There are 64 codons and 20 amino acids. which of the following is not true?
a. several different codons can specify the same amino acid.
c. all amino acids are linked to a codon.
d. each amino acid is specified by only one codon.

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star. reset submit

What did you notice about the onion root tip cells that you saw at 40x power?