C3 and C4 Photosynthesis

Which of the following is the correct NET equation for photosynthesis

• 6CO₂ + 6H₂O --> 6O₂ + C₆H₁₂O₆

• 6CO₂ + C₆H₁₂O₆ + 6H₂O --> O₂ 

• 6O₂ + 6H₂O --> 6CO₂ + C₆H₁₂O₆

• C₆H₁₂O₆ + 6O₂ ---> 6H₂O + 6CO₂ 

Tags

NGSS.HS-LS1-5

NGSS.HS-LS2-5

Which of the following outputs of the light dependent reactions of photosynthesis are used in the Calvin cycle?

• CO2 and glucose
• H2O and O2
• electrons and H+
• ATP and NADPH

The enzyme responsible for Carbon Fixation in C3 Photosynthesis is

• RuBisCo
• PEP Carboxylase
• Hexokinase
• Pyruvate DeHydrogenase

Tags

NGSS.HS-LS1-5

NGSS.HS-LS2-5

Rubisco is important in which step of photosynthesis

• energizing the electrons in chlorophyll in order to activate NAD+

• carbon fixation of CO2 during the Calvin cycle

• regeneration phase as RUBP is made during the Calvin cycle

• reduction of the carbon chain during the Calvin cycle

Photorespiration lowers the efficiency of photosynthesis by

• preventing carbon dioxide molecules from being produced

• Preventing the fixation of CO2 by Rubisco

• Prevents formation of ATP molecules

• Prevents oxygen reduction by Rubisco

Compared to C3 plants, C4 plants

• have higher rates of photorespiration when the temperature increases

• can continue to fix CO2 even at relatively low CO2 concentrations and high oxygen concentrations.

• do not use rubisco for carbon fixation.

• grow better under cool, moist conditions.

In C₄ plants the initial reactions to fix CO₂ occur in the

• Guard cells

• Epidermal cells

• Mesophyll cells

• Bundle-sheath cells

Where does the Calvin cycle take place during C3 photosynthesis

• Stroma of the chloroplasts of mesophyll cells

• thylakoid membrane of chloroplast in the mesophyll cells

• Thylakoid membranes of chloroplasts in the Bundle sheath cells

• Stroma of chloroplasts in guard cells

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

• fix CO2 into organic acids (e.g. malate) and store it in vacuoles during the night when stomata are open due to cool temperatures.

• fix CO2 into by combining it with RuBP in the Calvin cycle during the night time.

• obtain CO2 through their roots during the day and convert it into malate to be transported by xylem to the leaves.

• fix CO2 into organic acids in the mesophyll cells and then transport it to bundle sheath cells for the Calvin cycle.

Tags

NGSS.HS-LS2-5

Why are C₄ plants able to carry out photosynthesis efficiently?

• They do not use the Calvin cycle during photosynthesis

• They use enzymes (PEP carboxylase) to fix carbon dioxide into malate before entering the Calvin cycle

• They are adapted to cold climates and absorb CO2 efficiently throughout the day

• They conserve water efficiently and have a higher rate of photosynthesis than other plants.