Females who have one abnormal copy of a mutated gene on the X chromosome are known as:

• A. hemizygotes
• B. carriers
• C. homozygotes
• D. affected individuals

Answer: (B)

Verified step by step guidance

1. Understand the genetic context: Females have two X chromosomes, so they have two copies of genes located on the X chromosome.
2. Define the term 'hemizygote': This refers to individuals (usually males) who have only one copy of a gene on the X chromosome because they have one X and one Y chromosome.
3. Define 'homozygote': This refers to individuals who have two identical alleles of a gene, either both normal or both mutated.
4. Define 'affected individuals': These are individuals who express the disease phenotype, often because they have two mutated copies or a mutation on their single X chromosome (in males).
5. Recognize that females with one mutated and one normal copy of an X-linked gene typically do not show full disease symptoms but can pass the mutation to offspring; such females are called 'carriers'.