A scientist is investigating cell transport. She observes molecules being transported into a cell through proteins present in the cell membrane. These proteins do not use energy to transport the molecules. Which of the following best explains the type of cell transport observed by the scientist? A. Active transport because membrane proteins were used B. Diffusion because the molecules were entering the cell C. Facilitated diffusion because the proteins were not using energy D. Osmosis because the molecules were moving against the concentration gradient

Look at the photo of the leaf. which term best describes this leaf?

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

Female luna moths (actias luna) attract males by emitting chemical signals that spread through the air. a male hundreds of meters away can detect these molecules and fly toward their source. the sensory organs responsible for this behavior are the comblike antennae visible in the photograph shown here. each filament of an antenna is equipped with thousands of receptor cells that detect the sex attractant. based on what you learned in this chapter, propose a hypothesis to account for the ability of the male moth to detect a specific molecule in the presence of many other molecules in the air. what predictions does your hypothesis make? design an experiment to test one of these predictions.