Theoretically, a protein could assume a virtually infinite number of configurations and conformations. Which of the following features of proteins drastically limit the actual number of available conformations and configurations? A. Only L-amino acids (except for glycine) are used in proteins.
B. The partial double bond character of the α-C-N bond in the peptide group limits the conformations of the peptide group.
C. Hydrogen bonding within elements of secondary structure stabilize certain atomic geometries.
D. Although any one of 20 amino acids is possible at each position, only one is used.
E. The ability of a protein to rearrange its geometry is dramatically limited by the interactions of polar and charged amino acids with water.

A. Only L-amino acids (except for glycine) are used in proteins.

B. The partial double bond character of the α-C-N bond in the peptide group limits the conformations of the peptide group.

C. Hydrogen bonding within elements of secondary structure stabilize certain atomic geometries.

D. Although any one of 20 amino acids is possible at each position, only one is used.

Explanation:

Proteins are biomolecules composed of one or more chains of amino acid residues which are joined together by peptide bonds (this sequence represents the primary structure of the protein). Proteins are made up of 20 types of amino acids which have diverse properties. The secondary structure of a protein refers to the local structure of the protein backbone, which is stabilized by hydrogen bonding between amino groups (​—NH2) and carboxyl groups (—COOH) in neighboring areas of the protein. The most common secondary structures in proteins include alpha helices, beta sheets, and random turns. Moreover, the tertiary structure in proteins describes the packing of these secondary structures. The peptide bond (CO–NH) is a stable covalent bond that has a rigid planar structure and acquires partial double-bond properties, thereby peptide bonds undergo very little rotation (i.e., rotation around peptide bonds is restricted). With the exception of glycine, all amino acids are stereoisomers, i.e., there exist mirror images of their structures which are labeled as L (left-handed) and D (right-handed) in order to differentiate between mirror images. All amino acids in proteins have the L-configuration.

mountains can affect the climate of nearby lands. in some areas, mountains block rain, so that one side of a mountain range may be rainy and the other side may be a desert. much of airborne moisture falls as rain on the windward side of mountains.

explanation:

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.