factors affecting the rate of photosynthesis

Question 1

what are the factors affecting the rate of photosynthesis?

Answer 1

light, light colour, temperature, pH, carbon dioxide concentration, water concentration, enzyme inhibition

Question 2

why is light required for the light dependent stage of photosynthesis in terms of reaction rate?

Answer 2

without light in the light dependent stage of photosynthesis, reaction rate is limited/

Question 3

why does the rate of photosynthesis plateau at some point?

Answer 3

at some point maximum rate plateaus due to maximum rate of photosynthesis being achieved.

Question 4

what do we have to assume in order to assume the rate of photosynthesis plateaus?

Answer 4

we have to assume that other factors of photosynthesis are unlimited.

Question 5

why can maximum rate of photosynthesis not be increased?

Answer 5

due to the enzymes within chloroplast reaching their stauration point due to operating at their full capacity.

Question 6

why is the idea of maximum rate of photosynthesising not increasing/plataeuing mainly theoretical?

Answer 6

as there is usually a limited supply of inputs for photosynthesis, this idea is more theoretical.

Question 7

what is a limiting factor in photosynthesis?

Answer 7

limiting factor in photosynthesis refers to a reactant that is insufficient compared to others, restricting the reaction rate.

Question 8

what happens when we increase the limiting factor?

Answer 8

increasing the limiting factor boosts the overall reaction rate.

Question 9

How does light influence C3, C4 and CAM plants and why?

Answer 9

Light influences C3, C4 and CAM in the same manner, due to them having the same light dependent reactions.

Question 10

Which colour increases rate of photosynthesis?

Answer 10

Violet or red light

Question 11

Which colour decreases the rate of photosynthesis?

Answer 11

Green light

Question 12

At what temperature is rate of photosynthesis greatest at?

Answer 12

The temperature varies for different plants, but at optimal temperature the rate of photosynthesis is greatest

Question 13

At what pH is rate of photosynthesis greatest at?

Answer 13

PH varies across plants, but it is greatest at optimal pH

Question 14

Why does rate of photosynthesis increase towards the enzyme’s optimal temperature?

Answer 14

Due to more frequent enzyme-substrate collisions

Question 15

What happens at hot temperatures?

Answer 15

Enzyme denatures

Question 16

what happens to enzyme if pH is low or high

Answer 16

It denatures both ways

Question 17

Effect of temperature on C3, C4 and CAM plants?

Answer 17

C4 and CAM are better adapted to hot and dry environments, whereas C3 plants are adapted to cooler temperatures

Question 18

how does CO2 help achieve maximum theoretical rate of photosynthesis?

Answer 18

theoretical maximum rate of photosynthesis can be increased by increasing CO2

Question 19

what do we have to consider when assuming the maximum theoretical rate of photosynthesis?

Answer 19

we have to assume light and water are unlimited and temperature is optimal.

Question 20

what is another reason as to why CO2 concentration plateaus?

Answer 20

another requirement has become the limiting factor. CO2 was the limiting factor before the plateau, but now it could be light, water or temperature.

Question 21

why does the concentration of CO2 plateau?

Answer 21

maximum rate of photosynthesis has been achieved due to the enzyme catalysed sustems within the chloroplast being fully saturated.

Question 22

Effect of CO2 concentration on C3 plants?

Answer 22

C3 plants do not have a strategy compared to C4 and CAM plants in terms of countering O2 and preventing rubisco from initiating photorespiration. Thus, C3 plants are more susceptible to low levels of CO2 concentration and having rubisco initiating photorespiration instead of photosynthesis.

Question 23

Effect of CO2 concentration on C4 and CAM plants?

Answer 23

C4 and CAM plants have evolved adaptations to counter photorespiration and expose Rubisco to greater levels of CO2. Because of this, C4 and CAM plants are less susceptible to the impacts of low CO2 concentration on the rate of photosynthesis compared to C3 plants, which have no strategy to combat photorespiration.

Question 24

why is water not typically a limiting factor

Answer 24

water is generally abundant for plants to undergo photosynthesis

Question 25

how can water influence the rate of photosynthesis?

Answer 25

Water can also influence the rate of photosynthesis given it is an input in the light- dependent stage of photosynthesis and influences the opening and closing of stomata.

Question 26

how does water decrease the rate of photosynthesis?

Answer 26

water stress due to drought and hot weather can cause plants to close their stomata to prevent water loss. this restricts exchange of CO2 and O2 with the environment, affecting light independent stage of photosynthesis. this leads to more O2 build up compared to CO2, increasing the affinity of rubisco binding with O2, initiating photorespiration which wastes energy and reduces overall rate of photosynthesis.

Question 27

comparison of water unavailabilty on C3, C4 and CAM plants and how it affects rate of photosynthesis?

Answer 27

C3 plants are affected by water availabilty, due to a lack of adaption, as they rely on keeping their stomata closed for longer periods during hot weather to conserve their water, leading to higher O2 conc and affinity of rubisco with O2 instead of CO2, which leads to lower rate of photosynthesis. In contrast, C4 and CAM plants have evolved more efficient carbon dioxide concentrating mechanisms, allowing them to perform photosynthesis by constantly exposing rubisco to CO2, allowing them to photosynthesise even when there is a lack of water, thereby minimising the chance of reducing rate of photosynthesis.

Question 28

how does enzyme inhibition affect rate of photosynthesis?

Answer 28

presence of inhibitors lowers rate of photosynthesis.

Question 29

how can effect of COMPETITIVE REVERSIBLE inhibitors be overcome?

Answer 29

by increasing substrate concentration continually.

Question 30

on which types of inhibitors will increasing substrate concentration not work on?

Answer 30

increasing substrate concentration will not reduce effect of irreversible inhibitors or reversible non-competitive inhibitors.

Question 31

effect of enzyme inhibition on C3, C4 and CAM plants?

Answer 31

All C3, C4 and CAM plants are susceptible to nergative impact of inhibitors

Question 32

what could CRISPR CAS 9 do to imprive efficiency of photosynthesis?

Answer 32

One method to increase the photosynthesis efficiency in agricultural plants using CRISPR-Cas9 is to engineer crops that bypass photorespiration, somewhat mimicking the function of C4 and CAM plants. Other possible changes to maximise photosynthesis efficiency could be to target Rubisco’s function directly, or edit the function of chloroplasts to make them more efficient, or target stomata to reduce the impacts of water stress.