An amino acid is synthesized by the prokaryote, e coli. the genes for the enzymes responsible for synthesizing this amino acid are encoded in an operon. the operon is regulated by a repressor. when the amino acid binds to the repressor, the repressor changes shape so it can bind to the operator. which of the following statements is true?
a) when levels of the amino acid are high, it binds to the repressor, allowing synthesis of this amino acid to proceed.
b) when levels of the amino acid are low, it binds to the repressor, allowing synthesis of this amino acid to

Food provides molecules that serve as fuel and building material for all organisms. plants undergo photosynthesis and make their own food. other organisms, like us and the horse seen above, are consumers and eat food. how do all organisms use food as fuel? be sure to include the name of the process in your answer. me.

If you are in a chronic state of anxiety but also suffer from moment of sudden, intense fear you are problably suffering. from

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.