External factors affecting the rate of photosynthesis

Question 1

what are the three factors that affect the rate of photosynthesis?

Answer 1

-light intensity
-carbon dioxide
-temperature

Question 2

what is the definition of a limiting factor?

Answer 2

-if a factor is limiting, increasing its amount will increase the rate of photosynthesis

Question 3

what is the effect of increasing another factor that is not the limiting factor?

Answer 3

-increasing the rate of the other non limiting will not increase the rate of photosynthesis if the limiting factor is left unchanged

Question 4

look at the graph in the book

Answer 4

bfsbh

Question 5

in most ecosystems when does light become a limiting factor? when is does light then not be a limiting factor anymore, after what time?

Answer 5

-as darkness approaches
-so photosynthesis will be unable to take place
-in early morning light usually ceases to be the limiting factor

Question 6

what is the effect of light being a limiting factor in terms of the light dependent stage?

Answer 6

-not enough ATP and NADPH will be produced

Question 7

what is the atmospheric level of carbon dioxide? what does increasing this level result in?

Answer 7

-0.04%
-this is sub optimal in for plants so increasing the level of CO2 can lead to higher levels of photosynthesis

Question 8

when is CO2 the limiting factor?

Answer 8

-on a bright summers day when light intensity and temperature are high CO2 is the limiting factor

Question 9

what is the effect of increasing CO2 levels in terms of the light independent stage?

Answer 9

-more CO2 would then be available for carboxylation of RuBP which then allows more glycerate phosphate to be formed

Question 10

when does temperature become the limiting factor? How can this be changed?

Answer 10

-during winter
-glasshouse growers can produce optimum growing conditions by increasing temperature as necessary

Question 11

what is the effect of increasing temperature in terms of the speed of the light independent stage?

Answer 11

-if temperature is increased to enzyme catalysed reactions of the light independent stage occur at a faster rate

Question 12

what is one other factor that affects plants but not photosynthesis directly?

Answer 12

-water shortage

Question 13

what happens if water is in short supply to the leaf?

Answer 13

-the stomata will close
-photosynthesis cannot occur then
-leaf will start to wilt

Question 14

what does the net gain of photosynthesis mean?

Answer 14

-the difference between photosynthetic gains and respiratory losses

Question 15

what is the equation for gross photosynthesis?

Answer 15

-net photosynthesis + respiration

Question 16

what is the rate of respiration like in low light intensities?

Answer 16

-the rate of respiration exceeds the rate of photosynthesis so there is more CO2 given out than taken in

Question 17

what is the compensation point?

Answer 17

-the rate of respiration and photosynthesis are equal
-the amount of CO2 given out and taken in is the same

Question 18

look at graphs in book