class 10 science practical experiment 3 part b tell me with diagram
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NCERT Class 10 Science Lab Manual Experiment 3
Aim
To show experimentally that carbon dioxide is given out during respiration.
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.
NCERT Class 10 Science Lab Manual CO2 is Released During Respiration 1
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:
NCERT Class 10 Science Lab Manual CO2 is Released During Respiration 2
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.
NCERT Class 10 Science Lab Manual CO2 is Released During Respiration 3
(A) Test for release of CO2 during respiration in animals.
Materials Required
Two test tubes, a cork with two holes, two glass tubes, syringe, lime water.
Procedure
Take some freshly prepared lime water in two test tubes.
Fit cork with two holes in test tubes A and B.
Fix two glass tubes in this cork of test tube A as shown in the figure.
Exhale air into the tube and record your observations.
In another test tube B, which has lime water, pass air through syringe and record your observations.
NCERT Class 10 Science Lab Manual CO2 is Released During Respiration 4
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
The glass tube should be dipped in the lime water.
The lime water should be freshly prepared.
I hope it helps you.
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Explanation:
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