AP Bio Unit 5 Practice Test
Introns are significant to biological evolution because a. their presence allows exons to be moved around more easily, creating proteins with new combinations of functional domains b. they protect the mRNA from degeneration c. they are translated into essential amino acids d. they maintain the genetic code by preventing incorrect DNA base pairings e. they correct enzymatic alterations of DNA bases
A
Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes a. excision of introns b. fusion into circular forms known as plasmids c. linkage to histone molecules d. union with ribosomes e. fusion with other newly transcribed mRNA
A
Plasmids are important in biotechnology because they are a. a vehicle for the insertion of foreign genes into bacteria. b. recognition sites on recombinant DNA strands. c. surfaces for protein synthesis in eukaryotic recombinants. d. surfaces for respiratory processes in bacteria. e. proviruses incorporated into the host DNA.
A
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is a. TTT b. UUA c. UUU d. AAA e. either UAA or TAA, depending on first base wobble
C
Bacteria containing recombinant plasmids are often identified by which process? a. examining the cells with an electron microscope b. using radioactive tracers to locate the plasmids c. exposing the bacteria to an antibiotic that kills cells lacking the plasmid d. removing the DNA of all cells in a culture to see which cells have plasmids e. producing antibodies specific for each bacterium containing a recombinant plasmid
C
Restriction fragments of DNA are typically separated from one another by which process? a. filtering b. centrifugation c. gel electrophoresis d. PCR e. electron microscopy
C
What is the effect of a nonsense mutation in a gene? a. It changes an amino acid in the encoded protein b. It has no effect on the amino acid sequence of the encoded protein c. It introduces a stop codon into the mRNA d. It alters the reading frame of the mRNA e. It prevents introns from being expressed
C
Where is eukaryotic ribosomal RNA transcribed? a. the Golgi apparatus b. ribosomes c. the nucleolus d. X chromosomes e. prokaryotic cells only
C
All of the following are directly involved in translation except a. mRNA b. tRNA c. ribosomes d. DNA e. aminoacyl-tRNA synthetase enzymes
D
Alternative RNA splicing a. is a mechanism for increasing the rate of transcription b. can allow the production of proteins of dramatically different sizes from a single mRNA c. can allow the production of proteins of dramatically different amino acid sequences from a single mRNA d. B and C only e. A, B, and C
D
During translation, chain elongation continues until what happens? a. No further amino acids are needed by the cell b. All tRNAs are empty c. The polypeptide is long enough d. A stop codon is encountered e. The ribosomes run off the end of mRNA
D
What is the enzymatic function of restriction enzymes? a. to add new nucleotides to the growing strand of DNA b. to join nucleotides during replication c. to join nucleotides during transcription d. to cleave nucleic acids at specific sites e. to repair breaks in sugar-phosphate backbones
D
A frameshift mutation could result from a. a base insertion only b. a base deletion only c. a base substitution only d. deletion of three consecutive bases e. either an insertion or a deletion of a base
E
As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs? a. The tRNA that was in the A site moves into the P site b. The tRNA that was in the P site moves into the A site c. The tRNA that was in the P site moves to the E site and is released d. The tRNA that was in the A site departs from the ribosome e. Both A and C are correct
E
Which of the following is (are) true of snRNPs? a. They are made up of both protein and RNA b. They bind to splice sites at each end of the intron c. They join together to form a large structure called the spliceosome d. Only A and C are true e. A, B, and C are true
E
A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of 400 amino acids. This is best explained by the fact that a. many noncoding nucleotides are present in mRNA b. there is redundancy and ambiguity in the genetic code c. many nucleotides are needed to code for each amino acid d. nucleotides break off and are lost during the transcription process e. there are termination exons near the beginning of mRNA
a
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately, what percentage of the nucleotides in this sample will be thymine? a. 12 b. 24 c. 31 d. 38 e. It cannot be determined from the information provided.
a
It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in its a. sequence of bases d. side groups of nitrogenous bases b. phosphate-sugar backbones e. different five-carbon sugars c. complementary pairing of bases
a
What kind of chemical bond is found between paired bases of the DNA double helix? a. hydrogen d. sulfhydryl b. ionic e. phosphate c. covalent
a
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent a. leading strands and Okazaki fragments b. lagging strands and Okazaki fragments c. Okazaki fragments and RNA primers d. leading strands and RNA primers e. RNA primers and mitochondrial DNA
a
RNA polymerase moves along the template strand of DNA in the ________ direction, and adds nucleotides to the ________ end of the growing transcript. a. 3' to 5'; 5' b. 3' to 5'; 3' c. 5' to 3'; 5' d. 5' to 3'; 3'
b
The strands that make up DNA are antiparallel. This means that a. the twisting nature of DNA creates nonparallel strands b. the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand c. base pairings create unequal spacing between the two DNA strands d. one strand is positively charged and the other is negatively charged e. one strand contains only purines and the other contains only pyrimidines
b
What are the coding segments of a stretch of eukaryotic DNA called? a. introns b. exons c. codons d. replicons e. transposons
b
All of the following are found in prokaryotic mRNA except a. the AUG codon b. the UGA codon c. introns d. uracil e. cytosine
c
What determines the nucleotide sequence of the newly synthesized strand during DNA replication? a. the particular DNA polymerase catalyzing the reaction b. the relative amounts of the four nucleoside triphosphates in the cell c. the nucleotide sequence of the template strand d. the primase used in the reaction e. both A and D
c
What is the function of DNA polymerase? a. to unwind the DNA helix during replication b. to seal together the broken ends of DNA strands c. to add nucleotides to the end of a growing DNA strand d. to degrade damaged DNA molecules e. to rejoin the two DNA strands (one new and one old) after replication
c
Which enzyme catalyzes the elongation of a DNA strand in the 5' à 3' direction? a. primase d. topoisomerase b. DNA ligase e. helicase c. DNA polymerase
c
Which of the following is least related to the others on the list? a. Okazaki fragments d. DNA polymerase b. replication fork e. semiconservative model c. telomerase
c
Which of the following is true for both prokaryotic and eukaryotic gene expression? a. After transcription, a 3' poly-A tail and a 5' cap are added to mRNA b. Translation of mRNA can begin before transcription is complete c. RNA polymerase binds to the promoter region to begin transcription d. mRNA is synthesized in the 3' ? 5' direction e. The mRNA transcript is the exact complement of the gene from which it was copied
c
A particular eukaryotic protein is 300 amino acids long. Which of the following could be the maximum number of nucleotides in the DNA template strand that codes for the amino acids in this protein? a. 3 b. 100 c. 300 d. 900 e. 1800
d
For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. This is because a. proteins have a greater variety of three-dimensional forms than does DNA b. proteins have two different levels of structural organization; DNA has four c. proteins are made of 20 amino acids and DNA is made of four nucleotides d. Only A and C are correct e. A, B, and C are correct
d
Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because a. RNA is much more stable than DNA b. RNA acts as an expendable copy of the genetic material, allowing the DNA to serve as a permanent, pristine repository of the genetic material c. many mRNA molecules can be transcribed from a single gene, increasing the potential rate of gene expression d. B and C only e. A, B, and C
d
What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG a. met-arg-glu-arg-glu-arg b. met-glu-arg-arg-gln-leu c. met-ser-leu-ser-leu-ser d. met-ser-ser-leu-ser-leu e. met-leu-phe-arg-glu-glu
d
Which of the following are transcribed from DNA? a. protein b. exons c. rRNA d. B and C only e. A, B, and C
d
Which of the following is not a part of the eukaryotic transcription initiation complex? a. promoter b. RNA polymerase c. transcription factors d. snRNP e. TATA box
d
Which of the following represents a similarity between RNA and DNA? a. Both are double-stranded b. the presence of uracil c. the presence of an OH group on the 2' carbon of the sugar d. nucleotides consisting of a phosphate, sugar, and nitrogenous base e. Both are found exclusively in the nucleus
d
Which of the following statements is false when comparing prokaryotes with eukaryotes? a. The prokaryotic chromosome is circular, whereas eukaryotic chromosomes are linear b. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many c. The rate of elongation during DNA replication is higher in prokaryotes than in eukaryotes d. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not e. Eukaryotes have telomeres, and prokaryotes do not
d
A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be a. 5' TTG-CTA-CAG-TAG 3' d. 3' AAA-AAT-ATA-ACA 5' b. 3' AAC-GAC-GUC-AUA 5' e. 3' AAA-GAA-TAA-CAA 5' c. 5' AUG-CTG-CAG-TAT 3'
e
In an analysis of the nucleotide composition of DNA, which of the following is true? a. A = C d. G + A = T + C b. A = G and C = T e. both C and D c. A + C = G + T
e
Suppose one were provided with an actively dividing culture of E. coli bacteria to which radioactive thymine had been added. What would happen if a cell replicated once in the presence of this radioactive base? a. One of the daughter cells, but not the other, would have radioactive DNA b. Neither of the two daughter cells would be radioactive c. All four bases of the DNA would be radioactive d. Radioactive thymine would pair with nonradioactive guanine e. DNA in both daughter cells would be radioactive
e
What is the sequence of a peptide based on the mRNA sequence 5' UUUUCUUAUUGUCUU 3' ? a. leu-cys-tyr-ser-phe b. cyc-phe-tyr-cys-leu c. phe-leu-ile-met-val d. leu-pro-asp-lys-gly e. phe-ser-tyr-cys-leu
e
Which of the following helps to stabilize mRNA by inhibiting its degradation? a. TATA box b. spliceosomes c. 5' cap d. poly-A tail e. both C and D
e
