Chapter 10

Question 1

photosynthesis

Answer 1

energy + 6CO2 + 6H2O –> C6H12O6 + 6O2

Question 2

autotrophs

Answer 2

sustain themselves without eating anything derived from other living beings; plants

Question 3

heterotrophs

Answer 3

unable to make their own food, living off of compounds produced by other organisms; animals

Question 4

two stages of photosynthesis

Answer 4

1. light reactions
2. Calvin cycle

Question 5

phosphotophorylation

Answer 5

generating ATP from ADP and inorganic phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis

Question 6

carbon fixation

Answer 6

initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism

Question 7

photon

Answer 7

light particle; energy from absorbed photons excite electrons to a higher-energy orbit, then that electron moves into a slightly lower-energy orbit, and then the electron falls back to ground state, emitting a photon and causing energy to be transferred from molecule to molecule

Question 8

light reaction

Answer 8

1. energy from absorbed photons excite electrons to a higher-energy orbit, then that electron moves into a slightly lower-energy orbit, and then the electron falls back to ground state, emitting a photon and causing energy to be transferred from molecule to molecule
2. energy is passed to P680 in photosystem II which is used to transfer an electron to the primary acceptor, so P680 is changed to P680+ because it lost an electron
3. P680+ takes electrons from water (split by enzymes) producing protons and O2 and regenerating P680
4. still in photosystem II in the ETC, electrons are passed from the primary acceptor to Pq to a cytochrome complex to Pc, and ATP is made
5. electron at Pc goes to P700+ in photosystem I, energy from a photon has donated an electron from P700 to primary acceptor, electron passed to NADP+, generating NADPH

Question 9

Calvin cycle

Answer 9

in the stroma, 3 cycles nets 1 G3P and uses 9 ATP, 6 NADPH, 3 rubisco, and 3 CO2

Question 10

photorespiration

Answer 10

metabolic pathway that consumes O2 and ATP, releases CO2, and decreases photosynthesis output; occurs on hot, dry, bright days, when the stomata close and the O2:CO2 ration in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco

Question 11

C4 plants

Answer 11

1. spatially separate the fixation of CO2 from the Calvin cycle
2. stomata open at night, use PEP carboxylase to catalyze the reaction phosphoenolpyruvate + HCO3- –> oxaloacetate + Pi-
3. oxaloacetate is then converted to malate to store a CO2 in the reaction malate + NADP+ –> pyruvate + CO2 + NADPH
4. keep rubisco in bundle sheath cells; keep CO2 high here by transporting malate into these cells

Question 12

CAM plants

Answer 12

1. temporally separate the fixation of CO2 from the Calvin cycle
2. stomata open at night, use PEP carboxylase to catalyze the reaction phosphoenolpyruvate + HCO3- –> oxaloacetate + Pi-
3. oxaloacetate is then converted to malate to store a CO2 in the reaction malate + NADP+ –> pyruvate + CO2 + NADPH
4. store malate in the vacuole like a CO2 savings account
5. release CO2 over the course of the day
6. when night comes again, open stomata and replenish using the CO2 rich air that comes in