- Life Sciences
the membrane that surrounds the nucleus. It is similar in structure and function to the cell membrane.
bacteria that convert nitrogen in the air into compounds such as nitrites, nitrates and ammonia...
(also called selectively permeable membrane) a membrane which allows some substances to cross it...
blood vessels that transport deoxygenated blood from the heart to the lungs.
water that is found on the surface of the earth, e.g. in rivers, streams, and lakes etc.