Under which of these conditions would scientists use the polymerase chain reaction (PCR) before they analyze a DNA sample? A
The DNA sample comes from a bacterium or virus,

B. The DNA sample has been cut into fragments by restriction enzymes.

COnly a small amount of the DNA sample is available,

D.
The DNA sample includes regions that are transcribed into mRNA,

Waste water from industries and domestic sources can be treated by chlorination or ultraviolet radiation. there are pros and cons to using either chlorine or uv radiation to kill harmful microorganisms. what is one reason chlorination would be preferred over ultraviolet radiation? a) chlorine only eliminates visible impurities and is ineffective against microorganisms. b) chlorine not only kills bacteria but provides a residual effect on returning microorganisms. c) uv radiation can be used only to treat drinking water and is ineffective in treating waste water. d) ultraviolet radiation is more effective