU BIO 320 ECOLOGY EXAM 2
QUESTIONS AND ANSWERS 100%
CORRECT.
Biology = Life - ANSWEREnergy → nutrients → descendants.
All comes from the sun
Energy Sources - ANSWERLight; Organic Molecules; Inorganic Molecules
Autotrophs - ANSWERSelf feeders; photosynthetic and chemosynthetic (mainly plants)
Heterotrophs - ANSWERAnimals; herbivores, carnivores, detritivores, omnivores
Organisms can be classified: - ANSWERby trophic biology. Ecological rather than
evolutionary classification
Prokaryotes (bacteria, archaea) - ANSWERHeterotrophic, Photosynthetic,
Chemosynthetic.
Who draws on a greater variety of energy than any other organism? -
ANSWERProkaryotes
Protists - ANSWERHeterotrophic and Photosynthetic
Plants - ANSWERMainly photosynthetic with a few heterotrophs
Fungi - ANSWERHeterotrophic
Animals - ANSWERHeterotrophic
5 autotrophs - ANSWERProkaryotes (bacteria, archaea), protists, plants, fungi, animals
2 trophic levels: - ANSWERAutotrophs (self feeders), heterotrophs (animals)
Photosynthetic autotrophs use: - ANSWERCO2 + light = organic compounds
Light as an energy source - ANSWER1. Propogates as a wave
2. Interacts with matter as a particle (photon) with finite energy absorbed by chlorophyll
3. Plants use visible spectrum (photosynthetically active radiation: PAR, 400-700 nm;
45% of solar spectrum; infrared good temp but not enough E; UV too much E actually
kills plants)
4. We measure PAR as photon flux density = #photons/m^2 (surface area of leaf)
, 5. This is the basis for (almost) all terrestrial and aquatic ecosystems (w/out it we would
have no energy)
Photosynthesis uses: - ANSWERsunlight for energy
Photons absorbed: - ANSWERby chlorophyll pigments (ignites electron donation, this E
used to synthesize ATP, which carries E towards synthesis of sugars)
Sunlight: - ANSWERto E-rich molecules that feed life
Ultimate goal of photosynthesis: - ANSWERto make sugar
3 distinct biochemical pathways - ANSWERC3 (most common), C4, CAM
Photosynthetic ("C fixation") Pathways C3 - ANSWERC3 pathway - ancestral, most
common. CO2 is fixed at same time and in same cell as Calvin Benson Cycle
CO2 + RuBP --> PGA --> Sugars
C3 plants are adapted to non arid climates. Why? - ANSWERVery high photosynthesis
rates. Very high rates of transpiration (water loss)
C4 pathway - ANSWERCO2 + PEP --> 4 carbon acid
More efficient way to spend and costs less to get CO2
C4 pathway:
CO2 fixed in mesophyll cells; calvin benson cycle in sheath cells; displaced in space
(notice PEP has higher affinity for CO2 than does RuBP. This combined with spatial
separation of C fixation and sugar production eases water loss)
C4 pathway benefits: - ANSWERmeans increased gradient from atmosphere to leaf;
means fewer stomata open; means reduced transpiration
C4 pathway costs: - ANSWERdecreased photosynthetic rates
CAM Pathway - ANSWERCrassulacean acid metabolism. Multiple origins (convergent
evolution). Cacti (succulents, arid). CO2 fixed in mesophyll cells during night; calvin
benson cycle also occurs in mesophyll but does so during day (displaced in time)
Water loss: - ANSWERC3 - 380-900 g water/g tissue
C4 - 250-350 g water/g tissue
CAM- 50 g water/g tissue
CAM benefits: - ANSWERvery low water loss
CAM costs: - ANSWERlower rates of photosynthesis
C3 - ANSWER- One tissue (mesophyll)
QUESTIONS AND ANSWERS 100%
CORRECT.
Biology = Life - ANSWEREnergy → nutrients → descendants.
All comes from the sun
Energy Sources - ANSWERLight; Organic Molecules; Inorganic Molecules
Autotrophs - ANSWERSelf feeders; photosynthetic and chemosynthetic (mainly plants)
Heterotrophs - ANSWERAnimals; herbivores, carnivores, detritivores, omnivores
Organisms can be classified: - ANSWERby trophic biology. Ecological rather than
evolutionary classification
Prokaryotes (bacteria, archaea) - ANSWERHeterotrophic, Photosynthetic,
Chemosynthetic.
Who draws on a greater variety of energy than any other organism? -
ANSWERProkaryotes
Protists - ANSWERHeterotrophic and Photosynthetic
Plants - ANSWERMainly photosynthetic with a few heterotrophs
Fungi - ANSWERHeterotrophic
Animals - ANSWERHeterotrophic
5 autotrophs - ANSWERProkaryotes (bacteria, archaea), protists, plants, fungi, animals
2 trophic levels: - ANSWERAutotrophs (self feeders), heterotrophs (animals)
Photosynthetic autotrophs use: - ANSWERCO2 + light = organic compounds
Light as an energy source - ANSWER1. Propogates as a wave
2. Interacts with matter as a particle (photon) with finite energy absorbed by chlorophyll
3. Plants use visible spectrum (photosynthetically active radiation: PAR, 400-700 nm;
45% of solar spectrum; infrared good temp but not enough E; UV too much E actually
kills plants)
4. We measure PAR as photon flux density = #photons/m^2 (surface area of leaf)
, 5. This is the basis for (almost) all terrestrial and aquatic ecosystems (w/out it we would
have no energy)
Photosynthesis uses: - ANSWERsunlight for energy
Photons absorbed: - ANSWERby chlorophyll pigments (ignites electron donation, this E
used to synthesize ATP, which carries E towards synthesis of sugars)
Sunlight: - ANSWERto E-rich molecules that feed life
Ultimate goal of photosynthesis: - ANSWERto make sugar
3 distinct biochemical pathways - ANSWERC3 (most common), C4, CAM
Photosynthetic ("C fixation") Pathways C3 - ANSWERC3 pathway - ancestral, most
common. CO2 is fixed at same time and in same cell as Calvin Benson Cycle
CO2 + RuBP --> PGA --> Sugars
C3 plants are adapted to non arid climates. Why? - ANSWERVery high photosynthesis
rates. Very high rates of transpiration (water loss)
C4 pathway - ANSWERCO2 + PEP --> 4 carbon acid
More efficient way to spend and costs less to get CO2
C4 pathway:
CO2 fixed in mesophyll cells; calvin benson cycle in sheath cells; displaced in space
(notice PEP has higher affinity for CO2 than does RuBP. This combined with spatial
separation of C fixation and sugar production eases water loss)
C4 pathway benefits: - ANSWERmeans increased gradient from atmosphere to leaf;
means fewer stomata open; means reduced transpiration
C4 pathway costs: - ANSWERdecreased photosynthetic rates
CAM Pathway - ANSWERCrassulacean acid metabolism. Multiple origins (convergent
evolution). Cacti (succulents, arid). CO2 fixed in mesophyll cells during night; calvin
benson cycle also occurs in mesophyll but does so during day (displaced in time)
Water loss: - ANSWERC3 - 380-900 g water/g tissue
C4 - 250-350 g water/g tissue
CAM- 50 g water/g tissue
CAM benefits: - ANSWERvery low water loss
CAM costs: - ANSWERlower rates of photosynthesis
C3 - ANSWER- One tissue (mesophyll)
