Some traits, such as earlobe attachment, blood type, and the presence or absence of dimples, have limited variation throughout t
he human population because they are controlled by a single gene. Other traits, such as skin color and human height, are widely variable throughout the human population because. A. they can not be affected by environmental factors
The right option is; C. They are controlled by more than one gene
Traits such as skin color, human height and eye colour are known as polygenic traits. These traits have wide variation throughout the human population and are controlled by two or more genes. For example the human height is controlled by at least three genes with six alleles. The quantities of the genes are usually large but often have a little effect.
About 63% of the bacteria tested were Gram-negative, which means that they have a cell wall that is more resistant to certain classes of antibiotics than the cell walls of Gram-positive bacteria.
