The colourless colonies are only the gram-negative bacterium that will grow as the selective media Eosin Methylene Blue (EMB) followed by mannitol salt agar (MSA), which will only allow one type of microorganism to grow.
Eosin Methylene Blue (EMB) agar is a differential microbiological medium that gives a colour indicator to distinguish between organisms that digest lactose and those that do not while significantly inhibiting the development of Gram-positive bacteria. In laboratories, the selective medium is crucial for differentiating gram-negative microorganisms.
Both EMB (Eosin methylene blue) and Mannitol Salt Agar (MSA) are selective in that they only permit the growth of Gram-negative bacteria.
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Answer:
Fossil records provide evidence of an increase in animal species at the same time that atmospheric oxygen levels increased.
Explanation:
A huge diversification among animal species occurred with the increase in the levels of atmospheric oxygen. The reason why the number of species increased drastically was that a whole new world opened up, the land. The land was open for exploitation and taking over, with every single niche free, so animals diversified and filled in pretty much all of the niches. The fossil records give us clues when this happened, as from only microorganisms there is a sharp rise in complex animals, coinciding with the increase of oxygen levels.
If it wasn't for the increase of atmospheric oxygen though this wouldn't have been possible. The oxygen in the atmosphere enabled animals to breathe on land. Also, it cooled off the global temperatures which were too high before the increase of atmospheric oxygen, making them suitable for life. And last but not least, the atmospheric oxygen resulted in the formation of the ozone layer, a layer that started to act as protection from the UV rays.
Yes, there are living things in water, but water itself is NOT a living thing. Abiotic = not living, so water is an abiotic factor...
Answer: True
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Frequency theory of hearing
According to the frequency theory of hearing the auditory nerve's impulse corresponds to the frequency of a tone. This allows the recognition of pitch. Sounds are detected in the ear as acoustic signal in the external and middler ear. It is later on transformed in an electrical impulse that a nerve can detect in the cochlea. The theory assumes that a nerve can fire at rates of 20 to 20000 times per second. This is the assumption that the frequency of human hearing range is at 20 to 20000.
Answer:
Explanation: I think it’s the first one
