Photosynthesis Experiment Quiz

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Questions and Answers

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

To measure the temperature of the leaf

To create a control set-up that is not exposed to light (correct)

To increase starch production in the wrapped area

To enhance light absorption in that part of the leaf

Why is it important to include a control set-up in the experiment?

To provide alternative results in case of errors

To ensure the experiment is performed more quickly

To isolate the effect of light on photosynthesis (correct)

To obtain a larger sample size for better results

What safety precaution should be taken when using alcohol in the experiment?

Use it only in a dark room

Use the largest volume possible

Wear protective eyewear only

Ensure the room is well-ventilated and avoid naked flames (correct)

Which of the following steps is taken after wrapping the leaf and exposing it to light?

Carry out the iodine test on the leaf after removing the foil Signup and view all the answers

In the context of photosynthesis, what does the term 'destarched plant' refer to?

A plant that has not accumulated starch in its leaves Signup and view all the answers

What result is expected from the part of the leaf that is not exposed to light?

Absence of starch, indicating no photosynthesis Signup and view all the answers

Which apparatus is NOT mentioned as necessary for conducting the experiment?

Digital thermometer Signup and view all the answers

What is the significance of performing the iodine test on the leaf?

To determine if starch has been produced during photosynthesis Signup and view all the answers

What is the purpose of using a destarched plant in the experiment?

To ensure that any starch detected in the experiment is a result of the experiment and not from the plant's initial reserves Signup and view all the answers

What is the purpose of the initial iodine test?

To establish a baseline for starch presence Signup and view all the answers

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

To establish a control setup Signup and view all the answers

What is the significance of drawing a labelled diagram of the leaf showing which parts are exposed to light and which part is not?

To record the exact areas of light exposure and non-exposure Signup and view all the answers

Why is it important to remove the aluminium foil carefully?

To avoid damaging the leaf tissue Signup and view all the answers

What does the final iodine test aim to reveal?

The presence or absence of starch in different parts of the leaf Signup and view all the answers

What would you expect to observe in the part of the leaf that was exposed to light, after completing Step 9?

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

What result would you anticipate for the part of the leaf that was covered with aluminum foil in Step 4?

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

How would the results of the iodine test in Step 3 likely compare to those in Step 9?

Step 3 would show no starch, while Step 9 would show starch in some areas Signup and view all the answers

What conclusion can be drawn if the exposed part of the leaf turns blue-black with iodine in Step 9?

Light is necessary for photosynthesis Signup and view all the answers

If the experiment is successful, how would you expect the results to support the aim stated at the beginning?

By showing starch production only in the light-exposed areas Signup and view all the answers

What would be the expected result if the experiment was conducted in complete darkness instead of bright light in Step 6?

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

How might the results differ if the experiment was conducted over 8 hours instead of 4 hours in Step 6?

Possibly more pronounced starch presence in light-exposed areas Signup and view all the answers

What would be a reasonable conclusion if both covered and uncovered parts of the leaf show the same result in Step 9?

The experiment may need to be repeated due to potential errors Signup and view all the answers

If the experiment is repeated with a red light instead of bright white light in Step 6, how might the results change?

Less starch production Signup and view all the answers

What additional conclusion about chlorophyll can be drawn if the experiment shows positive results?

Chlorophyll is likely involved in light-dependent reactions of photosynthesis Signup and view all the answers

Study Notes

Aim

To determine if light is needed for photosynthesis.

Apparatus and Materials

Boiling tube (1)
Insulating mat (2)
Gas lighter (1)
Beaker (250 cm³) (1)
Tripod (1)
Forceps (1 pair)
Wire gauze (1)
Scissors (1 pair)
Glass rod (1)
Aluminium foil (1 piece)
Paper clip (1)
Iodine solution (1)
Alcohol (70%) (1)
White tile (1)
Bunsen burner (1)
Table lamp (1)
Potted plant with leaves (1)

Carrying out the Experiment

Use a destarched plant. Choose a leaf.
Test for starch in the leaf (see Practical 7.3).
Cover part of a leaf with aluminum foil. This part will not be exposed to light. This is the “control”.
Draw a diagram labeling the leaf area exposed to light and the area covered.
Place plant in bright light for four hours.
Carefully perform the iodine test again to test for the presence of starch in the leaf.
Remove the aluminium foil from the leaf.
Observe and draw a labelled diagram on which part of the leaf was exposed to light and which wasn't.
Note: Use disposable gloves when working with chemicals. Use small amounts of flammable alcohol and use only in areas with no naked flames.

Designing Control Set-Ups

A control setup is needed to determine if changes observed in an experiment are due to the factor of interest, or other factors. The control setup should be the same as the experimental setup, except the variable under investigation is absent.
Examples: The experimental setup is exposed to light; the control setup is not exposed to light.

Identifying Variables

Independent variable: Presence of light
Dependent variable: Presence of starch
Controlled variables: Supply of Carbon dioxide, Supply of water, Supply of oxygen, Temperature, Presence of chlorophyll, Supply of light.

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Description

Test your knowledge on the experiment to determine the necessity of light for photosynthesis. This quiz covers the materials used, the procedure, and the analysis of the results. Perfect for biology students studying plant processes and their importance.