Bio. Lab. Report - Membrane Transport

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Objectives:
To study the effects of hypotonic, hypertonic and isotonic solutions on plant and animal cells. Materials and Apparatus:
* Microscope
* Electronic balance
* Stirring rod
* Small knife
* Glass slide and cover
* 250, 500 ml beakers
* Distilled water
* Cotton
* Test tubes
* Spatula
* Onion
* Ethanol (70%)
* Filter paper
* Table sugar (sucrose)
* Table salt (NaCl)
* Potato

EXPERIMENT 1
PART 1
Procedure:
1. The epidermal layer of an onion is scaled off carefully and placed on a drop of distilled water on the glass slide; 2. The glass slide is slowly lowered down on the epidermal layer using the needle;

3. The onion cells are examined through the microscope;
4. The structure of the onion cells is drawn as observed under the microscope.

Results & Observations:
In the hypotonic solution the water will move from the solution to the onion cells which will become bigger.

PART 2
Procedure:
1. The distilled water is removed using the filter paper; 2. A drop of 5% of sucrose solution is placed at a side of the cover slip and the solution across the epidermal layer is drawn by placing filter paper on the other side of the cover slip; 3. The onion cells are examined once again through microscope. The structure of the onion cells is drawn as observed under the microscope.

Results & Observations:

In the isotonic solution, there is no difference in the osmolarity, no change in the cells sizes.

PART 3
Procedure:
1. Repeat step (1 – 3 of PART 2) using 30% of sucrose solution. Results & Observations:

In the hypertonic solution we can notice the shrinking of the cell membrane due to the loose of water. Discussion & Conclusion:
Water will move in or out of the onion cells according to the concentration of sucrose in and out of the onion cells: in an isotonic solution no change will happen; in a hypertonic solution the cells...
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