Answer:
The nucleotide triplet that encodes an amino acid is called a codon. Each group of three nucleotides encodes one amino acid. Since there are 64 combinations of 4 nucleotides taken three at a time and only 20 amino acids, the code is degenerate (more than one codon per amino acid, in most cases).
Mario sets up an experiment to determine the source of the oxygen gas produced by photosynthesis. To determine this, he uses an isotope of oxygen called O-18. He labels the O-18 oxygen so he can follow its path through photosynthesis. Plant A is given carbon dioxide that contains the O-18 isotope. Plant B is given water that contains the O-18 isotope. When he examines the oxygen from both plants, only plant B produced O-18 oxygen. This indicates that the source of oxygen is water. The photosynthesis involves the transfer of electrons between the photosystem I and II. The water gets split into oxygen, hydrogen ions and electrons in the photosystem I. The electrons move to the photosystem II where the carbon fixation into sugars takes place. The plant A will have O-18 isotope in its synthesised sugar molecule, which gets stored inside it.
The correct answer is A. Inhale odor molecules into nasal cavity.
