CORE PRACTICAL - Effect Of Light Intensity On Photosynthesis

Question 1

Which indicator is used in the core practical?

Answer 1

H2CO3 - hydrogen carbonate indicator

Question 2

WHat is the method for the light intensity core practical?

Answer 2

1) prepare different clear glass bottles with 20 algae balls each
2) add the same amount of indicator to each bottle and put the lid on
3)Place each bottle in equal intervals away from the lamp (e.g. 20cm,40cm, 60cm etc)
4) Compare colour to find pH at the start with the colour chart
5) set up a water tank between the lamp and area where the tubes are
6)Cover one in foil (so it is in the dark)
7) Turn on the lamp until you can see obvious changes in the colour
8)Work out the pH at the end (compare colour to start)
9 ) Calculate change in pH/hour (end- start)
10 ) Plot a suitable graph to show the change in pH/hour and distance

Question 3

How does the colour of the indicator change further away from the lamp i the light intensity core practical?

Answer 3

Orange and yellow = high CO2 levels - closer to lamp

Red in atmospheric air

Red to magenta to deep purple as CO2 is removed

Question 4

Change in pH/hour is the measure the rate of _____

Answer 4

Photosynthesis

Question 5

What is the dependent variable in this light intensity experiment?

Answer 5

Change in pH/hour

Question 6

What is the independent variable in this light intensity experiment?

Answer 6

The distance from the lamp (cm)

Question 7

In what way is the rate of photosynthesis proportional to light intensity?

Answer 7

Directly proportional
This is because: one increases, the other increases
More sunlight = more energy to convert reactants of photosynthesis into products

Question 8

In what way is the distance from light source proportional to the rate of photosynthesis?

Answer 8

Indirectly proportional

The further away from light source = less energy for photosynthesis