Question

1. Photorespiration
   1. Why do high oxygen levels inhibit photosynthesis?
   2. What happens during photorespiration and why is it considered bad for plants?
   3. What do C4 and CAM plants do to prevent photorespiration from occurring
   4. 2- Calvin Cycle:
      1. Where does the Calvin cycle take place?
      2. What is the overall point of the light independent reactions?
      3. What are the starting compounds of the Calvin cycle? Which enzyme joins them together?
      4. What is the point of each of the following phases of the Calvin cycle?
         1. Carbon fixation
         2. Reduction
         3. Regeneration
      5. The product of the Calvin cycle is ____________________. How many times does the Clavin Cycle need to take place to make the product?

Answer 1

a High Oxygen levels inhibit photosynthesis because High level of oxygen in chloroplast can lead to photo respiration Rubisco act as oxygenase at higher concentration of O2 which does not produce ATP, NADH & Sugar (b) Rubisco Catalyse both Carboxylation & Oxygenation of RubP. O2 & Co2 competes for same enzyme Rubisco & same substrate Rubp at the same active site At Higher O Concentration , Rubisco react with Oxygen rather than co₂ . This process is photo respiration Co₂ fixation decreases due to photonespiration Photorespi- oration does not produce ATP, NADPH & Sugar but involves oxidation of coganic compounds so it is wasteful process ( c. Cu blant Reduces photo respiration Because co enter in the cytoplasm of mesophyle cell where enzyme Carbonic anhycbase convert Co₂ into H₂CO3. RuBP & Rubisco is absent in Mesophyll cell where o Concentration is high. In Bundle sheath cell, can concentration is vory high due to decarboxylation of Cu acid & O₂ concen- tration is very low due to absence of PS I So, in Bundle sheath cell only carboxylation reaction is favoured In Cam Mechanism, Carboxylation & decarboxylation spacially and temporally separated. As in Cam plant Stomata open at night & closed during day.

uy Co, accepter in Cam blants are PEP 2. Calvin Cycle H2O Pit H003 AMPAPP: PEP PEP (3C) ATP PEP CAA Cose PPDK (309 Cuc) . Chcroplast Pyruvate (30) starch Ghkroplast - >02 - NADPH +47 (Calvin ( Cycle Mataite (malicacid (UC) INADPT Mah (4) 19 Malic acid Malic Aid Vacuole Vacuole During night During day.

a Calvin Gydle take place in stooma of chloroplast b. Calvin Cycle or Dark Reaction is light independent mechanism. Activation of enzymes in Calvin cycle dan require Sunlight c) 3- Phosproglyceric Acid (3PCA) is the first Stable product

160 6 x34A DAT Glycerate kinase Rubisco Ai fortab14 GOTG-3-p ANA " GetDHYANADF Glycolytes starska Sucrose 3. Rubl(is) Ribuere Kincke 3x Rebulose-se 6xG 3 p Inese isomerase (2 mael I Ribolest Ribun-S-P Epimerase Transadolase 741 BU DHAP [34] Tanatuet - Xylulose-5-1 Transketare 46 BL [6] Pia Phosphatore de co Pepe Phosphatcure Sedohiptwork 1 -AR Enthrose-up 6701 Transabdase (40) Transaldotare

( do ci Carbon fixation : Carboxylation of the CO2 accepter molecule that from two molecule 3PGA by Enzyme Rubisco i) Reduction. By using NADH THT & ATP (Product of light reaction) 3PGA —— 6-3-. cu Regeneration fromation of con acceptor molecule from - G&P (Glyceraldehyde-3-phosphate) By using ATP. e. The product of C3 Cycle és G-3-p that utilized in different pathway (like Glycolysis, stanch formation et). 6 turn of Calvin cycle is required to from & Glucose.