Achondroplasia Is a Common Cause of Dwarfism in Humans

question 9

Multiple Choice

Achondroplasia is a common cause of dwarfism in humans. All individuals with achondroplasia are thought to be heterozygous at the locus that controls this trait. When two individuals with achondroplasia mate, the offspring occur in a ratio of 2 achondroplasia : 1 normal. What is the MOST likely explanation for these observations?

• A) Achondroplasia is incompletely dominant to the normal condition.
• B) Achondroplasia is codominant to the normal condition.
• C) The allele that causes achondroplasia is a dominant lethal allele.
• D) The allele that causes achondroplasia is a recessive lethal allele.
• E) The allele that causes achondroplasia is a late-onset lethal allele.

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Definitions:

Aromatic

Refers to organic compounds containing one or more planar rings of atoms that are stable due to resonance of bonding electrons.

Antiaromatic

A type of compound that is cyclic, planar, and conjugated, but does not follow Huckel's rule, having 4n π electrons which destabilize it.

Nonaromatic

A compound that does not contain a benzene-like ring and does not exhibit the stability typical of aromatic compounds.

2,4,6-trichlorophenol

A chlorinated phenol known for its antiseptic properties, used in the synthesis of pesticides and other chemicals.