1. Which of the following is required for active transport to occur across a cell membrane?  * A. 
a concentration gradient
* B. 
a storage vacuole
* C. 
energy
* D. 
water

The zone, which exists from a depth of 0 to 600 feet, is home to the majority of ocean life.

Twind is considered to be an abiotic factor because it.?

Which best describes a benefit of using dna technology in medicine? a) medicine can be produced in mass quantities. b) medicine can be distributed at a reduced cost. c) medicines have fewer side effects. d) medicines are resistant to antibiotics.