CMB Practical Test Flashcards
What is the Laboratory Safety Conduct?
All students must comply with these requirements:
1. Laboratory overalls must be worn while in the laboratory.
2. Covered shoes must be worn at all times in the laboratory.
3. Safety goggles must be worn when you work with any chemicals or work within 3m of anyone working with chemicals. This rule applies to laboratory users who are not wearing glasses.
4. All volatile solvents, acids, ammonia and smelly chemicals must be handled in the fume hoods to avoid building up of such volatile chemicals in the laboratory.
5. Broken glassware must be swept up immediately and placed in designated boxes for broken glasses.
6. Food and drinks must not be consumed in the laboratories
Good Laboratory Housekeeping and Procedures
- Hazardous waste must not be poured into the sink drain. They must be deposited into labeled receptacles designated for separate classes of hazardous waste, i.e. water soluble solvents, water insoluble solvents, toxic chemicals, acids etc.
- Wash your hands thoroughly before you leave the laboratory.
What are some common equipment bench top items? (7 examples)
- Micropipette
- Latex gloves
- Face mask
- Safety goggles
- Vortex Mixer
- Ethanol / water spray bottle
- Bench top centrifuges (provides centrifugal force to separate a fluid from a fluid or from a solid substance)
What are some common waste disposal bench top items? (4 examples)
- Sharps bin
- Biohazard waste bag
- Normal waste bag
- Broken glass bins
What are examples of chemical safety and clean work? (2 examples)
- Fume hood
- Laminar flow hood
What is a fume hood?
Ventilated box used when working with hazardous substances
What is a laminar flow hood?
Workspace with HEPA filter used to protect samples from contamination
(HEPA - high efficiency particle)
*Only laminar flow hood has HEPA filter to help maintain a sterile environment
What are some common symbols found in the lab? (5 examples)
- Biohazard
- Radioactive
- Toxic
- Corrosive
- Flammable
What do you do after each lab session? (3 steps)
- Ensure that the lab is clean and tidy
- Wipe the bench tops
- Wash your hands before leaving the lab
A. Proper use of micropipettes
How to withdraw fluid? (4 steps)
- Fit the pipette with the correct tip.
- Depress plunger to first stop and hold. Dips tip into fluid and gently release thumb.
- Slide pipette tip out along wall of tube to dislodge remaining droplets adhering to the outside of the tip.
- Check that there is no air space at the very end of the tip.
B. Proper use of micropipettes
How to expel sample into reaction tube? (4 steps)
- Touch tip to wall of tube.
- Slowly depress plunger to first, and then to the second stop to expel fluid.
- While keeping the plunger at the second stop, slide the tip out the fluid, along the tube wall and out of the tube.
- Eject the tip into the trash.
C. Proper use of micropipettes
How to prevent cross contamination of reagents? (6 steps)
- Never rotate volume adjustor beyond the upper or lower range.
- Never use without a tip in place.
- Never lay pipette down with filled tip – fluid could run back into the piston.
- Never let the plunger snap back after withdrawing or ejecting fluid. This could damage the piston.
- Never immerse anything other than the disposable tip in liquid.
- Never flame the micropipette tip.
Practical 1 Lab Experiment
What is a micropipette?
The micropipette is a specialized tool that if properly used will allow you to accurately transfer small volumes of liquid.
Practical 1 Lab Experiment
What is a spectrophotometer?
A spectrophotometer is an instrument that measure the amount of light absorbed by molecules in a solution at a given wavelength.
It can be used to indirectly determine the amount of a compound present. The higher the concentration of the solutes in the solution, the greater will be the absorbance.
Practical 1 Lab Experiment
What is the range of a P200 micropipette and what coloured tip to use?
Range: 20 - 200 microliter
Tip: Yellow tips
Practical 1 Lab Experiment
What is the range of a P1000 micropipette and what coloured tip to use?
Range: 200 - 1000 microliter
Tip: Blue tips
Practical 1 Worksheet
Briefly describe how you would aspirate or draw up 1070 microliter of reagent using only two different micropipettes and least number of volume adjustments on the micropipette.
- Firstly, I will draw up 1000 microliter of reagent using a P1000 micropipette (using a blue pipette tip).
- Secondly, the remaining 70 microliter of reagent, I will draw it up using a P100 micropipette (using a yellow pipette tip).
Practical 1 Worksheet
Given a stock solution of 5% KMNO4, show how you would prepare 200 microliter of a solution with a concentration of 0.5% KMNO4. Distilled water is used as a diluent.
C1V1 = C2V2
(C1 = starting concentration), (V1 = starting volume)
(C2 = final concentration), (V2 = final volume)
C1 = 5%, V1 = ? microliter
C2 = 0.5%, V2 = 200 microliter
C1V1 = C2V2
V1 = C2V2/C1 = 0.5% * 200 microliter / 5%
V1 = 20 microliter
Distilled water = 200 - 20 = 180 microliter
Therefore, add 20 microliter of 5% of KMNO4 solution to 180 microliter of distilled water to get 200 microliter of 0.5% KMNO4 final solution.
Practical 1 Assignment
What is the volume reading on this micropipette dial?
a) P200 => 067
b) P1000 => 020
c) P100 => 070
d) P1000 => 100
Volumes:
a) 67 microliter
b) 200 microliter
c) 70 microliter
d) 1000 microliter
Practical 1 Assignment
Fill in the following volume readings in the micropipette dial
a) P10 => 7.8 microliter
b) P200 => 167 microliter
c) P20 => 12.4 microliter
d) P100 => 34 microliter
Readings on dial:
a) 078
b) 167
c) 124
d) 034
Practical 1 Assignment
Given a stock solution of 2.5% KMNO4, show how you would prepare 150 microliter of a solution with a concentration of 0.5% KMNO. Distilled water is used as a diluent.
C1V1 = C2V2
(C1 = starting concentration), (V1 = starting volume)
(C2 = final concentration), (V2 = final volume)
C1 = 2.5%, V1 = ? microliter
C2 = 0.5%, V2 = 150 microliter
C1V1 = C2V2
V1 = C2V2/C1 = 0.5% * 150 microliter / 2.5%
V1 = 30 microliter
Distilled water = V2 - V1 = 150 - 30 = 120 microliter
Therefore, to prepare 150 microliter of solution with a concentration of 0.5% KMNO4, add 30 microliter of 2.5% KMNO4 to 120 microliter of distilled water.
Practical 2 Lab Experiment
What is a dissecting microscope?
A dissecting microscope can be used to examine larger objects and a compound microscope to view smaller specimens.
Practical 2 Lab Experiment
What is a compound microscope?
The compound microscope uses the magnifying powers of two lenses to produce a greatly enlarged image of structures too small to be viewed by the naked eye. Using the compound microscope, we can view plant and animal cells. Cell walls and plasma membranes and nuclei can be easily visualized.
Practical 2 Lab Experiment
Disadvantage of compound microscope?
Most structures within the cell are too small to be resolved by the compound microscope. However, these can be resolved by the use of more powerful microscopes such as the electron microscope.
Practical 2 Lab Experiment
What are the rules to use compound microscope? (5 steps)
Notes to students:
1. The compound microscope is a precision instrument. Handle it with care!
2. When carrying the equipment always use two hands. Place one hand on the arm and the other to support the base.
3. Place it down on the workbench gently without jarring. Always lift to move it.
4. Keep the lenses and stage clean and dry.
5. Only use lens tissue to wipe the lenses.
Practical 2 Lab Experiment
What are the parts of a compound microscope? (10 examples)
- Eyepiece
- Objective lenses
- Revolving nosepiece
- Microscope stand
- Mechanical stage
- Condenser (aperture iris diagram)
- Coarse focus adjustment knob (big)
- Fine focus adjustment knob (small)
- Light source
- Base
Practical 2 Lab Experiment
What are the types of lenses of a microscope? (4 types)
- 4x objective
- 10x objective
- 40x objective
- 100x oil immersion objective
Practical 2 Lab Experiment
How can the overall magnification be determined?
The overall magnification is determined by multiplying the power of eyepiece lens (10x) and the objective lens.
Practical 2 Lab Experiment
What is 100x objective lens?
100 x objective is an “oil immersion” lens and can be identified by the presence of a black or white band on the lower part of the lens.
Practical 2 Lab Experiment
What is oil immersion?
Oil immersion refers to the fact that “immersion oil” must be used to improve resolution. When using this lens, oil is placed on the slide and the slide is then viewed through the oil and not through the air.
Practical 2 Lab Experiment
Can we use oil with non-oil immersion lenses?
Never use oil with non-oil immersion lenses and always remove the oil with lens paper after use.
Practical 2 Lab Experiment
How do we care and maintain the microscope? (5 steps)
- Care should be taken not to scratch the lens surface.
- Clean lens externally with a lens tissue. Never disassemble an objective lens.
- Always remove immersion oil immediately after use, since it hardens upon drying.
- Stains should be removed by gentle cleaning with lens tissue moistened in distilled water.
- The microscope should be clean, dry and in good order before replacing it in its box
Practical 2 Lab Experiment
At the end of the class, do we need to clean the lenses and how?
At the end of your class you must clean the lenses with lens paper sprayed with 70% alcohol and then put the microscope away.
Practical 2 Lab Experiment
Describe what would you do to view a slide? (4 steps)
- Examine these living cells using LOW POWER.
- Select one cell that shows its contents clearly and move it to the center of the microscopic field.
- Using HIGH POWER, examine all the parts of the cell.
- Remember to only use FINE ADJUSTMENT when using the high power objective.
Practical 2 Worksheet
Which part of the microscope is known as the supporting stand and rest on the bench?
Base
Practical 2 Worksheet
Which part of the microscope contains a system of lenses that focuses light on your specimen?
Condenser
Practical 2 Worksheet
Which part of the microscope has a horizontal surface on which the slide is placed?
Mechanical Stage
Practical 2 Worksheet
Under the microscope, what is the shape and color of a blood cell? (epithelial cells)
Circle and Red
Practical 2 Worksheet
Under the microscope, what is the shape and color of an elodea? (onion cells)
Rectangular and Green
Practical 3 Lab Experiment
What is the protocol for chlorophyll extraction? (11 steps)
- Turn on the spectrophotometer. Use 80% acetone as the reference blank.
- Wash spinach leaves and place about 30 g of deveined leaves in a blender with 150 ml ice-cold buffer.
- Blend the tissues at high speed until it forms a homogenous “soup” (about 30 s).
- Filter the homogenate through 4 layers of cheese cloth lining a filter funnel and collect the filtrate in a beaker standing in ice.
- Transfer equal quantities of filtrate into two centrifuge tubes and centrifuge at 3000 rpm for 2 min at 40C.
- Discard supernatant and gently resuspend the green pellet (combine from both tubes) in 10 ml of ice cold buffer. Stand on ice.
- Take 100 microliter of the chloroplast suspension and add 900 microliter of deionized water in a fresh test tube.
- Add 4 ml of acetone. Mix well.
- Transfer to a centrifuge tube and cap tightly.
- Centrifuge at 3000 rpm for 3 min at 40C. (Ensure tubes are balanced).
- Take 1 ml of supernatant into a quartz cuvette to measure the absorbance at 645 and 663 nm.
