1. what's a stalactite?
a. large mound of dirt created by erosion
b. poisonous mass found in caves that is formed by polluted water
c. mound-shaped stone shaped by weathering
d. dripstone produced by a buildup of minerals precipitated from groundwater
and
2. which of the following statements describes rill erosion?
a. the population increases next to a shoreline.
b. sand along a shoreline is repeatedly picked up by waves.
c. sediment is deposited by a river.
d. running water cuts small channels into a slope.

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food

How can an organ, such as the lungs, work for multiple body systems?

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.