Why is polymerase chain reaction (PCR) especially useful when only small amounts of the original DNA are available?

Question#29: why does the tropical ocean have a greater temperature range than the temperate ocean?

Which type of respiration takes place when there is no oxygen present

Plz fast biotechnology is a growing field of applied biology. many crops such as corn have been engineered to be resistant to herbicides. therefore farmers can spray these chemicals to kill weeds growing near the crop without worries of killing the crop itself how does this type of biotechnology work? a. by changing the genetic make up of the crops. b. by causing the crops to kill the weeds. c. by changing the type of crops used. d. by changing the location of the crops.