What is the basic unit that is put together over and over to build a strand of dna?

The basic units that are put together over and over to build a strand of dna are called as nucleotides.

Explanation:

DNA is a heteropolymer that involves many monomers that is the nucleotides that are joined together by phosphodiester bonds in order to develop a complete DNA. The nucleotides consists of nitrogenous bases, phosphate groups and the sugar molecules that are bound together to form a complete nucleotide. The phosphate groups form a backbone through which the nucleotides are joined together.

The statement that best summarizes the flow of energy in a producer is the third statement: Sun > chloroplasts > mitochondria. The sun is the main source of energy (solar energy). This is essential in photosynthesis and producing food. Photosynthesis occurs in the chloroplasts. Products of photosynthesis (oxygen and glucose) is used in cellular respiration. This process occurs in the mitochondria.