Laboratorio De Biologia

Lab No. 2
The effects of osmotic balance and imbalance in living cells
* I) Objectives:
1) Review the process of diffusion and osmosis.
2) Students will prepare a wet mount of elodealeaf in tap water and another one in salt water for microscopic observation.
3) Students will observe and diagram cells in both wet mounts.
4) Students will distinguish between osmotic balanceand osmotic imbalance in elodea leaf cells.
* II) Materials :
* Microscope
* Microscope slides
* 6% salt solution (hypertonic solution)
* Cover slips
* Elodeaplant
* Medicine droppers
* Water
* Methods:
Part A Osmotic Balance
1) A wet mount of an elodea leaf in tap water for microscopic observation was prepared.
2) The elodea leafcell where observed under low, then medium and last in high power magnification. A single cell along the leaf edge was located. Then the location of the chloroplast in relation to the cell was alsoobserved.
3) A drawing was made for what the student saw.
4) The slide was saved for part B.
Part B Osmotic Imbalance
1) A second wet mount using another elodea leaf was prepared using 6%salt solution instead of water.
2) The wet mount was left for about 3 minutes and the cells of the leaf using the same process as in part A was observed.
3) A drawing was made for what it wasseen in the field.
4) The saltwater leaf and the tap of the water were compared. The salt water slide was checked carefully. The location of the chloroplast was observed in relation to the cellwall when viewed under the high power.
5) Observations and drawings were made, the cell wall, plasma membrane and chloroplast were labeled in both cells. (two different fields of view).
* III)Observations and Data:

The elodea leaf in water was observed as little green squares filled with little dots known as the chloroplast. The structure was well organized

The elodea leaf...