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CO₂ Released During Respiration

Biology Difficulty: Normal

Aim

To show experimentally that carbon dioxide is released during respiration.

Materials Required

Germinating seeds
Boiled seeds (dead)
KOH solution
Lime water
Conical flask
Delivery tube
Test tubes

Procedure

  1. Set up two conical flasks: Flask A with germinating seeds and Flask B with boiled (dead) seeds.
  2. Connect each flask via a bent delivery tube to a test tube containing freshly prepared clear lime water.
  3. Suspend a small vial containing KOH solution in both setups (optional for absorbing initial CO₂, though often used to create a vacuum in other variations; here we focus on lime water turning milky).
  4. Ensure all connections are completely airtight using petroleum jelly or vaseline.
  5. Leave the experimental setups undisturbed for 1-2 hours.
  6. Observe the changes in the lime water in both test tubes.

Precautions

  • Use freshly germinated seeds for the best results.
  • The experimental setup must be completely airtight.
  • Use freshly prepared clear lime water.
  • Boiled seeds should be washed with a mild antiseptic (like carbolic acid) to prevent bacterial respiration.
Time Elapsed (mins)
00:00
Temp A (Germinating)
25.0 °C
Temp B (Dead)
25.0 °C

Observation Table

S.No. Flask Content Lime Water Before Lime Water After Inference

Experiment Demonstration

Test Your Understanding

1. Respiration releases:

2. Lime water turns milky due to:

3. KOH is used to:

4. Boiled seeds are used as:

5. Respiration is a:

Experiment Report

Observations

  • No observations recorded yet. Complete the simulation first.

Conclusion / Result

Germinating seeds release CO₂ during respiration which turns lime water milky. Dead seeds (control) show no change, confirming that CO₂ is released only during active respiration.