Ascientist testing the effects of a chemical on apple yield sprays an orchard with the chemical. a second orchard does not receive the chemical. in the fall, the number of apples harvested from each forest is counted. which of the following is the independent variable in the experiment? a) the chemical
b) the number of apples
c) the first orchard
d) the second orchard

What is the difference between the conducting zone and the respiratory zone of the respiratory system? the conducting zone is a series of cavities and tubes that move air to the respiratory zone where gases exchange with the bloodstream. the conducting zone exchanges gases between the lungs and the alveoli and the respiratory zone is a series of cavities and tubes that move air to the conducting zone. the conducting zone moves oxygen into the cells and the respiratory zone takes carbon dioxide away from the cells. the conducting zone moves oxygen into the bloodstream and the respiratory zone takes carbon dioxide away from the bloodstream.

Restriction enzymes are used in making recombinant dna. describe the role restriction enzymes perform when constructing recombinant dna.

Explain how sequences of amino acids in proteins can be used to reveal relationships among organisms.