Photosynthesis
Q1.
A student investigated the effect of light intensity on the rate of photosynthesis.
The diagram shows the apparatus the student used.
 
This is the method used.
1.   Set up the apparatus as shown in the diagram above.
2.   Place the lamp 10 cm from the pondweed.
3.   Turn the lamp on and count the number of bubbles produced in one minute.
4.   Repeat with the lamp at different distances from the pondweed.
(a)     Complete the hypothesis for the student’s investigation.
‘As light intensity increases, ____________________________________________
_________________________________________________________________ .’
(1)
(b)     What was the independent variable in this investigation?
Tick one box.
 
Light intensity		
Number of bubbles produced		
Temperature		
Time		
(1)
(c)     The teacher suggests putting the boiling tube into a beaker of water during the investigation.
Suggest why this would make the results more valid.
___________________________________________________________________
___________________________________________________________________
(1)
Table 1 shows the student’s results.
 
Table 1	
Distance of lamp from pondweed in cm	Number of bubbles produced per minute	
	Trial 1	Trial 2	Trial 3	Mean	
10	67	66	69	67	
20	61	64	62	62.3	
30	53	51	52	X	
40	30	32	31	31	
50	13	15	15	14	
(d)     Calculate value X in Table 1.
___________________________________________________________________
___________________________________________________________________
X = ____________________ bubbles per minute
(1)
(e)     State one error the student has made when completing the results at 20 cm.
___________________________________________________________________
___________________________________________________________________
(1)
(f)      What evidence in Table 1 shows that the data is repeatable?
Tick one box.
 
The number of bubbles decreases as distance decreases.		
The numbers of bubbles at each distance are similar.		
The student calculated a mean for each distance.		
The student did the experiment three times.		
(1)
Another student investigated the effect of the colour of light on the rate of photosynthesis.
The results are shown in Table 2.
 
Table 2	
Colour of light	Rate of photosynthesis in arbitrary units	
Blue	24	
Green	4	
Red	17	
Yellow	8	
(g)     Plot the data from Table 2 on the graph.
You should label the x-axis.
 
(3)
(h)     Give two conclusions from the graph above.
1. _________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
___________________________________________________________________
(2)
(i)      The glucose produced in photosynthesis can be converted into amino acids to make new proteins for the plant.
Complete the sentences.
The glucose produced in photosynthesis can also be used in other ways.
Glucose can be used in respiration to release _________________ .
Glucose can be converted to cellulose to strengthen the _________________ .
Glucose can be stored as _________________ .
(3)
(Total 14 marks)