Deletion of 4 bases from the coding region of a gene will give（）
A. nonsense mutations
B. missense mutations
C. silent mutations
D. frameshift mutations
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A major difference between prokaryotic and eukaryotic DNA replication mechanisms is（）
A. no Okazaki fragments are made in eukaryotes
B. both leading and lagging strands are continuous in eukaryotes
C. no primer synthesis is needed in eukaryotes
D. the replication fork moves slower in eukaryotes
Fragments on the lagging strand are joined by the enzyme__（）
A. DNA polymerase I
B. DNA synthase
C. DNA primosome
DNA ligase
Which of the following are true statements regarding telomeres（）
A. they consist of a short repeating sequence
B. they are primarily in eukaryotes
C. they are located at chromosome ends and stabilize linear chromosomes
D. all of the above
Ethyl methane sulfonate （EMS） is a kind of _____ which can cause base mutation on DNA strands（）
A. base analog
B. base modifier
C. intercalating agent
D. Physical mutagens
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