photosynthesis practical

Question 1

what are the 4 apparatus needed

Answer 1

led light source, boiling tube filled with sodium hydrogen carbonate solution, pondweed, ruler

Question 2

step 1
t- t-

Answer 2

start by taking a test tube and place it 10cm away from the light source

Question 3

step 2
sol-

Answer 3

fill tube with the solution which releases co2

Question 4

step 3
pon-

Answer 4

put a piece of pondweed, with the cut side should be facing at the top

Question 5

step 4
acc-

Answer 5

leave it for 5 mins for it to acclimatise to conditions in the boiling tube

Question 6

step 5
g- pr-

Answer 6

bubbles of gas should be produced by the top end of the seaweed
this gas is oxygen produced by photosynthesis

Question 7

step 6
co-

Answer 7

start a stopwatch and count the number of bubbles produced in 1 minute

Question 8

step 7
re-

Answer 8

repeat experiment 2 more times, calculate mean number of bubbles produced in a minute
repeat the experiment at different distances

Question 9

what are 2 problems with the bubbles

Answer 9

the number of bubbles can be too fast to count accurately
bubbles arent always the same size, large bubbles count the same as a small bubble

Question 10

what is a solution for the bubble problem

Answer 10

place the pondweed under a funnel and catch bubbles in a measuring cylinder
use it to measure volume of oxygen produced

Question 11

what is the inverse square law

Answer 11

if we double the distance the light intensity falls by 4 times because we need light for photosynthesis, it causes n.o oxygen bubbles to fall by 4 times