T level Science Core B Biology Practice Test

A nucleotide in DNA is composed of three essential components: a sugar molecule, a phosphate group, and an organic base. The sugar in DNA is deoxyribose. The phosphate group forms the backbone of the DNA strand, linking the sugar molecules together through phosphodiester bonds. The organic base can be one of four types: adenine, thymine, cytosine, or guanine. These bases are crucial for encoding genetic information as they pair specifically in the double helix structure of DNA, facilitating the storage and transmission of genetic data.

The other options do not contain the correct combination of components that define a nucleotide. For example, glycerol and glucose are not part of nucleotides, and amino acids and fatty acids are associated with protein and lipid structures rather than nucleic acids like DNA. Similarly, steroids and triglycerides relate to lipid biochemistry, further confirming that the only valid option representing the components of a nucleotide is the combination of sugar, phosphate, and an organic base.