Requirements For Photosynthesis 22151n

Investigating the Requirements for Photosynthesis Chlorophyll Aim: To demonstrate the need of chlorophyll in photosynthesis. Hypothesis: When iodine is added onto the leaf, it will turn bluish black. Materials:  Leaf  Beaker  Tripod  Wire gauze  Bunsen burner  Test-tube  Matches  Water  Methylated spirits Risk Assessment: Risk Methylated spirits are flammable Boiling water can burn your skin and spills are highly likely Iodine can stain your skin

Level High High

Moderat e

Control Measures Closed footwear, gloves and safety glasses must always be worn. Ensure footwear is enclosed and carefully wipe off any spills with paper towels. Wear gloves at all times and handle with care

Variables:   

Independent: Amount of chlorophyll Dependent: Amount of starch Controlled: Leaf

Method: 1. 2. 3. 4. 5. 6.

Collect sample of variegated leaves Set up the water bath Heat the water for five minutes Fill the test-tube with methylated spirits Draw the leaf before putting it in the test-tube Put the leaf in the test-tube and then place the test-tube in the beaker 7. Remove the leaf after it turns pale 8. Put iodine on the leaf 9. Observe and record results

Results:

TEST

BEFORE

AFTER

COLOUR STARCH

Green Yes

Bluish black Yes

As iodine was added to the leaf it turned bluish black which confirms the presence of starch in the leaf.

Conclusion: The hypothesis was proven right that when iodine is added onto the leaf, it will turn bluish black. The experiment shows that plant leaves produce starch and that chlorophyll is necessary for photosynthesis to occur. Discussion: Photosynthesis is a process by which plants use sunlight and chlorophyll to combine water and carbon dioxide to produce glucose and oxygen. The glucose is mainly stored in the form of starch. This experiment was conducted to demonstrate the need of chlorophyll for photosynthesis. The results obtained show that the leaf contained starch as it turned bluish black at the edges when iodine was added. It remained

white in the middle as there was no chlorophyll present there from the beginning. The edges were green which meant that there was chlorophyll there and this was proven right because of the iodine test and thus validating the experiment. Also correct procedure was followed and the variables were controlled such as the leaf used. This experiment was accurate as the correct use of equipment was ensured. The experiment was reliable as the results were compared with other groups and they obtained the same results. Also the experiment has been repeated more than once as three samples were tested at the same time. This experiment could have been improved by using different types of leaves from different plants to make sure that it doesn’t just test right on that particular plant’s leaves.

Light Aim: To demonstrate the need of sunlight for photosynthesis. Hypothesis: The plants require sunlight in order for photosynthesis to occur. Materials:         

Leaf Beaker Tripod Wire gauze Bunsen burner Test-tube Matches Water Methylated spirits

Risk Assessment: Risk Methylated spirits are flammable Boiling water can burn your skin and spills are highly likely Iodine can stain your skin

Level High High

Moderat e

Control Measures Closed footwear, gloves and safety glasses must always be worn. Ensure footwear is enclosed and carefully wipe off any spills with paper towels. Wear gloves at all times and handle with care

Variables:  

Independent: Availability of light Dependent: Amount of starch



Controlled: Amount of methylated spirits

Method: 1. Collect a sample of leaves (the ones that have been exposed to sunlight) 2. Cover the leaves with aluminium foil 3. Collect the leaves after one day 4. Remove aluminium foil 5. Set up the water bath 6. Heat the water for about 5 minutes 7. Fill the test-tube with methylated spirits 8. Draw the leaf before putting it in the test-tube 9. Put the leaf in the test-tube and then place the test-tube in the beaker 10. Remove the leaf after it turns pale 11. Put iodine on the leaf 12. Observe and record results

Results:

TEST

BEFORE

AFTER

COLOUR STARCH

Green Yes

Pale green No

Conclusion: The hypothesis was proven right that the leaves require sunlight in order to carry out photosynthesis. The experiments shows that the plants will consume all of its starch if there is no sunlight present to

produce more. Thus proving that sunlight is necessary for photosynthesis to occur. Discussion: Photosynthesis is a process by which plants use sunlight and chlorophyll to combine water and carbon dioxide to produce glucose and oxygen. The glucose is mainly stored in the form of starch. This experiment was conducted to demonstrate the need of sunlight for photosynthesis. The results obtained show that the leaf did not contain starch as it there was no effect seen when iodine was added. This was because the leaf consumed all of its stored starch since it could not produce more due to the lack of sunlight. This experiment was valid as the correct procedure was followed and also the variables were controlled such as the amount of methylated spirits. This experiment was accurate as the correct use of equipment was ensured. The experiment has been repeated more than once as three samples were tested at the same time. However, the experiment was not reliable because when the results were compared with other groups and they did not obtain the same results. This experiment could have been improved by repeating the experiment even more times until the desired results were obtained. Also a separate water bath should have been used for the chlorophyll experiment rather than doing all of them in one and overcrowding everything.