Question

Is co2 essential for photosynthesis,name two ways the validity of this investigation can be ensured

Answer 1

Carbon dioxide is essential for the plants to sustain, as it is the carbon fixed from the carbon dioxide during photosynthesis is used for synthesizing glucose. This glucose is then later used during cellular respiration to make ATP, the energy molecule. It is also used by plants as a vital source of carbon to produce a major part of the plant mass.

The importance of carbon dioxide for plants can be proved by a small experiment:

1. Take two healthy potted plants.
2. Keep them in dark for 2-3 days, so that all the carbon dioxide fixed till that gt used up by the plant.
3. Take the plants and keep both in two separate closed bell jar containers that are air-tight. In one of the jar, keep an open beaker containing potassium hydroxide (KOH) solution along with the plant. KOH can absorb carbon dioxide, so the jar containing KOH is devoid of carbon dioxide.
4. Keep both the jars in sunlight for 4 hours.
5. Pluck the leaves from plants in both jars and remove chlorophyll by boiling in ethanol.
6. Apply iodine solution over the leaves. The leaves of the plant present in the jar without KOH solution turns blue-black color, as the starch in the leaves reacts with iodine. But, the leaves of the plant in the jar with KOH does not change color as in the absence of carbon dioxide the plant cannot produce starch.

Answer 2

Insert a part of the leaf of a destarched plant into a conical flask containing potassium hydroxide. Potassium hydroxide solution absorbs the carbon dioxide gas from the air present in the glass bottle. Leave the plant sunlight. After few hours, perform a starch test to this and another leaf of the same plant.

Conclusion: In this experiment, we can conclude that carbon dioxide is essential for photosynthesis. Both the portion of leaf received the same amount of water, chloroplasts, and sunlight but the half part which was inside the glass bottle did not receive carbon dioxide.