Astudent wants to study the effect of removing thermal energy from a system. which of the following experiments should the student perform? close a circuit by adding a penny and record if the blub glows. close a circuit by adding a nail and record if the bulb glows. gradually warm a liquid and record its change in state. gradually cool a gas and record its change in state.

Which kind of aquatic ecosystem does the photograph most likely show? a. marsh b. swamp c. lake d. river

Next pretest: evolution select the correct answer in a laboratory population of flies, the female flies are gray and the males are yellowish gray. biologists observed that all the male flies had an equal chance for reproduction, but the male flies with the brightest colors were more likely to successfully reproduce. what phenomenon could explain such a change? a sexual selection b. disruptive selection c. stabilizing selection d. directional selection

Darrel conducted an experiment with the following procedure: fill two cups with ice water. place an uninflated balloon snuggly onto your left index finger. blow a little air into an identical balloon, and place it onto your right index finger. place both fingers into the cups of ice water. darrel noticed that his right finger felt warmer in the ice water than did his left finger. which of the following does the experiment show? a. air is a good radiator of heat. b. air is a good insulator of heat. c. air is a good conductor of heat. d. air is a good convector of heat.