Gavin is using a microscope to observe a sample of zooplankton from Lake Superio

Question

Gavin is using a microscope to observe a sample of zooplankton from Lake Superior. Describe how he should handle the microscope for the following procedures. a. Count the zooplankton under 100x magnification. b. Identify the zooplankton under 400x magnification. c. Put the microscope away (name at least two important steps to take).

2. Another lab technician, Malia, is preparing phytoplankton samples for spectrophotometric analysis. Her lab station is equipped with a p1000, p200, and p20. Which pipette should she use in each step of the following protocol? a. Combine 1mg of macerated phytoplankton with 500 µl of acetone in a test tube. b. Stir for 2 minutes, then allow the mixture to sit for 10 minutes. Transfer 180 µl of the liquid to another test tube and add 96 µl of DI water. c. Transfer the resulting mixture from “b” to a microcentrifuge tube.

3. Malia multiples the above reaction by 10. Write out the new measurements of reagents in proper metric units and determine whether her choice of pipette should change for each step.

I did #2, so I need #1 and 3.

Explanation / Answer

1. a.when we use microscope for 100 X magnification, we are actually speaking of total magnification. We can calculate total magnification by

Total magnification = Object magnification X ocular magnification ( magnificaiton we get from eyepiece or occular lense)

thus for 100 X magnification, Gavin need to adjust the objective lense to 10X, , so that he can have total magnificaiton of 10 X 10 = 100 X magnification.

b.

similarly to identify the zooplankton at 400 X, he need to adjust the objective lense to 40X, so that the total magnificaiton will be 40X 10= 400 X

c. to put the microscope following step has to be taken-

3. If malia requires to multiply the reaction by 10 time.

a. Combine 10mg of macerated phytoplankton with 5000 µl of acetone in a test tube. ( p1000 pipette).

b. Stir for 2 minutes, then allow the mixture to sit for 10 minutes. Transfer 1800 µl ( p1000 pipette- set the p1000 pipette to 900 µl and take 2 time ) of the liquid to another test tube and add 960 µl of DI water ( p1000 pipette).

c. Transfer the resulting mixture from “b” to a microcentrifuge tube.

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