Light is Necessary for Photosynthesis | Science Experiment

by | Jun 21, 2022 | Biology, Experiments

Introduction

In this experiment, we will see how light is necessary for Photosynthesis in the process of photosynthesis.

Basic Building Concept

1. Photosynthesis is the process by which plants make their food using carbon dioxide and water in the presence of sunlight and release oxygen as a by-product.

2. The process of photosynthesis is described by the equation-

Sunlight

6CO2 + 12H2O → C2H12O6 + 6H2O + 6O2

Chlorophyll

Aim

To show light is necessary for the process of photosynthesis.

Requirements

1. A potted plant,

2. Black paper strips,

3. Clips or sellotape,

4. Alcohol,

5. Iodine solution,

6. Water bath,

7. Beaker,

8. Burner,

9. Water,

10. Petri dish,

11. Dropper.

Theory

1. One of the requirements of photosynthesis is light

2. When we cover the leaf with a black paper strip, light does not enter into leaves which protects them from the process of photosynthesis.

3. But the light will enter into the uncovered part of the leaf, and there will be the process of photosynthesis.

4. Through the uncovered part of the leaves, glucose will synthesise and will be utilised in various metabolism activities. The remaining glucose will get converted into starch.

5. To detect the presence of starch, we perform an iodine test that will also confirm photosynthesis.

Procedure

Step 1: Take a healthy potted plant and place it in a dark room for de-starching for twenty-four hours.

Step 2: After twenty-four hours, cover the upper and lower parts of the leaves of potted plants with black strip paper.

Step 3: Place this potted plant under sunlight for three to five hours.

Step 4: After this, pluck the leaf and remove the black strip from it.

Step 5: Boil the plucked leaves for two minutes.

Step 6: To decolourise the leaf, take out the leaf from the beaker and place it in a beaker containing ethanol.

Step 7: In a water bath, boil this leaf.

Step 8: After boiling this leaf, take it out from the beaker and wash it in the water at room temperature.

Step 9: Now, place this leaf in a petri dish and add a few drops of iodine solution to it.

Step 10: Uncovered parts of the leaf perform photosynthesis and have starch which turns the iodine solution blue-black.

Step 11: The covered part of the leaf does not perform photosynthesis and remains yellow.

Light is Necessary for Photosynthesis

Observation

1. The part which was uncovered, turned blue-black showing the presence of starch in the leaves.

2. Presence of leaves confirmed the process of photosynthesis.

3. The covered leaves do not show photosynthesis and remain yellow.

Result

The presence of starch confirms the process of photosynthesis.

Conclusion

Through this experiment, we have proved that light is necessary for the process of photosynthesis.

Viva Questions with Answers

Q.1 What was the aim of our experiment?

ANS. To show light is necessary for the process of photosynthesis.

Q.2 What do you understand about photosynthesis?

ANS. Photosynthesis is the process by which plants make their food using carbon dioxide and water in the presence of sunlight and release oxygen as a by-product.

Q.3 What is the equation for photosynthesis?

ANS.                                                                                    Sunlight

6CO2 + 12H2O → C2H12O6 + 6H2O + 6O2

Chlorophyll

Q.4 Name the cell which is the site for photosynthesis in plants.

ANS. Mesophyll

Q.5 How can the starch be detected in a leaf?

ANS. The presence of starch can be detected by iodine solution.

Q.6 Iodine changes the leaf in which colour?

ANS. Blue-Black

Q.7 What are the by-products of photosynthesis?

ANS. Oxygen and glucose.

Q.8 How do you decolourise the leaf?

ANS. By boiling it in alcohol

Q.9 Name the cell whose energy currency?

ANS. Adenosine triphosphate.

Q.10 In which cell organelle does the process of photosynthesis take place?

ANS. Chloroplast.

 

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