The cell membrane is said to be selectively permeable is because it allows a select few things to go through while stopping the passage of other stuff.
The answer is A, a cell wall
Answer:
Attached R side groups
Explanation:
The proteins are one of the important biomolecules which are directly coded by the genetic material of an organism.
The proteins are composed of the amino acids which possess, an amine group, a carboxylic group and an attached side group called the R group.
It is the R group of an amino acid which determines whether the amino acid will a polar or a non-polar amino acid molecule thus it determines the properties of the amino acid in terms of chemical properties. The R side group are involved in the formation of bonds with the substrate of the environment and the tertiary structure of the proteins.
Thus, the presence of different R group is the key difference in 20 amino acids.
Climate change is usually negative because if it dramatic it could kill most of species.
