Final answer:
A human male cannot be a carrier of red-green color blindness because it is an X-linked recessive trait and males have only one X chromosome. If they inherit the colorblindness allele, they will be colorblind; they cannot be silent carriers.
Step-by-step explanation:
Can a human male be a carrier of red-green color blindness? The answer is no, because red-green color blindness is an X-linked recessive trait. In the context of genetic inheritance, being a 'carrier' typically refers to someone who has one copy of a recessive allele but does not express the trait because they also have a dominant allele that masks it. This is relevant in cases where the trait is autosomal. However, with sex-linked traits such as color blindness, the situation differs.
Boys have only one X chromosome, which means that if their single X chromosome carries the gene for colorblindness, they will exhibit the condition. They cannot be carriers in the typical sense because they do not have another X chromosome with a potentially dominant allele to mask the expression of the trait. Girls, on the other hand, carry two X chromosomes, so a girl could be a carrier of color blindness if one of her X chromosomes has the colorblind gene while the other has a normal vision gene.