Which labels best complete the diagram? X: Two-chambered heart
Y: Swim bladder
X: Single-chambered heart
Y: Swim bladder
X: Gills
Y: Lateral line
X: Lungs
Y: Lateral line

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

Explain the causes and effect of damage to the genetic code.

Plants need carbon dioxide from their environment to produce glucose during which stage of photosynthesis?