Microbiology Lab Practical 1 (Pearson Education Edition) Exam Questions and Answers 100% Pass

Microbiology Lab Practical 1 (Pearson Education Edition) Exam Questions and Answers 100% Pass What bacterial shape is observed? - Bacillus What bacterial shape is observed? - Coccus What bacterial shape is observed? - Spiral/spirochete How does increase in magnification affect field of vision? - It makes it smaller How does increased magnification affect depth of field? - Depth of field becomes larger Why is it desirable that microscope objectives be parfocal? - So each objective does not require further focusing 2 100% Pass Guarantee Katelyn Whitman, All Rights Which objective focuses the closest to the slide when it is in focus? - The dry-oil / oil lens objective Which controls on the microscope affect the amount of light reaching the ocular lens? - The rheostat and the diaphragm Assume the diameter of the field of vision in your microscope is 2mm under low power. If one Bacillus cell measures 2 um, how many Bacillus cells could fit end-to-end across the field? - 2,000 Bacillus cells at 2mm low power How many 10 um yeast cells could fit across the field? - 200 yeast cells at 2mm low power What are the advantages of the low-power objective over the oil immersion / dry-oil objective for viewing fungi or algae? - The organism can be viewed in its entirety, rather than being limited to only one area and one plane at a time. 3 100% Pass Guarantee Katelyn Whitman, All Rights What would occur if water were accidentally used in place of oil immersion / dry oil? - It would act as another lens and distort the focusing power, or distort the image being viewed. Assume you are looking for microorganisms in a tissue sample from a lung biopsy. The microbes become apparent when you switch to 1000X. What type of microbe is most likely? - Bacteria (because it is a prokaryote, and they are much smaller, and therefore much more difficult to see at lower powers under the microscope) What is Brownian movement? - Movement caused by the molecules in the liquid striking an object and causing that object to bounce. What is true motility? - Motile microorganisms are able to move from one position to another of their own accord. How do you distinguish true motility from Brownian movement or motion of the fluid? - True motility has purposeful movement. Brownian movement consists mostly of shaking. 4 100% Pass Guarantee Katelyn Whitman, All Rights What, if any, practical value do the wet mount and hanging drop techniques have? - Allows the viewing of activity of living cells, how they move, and interact with their environment. Why are microorganisms hard to see in wet preparations? - The microorganisms have not been dyed, and so, since they do not have any color to them, they do not contrast against the environment. Can you distinguish the prokaryotic organisms from the eukaryotic organisms? Explain. - Yes, prokaryotic organisms are much smaller, have no membranous organelles, nor a nucleus. Eukaryotic organisms are much larger, have membrane bound organelles, and a nucleus. A wet mount may be used for quick examination of fecal samples. Is this the most useful for identifying protozoan or bacterial parasites? - This is most useful for identifying protozoan parasites because they are eukaryotic and therefore much larger than bacterial parasit