Students set up a controlled experiment. they put up five crickets in each of three identical containers. they set one container to 15 degrees Celsius one to 20 degrees Celsius and one to 25 degrees Celsius then they count the number of chirps in each container during 1 hour what is the manipulated variable in this experiment
a. the kind of container used
b. the temperature of each container
c. the number of cricket chirps
d. the number of crickets in each container

the answer is B the temperature of each container

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.