Q1.
To make a hay infusion, follow the steps given below — 1. Collect a small sample of grass after the lawn has been mowed, or collect straw or fodder. 2. Take a small glass bottle and fill one fourth of it with the grass, straw or fodder. 3. Fill the bottle with stagnant water or pond water and mix it with the collected plant material. 4. Cover the bottle with a muslin cloth and tie it using a thread. 5. Keep the bottle aside undisturbed for a week. 6. Slightly open the mouth of the bottle by removing the muslin cloth, just enough to insert a dropper inside it and carefully take a drop of water. 7. Put the drop of water on a clean slide and observe it under a microscope.
Answer
Follow the seven steps exactly. What matters is why each step is there — the activity is a small, deliberate experiment, not just a jar of dirty water.
| Step | What it is for |
|---|---|
| Grass, straw or fodder | Supplies dead organic matter — the food that bacteria will multiply on first |
| Stagnant or pond water | Supplies the starting protists; clean tap water would give you almost nothing |
| Muslin cloth, tied | Lets air (oxygen) in but keeps insects and dust out |
| Undisturbed for a week | Time for the population to build up. Bacteria bloom on the decaying grass, then protists that eat bacteria multiply on them |
| One drop on a clean slide | A thin film — thick water will not focus, and the organisms swim out of the plane of view |
Caution — follow the book's safety rule. The hay infusion may smell bad. Wear a lab coat, mask and hand gloves, and discard the hay infusion after autoclaving. Autoclaving kills everything in it before it goes down the drain.
Tip: take the drop from near the surface and from the edge of the floating scum, not from the clear middle — that is where the protists concentrate. Lower a coverslip at an angle to avoid air bubbles.