Nutrition

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Question 39

Photosynthesis is the fundamental biological process by which autotrophic organisms convert solar energy into chemical energy stored in organic molecules.

Write the balanced chemical symbol equation for this process, indicating the conditions required for the reaction to proceed.

[2]

An agricultural science student investigates carbohydrate storage in a Pelargonium plant by testing a leaf for the presence of starch. The experimental protocol is detailed below:

Submerge the leaf in a beaker of boiling water for $seconds45\text{ seconds}$ .
Extinguish the Bunsen burner flame.
Using forceps, transfer the leaf into a boiling tube half-filled with ethanol. Place this tube into the hot water in the beaker.
Once the leaf has lost its green colour, remove it and rinse it briefly in a beaker of warm water.
Spread the leaf flat on a white tile and add several drops of iodine-potassium iodide solution.

Explain why step 2 is a crucial safety precaution before executing step 3, referring to the physical properties of the solvent used.

[2]

Explain, in terms of cellular structure and biochemistry, why the leaf is initially submerged in boiling water in step 1.

[2]

Clarify why removing the photosynthetic pigments in step 3 is essential for the interpretation of the assay in step 5.

[2]

Outline the specific preparation protocols the student must carry out on the plants prior to performing the starch test to demonstrate that each of the following factors is required for photosynthesis: light (photons)

[2]

light-harvesting pigments (chlorophyll)

[2]

carbon dioxide ( $CO2\text{CO}_2$ )

[2]

Nutrition

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Question 39

Photosynthesis is the fundamental biological process by which autotrophic organisms convert solar energy into chemical energy stored in organic molecules.

Write the balanced chemical symbol equation for this process, indicating the conditions required for the reaction to proceed.

[2]

An agricultural science student investigates carbohydrate storage in a Pelargonium plant by testing a leaf for the presence of starch. The experimental protocol is detailed below:

Submerge the leaf in a beaker of boiling water for $seconds45\text{ seconds}$ .
Extinguish the Bunsen burner flame.
Using forceps, transfer the leaf into a boiling tube half-filled with ethanol. Place this tube into the hot water in the beaker.
Once the leaf has lost its green colour, remove it and rinse it briefly in a beaker of warm water.
Spread the leaf flat on a white tile and add several drops of iodine-potassium iodide solution.

Explain why step 2 is a crucial safety precaution before executing step 3, referring to the physical properties of the solvent used.

[2]

Explain, in terms of cellular structure and biochemistry, why the leaf is initially submerged in boiling water in step 1.

[2]

Clarify why removing the photosynthetic pigments in step 3 is essential for the interpretation of the assay in step 5.

[2]

light-harvesting pigments (chlorophyll)

[2]

carbon dioxide ( $CO2\text{CO}_2$ )

[2]

Nutrition

Question 39

Nutrition Questions

Nutrition

Question 39

Nutrition Questions