The classical form of the metabolic disease phenylketonuria is caused by a mutation in the gene encoding the enzyme phenylalanine hydroxylase (PAH), which converts phenylalanine to tyrosine. A variant form of phenylketonuria is caused by a mutation in a separate gene that encodes a different enzyme involved in the synthesis of a cofactor needed for PAH to function. Which of the following phenomena is illustrated by these two forms of phenylketonuria?
A) Allelic heterogeneity
B) Compound heterozygosity
C) Locus heterogeneity
D) Anonymous polymorphism
C) Locus heterogeneity
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a. artificial selection b. selective breeding c. transfer of a genetic trait from a different species into the plant's cells d. culturing adult stem cells e. cutting DNA with restriction enzymes and separating the DNA fragments by size
Endocrine glands secrete their products
A) into a synapse. B) into a gap junction. C) into ducts that open into a body cavity. D) into interstitial fluid. E) directly into target cells.
Which gas is increasing the most in the atmosphere, thereby intensifying the greenhouse effect?
A. Carbon dioxide B. Carbon monoxide C. Ozone D. Nitrogen E. Oxygen
Critics of GM foods often cite the ________ as reason to be skeptical of the safety of GM foods
A) the in depth testing of DNA that makes it through the food refinement process B) fact that most GM foods are not directly consumed by humans C) vast number of studies conducted on the consumption of GM foods D) the extreme governmental oversight of GM food production