Animals, they only have a cell membrane, not cell walls.
I don't know what the answer choices were, though, but I hope this helps.
Answer:
Phosphate sugar backbone:
The sugar-phosphate backbone forms the structural framework of nucleic acids, including DNA and RNA. This backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.
Nitrogenous base:
Nitrogen bases are the molecules that make up the steps of the ladders. There are four different nitrogen bases, namely; Guanine, Thymine,Adenine and Cytosine.
Pyrimidines are compounds that make a single 6-sided ring. Examples of pyrimidines are Cytosine and Thymine.
Purines on the other hand make 5-sided and 6-sided rings. Examples of purines are Guanine and Adenine.
The nitrogen bases are helped together through hydrogen bonds.
Hydrogen Bonds:
A weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.
HOPE IT HELPS!
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A) agonist is the correct answer
<span>cells are the units of structure and different functions in livings things
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