What is needed for work to be done?
a force must push on an object without moving it.
a force must pull on an object without moving it.
aforce must cause an object to move along the same direction as the force.
aforce must act on an object while an equal force acts oppositely on the object.

This is an active transport mechanism by which cells pump sodium and potassium ions against the concentration gradient

Methane gas created by a cows flatulence especially in a large herd is a greenhouse gas. true or false.

Monarch butterflies have brightly colored orange wings with black patterns on them, making them easily visible to birds that eat butterflies and moths, yet birds rarely eat the monarchs. likewise, the monarch caterpillars are brightly striped yellow and white and black, and they also are rarely eaten by birds, although some wasps will attack them and feed them to their young. what can be inferred from these observations? monarchs must threaten and attack birds, but not wasps. monarchs have a way of discouraging bird predation that does not involve hiding. monarchs’ wings are so colorful that most birds must find them difficult to eat. monarchs lay more eggs than other less conspicuous butterflies.