Question

Wet cotton wool was put in two flasks M and N. Soaked seeds are added to M and an equal number of boiled seeds to N. Both groups of seeds were first soaked in sodium hypochlorite solution before being put in the flasks. The flasks were securely corked and left in the same conditions of light and temperature for ten days. The cork from each flask was removed and each tilted over a test-tube of calcium hydroxide solution as shown in T.

1. What was the aim of the experiment?
2. Explain the observations made in Flask M and N. 
3. Why were the seeds soaked in sodium hypochlorite for fifteen minutes?

Answer 1

1. To show that carbon(IV) oxide is produced by germinating seeds;
2.    
   • M - Germinating seeds used up oxygen in the flask for respiration; producing carbon(IV) oxide which forms a white precipitate with calcium hydroxide solution;
      
   • N - Boiled seeds did not respire no carbon(IV) oxide was produced hence the calcium hydroxide solution remained clear/ no white precipitate formed in calcium hydroxide solution;
3. To kill bacteria/ fungi which may produce carbon(IV) oxide;