6. Membranes are essential to life processes. Which of the following best
defines a membrane?
A. Membranes are phospholipid bilayers.
B. Membranes are selectively permeable barriers.
C. Membranes are the sites of energy transformations.
D. Membranes are barriers that protect organelles from outside substances.

The influenza virus cause the flu, but not other diseases. why?

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.

Long-period comets come from the oort cloud particles in earth’s atmosphere material from the asteroid belt the kuiper belt