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Reil [10]
3 years ago
15

If a person is in front of a smooth surface from which a sound is reflected, the person would hear a sound that

Biology
1 answer:
Dmitry_Shevchenko [17]3 years ago
8 0
If a person is in front of a smooth surface from which a sound is reflected, the person would hear a sound that seems to come from behind the surface (B). In theory, the sound waves hit the smooth surface and bounce off the surface.  The sound also repeats itself. This is known as an echo. There needs to be a time gap between the sound and the echo otherwise the listener will not hear the echo. It will still be present but form part of the original sound.
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Answer:

Given:

Number of colonies on plate = 40

Amount of DNA used for transformation = 100ng

Volume of competent cells used = 100ul

Total volume = 1ml (1000ul)

Volume plated for growth = 200ul

The amount of cells transformed per 1 µg of DNA is called the transformation efficiency

(CFU is colony forming units) => (number of colonies on plate/ng of DNA plated) X 1000 ng/µg = CFU/µg of DNA

Amount of DNA used for plating = 100ng * (200/1000)

                                                      = 100ng * (1/5)

                                                      = 100/5 = 20ng

Efficiency calculation = 40 colonies / 20ng = 2 colonies/ng

               (2 colonies/ng) * (1000 ng/µg) = 2000 CFU/ug DNA

Transformation efficiency = 2000 Transformants / ug DNA

                                          = 2 x 10³ Transformants / ug DNA

Explanation:

Efficiency of transformation is highest in the 100 pg-1 ng range, so Low transformation efficiency could be because of high amount of DNA used for transformation.

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