Plants make their own food through the process of photosynthesis. To do this, they need energy from the Sun, carbon dioxide from
the air, and water and other nutrients from their roots.
Carbon dioxide enters the plant through tiny openings on the underside of leaves known as stomata. However, whenever the plant
opens its stomata to let carbon dioxide in, it also releases water vapor into the atmosphere. This latter process is known as
transpiration.
Under which of the following environmental conditions would you expect the stomata to be closed more often than they are open?
A. on a hot, dry day
B. on a cool, cloudy day
c. on a wet, rainy day
D. on a warm, windy day

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

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.

Which statement correctly compares metaphase i and metaphase ii? in metaphase ii twice as many chromosomes line up along the middle of the cell as in metaphase i. in metaphase i twice as many chromosomes line up along the middle of the cell as in metaphase ii. in metaphase ii twice as many chromosomes are pulled to opposite ends of the cell as in metaphase i. in metaphase i twice as many chromosomes are pulled to opposite ends of the cell as in metaphase ii.