Figure 1. Types of movement across membranes. Molecules can diffuse across a. membrane down a concentration gradient without the aid of a protein or the input of. energy. Passive and active transport require membrane transport proteins. Channel. proteins carry out passive transport, but carrier proteins can carry out passive or active. transport.
Akron, Iowa. Akron is a city in Plymouth County, Iowa, United States. The population was 1,486 at the 2010 census.
Books, magazines, ebooks, audiobooks, movies, music, programming and events for all Akron-Summit County Public Library cardholders.