They have a spine
hope it helps
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A Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene.
Answer:
DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases. To form a strand of DNA, nucleotides are linked into chains, with the phosphate and sugar groups alternating.
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the gas bladder in fishes as it can help them to maintain their buoyancy in water
