AP Biology Photosynthesis Questions and Standards

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1982 1986

PHOTOSYNTHESIS QUESTION 1982: L. PETERSON/ECHS

Describe the similarities and differences between the biochemical pathways of aerobic respiration and photosynthesis in eukaryotic cells. Include in your discussion the major reactions, the end products, and energy transfers.

STANDARDS: 7 points Maximum for Photosynthesis section 7 points Maximum for Respiration section PHOTOSYNTHESIS: ___Conversion of light energy to chemical energy ___Fixation of CO2 ___Occurs in chloroplasts ___Split H2O (photolysis) ___Chlorophyll needed ___ATP in light reaction ___NADPH2 produced ___Anabolic (Constructive) ___Oxygen released LIGHT REACTION (Diagram and/or Discuss) ___Photosystem I & II ___Energy "input" (electron flow) ___Chemiosmotic DARK REACTION (CO2 FIXATION) ___Carboxylative phase ___Reductive phase ___Regenerative phase NET REACTION ___ENERGY + CO2 + H20 -> C6H12O6 = O2 ___"Uphill" Reaction - possess more free energy and/or stores 686,000 cal/mole glucose ___Coupling of light and dark reactions RESPIRATION ___Conversion of chemical energy to metabolic ___Release of CO2 ___Occurs in mitochondria ___Form H2O (reduction) ___Cytochromes needed ___ATP in oxidative phosphorylation ___NADH produced ___Catabolic (destructive) OXIDATIVE PHOSPHORYLATION (Diagram and/or Discuss) ___ETS (NAD, FAD, cytochromes) ___Energy "release" (electron flow) ___Chemiosmotic

___Glycolysis ___Krebs Cycle NET REACTION ___O2 + C6H12O6 -> CO2 + H2O + ENERGY ___"Downhill"Reaction - possess less free energy and/or releases 686,000 cal/mole glucose BONUS POINTS 3 points MAX ___Dark reaction is reverse of anaerobic glycolysis ___Both processes are complementary and/or supply materials for each other ___Thorough contrast of photosynthesis and cellular respiration

PHOTOSYNTHESIS QUESTION 1986: L. PETERSON/ECHS

Describe the light reactions of photosynthesis and, for both a C3 and a C4 plant, trace the path of a carbon dioxide molecule from the point at which it enters a plant to its incorporation into a glucose molecule. Include leaf anatomy and biochemical pathways in your discussion of each type of plant.

STANDARDS:

LIGHT REACHTIONS: Max. = 9 points __ Light required __ Light reactions on thylakoids (in grana) __ Cyclic and non-cyclic photophosphorylation/photosystems I & II __ H2O used/split/required __ Chlorophyll absorbs light __ Quality of light/color of light/wavelength of light must be correct __ Chlorophyll e-s excited/boosted to higher orbit __ Energy of e-s used to make ATP __ Chemiosmotic photophosphorylation/Mitchell hypothesis (proton gradient) __ Energy of e-s used to make NADPH+ __ ADP or NADP used __ Carrier molecules for ATP or NADPH+ production __ Electrons of P700 replaced <- P680 (PSI <- PSII) __ Electrons of P680 replaced <- H2O (PSII <- H2O) __ O2 comes from H2O __ O2 released to air __ Redox mentioned

C3 AND C4 ANATOMICAL AND BIOCHEMICAL PATHWAYS: Max. = 9 points __ CO2 enters through stomates __ CO2 diffuses from intercellular spaced into mesophyll __ Dark reaction/CO2 fixation in stroma (fluid) __ CO2 used/fixed/required __ Energy of ATP used __ Energy (e-s/Hs) of NADP reused __ C3 plants have palisade and spongy mesophyll __ C4 plants have functional mesophyll around bundle sheaths __ C4 plants have Kranz anatomy __ C4 plants have chloroplasts in bundle sheath cells __ C3 plants combine CO2 with RuBP __ C4 plants combine CO2 with PEP __ C4 plants use CAM pathway __ Steps in PEP -> 4-C -> PEP __ C4 plants send 4-C to bundle sheath __ C3 and C4 plants put CO2 into Calvin cycle -> glucose __ Steps in Calvin cycle __ Mention of C3, C4 pathway enzymes