Light and photosynthesis - CSR

How long does it take to de-starch a plant?

• A few hours

• 2 days

• 3 days

• 4 days

Why is it necessary to de-starch the plant before determining if sunlight is needed for photosynthesis?

• To ensure that any starch present in the leaf at the end of the experiment was formed during the course of the experiment.

• To ensure that there will be no starch in the leaf at the end of the experiment.

• To prevent any starch from forming in the leaf during the experiment

• To prevent oxygen from being produced by the plant during the course of the experiment.

Why is a part of the leaf covered with foil or dark paper?

• To prevent this part of the leaf from converting glucose to starch

• To allow this part of the leaf to remain de-starched

• To deprive that part of the leaf of sunlight

• To deprive that part of the leaf of carbon dioxide

Which of these leaves shows a positive test for starch with iodine solution?

• A

• B

The portion of the leaf unaffected by iodine

• contains starch

• contains glucose

• contains no starch

• contains no chlorophyll

The portion of the leaf unaffected by iodine

• was deprived of sunlight

• was deprived of carbon dioxide

• was deprived of water

• was deprived of chlorophyll

Why was the leaf boiled in ethanol?

• To evaporate any glucose formed

• To remove starch from the leaf

• To remove chlorophyll from the leaf (decolorize it)

• To infuse the leaf with ethanol so the iodine could work better

If glucose and oxygen are the products of photosynthesis, why is the leaf being tested for starch?

• Starch is another name for glucose

• Glucose is converted to starch

• Oxygen is converted into starch

• Starch is another name for oxygen

The negative test for starch on the portion of the leaf deprived of sunlight, confirms that

• starch is needed for photosynthesis

• chlorophyll is needed for photosynthesis

• carbon dioxide is needed for photosynthesis

• sunlight is needed for photosynthesis

Why is sunlight needed for photosynthesis?

• Sunlight traps the carbon dioxide needed for the process

• Sunlight provides the energy for the process

• Sunlight slows down the process

• Sunlight traps the water needed for the process