Dna is a nucleic acid polymer composed of which repeating structural unit? nucleotides phosphate groups ribosomes proteins

The answer is nucleotides.DNA is a nucleic acid (desoxirribunocleic acid) polymer composed of units, this is monomers, named nucletoids. Nucleotids are organic molecules with several functional groups ( phosphates, OH, NH2). The monomers bond each other to form a large chain (a polymer) which is the DNA.

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.