ICSE Class 9 Answered
2. Mercury is used in the experiments o demonstrate anaerobic respiration because:
- It is the only metal which occurs in liquid state and is a good conductor of heat.
- It does stick to the walls of the capillary and hence, gives accurate results.
- It has a uniform rate of expansion and contraction.
- It can be easily obtained in its pure state.
- It has a low specific heat.
3. ATP – Adenosine Triphosphate, ADP- Adenosine Diphosphate
4. Cell respiration cannot occur at such a high temperature of 65°C in any organism because the temperature strongly influences enzyme activity. Optimum temperature in most of the organisms for maximum enzyme function is usually about 35-40°C. Reactions proceed slowly below optimal temperatures. Above 45°C most of the enzymes are denatured. Also, at high temperatures, the cell gets damaged and may eventually die.
5. Balanced chemical equations:
Aerobic respiration:
Anaerobic respiration:
6. Uses in experiments:
Soda lime: To absorb any carbon dioxide released.
Alkaline pyrogallic acid: To absorb any oxygen released.
Lime water: To detect any carbon dioxide released
Potassium hydroxide: To absorb any carbon dioxide released.
7. In respiration experiments, the seeds taken as control are boiled so that they do not germinate and utilise oxygen or produce carbon dioxide gas, which would then interfere with the progress of the experiments.
8. Tilling of the soil allows sufficient aeration so that the roots of the crop plants can respire easily.