Organisms must have variation within a population in order for natural selection to occur. which situation is an example of this variation?

Aboy with an extra x chromosome probably has which of the following syndromes?

How does the study of genetic disorders such as pku biologists understand normal alleles?

'which of these statements about the scientific method is not true? all experiments must follow the same number of steps in the procedure. experiments may be repeated several times. some unexpected results can be beneficial. experimental results may or may not support the hypothesis.