The answer would have to be D
The sequence of Nucleotides in a DNA molecule determine the protein that will be produced. Nucleotides are the basic structural unit of DNA.
Traditionally the unit was the kilo-calorie but commonly just referred to as calorie. today's SI unit is the Joule...
1. electrical signals travel toward the heart. 2. signal received by the atrioventricular node. 3.signal by the nodes in the atrium. 4.the atria contracts. 5. signal transferred to the ventricles. 6. the ventricles contract.
Is this a multiple choice question or...??
If not, I'd say, that its simple as scientists can easily decipher which variable caused the situations result. And thats because you may have one manipulated variable to be able to know the responding variable.
