chapter 5 (photosynthesis)

Question 1

photosynthesis equation

Answer 1

SUNLIGHT
6CO2 + 6H2O ——-> C6H12O6 + 6O2

Question 2

Enzyme function in photosynthesis

Answer 2

• coenzymes energise the light independent stage this is why it does not require light to occur
• coenzymes (NADPH, ATP) donate their energy in the light-independent stage forming ‘unloaded’ NADP+, ADP + Pi which return back to the light dependent reaction and the cycle continues

Question 3

LIGHT DEPENDENT STAGE: location

Answer 3

• occurs on the thylakoid membranes of the chloroplast

Question 4

LIGHT DEPENDENT STAGE: inputs

Answer 4

• H2O
• NADP+
• ADP + Pi

Question 5

LIGHT DEPENDENT STAGE: outputs

Answer 5

• O2
• NADPH
• ATP

Question 6

LIGHT INDEPENDENT STAGE: location

Answer 6

• Occurs in the stroma of the chloroplast

Question 7

LIGHT INDEPENDENT STAGE: inputs

Answer 7

• CO2
• NADPH
• ATP

Question 8

LIGHT INDEPENDENT STAGE: outputs

Answer 8

• glucose (C6H12O6)
• H2O
• NADP+
• ADP+Pi

Question 9

Role of rubisco in photosynthesis

Answer 9

• Key enzyme in the light independent stage
• Its responsible for the initial changes to carbon dioxide in the first stage of the calvin cycle

Question 10

rubisco process

Answer 10

• rubisco binds CO2 and fixes the carbon into 3-PGA
• the 3-PGA is converted to make a different G3P
• G3P is used to make glucose
• the remaining is recycled to
  regenerate and the cycle restarts

CARBON FIXATION, REDUCTION & REGENERATION

Question 11

C3 plant

Answer 11

• Limit photorespiration: No
• Stomata open: Day
• Advantages: Does not consume extra energy
• Disadvantages: Susceptible to photorespiration
• Best to adapt: Moderate, cool, wet environments
• Examples: Rice, wheat, all trees

Question 12

C4 plant

Answer 12

• Limit photorespiration: Yes
• Stomata open: Day
• Advantages: Minimises photorespiration
• Disadvantages: Consumes extra energy
• Best to adapt: Hot, sunny habitats
• Examples: Corn, sugarcane

Question 13

CAM plant

Answer 13

• Limit photorespiration: Yes
• Stomata open: Night
• Advantages: Minimises photorespiration, reduces water loss
• Disadvantages: Consumes extra energy
• Best to adapt: Very hot, dry habitats
• Examples: Cati , pineapple

Question 14

Factors that affect photosynthesis: light

Answer 14

• as light intensity increases the photosynthesis rate increases - until a certain point where it plateaus

Question 15

Factors that affect photosynthesis: temperature

Answer 15

• enzymes function best at optimal, photosynthesis increases towards enzymes optimal temperature

Question 16

Factors that affect photosynthesis: CO2 concentration

Answer 16

• as carbon dioxide concentration increases the rate of photosynthesis increases - until it plateaus

Question 17

Factors that affect photosynthesis: water

Answer 17

• can influence the opening and closing of the stomata
• Increased = stomata stay open = increased photosynthesis
• Decreased = stomata closes = lower co2 concentration = decreased photosynthesis

Question 18

what does X mean on the graph

Answer 18

X = saturation point