chapter 5

Question 1

where does the light-dependent stage of photosynthesis occur?

Answer 1

thylakoids OR grana

Question 2

what are the inputs of the light-dependent stage of photosynthesis stage?

Answer 2

light, h2o ,NADP ,ADP+pi

Question 3

what are the outputs of the light-dependent stage of photosynthesis stage?

Answer 3

o2, NADPH, ATP

Question 4

where does the light-independent stage of photosynthesis occur?

Answer 4

stroma

Question 5

what are the inputs of the light-independent stage?

Answer 5

ATP, NADPH, CO2

Question 6

what are the outputs of the light-independent stage?

Answer 6

Glucose, NADP, ADP+Pi, H2O

Question 7

what is the role of rubisco?

Answer 7

rubisco controls the first reaction in the light dependent stage of photosynthesis, it is responsible for the initial changes to CO2 at the beginning of the stage.

Question 8

what is the problem with rubisco?

Answer 8

sometimes rubisco uses O2 as a substrate rather than using CO2. Without CO2, photosynthesis cannot occur.

Question 9

what is photorespiration?

Answer 9

when rubisco binds to O2 rather than CO2, it is wasteful and unwanted in plants

Question 10

What are C4 plants adaptations with reference to rubisco?

Answer 10

its light independent process is separated into 2 cells. Carbin fixation occurs in the mesophyll cell but the rest happens in the bundle sheath cell. Rubisco is located here where there is more CO2/

Question 11

What are CAM plants adaptations?

Answer 11

At night CAM plants stomata open to bring in CO2 where is reserved for daytime. In the daytime, CAM planta do not open their stomata to prevent water loss.

Question 12

which coenzymes are cycled through photosynthesis?

Answer 12

NADPH and ATP

Question 13

what is the role of NADPH and ATP in photosynthesis?

Answer 13

NADPH transfers hydrogen ions while ATP transfers energy.

Question 14

how does temperature affect rate of photosynthesis?

Answer 14

enzymes work at optimal temp, too hot = denaturation

Question 15

how does pH affect rate of photosynthesis?

Answer 15

graph is more symmetrical than temp, optimal pH, both ends denature, too acidic/too basic

Question 16

how does substrate concentration (CO2) affect rate of photosynthesis?

Answer 16

initial increase but then plateaus as the chloroplasts become saturated with CO2 or other factors become limiting (e.g. light intensity).

Question 17

what are competitive inhibitors?

Answer 17

bind to active sites on enzymes to prevent catalysis of substrate (reversible)

Question 18

what are non-competitive inhibitors?

Answer 18

bind to allosteric sites that cause the active site to change (irreversible)

Question 19

what are potential changes to crops using CRISPR-cas9?

Answer 19

increase chloroplast effiency, change c3 to c4 or CAM plants, adjust stomata to take up more CO2, drought resistance, longer shelf life

Question 20

why does the rate of photosynthesis increased with light intensity?

Answer 20

because more chlorophyll molecules can be excited and provides more energy for photosynthesis

Question 21

Describe the chemical changes that occur at the grana, thylakoid membrane

Answer 21

Water is split to form oxygen gas
Water is split to form H+, or NADPH is formed
ATP is formed (from ADP + Pi)

Question 22

Describe the chemical changes that occur at the stroma

Answer 22

CO2 combines with the hydrogen from NADPH in a series of reactions to form glucose and water

Question 23

why it is beneficial for a plant to have a high level of carbon dioxide in its leaves?

Answer 23

Increasing the rate of photosynthesis and therefore increasing production of glucose/growth