Viruses are able to infect cells because they share a common code and are able to use host cell enzymes to carry out protein synthesis

Viruses are able to infect cells because they share a common genetic code and they use host cell machinery to carry out protein synthesis. Virus infecting a bacteria is called bacteriophage. These bacteriphages can use two different pathways to infect the virus: a) lytiic b) lysogenic. In lytic cycle the virus makes several copies of itself within bacteria and at the end bacterial cell is lysed. In lysogenic cycle virus integrates its DNA into bacterial  genome.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added