2. Which of the following best describes the permeability of the cell membrane? A. All substances can pass directly through the membrane
B. No substances can pass directly through the membrane
C. Some substances can pass directly through the membrane, especially small nonpolar
molecules
D. Some substances can pass directly through the membrane, especially large polar
molecules
Can

which

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.