271 BOT

imbibitions  Imbibition is when the water goes inside the seed  imbibition is necessary for germination.

AIM To demonstrate that water molecules attach to the molecules of colloids during imbibitions.

 Water softens the seed coat  Therefore Root and Shoot comes out.

MATERIALS  Test tubes  Seeds  Filter paper  Weighing scale  Water

PROCEDURE 1. Take dry seeds. 2. Place them on a filter paper in Petri dish (A) With water (B) Without water 3. Weigh the dry seeds-- W 1 4. Add them to a test tube 5. Fill it with water. 6. Weigh again after 8-10 hrs—W 2

OBSERVATION The seed increase in size and weight.

INFERENCE Water moves by imbibition inside the seeds then helps movement of radicle and plumule.

AIM To demonstrate the principle of Osmosis with the help of a potato osmoscope (living system).

MATERIALS  Fresh potato  Concentrated Sucrose or salt solution  Petri dish  Water  Pin  Peeler  Cork borer

PROCEDURE  Peel the skin of a potato  One of its ends is cut to make it flat.  At the other end form a cup/hollow cavity with the help of cork borer.  Pour 5% or 10% sugar solution in to the potato cup up to a particular level.  Pierce a pin to mark the initial level.  This set up is called potato osmoscope or potato osmometer.  Place the potato osmoscope in a Petri dish containing water.  Leave the experimental set up undisturbed for about 30 minutes.  Observe for the change in the level of sugar solution in the potato cup.

OBSERVATION  You will be able to record an increase in level caused by osmotic movement of water.  You can repeat the experiment by reversing the situation. Take sugar solution in the container and water in the potato cup.  Mark the initial level. At the end of 30 minutes note the final level.

INFERENCE  water moves from weaken solution to stronger solution by osmosis, therefore the level rises.  potato work like a semi permeable membrane.

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