Rates Of Photosynthesis

Question 1

Chemical formula?

Answer 1

carbon dioxide + water → glucose + Oxygen 6CO2+6H2O→ C6H12O6+6O2

Question 2

What is it?

Answer 2

When green plants use carbon dioxide and water in the presence of light energy to produce glucose and oxygen

Question 3

What you need to do in the practical

Answer 3

You need to investigate how various different factors could affect the rate of photosynthesis. Look how we can change light intensity and how that can affect the rate in the practical.

Question 4

Step 1

Answer 4

Put some sodium hydrogen carbonate in the boiling tube as this will encourage the pond weed to photosynthesise

Question 5

Step 2

Answer 5

Take a nice sized piece of pond weed in the sodium hydrogen carbonate, make sure the pond weed is well submerged

Question 6

Step 3

Answer 6

Cut the stem of the pond weed and count the bubbles leaving that cut stem

Question 7

Step 4

Answer 7

Count the number of bubbles of oxygen produced in one minute that will give us the rate of photosynthesis

Question 8

What is the independent variable?

Answer 8

It’s going to be the light intensity, and change that by changing the distance between the pond weed and the light source

Question 9

Why should you use an LED light source instead of the halogen bulbs?

Answer 9

Because the LED sources don’t give out much heat energy because the temperature could affect the rate of the photosynthesis

Question 11

Step 5

Answer 11

Don’t take the results immediately as the pond weed needs to adjust to the light, so leave the pond weed a few mins under the light

Question 12

Why should you only count the bubbles that come out of the stem?

Answer 12

To make it a fair test. (Don’t count the bubbles from the leaves!)

Question 13

Step 6

Answer 13

After a min, it’s time to change the variable, after the vhange leave the pond weed to adjust to the new distance of light

Question 14

Step 7

Question 15

Step 7