If a son expresses an X-linked recessive gene, he inherited the trait from ____
a. his mother
b. his father
c. both parents
d. neither parent
e. his grandmother
ANSWER: a
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In rats, gene B produces black coat color if the genotype is B-, but black pigment is not produced if the genotype is bb. At an independent locus, gene D produces yellow pigment if the genotype is D-, but no pigment is produced when the genotype is dd. Production of both pigments results in brown coat color. If neither pigment is produced, coat color is cream. The phenotype of parents of litters with the following phenotype distribution 3 brown, 3 yellow, 1 black, 1 cream is:
a. Black and cream. b. Black and yellow. c. Brown and cream. d. Brown and yellow.
Antibiotics that block the synthesis of a cell wall would be least likely to affect cells from which organisms?
A. animals B. archaea C. plants D. fungi E. bacteria
Vibrio cholerae causes Asiatic cholera. It has a corkscrew shape, so we would say it has this form
A) coccus B) bacillus C) spirillum D) clostridia
Study of the origin of life has resulted in the breakdown of cellular development into overlapping stages, beginning with the synthesis of precursor molecules for the synthesis of nucleotides and amino acids and ending in polymers enclosed in membranes acquiring cellular properties. Which of these stages were a focus of study for Miller and Urey in their FIRST experiment?
A. Stage 1: Nucleotides and amino acids were produced prior to the existence of cells. B. Stage 2: Nucleotides became polymerized to form RNA and/or DNA, and amino acids became polymerized to form proteins. C. Stage 3: Polymers became enclosed in membranes. D. Stage 4: Polymers enclosed in membranes acquired cellular properties. E. Stage 5: Ribosomes were developed inside the membrane.