title of experiment: conducting an experimental investigation in biology: respon
ID: 5855 • Letter: T
Question
title of experiment: conducting an experimental investigation in biology: responses of plant cells to different types of solutions
these are the procedures of the experiment:
1. Bend a piece of Rhoeo discolor leaf, lower surface up,between your thumb and forefinger. With forceps, strip a portion of the lower epidermis.
2. Mount the epidermis in a drop of water, cover with a cover slip, and observe under LPO and HPO.
3. Identify individual cells and take note of the following visible structures: cytoplasm, cell wall, stoma, guard cells,nucleus.
4. Sketch to show 2-3 pairs of guard cells and surrounding purplish hexagonal epidermal cells. Take note of the position of the cytoplasm with respect to the cell walls. DO NOT ALLOW YOUR MOUNT TO DRY UP! (Note the hexagonal cells. The pairs of crescent -shaped cells are guard cells of the stomatal pore. When the leaf is actively photosynthesizing and water is abundant, the guard cells are swollen or turgid, and the stoma is consequently open. When photosynthesis and water become limiting, guard cells collapse,thus closing the stoma.)
5. Now, add 2 - 3 drops of 40% NaCl to one edge of the cover slip. Touch a piece of tissue paper to the fluid under the opposite edge of the cover slip. This will wick the salt solution under the cover slip.
6. Observe the cells under LPO and HPO. Observe what happenedto the guard cells and surrounding epidermal cells under both hypotonic and hypertonic solutions. Note that the cytoplasm is no longer pressed against the cell wall. This shrinkage is called plasmolysis. Take note also of the displacement of the pigment on one side of the mount.
materials: microscopes, hypotonic solution (distilled water),hypertonic (40%) salt solution, Rhoeo discolor leaves, forceps,blade, glass slides and cover slips, droppers, rubber bulbs.
This was the result of this experiment: When not submerged in any solution, the Rhoeo discolor leaf's guard cells are neutral. Once submerged on the hypertonic solution, the guard cells shrunk and diffused since the liquid in the cytoplasm moved from a greater to a lesser concentration. When the cell was submerged on hypotonic solution, the guard cells bloated because it absorbed the liquid around it.
Explanation / Answer
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B73GY-48B686V-3R&_user=10&_coverDate=11%2F30%2F1984&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1393858658&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=66c77f8bdac98d7d5d1ba15f00941f46 this might help
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