This is the repeating structural unit that forms rna and dna.

The correct answer will be option-nucleotides.

Explanation:

The nucleic acids-DNA and RNA are one of the biomolecules made up of small structural units called monomers.

The structural unit of nucleic acid is made up of "nucleotides" which is composed of a 5 carbon sugar, a phosphate group and a nitrogenous base. Each nucleotide is joined to another nucleotide via a phosphodiester bond between 5' phosphate group of one nucleotide to 3'-OH group of another nucleotide.

Thus, a nucleotide is the correct answer.

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.

thinking it would be physical characteristics