Asha observed that cockroach are killed by putting them on soap water. Teacher said it is due to its peculiar respiratory system. How?

There were two cut logs of wood lying in the campus. One had growth rings and other didn't. Teacher said it is due to differences in their pattern of growth which is dependent on season. How?

Students were observing, a film on Paramoecium. But underwent a process of reproduction. Teacher said it's due to cell division. But Students objected and said that there was no disappearance of nuclear membrane and no spindle formation, how can it be cell division?-"Can you clarify?

Apparatus: Two plastic bottles, measuring cylinder, thermometer, etc Chemicals: Potassium nitrate, sodium hydroxide, water, etc. (Sodium hydroxide being corrosive, handle it carefully in presence of teacher.) Procedure: Take I 00 mL water in each of the two plastic bottles. Plastic being insulator of heat, the dissipation of heat can be prevented. Note the temperature of water in the bottles. Put 5 g potassium nitrate (KNO_3) in the bottle and shake well. Note the temperature of the solution formed. Put 5 g sodium hydroxide (NaOH) in the other bottle. Shake the bottle well. Note the temperature. In the first bottle, the process of dissolution of potassium nitrate took place while in the second bottle, the process of dissolution of sodium hydroxide took place As per your observation which one is exothermic process and which is an endothermic process?

Search for a pond with greenish water. Collect some of the green fibres from the water. Put the fibres in a petridish and wash them clean with water. Put one of the fibres in a drop of water on a glass slide and spread it out straight. Put a cover-slip over the slide and observe under a compound microscope.