A student wants to prove that amphibians appeared on earth before birds. The student should use the fossil findings as evidence to provide the most reliable information about the periods when amphibians and birds appeared on earth. Fossils would throw light on the internal body structures that bear the closest similarity to either the amphibians or the birds. The radiocarbon dating of the fossils will reveal its age. This can be used to figure out the time of divergence of the two types.
The nitrogenous base found in DNA but not RNA is called thymine. That's what it bonds to.
The members of the phylum arthropoda have jointed legs. the number of jointed legs are variable, may be three pairs as in cockroaches, four pairs in prawns and even hundred pairs in centipedes. Members of this phylum have ability to shed their their exoskeleton(molting) and body is divided into three fused segments - head, thorax and abdomen.
TRNA stands for transfer-RNA which is used in the process of protein synthesis or translation. tRNA is a unique clover leaf like structure that has 4 arms- amino acid acceptor site (acceptor arm), D loop, T psi C loop and anticodon loop. It also has a small variable loop. The anticodon loop consists of a sequence of 3 bases that is complementary to the 3 bases present of mRNA to be translated. A tRNA for alanine will have an anticodon for alanine while a tRNA for lysine will have an anticodon for lysine. For a tRNA to insert an alanine in place of lysine in a forming peptide, the anticodon and the amino acid acceptor site should be altered so that it accepts lysine in place of alanine and add it to the growing polypeptide.