An isolated colony on a selective medium is not considered a pure culture because inhibited organisms might be masked by the colonies. This statement is true.
On the basis of their constitution or usage, culture media can be classified into various groups; these include defined, complex, selective, as well as enrichment medium.
A selective medium consists of dyes or noxious substances/chemicals which inhibit the growth of specific microorganisms but promote the growth of other microbes.
A pure culture is a laboratory culture which contains a single species of microorganism. It is free from other microorganisms.
Since selective media affects the growth of distinct organisms differently, therefore, an isolated colony formed in such type of medium is not considered a pure culture.
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No doubt, the United States is a powerful country in the world today. It has made its mark in the history by building a strong economy that every other nation envies, and idolizes as well. But, all that glitters is not gold. And every country has its pluses and minuses. There are some serious social issues in the United States as well that need to be dealt with to maintain the position of power and prestige, and set a true example of ideal society in the world.
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The vacuole usually acts as storage for materials needed by the cell.
Answer:
Mantle is composed of rocks where as core is composed of metals.
Explanation:
Mantle and core both are part of the earth's crust. Though there have a difference between them- The mantle is consists of semi solidified rocks and core is consists of hot metals like iron and nickel. Core is the inner most layer surrounding the earth's center. The portion of the interior beyond the crust is called mantle. The core is the densest layer of the earth with its density ranges from 9.5-14.5 g/cm^3 where the density of mantle varies between 2.9-3.3 g/cm^3.