UNIT 5: PHOTOSYNTHESIS AND PLANT ADAPTATIONS
Photosynthesis
● Diets of heterotrophs and autotrophs
- Heterotrophs: eats other plants/ animals for energy
- Autotrophs: generate their own energy
● The general equation of photosynthesis
6H2O + 6CO2 + light energy ⇒ C6H12O6 + 6O2
● The two main reactions of photosynthesis and their locations
- Chloroplast ⇒ thylakoid + stroma
→ thylakoid: disks with green pigment (light reactions)
→ stroma: cytoplasm of the chloroplast (calvin cycle)
● The chloroplast structures associated with photosynthesis
- Thylakoid and stroma
● How the light reactions and dark reactions are connected to each other
- Light reactions send ATP and NADPH to Calvin Cycle
- Calvin cycle sends back NADP+ and ADP
● Comparisons between cellular respiration and photosynthesis
- Cellular respiration: releases CO2 + water, uses glucose + O2
- Photosynthesis: releases O2 (stores glucose), requires CO2 + water + sunlight
● The roles of the electron carriers in photosynthesis, and the names of the carriers
- Electron carriers: NADP+ → NADPH, ADP → ATP
● Roles of NADPH and ATP in photosynthesis
- NADP+ gets electrons and turns it into NADPH
- NADPH (carries electrons) to the dark reaction and dark reactions return NADP+
to light reactions
- ATP is sent to dark reactions and dark reactions return ADP to light reactions
● The purpose of multiple pigments in plants
- Multiple pigments in plants means that the plants can absorb light of
different wavelengths (allows them to absorb maximum sunlight) + allows plants
to do cellular respiration and photosynthesis
● Detailed steps of the light reactions
1. Electrons are dropped off in photosystem II (PSII) by NADP+
2. Light is absorbed in PSII and it excites the electron
3. H2O → ½O2 + 2H+
4. Excited electron moves through protein complexes, actively transporting H+ from
the stroma into the thylakoid
5. Electrons reach PSI and it absorbs light again
6. Electrons move through protein complexes
7. NADP+ changes into NADPH after it accepts electron
8. H+ moves through ATP synthase and turns to turn ADP into ATP
● Alternate mechanisms of mainstream photosynthesis, such as C4 and CAM
- Photorespiration: pathway that occurs when calvin cycle enzyme, rubisco, will
add oxygen instead of carbon dioxide onto RuBP (because there are high
temperatures + hot dry days + low CO2:O2 ratio)
- ATP is used for photorespiration but CO2 is released
- On normal days: rubisco acts on CO2 and uses ATP to create and store sugar
- C3 plants: allow photorespiration to happen, not efficient
- C4 plants: minimize photorespiration by fixing CO2 into a four-carbon
compound; like C3 plants, C4 plants will close their stomata, but unlike C3
plants, C4 plants will continue making sugars using photosynthesis by fixing
CO2 with PEP to make oxaloacetic acid → goes into bundle sheath cell and
Photosynthesis
● Diets of heterotrophs and autotrophs
- Heterotrophs: eats other plants/ animals for energy
- Autotrophs: generate their own energy
● The general equation of photosynthesis
6H2O + 6CO2 + light energy ⇒ C6H12O6 + 6O2
● The two main reactions of photosynthesis and their locations
- Chloroplast ⇒ thylakoid + stroma
→ thylakoid: disks with green pigment (light reactions)
→ stroma: cytoplasm of the chloroplast (calvin cycle)
● The chloroplast structures associated with photosynthesis
- Thylakoid and stroma
● How the light reactions and dark reactions are connected to each other
- Light reactions send ATP and NADPH to Calvin Cycle
- Calvin cycle sends back NADP+ and ADP
● Comparisons between cellular respiration and photosynthesis
- Cellular respiration: releases CO2 + water, uses glucose + O2
- Photosynthesis: releases O2 (stores glucose), requires CO2 + water + sunlight
● The roles of the electron carriers in photosynthesis, and the names of the carriers
- Electron carriers: NADP+ → NADPH, ADP → ATP
● Roles of NADPH and ATP in photosynthesis
- NADP+ gets electrons and turns it into NADPH
- NADPH (carries electrons) to the dark reaction and dark reactions return NADP+
to light reactions
- ATP is sent to dark reactions and dark reactions return ADP to light reactions
● The purpose of multiple pigments in plants
- Multiple pigments in plants means that the plants can absorb light of
different wavelengths (allows them to absorb maximum sunlight) + allows plants
to do cellular respiration and photosynthesis
● Detailed steps of the light reactions
1. Electrons are dropped off in photosystem II (PSII) by NADP+
2. Light is absorbed in PSII and it excites the electron
3. H2O → ½O2 + 2H+
4. Excited electron moves through protein complexes, actively transporting H+ from
the stroma into the thylakoid
5. Electrons reach PSI and it absorbs light again
6. Electrons move through protein complexes
7. NADP+ changes into NADPH after it accepts electron
8. H+ moves through ATP synthase and turns to turn ADP into ATP
● Alternate mechanisms of mainstream photosynthesis, such as C4 and CAM
- Photorespiration: pathway that occurs when calvin cycle enzyme, rubisco, will
add oxygen instead of carbon dioxide onto RuBP (because there are high
temperatures + hot dry days + low CO2:O2 ratio)
- ATP is used for photorespiration but CO2 is released
- On normal days: rubisco acts on CO2 and uses ATP to create and store sugar
- C3 plants: allow photorespiration to happen, not efficient
- C4 plants: minimize photorespiration by fixing CO2 into a four-carbon
compound; like C3 plants, C4 plants will close their stomata, but unlike C3
plants, C4 plants will continue making sugars using photosynthesis by fixing
CO2 with PEP to make oxaloacetic acid → goes into bundle sheath cell and
