The role of light in photosynthesis practical

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the purpose of wrapping a part of the leaf with aluminium foil in the experiment?

To enhance the light absorption of the leaf.

To block exposure to light, acting as a control. (correct)

To provide nourishment to the plant.

To prevent water loss from the leaf.

What is the function of iodine solution in the experiment?

To nourish the plant.

To measure light intensity.

To increase photosynthesis rates.

To test for the presence of starch. (correct)

What is indicated by the presence of starch in the leaf after the experiment?

Photosynthesis occurred where light was available. (correct)

The control set-up was affected by external factors.

The plant was unhealthy before the experiment.

Light was not necessary for photosynthesis.

Why is a control set-up important in this experiment?

It ensures external factors do not affect the results. Signup and view all the answers

What safety precautions must be taken when using alcohol in the experiment?

Ensure adequate ventilation and avoid naked flames. Signup and view all the answers

What is the significance of using a destarched plant in this experiment?

To provide a clean starting point without stored starch. Signup and view all the answers

What is the purpose of using a destarched plant from the beginning of this experiment?

To ensure any starch detected in the experiment is produced by the plant during the experiment. Signup and view all the answers

What part of the plant is used as a 'control' in this experiment?

The part of the plant that is wrapped in aluminium foil. Signup and view all the answers

In this experiment, what is the independent variable?

Presence of light. Signup and view all the answers

What are two important factors that are kept constant during this experiment?

Supply of oxygen Signup and view all the answers

What would you expect to observe when you test the part of the leaf that was exposed to light?

A blue-black color, indicating the presence of starch Signup and view all the answers

What would you expect to observe after testing the part of the leaf that was covered with aluminium foil?

No change in color when tested with iodine Signup and view all the answers

What would be the expected result, if the experiment was conducted in complete darkness instead of bright light?

No starch production in any part of the leaf Signup and view all the answers

What would be a reasonable conclusion to draw from the experiment, if both the covered and uncovered parts of the leaf show the same results?

The experiment might need to be repeated to investigate why the expected results were not observed. Signup and view all the answers

If the experiment was repeated with red light, instead of bright white light, what might be the difference in the results?

Starch production might be less, because red light is not as effective at driving photosynthesis as white light. Signup and view all the answers

Study Notes

Aim of Experiment

To determine if light is necessary for photosynthesis

Apparatus and Materials

Boiling tube
Beaker (250 cm³)
Forceps
Glass rod
Scissors
Wire gauze
Insulating mat
Gas lighter
Potted plant with leaves
Aluminium foil
Paper clip
White tile
Bunsen burner
Table lamp
Iodine solution
Alcohol (70%)
Tripod

Procedure

Obtain a destarched plant and select a leaf.
Test the leaf for starch using iodine solution (see Practical 7.3).
Cover part of a leaf with aluminium foil.
The foil-covered part is the control (not exposed to light).
Draw a labeled diagram of the leaf showing the covered and uncovered parts.
Place the plant in bright light for 4 hours.
Remove the foil from the leaf.
Test the leaf for starch using iodine solution.

Safety Precautions

Wear disposable gloves.
Avoid contact with iodine, as it is harmful.
Use the minimum amount of alcohol possible and ensure the room is well-ventilated.
Only use alcohol in the absence of a naked flame.
Alcohol is flammable.

Control Set-up

A control set-up is used to ensure that any changes observed are due to the factor under investigation and not other factors.
The control setup is identical to the experimental setup except the factor under investigation is absent (no light in this case).

Variables

Independent Variable: Presence of light
Dependent Variable: Presence of starch
Controlled Variables: Supply of CO2, water, temperature, chlorophyll, the supply of light, and temperature.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your understanding of the experiment to determine if light is essential for photosynthesis. This quiz covers the apparatus used, the procedure followed, and important safety precautions. Perfect for reinforcing your knowledge of plant biology.