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photosynthesis & cellular respiration Flashcards

1
Q

what is the function, origin and fae of the photosynthesis inputs and outputs?

A
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2
Q

what is carbon fixation?

why?

A

first step of calvin cycle
- inorganic co2 is turned into organic molecules

more useful to cells

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3
Q

why are carbon molecules cycled so many times

A

waste too much energy converting co2 directly into glucose
= effectively use co2 to produce glucose

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4
Q

what is rubisco and its role

A

enzyme that catalyzes the first step of the light independent reaction (carbon fixation)
- binding co2 and fixing the carbon into the organic 3-pga= initiating the calvin cycle

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5
Q

what is the flaw of rubisco?

A
  • slow, inefficient enzyme
  • not specific to co2-> o2 can bind to active site
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6
Q

what is photorespiration

A

unwanted and wasteful process initiated by rubisco that limits photosynthesis

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7
Q

why is photorespiration bad

A
  • photorespiration ↑= photosynthesis ↓
  • no glucose made= stunts growth
  • survival and reproduction ↓

plants dont die right away

remain alive wo growing= saving glucose produced-> energy used for survival not growing

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8
Q

when is photorespiration likely to occur? what are the two factors that affect what rubisco binds to?

A

hot and dry weather
- temperature and substrate concentration

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9
Q

what are the effects of hot weather on photorespiration?

A

↑ temp= ↑ affinity for o2
- ↑ conc o2 in cell= ↑ photorespiration
-
↓ temp/regular= affinity for co2

affinity for o2= rubisco binds to o2 more often

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10
Q

what are the effects of dry conditions on photorespiration

A

plants want to expose rubisco to high co2 conc by opening stomata
- plant needs to conserve water= close stomata
- o2 produced build up
- ↑ substrate (o2) conc in cell= ↑ likely bind to rubisco
= ↑ photorespiration

substrate conc

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11
Q

how do plants counter photorespiration?

A

evolved adaptations to increase likelihood of rubisco binding to co2
= increase photosynthesis
= increase plant health

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12
Q

why is photorespiration a problem in c3 plants

A
  • co2 fixed directly from air= stomata must be open
  • exposes rubisco to o2= ↓photosynthetic efficiency+waste energy
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13
Q

how does c4 plants limit photorespiration

A

initial carbon fixation and calvin cycle seperated over space
- mesophyll cell: carbon fixed
- bundle sheath cell: calvin cycle complete
- mesophyll pump co2 into bundle sheath cell= ↑ conc of co2
- ↓chance rubisco picks up o2= ↑photosynthesis

bundle sheath deeper in leaf= further away from environment= less o2

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14
Q

how does cam plants limit photorespiration

A

initial carbon fixation and calvin cycle seperated over time
- night: opens stomata-> carbon fixed and stored in vacuoles
- day: stomata close-> calvin cycle
- release stored co2= ↑conc near rubisco
- photosynthesis ↑= photorespiration ↓

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15
Q

what are the advantages of c3 plants

A
  • expends less energy to photosynthesise= better in colder environments
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16
Q

what are the disadvantages of c3 plants

A
  • no adaptations to limit photorespiration and water loss
  • rubisco picks up more oxygen in hot weather
17
Q

what are the advantages of c4 plants

A
  • maximise photosynthesis in hot environments while minimising photorespiration
  • captures more co2/unit of time
18
Q

what are the disadvantages of c4 plants

A
  • uses more energy/costs additional atp
19
Q

what are the advantages of cam plants

A
  • photosynthesis maximised in hot, dry areas
  • stomata only opens at night where it is cooler and more humid= water is conserved
20
Q

what are the disadvantages of cam plants

A
  • requires additional atp
21
Q

what is cellular respiration

A
22
Q

what is anaerobic cellular respiration

A
23
Q

what are some uses of crispr cas9 technologies to improve photosynthetic efficiencies

A
  • alter rubisco’s affinity towards co2= bind to co2 more frequently
  • edit genome to increase efficiency of chloroplast= increase capture of light
  • adjust water capture ability= plant wont lose co2
    => increase photosynthetic rate
24
Q

what are some potential uses of crispr cas9 technologies to improve crop yields?

A
  • decrease susceptibilty to pests and disease= better survive known pathogens
  • drought, heat stress, frost tolerance= handle lack of rainfall
  • herbicide and pesticide resistance= whole field can be sprayed, resistant crops unaffected, weeds die= less comp for resources
    => crops grow larger and have greater yield

link to scenario !!

25
Q

what is biomass

A

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