I think B. I hope this helps.
Answer:
An amino acid can be encoded by more than one codon.
Explanation:
Codons are triplets of nucleotides in mRNA that are used for the protein synthesis (translation). A codon specifies a single amino acid, but there are exceptions. tRNA molecule contain anticodons, triplets of nucleotides that are complementary to codons. So, during the translation, tRNA carries the amino acid, that corresponds to the codon in mRNA.
Degenerate genetic code (more than one codon can code for the same amino acid) is important, because when point mutation occurs it is possible that the amino acid remains unchanged.
Answer:
Most cells within planarians tend to be very close to their gastrovascular cavity, in addition to their external environments. Also, planarians have the ability for oxygen and carbon dioxide to diffuse through the cells on their body walls: this makes it unnecessary for these varieties of flatworms to need a dedicated bodily system.
I think the deficiency of dedicated respiratory and circulatory systems in Planarians does not cause a problem because none of their cells are far removed from the gastrovascular cavity or from the external environment. Planarians are free-living flatworms and form the class Turbellarians in the Phylum Platyhelminthes. Flatworms have three tissue layers, that is the ectoderm, mesoderm, and endoderm.
hope this helps!!!!!....
Explanation:
<span>B.The existence of vestigial structures
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Vestigial structures have been used for long by evolutionists to support the theory of evolution. These organs are believed to have been in use in the past lives but as the species adapts to new forms of life and lifestyle,the vestige organs becomes obsolete,but are not removed by the body. An example of vestige organs in human being are the appendix,tail bone,and mammalian grands in men.
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