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MBIO 3401 EXAM 1 NEWEST 2025 ACTUAL
EXAM COMPLETE 200 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS) |ALREADY GRADED A+|BRAND
NEW!!
Who discovered that Penicillium mold generated a substance that kills bacteria? - ANSWER-Alexander Fleming.
Who purified penicillin and made it the first commercial antibiotic to save human lives? - ANSWER-Howard Florey and Ernst Chain.
Who first used solid medium using agar to grow pure cultures of microbes? - ANSWER-Angelina and Walther Hesse.
How does the human eye observe images? - ANSWER-Light focuses onto retina where photoreceptor cells fire signals that are transmitted to optic nerve to the brain to generate images.
Define Resolution. - ANSWER-The smallest distance by which two objects can be separated and distinguished. 1 / 4
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What is the resolution of the human retina? What does this mean? - ANSWER-150 micrometers, or, 0.15 mm.
This means that if two objects are closer than 150 micrometers together, the human eye cannot distinguish between the two objects.
Who was Ignaz Semmelweis? - ANSWER-Semmelweis ordered doctors to wash their hands with chlorine. He was the first to introduce aseptic techniques in the hospitals.
Who was Joseph Lister? - ANSWER-He developed carbolic acid to treat wounds and clean surgical instruments in 1865.
What type of microscopy generates a dark image over a light background? - ANSWER-Bright-field microscopy.
How do you find total magnification? - ANSWER-magnification of ocular multiplied by that of the objective.
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Example: ocular = 10x and objective = 20x. Total magnification
= 200x.
How do resolution and magnification work together to produce a clear image under microscope? - ANSWER-Increase of magnification results in larger image and increase in resolution produces a clearer image.
True or false: less than 0.1% of all microbial species can be
cultured in the laboratory. - ANSWER-True.
What is the wavelength of visible light? - ANSWER-400-750 nm.
Absorption. - ANSWER-Means that the photon's energy is acquired by the absorbing object.
Reflection. - ANSWER-Means that the wavefront bounces off the surface of an object.
Refraction. - ANSWER-The bending of light as it enters a substance that slows its speed. 3 / 4
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Scattering. - ANSWER-Occurs when the wavefront interacts with an object smaller than the wavelength of light.
How can we increase resolution when using Bright-Field Microscopy? (5 ways). - ANSWER-1. Use shorter wavelength light.
- Lessen the contrast.
- Use immersion oil.
- Use wider lens closer to specimen.
- Higher numerical aperture.
What kind of microscope is a system of multiple lenses designed to correct or compensate for aberration? - ANSWER-Compound microscope. Uses ocular lens, objective lens, and needs to be parfocal.
How are wavelength and resolution related? - ANSWER-The shorter the wavelength, the higher the resolution.
What is white light? - ANSWER-a mixture of different wavelengths.
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