Concentration gradient across the membrane. Proteins in the membrane allow specific molecules through, passively.
Answer:
I am pretty sure it is A or D sorry if this does not help
I believe it is gel electrophoresis.
Gel electrophoresis is a techniwue used to separate DNA fragments or other macromolecules such as RNA and proteins based on their size and charge. It can also determine the actual size of a piece of DNA by examining it next to a standard "yardstick" made up of DNA fragments of known sizes.
If you were studying climate change in general. The answer would be the last one which is ecosystem because it’s the study of the environment
Agriculture is the greatest use of groundwater.
Hope this helps!