Scientists wanted to cultivate fish in a closed system. what features should be included to ensure a closed system?
a.) allow incoming water from groundwater wells
b.) allow only one species of fish
c.)prevent precipitation from entering the tanks
d.) remove solid wastes produced from the fish in the tanks

How can you keep track of variables in a science experiment?

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water

Pls me i need this ! each cell has genes activated depending on it's job and what kind of cell it is. it is the presence of that causes the repressor protein to fall off and unblock the gene on the lac operon. if a gene is turned on then it is being an additional circular chromosome found in some bacteria that is used in genetic engineering.