A single, simple, recessively inherited mutation inactivates the enzyme that converts phenylalanine to tyrosine. Homozygous recessive individuals possess an excessive amount of phenylalanine and a deficiency of tyrosine. Additionally, these individuals may be mentally deficient, have abnormally light hair and abnormally light skin color. This disorder is an example of
A. incomplete penetrance.
B. incomplete dominance.
C. pleiotropy.
D. polygenic inheritance.
Answer: C
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To determine the evolutionary history of a gene, geneticists assume that the most prevalent alleles in a population
A) are dominant. B) have mutated the most. C) are the oldest. D) are the most recently acquired.
Which of the following vessels does NOT carry deoxygenated (lacking oxygen) blood?
a. inferior vena cava b. pulmonary artery c. pulmonary vein d. superior vena cava e. capillaries
Imprinting is a
a. response to a stimulus. b. learned behavior that occurs during a critical time period. c. fixed action pattern. d. decline in the level of a response to a nonthreatening stimulus. e. type of learning that involves solving novel problems
T lymphocytes mature in the (bone marrow/lymph node/thymus)
What will be an ideal response?