Question 1

If an organism's DNA contains 20% adenine nucleotides, what percentage of its DNA is composed of guanine nucleotides?

Accepted Answer

A)   10%
B)   15%
C)   20%
D)   30%
E)   40% Since 20% of the organism's DNA consists of adenine nucleotides, 20% consists of thymine nucleotides. The other 60% consists of guanine and cytosine. Since the amount of G=C, the DNA is 30% guanine and 30% cytosine.

Question 2

An intervening sequence of DNA that is not expressed is called an)

Accepted Answer

A)   intron.
B)   exon.
C)   gene.
D)   replicon.
E)   promoter. During mRNA processing, segments of the mRNA that do not code for an amino acid necessary for the protein are removed. These noncoding sequences that interrupt the "message" of the mRNA are called introns. A

Question 3

What would be the most likely result on the regulation of the lac operon from a nonfunctional repressor protein?

Accepted Answer

A)   transcription of the lactose metabolizing genes, even when lactose is absent
B)   no transcription of the lactose metabolizing genes, even when lactose is present
C)   binding of the repressor protein to the operator, even when lactose is present
D)   binding of the repressor protein to the regulatory gene in both the presence and absence of lactose
E)   no transcription of the regulatory gene, even in the presence of lactose

Question 4

Which of the following processes does not occur within the nucleus?

Accepted Answer

A)   DNA replication
B)   transcription
C)   intron removal
D)   translation
E)   primary mRNA splicing Translation occurs on ribosomes within the cytoplasm, or at the membrane of the rough endoplasmic reticulum.

Question 5

The information contained within a gene is not directly copied into which of the following chemical forms?

Accepted Answer

A)   tRNA, rRNA
B)   mRNA, tRNA
C)   rRNA, protein
D)   mRNA, protein
E)   tRNA, protein The information contained within a gene is transcribed into mRNA, and then into a protein. The other forms of RNA, tRNA, and rRNA, are necessary for the process of translation.

Question 6

For a DNA strand that contains the sequence AGT in the 5' to 3' direction, what nucleotides are found on the other DNA strand in the 5' to 3' direction?

Accepted Answer

A)   ACT
B)   TGA
C)   AGT
D)   TCA
E)   GTA By Chargaff's rules, T hydrogen bonds with A, C with G, and A with T. Since the opposite strand runs antiparallel, the correct order of these nucleotides is ACT. A

Question 7

The protein derived from a particular gene is different when it is found in a neuron than in a muscle cell. This is most likely due to

Accepted Answer

A)   alternative mRNA processing.
B)   regulation of mRNA translation.
C)   alteration of protein activity.
D)   mRNA editing.
E)   DNA excision. Exon inclusion or exclusion, or intron inclusion, as a result of alternative mRNA processing may yield different mRNA transcripts from the same gene, giving rise to multiple proteins from the same gene.

Question 8

A point mutation in the operator of the lac operon would most likely cause

Accepted Answer

A)   no transcription of the lactose metabolizing genes, even when lactose is absent.
B)   no transcription of the lactose metabolizing genes, even when lactose is present.
C)   no binding of the repressor protein to the operator, even when lactose is absent.
D)   binding of the repressor protein to the regulatory gene in both the presence and absence of lactose.
E)   no transcription of the regulatory gene, even in the presence of lactose. The repressor binds the operator when lactose is absent. Like a faulty repressor, a mutation in the operator would likely cause the repressor not to bind the operator, regardless of whether lactose is present.

Question 9

If RNA polymerase malfunctions,

Accepted Answer

A)   one of the subunits of rRNA will not be transcribed from DNA.
B)   amino acids will not be joined to their tRNA.
C)   mRNA cannot bind to rRNA.
D)   an mRNA will not be formed.
E)   mRNA cannot copy itself. RNA polymerase makes an mRNA transcript of the gene being transcribed. If RNA polymerase malfunctions, the mRNA is not made.

Question 10

Which of the DNA sequences shown in the figure is/are bound by a regulatory protein?

Accepted Answer

A)   1
B)   2
C)   3
D)   1 and 4
E)   2 and 3

Question 11

Signal transduction pathways can stimulate transcription activators.

Accepted Answer

A) True 
 B)False

Question 12

If an organism's DNA contains 20% adenine nucleotides, what percentage of its DNA is composed of thymine nucleotides?

Accepted Answer

A)   10%
B)   15%
C)   20%
D)   30%
E)   40% By Chargaff's rules, A=T and G=C; thus, 20% of the DNA will consist of thymine nucleotides.

Question 13

Which process requires the participation of all three types of RNA?

Accepted Answer

A)   transcription
B)   translation
C)   RNA processing
D)   replication
E)   complementary base pairing During translation, an mRNA is translated by a ribosome, which contains rRNA, and tRNA brings the specified amino acids to the ribosome.

Question 14

tRNAs carrying the correct amino acid recognize the proper codons on the mRNA because

Accepted Answer

A)   the anticodon of the tRNA hydrogen binds to the codon of the mRNA by complementary base pairing.
B)   the codon of the tRNA binds to the anticodon of the ribosome by complementary base pairing.
C)   the anticodon of the tRNA carries the correct amino acid.
D)   the amino acid binds to the anticodon of the mRNA and brings the correct tRNA with it.
E)   the codon of the mRNA binds the correct amino acid, and the tRNA stabilizes this interaction. The anticodon of the tRNA binds to the codon of the mRNA by complementary base pairing. The tRNA carries the encoded amino acid. A

Question 15

For a DNA strand composed of the sequence AGT in the 5' to 3' direction, the free phosphate is on the ________ nucleotide and the free hydroxyl is on the ________ nucleotide.

Accepted Answer

A)   T; A
B)   A; G
C)   A; A
D)   G; T
E)   A; T By convention, DNA sequences are written 5' to 3' from left to right. The free phosphate is thus found on the adenine nucleotide, and the free hydroxyl is found on the thymine nucleotide.

Question 16

mRNA must be processed in the cytoplasm before being used in protein synthesis.

Accepted Answer

A) True 
 B)False

Question 17

The two DNA strands must be separated before DNA replication or transcription can occur.

Accepted Answer

A) True 
 B)False

Question 18

What is the hereditary material found in all cells?

Accepted Answer

A)   DNA
B)   rRNA
C)   mRNA
D)   tRNA
E)   ATP While mRNA, tRNA, and rRNA are all necessary to express the genetic code of an organism, it is DNA that carries the information to make the other molecules and to make the proteins that carry out the necessary functions of the cell.

Question 19

If the maternal X chromosome is inactive and becomes the Barr body in one cell, then the maternal X chromosome becomes the Barr body in every cell of that woman's body.

Accepted Answer

A) True 
 B)False

Question 20

If an organism's DNA contains 17% adenine nucleotides and 33% guanine nucleotides, what percentage of its DNA is composed of cytosine nucleotides?

Accepted Answer

A)   8.5%
B)   17%
C)   25%
D)   33%
E)   50% By Chargaff's rules, the amount of G=C, so the DNA is also 33% cytosine.

Exam 11: DNA Biology and Technology

If an organism's DNA contains 20% adenine nucleotides, what percentage of its DNA is composed of guanine nucleotides?

Correct AnswerverifiedShow Answer

An intervening sequence of DNA that is not expressed is called an)

Correct AnswerverifiedA

What would be the most likely result on the regulation of the lac operon from a nonfunctional repressor protein?

Correct AnswerverifiedShow Answer

Which of the following processes does not occur within the nucleus?

Correct AnswerverifiedShow Answer

The information contained within a gene is not directly copied into which of the following chemical forms?

Correct AnswerverifiedShow Answer

For a DNA strand that contains the sequence AGT in the 5' to 3' direction, what nucleotides are found on the other DNA strand in the 5' to 3' direction?

Correct AnswerverifiedA

The protein derived from a particular gene is different when it is found in a neuron than in a muscle cell. This is most likely due to

Correct AnswerverifiedShow Answer

A point mutation in the operator of the lac operon would most likely cause

Correct AnswerverifiedShow Answer

If RNA polymerase malfunctions,

Correct AnswerverifiedShow Answer

Which of the DNA sequences shown in the figure is/are bound by a regulatory protein?

Correct AnswerverifiedShow Answer

Signal transduction pathways can stimulate transcription activators.

Correct AnswerverifiedShow Answer

If an organism's DNA contains 20% adenine nucleotides, what percentage of its DNA is composed of thymine nucleotides?

Correct AnswerverifiedShow Answer

Which process requires the participation of all three types of RNA?

Correct AnswerverifiedShow Answer

tRNAs carrying the correct amino acid recognize the proper codons on the mRNA because

Correct AnswerverifiedA

For a DNA strand composed of the sequence AGT in the 5' to 3' direction, the free phosphate is on the ________ nucleotide and the free hydroxyl is on the ________ nucleotide.

Correct AnswerverifiedShow Answer

mRNA must be processed in the cytoplasm before being used in protein synthesis.

Correct AnswerverifiedShow Answer

The two DNA strands must be separated before DNA replication or transcription can occur.

Correct AnswerverifiedShow Answer

What is the hereditary material found in all cells?

Correct AnswerverifiedShow Answer

If the maternal X chromosome is inactive and becomes the Barr body in one cell, then the maternal X chromosome becomes the Barr body in every cell of that woman's body.

Correct AnswerverifiedShow Answer

If an organism's DNA contains 17% adenine nucleotides and 33% guanine nucleotides, what percentage of its DNA is composed of cytosine nucleotides?

Correct AnswerverifiedShow Answer

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For a DNA strand composed of the sequence AGT in the 5' to 3' direction, the free phosphate is on the nucleotide and the free hydroxyl is on the nucleotide.

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