Astudent wants to test the effect of nitrogen rich fertilizers on the growth of rose bushes. which of the following is a variable that must be kept constant?

growth of the rose bush
amount of water the rose bush receives
the use of nitrogen rich fertilizer

Is there any solid scientific evidence that humans have been cloned?

Aremote community desperately needs more electrical energy. it is located in an area with the following characteristics: average wind speed of 15 – 20 km/hr some medium-sized rivers with slow-moving currents few coal deposits some oil exploration being conducted within 400 miles based on the above information, which energy source would be the most economical and safest for the community to pursue? a. fossil fuel b. hydroelectric c. nuclear d. wind

Why does controlling transcription affect prokaryotic gene expression?