Answer: C. carrying a gene or genes essential for survival
Explanation:
A plasmid can be defined as the small, extrachromosomal, double stranded DNA that can be found in the bacterial cell and in other prokaryotes. The plasmid DNA remain physically separated from the chromosomal DNA. The plasmid DNA can replicate independently.
The plasmid DNA carries genes which can facilitate the survival of the organism. This gene may provide the selective advantage like antibiotic resistance to the bacteria or any other organism. But the gene may not be essential for the survival of the organism.
Answer:
The field of view is widest on the lowest power objective. When you switch to a higher power, the field of view is closes in. You will see more of an object on low power.

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Microscope Notes
Accuracy describes how well a measuring instrument determines the variable it is measuring. How close the value is to real value. The level of accuracy of measuring tool determines the detail to which it can measure. In order to be accurate in their work scientists need first select a measuring instrument that allows an appropriate measure of accuracy and then to calibrate it. Calibrating an instrument involves measuring already known quantities to check how accurately it is. In the laboratory accuracy of a test is determined when possible comparing results from the test in question with results geenrated from an established reference method.
