An egg of bird was coated with varnish and then incubated . The egg did not hatch because the developing embryo

Options

A. could not excrete and died
B. could not utilize yolk in the presence of excess amount of nitrogenous wastes
C. died because of depleted `O_(2)` supply
D. died because of toxic effect of varnish

Answer

To solve the question, we need to analyze the situation where a bird's egg is coated with varnish and then incubated, leading to the failure of the egg to hatch. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Understanding the Structure of Bird Eggs**:
- Bird eggs are typically composed of a calcareous shell, which is made of calcium carbonate. This shell is porous, allowing for the exchange of gases (oxygen and carbon dioxide) between the developing embryo and the external environment.

2. **Role of Yolk**:
- The yolk inside the egg provides essential nutrients for the developing embryo. It is crucial for the growth and development of the embryo until it is ready to hatch.

3. **Incubation Process**:
- During incubation, the embryo requires a constant supply of oxygen for respiration. The porous shell allows oxygen to enter the egg and carbon dioxide to exit, which is vital for the embryo's survival.

4. **Effect of Varnish Coating**:
- When the egg is coated with varnish, it creates a non-porous barrier on the shell. This coating prevents the exchange of gases, thereby restricting the oxygen supply to the developing embryo.

5. **Consequences of Oxygen Deprivation**:
- Without adequate oxygen, the embryo cannot perform cellular respiration, which is necessary for its growth and development. As a result, the embryo will eventually die due to lack of oxygen.

6. **Conclusion**:
- Therefore, the reason the egg did not hatch is that the varnish coating prevented the necessary gas exchange, leading to depleted oxygen levels for the developing embryo.

### Final Answer:
The egg did not hatch because the varnish coating prevented gas exchange, leading to a lack of oxygen for the developing embryo.

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