MCQ Collection
MDCAT Biology MCQs
Practice MDCAT Biology questions with answers and explanations.
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Correct Answer: C. An allele expressed in a heterozygote
Explanation:
Dominance describes phenotype in a heterozygote.
It does not imply greater frequency or fitness.
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Correct Answer: D. RNA forming structural and catalytic parts of ribosomes
Explanation:
RRNA combines with proteins to form ribosomal subunits.
It helps catalyze peptide-bond formation.
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Correct Answer: D. UAA, UAG, and UGA
Explanation:
Stop codons do not encode amino acids.
They recruit release factors to end translation.
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Correct Answer: D. An allele expressed in a heterozygote
Explanation:
Dominance describes phenotype in a heterozygote.
It does not imply greater frequency or fitness.
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Correct Answer: A. Uracil
Explanation:
RNA uses uracil instead of thymine.
Uracil pairs with adenine.
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Correct Answer: B. RNA carrying coding information from DNA to ribosomes
Explanation:
MRNA contains codons specifying amino-acid sequence.
It is translated by ribosomes.
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Correct Answer: C. RNA carrying coding information from DNA to ribosomes
Explanation:
MRNA contains codons specifying amino-acid sequence.
It is translated by ribosomes.
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Correct Answer: A. Synthesis of RNA using a DNA template
Explanation:
RNA polymerase copies one DNA strand into RNA.
In eukaryotes, transcription occurs mainly in the nucleus.
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Correct Answer: B. Synthesis of RNA using a DNA template
Explanation:
RNA polymerase copies one DNA strand into RNA.
In eukaryotes, transcription occurs mainly in the nucleus.
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Correct Answer: C. Synthesis of RNA using a DNA template
Explanation:
RNA polymerase copies one DNA strand into RNA.
In eukaryotes, transcription occurs mainly in the nucleus.
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Correct Answer: D. RNA polymerase
Explanation:
RNA polymerase binds near a gene and builds an RNA strand.
It uses complementary ribonucleotides.
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Correct Answer: A. DNA polymerase
Explanation:
DNA polymerase extends a new strand using a template.
It adds nucleotides in the 5′ to 3′ direction.
