The rate of photosynthesis

Question 1

graph 1 - look at page 51

1) Not enough light slows down the rate of photosynthesis

Rate increases with light intensity and co2 and temp need to be increased

Answer 1

1) Light provides the energy needed for photosynthesis
2) as light lvl is raised, the rate of photosynthesis increases steadily - only to certain point
3) Beyond that it won’t make much difference and the rate will no longer increase because Co2 and temp lvl is now the limiting factor, not light.

4) In the lab you can change the light intensity by moving lamp closer to or further away from plant
5) if you plot a graph of rate of photosynthesis against distance of lamp from plant, you get a weird shaped graph. To get a graph you either need to measure the light intensity at the plant using light meter or do maths with your results

Question 2

Graph 2- check page 51
Too little co2 also slows it down

Plenty of light and warmth at the start but light or temp is later needed to be increased

Answer 2

1) Co2 is a raw material needed for photosynthesis
2) as with light intensity, the amount of co2 will only increase up to a point. After this the graph flattens out as the amount of co2 increases, the rate no longer increases. This shows that co2 is no longer the limiting factor.

As long as light and co2 are in plentiful supply than the factor limiting photosynthesis must be temp.

Question 3

graph 3 - check page 51
The temp has to be just right

Answer 3

1) usually if the temp is the limiting factor, its because its too low - the enzymes needed for photosynthesis work more slowly at low temps

But if the plant gets too hot, the enzymes it needs for photosynthesis and its other reactions will be damaged.

This happens at about 45 degrees