Question

content review
answer each of the following in complete sentences.

1. explain the function of a control in a scientific experiment.
2. why are scientific papers reviewed by other scientists before they are published?
3. why would the size of an elephant be expressed in meters but that of a bacterium in microns?
4. how is the total magnification of a compound microscope calculated?
5. explain the steps necessary in preparing materials to be viewed with the light microscope.
6. what are vital stains, and why are they used?
7. describe how a transmission electron microscope produces the image of a specimen.
8. explain the technique of centrifugation.
9. explain the principles behind chromatography.
10. how is spectrophotometry useful to a scientist?

Explanation:

1. Controls compare and validate results.
2. To ensure accuracy and quality.
3. Microns are more suitable for small sizes.
4. Multiply objective and eyepiece magnifications.
5. Sample prep, focus, adjust light.
6. Stains for cell - viability, visualization.
7. Electron - beam passes through sample.
8. Separates by density.
9. Separates by affinity.
10. Measures light absorption.

Answer:

1. A control in a scientific experiment is used to compare the results and validate the effect of the variable being tested.
2. Scientific papers are reviewed by other scientists before publication to ensure accuracy, reliability, and quality of the research.
3. The size of an elephant would be expressed in meters as it is a large - scale measurement, while a bacterium's size is expressed in microns as it is very small.
4. The total magnification of a compound microscope is calculated by multiplying the magnification of the objective lens by the magnification of the eyepiece lens.
5. Steps in preparing materials to be viewed with a light microscope include preparing the sample (slicing, staining if needed), placing it on a slide, adding a cover - slip, and adjusting the focus and light.
6. Vital stains are dyes that can stain living cells without killing them. They are used to visualize cellular structures and functions in living organisms.
7. In a transmission electron microscope, an electron beam passes through a thin sample, and the resulting image is formed based on the electrons that pass through and interact with the sample.
8. Centrifugation is a technique that separates components of a mixture based on their density by spinning the mixture at high speeds.
9. Chromatography is based on the principle that different substances have different affinities for a stationary phase and a mobile phase, which allows for their separation.
10. Spectrophotometry is useful to a scientist as it measures the amount of light absorbed or transmitted by a substance, which can be used for quantification and identification of substances.