Activity & Practical of carbon dioxide is given out during respiration. | Class 10th level

Activity & Practical of carbon dioxide is given out during respiration. | Class 10th level | edugrown

Respiration is the biochemical process during which organic food, mainly glucose that is present in the cell, breaks down into simpler substances and liberates carbon dioxide and energy. There are two types of respiration- aerobic and anaerobic respiration.

Aim

To show experimentally that carbon dioxide is given out during respiration

MATERIALS REQUIRED

Materials Required
Two test tubes, a cork with two holes, two glass tubes, syringe, lime water..

THEORY

All living things show respiration.
It is a chemical process that occurs inside the cell, hence called cellular respiration.
It involves the breaking down of food to release energy and carbon dioxide.
Its reaction is the reverse of photosynthesis.
There are two types of respiration in animals: Aerobic and anaerobic respiration.
Aerobic respiration needs oxygen and anaerobic respiration occurs in the absence of oxygen.
There are three pathways of respiration as shown below:
The energy released in cellular respiration is immediately used to synthesise a molecule called ATP.
Plants also release CO₂ during respiration.
The exchange of gases during respiration takes place through small pores on the leaf called stomata.
Carbon dioxide can be tested by lime water test.
A freshly prepared lime water is Ca(OH)₂ When CO₂ is allowed to pass through it an insoluble compound called CaCO₃ is formed which makes the lime water milky.

PROCEDURE-A (Test for release of CO2 during respiration in animals.)

1. 1. Take some freshly prepared lime water in two test tubes.
  2. Fit cork with two holes in test tubes A and B.
  3. Fix two glass tubes in this cork of test tube A as shown in the figure.
  4. Exhale air into the tube and record your observations.
  5. In another test tube B, which has lime water, pass air through syringe and record your observations.

Observation

In test tube A, the lime water turns milky sooner than in test tube B.

Conclusion

The exhaled air contains lot of CO₂ which turns lime water milky.
This proves that during respiration we exhale CO₂ gas.

Precautions

1. The glass tube should be dipped in the lime water.
2. The lime water should be freshly prepared.

PROCEDURE-B (To test release of C02 by plants during respiration)

Materials Required
A conical flask, small test tube, cork, thread, germinating seeds, a bent tube, a beaker, water and freshly prepared lime water.
Procedure

Take two conical flasks, add germinating seeds with little water sprinkled over it.
Fix the mouth of conical flasks with cork in which a bent tube is fixed.
Suspend a small test tube containing KOH solution in it with the help of a thread in conical flask A.
Allow the mouth of the bent tube to be immersed in water in set-up A and in lime water in set-up B as shown below.
Record your observations after few hours.

Observations

In set-up A, the water level in the bent tube dipped in beaker increases after few hours.
This is because the oxygen present in the conical flask is taken up by germinating seeds and CO₂ released due to respiration is absorbed by KOH present in small tube. Hence, the air pressure in the flask reduces and water level rises.
In set-up B, the freshly prepared lime water turns milky. This is due to excess CO₂ released into the test tube during respiration of germinating seeds.

Conclusion
This shows that CO₂ is given out during respiration.
Precautions

Lime water should be freshly prepared.
KOH solution should be freshly prepared.
Germinating seeds should have lot of moisture in them.

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