5.1 Photosynthesis - Limiting Factors (A-Level)

Question 1

define limiting factor

Answer 1

a factor that is preventing the rate from continuing faster

Question 2

define light compensation point

Answer 2

the point at which the rate of photosynthesis = the rate of respiration

Question 3

define saturation point

Answer 3

the point at which further increases in a factor will no longer result in an increased rate

Question 4

draw the graph for how light intensity affects the rate of photosynthesis

Answer 4

(check against notes)

Question 5

explain how light intensity affects the rate of photosynthesis

Answer 5

light is required for photolysis and photoionisation in the LDR
without it, ATP and NADPH which are needed in the LIR are not produced/are in smaller quantity
wavelength of light can also have an effect ie. green will be reflected by chlorophyll

Question 6

draw the graph for how carbon dioxide concentration affects the rate of photosynthesis

Answer 6

(check against notes)

Question 7

explain how carbon dioxide concentration affects the rate of photosynthesis

Answer 7

carbon dioxide is involved in the LIR
it is needed to bond to RuBP to form 2 lots of GP, (catalysed by the enzyme rubisco)
GP reduced to TP and so on

Question 8

draw the graph for how temperature affects the rate of photosynthesis

Answer 8

(check against notes)

Question 9

explain how temperature affects the rate of photosynthesis

Answer 9

same explanation as GCSE recap
note that hydrogen bonds will be the first to break in rubisco when denaturing as they are the weakest

Question 10

define net primary production, NPP

Answer 10

the amount of biomass that is accumulated in the same time period as GPP

Question 11

define gross primary production, GPP

Answer 11

the amount of glucose which is produced by photosynthesis in a set time period

Question 12

define R

Answer 12

the amount of glucose used in respiration

Question 13

equation for gross and net primary production in photosynthesis

Answer 13

NPP = GPP - R