Name: Kidney as the Body Filter
Uploaded: 2019-07-19
Duration: 4 min 4 s
Description: The kidney is the waste manager of our body. Let us look inside the kidney and understand how this wondrous filtration system works. Watch the video now.

Question

Prove experimentally that CO₂ (carbon dioxide) is essential for photosynthesis.

Accepted Answer

Aim : To prove experimentally that CO₂ (carbon dioxide) Is essential for photosynthesis.

Experimental material used: Two healthy potted plants of nearly the same size.

Instruments and Chemicals: Two glass plates, two bell-jars, Petri dish, beaker, 70% alcohol, iodine solution, Potassium hydroxide (KOH).

Method:

Keep the two healthy potted plant A and B in a dark room for 3 days. Now place each plant on separate glass plates.

Place a watch glass containing potassium hydroxide (KOH) by the side of one (A) of the plants.

Cover both plants (A) and (B) with separate bell-jars.

Use Vaseline to seal the bottom of the jars to the glass plates so that the set-up is airtight. Now keep the plants in sunlight for about two hours.

Pluck a leaf from each plant and boil hem in 70% alcohol solution separately. Now check the presence of starch.

Observation:
The leaf of the potted plant (A) turns colourless while the leaf of the potted plant (B) turns blue.

Conclusion:

In the potted plant (A), CO₂ present in the bell-jar is completely absorbed by KOH and turns into KHCO₃. Therefore, the leaf further was unable to absorb CO₂ and hence photosynthesis, as well as starch synthesis, does not occur.

In potted plant (B), leaf absorbed CO₂easily and exhibits photosynthesis. Therefore, the colour of the leaf is blue-black. Thus, we can conclude that CO₂is essential for photosynthesis.

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