Answer:a) a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates.
Explanation:
An ancestor - An earlier type of a species at any distant time — a progenitor.
A tetrapod is any vertebrate with four limbs. It includes any vertebrate (such as birds or snakes) that have evolved from early tetrapods — especially all members of the superclass Tetrapoda.
The presence of bones that support the appendages in Lobe – fin fish were found to be similar to the categorical skeletal supports found in the limbs of sample tetrapods. The sub class crossopterygii includes the Lobe – fin fish, which is seen as one of the recent common ancestor of living tetrapod today.
James Watson is credited with the discovery is the stricture of DNA.
he gibe the 3D structure of DNA in 1962 ,
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The stem and the middle of the peatals
The building blocks of protein are C. AMINO ACIDS.
Amino acids are made up of a center carbon atom bound positively to a charged amino group and a negatively charged carboxyl group and a side chain.
The primary structure of a protein is the sequence of an amino acids that are attached together by a peptide bond
The secondary structure of a protein, the polypeptide is folded through the mechanisms of amino acids rotating around bonds folding into a helix or a pleated sheet structure and stabilized by a hydrogen bond.
