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Biology

A Transpirational Seal
A number of teachers tell us that the most difficult part of performing the Transpiration experiment from Biology with Computers and Biology with CBL is getting a tight seal at the plant-tubing junction. We recently obtained a plastic hose clamp from Cole Parmer Instrument Company that solves this problem. In the past, it was necessary to select a portion of the plant stem slightly larger than the opening of the plastic tubing. The plant stem was then forced into the tubing, providing most of the seal and preventing any loss of water from the tubing. This is difficult to do and can lead to damaging the plant stem. Using the plastic hose clamp shown to the right, the plant stem can be smaller than the tubing opening and still maintain a water-tight seal around the plant stem. The clamps are reusable and come from Cole Parmer in packages of 100 for $17.00 (Cat. #FK-06832-01). While 100 clamps may seem like a lot, it never hurts to have a few extra since they are small and may get lost in the lab. Order from Cole Parmer at (800) 323-4340.

Maintaining Pressure
In February 1998, we began shipping accessories with the Biology Gas Pressure Sensor that are excellent for maintaining air-tight systems when using the Biology Gas Pressure Sensor. These accessories include the following:

• two ribbed, tapered valve connectors inserted into a #5 rubber stopper
• two Luer-lock connectors connected to the ends of a piece of plastic tubing
• one 2-way valve
• one 20-mL syringe

These accessories are helpful when performing respiration/fermentation experiments, such as Experiments 6, 12, 16, 23, and 24 from the Biology with Computers and Biology with CBL manuals. It is easy to create an air-tight system between the Biology Gas Pressure Sensor and a 20 X 150-mm test tube using some of the accessories and a single-hole #2 rubber stopper. Take one of the tapered valve connectors and insert it into a single-hole #2 rubber stopper. The plastic tubing, fitted with two Luer-lock connectors, can then be connected to the tapered valve in the stopper. When the stopper is assembled and connected to the 20 X 150-mm test tube, it should look like the picture above.

If your Biology Gas Pressure Sensor did not include the accessories, you can purchase the accessories as a kit from Vernier Software (PS-ACC, $5). The Pressure Sensor Accessories Kit includes all of the parts listed above (except the test tube).

Vernier Software at NABT
We will be at this year’s NABT meeting in Reno, NV on November 5-7. Be sure to stop by booth #218 and say hello. We will also be doing two workshops demonstrating the use of our biology sensors with computers and CBLs™. Our CBL workshop will be on November 6 at 9:00 a.m. Our computer workshop will be on November 7 at 9:00 a.m.