Answer:
a. most genes encode one polypeptide and can be operationally defined by the complementation test
Explanation:
Genes are the stretch of DNA that code for specific polypeptides. In general, one gene codes for the only polypeptide.
Genes are defined by complementation tests which in turn tell if two mutations have occurred in the alleles of the same gene or different gene.
For the purpose, an organism with the homozygous genotype for one recessive mutation is crossed with an organism having the homozygous recessive genotype for another mutation.
If the two mutations are in the same gene, the progeny would show the mutant phenotype. On the other hand, if two mutations are in different genes, the progeny would exhibit normal phenotype.
