<span>Controlled variable is a variable that was made constant in the research. That was because the controlled variables can influence the dependent or independent variable. If the variables is not made constant, it can alter the research result and made it invalid.
In this case, </span>the caffeine and alcohol intake might alter the physical activity or the blood glucose so it should be controlled.
Do you have a picture? It would really help answer your question
The viral capsid and envelope <span>plays a role in attaching a virion to the host cell.</span>
Not sure if I'm correct but my best guess is the cell membrane seeing as it surrounds the cell itself and is responsible for allowing certain molecules to diffuse in or out of the cell. Good Luck! :)
<span>Floods are the country's number one natural disaster.</span>
