AP Biology Test #3a - Molecular Genetics And Cellular Reproduction
The human body is made up of thousands of cells and these cells have a lifespan. We covered the process through which cells are replaced and the various types of cells that exist and their functions. Test yourself on how well you understood Molecular genetics and cellular reproduction below. All the best!
Questions and Answers
- 1.
The phage tail fibers contain the enzyme lysozyme which is necessary in which stage shown below
- A.
A
- B.
B
- C.
C
- D.
D
- E.
E
Correct Answer
B. BExplanation
The phage tail fibers contain the enzyme lysozyme, which is necessary in stage B. This suggests that the lysozyme enzyme plays a role in stage B of the process depicted above. Without further context or information, it is not possible to determine the specific function or purpose of stage B.Rate this question:
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- 2.
Genetic recombination can occur in bacteria by all of the following methods EXCEPT:
- A.
Transfer of DNA between bacteria through pili
- B.
DNA amplification
- C.
Mutation
- D.
Transformation
- E.
Transduction
Correct Answer
B. DNA amplificationExplanation
Genetic recombination in bacteria can occur through various methods, including transfer of DNA between bacteria through pili, mutation, transformation, and transduction. However, DNA amplification is not a method of genetic recombination in bacteria. DNA amplification refers to the process of producing multiple copies of a specific DNA sequence, such as through polymerase chain reaction (PCR). While DNA amplification is an important technique in molecular biology, it is not a mechanism by which bacteria naturally exchange genetic material.Rate this question:
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- 3.
A person infected with encapsulated, virulent form of Pneumococcus may have difficulty in combating the infection due to the
- A.
Proliferation of T-lymphocytes
- B.
Release of interferon
- C.
Production of antihistamines
- D.
Bacteria's capsule interfering with phagocytosis
- E.
Synthesis of steroids by the bacteria
Correct Answer
D. Bacteria's capsule interfering with phagocytosisExplanation
The correct answer is the bacteria's capsule interfering with phagocytosis. The capsule of Pneumococcus bacteria is a protective layer that helps the bacteria evade the immune system. Phagocytosis is a process where immune cells engulf and destroy pathogens. The capsule inhibits the ability of phagocytes to recognize and engulf the bacteria, making it difficult for the immune system to combat the infection effectively. This allows the bacteria to proliferate and cause more severe disease.Rate this question:
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- 4.
Microbiologists frequently culture bacteria from an ill person to determine which antibiotic will be the most effective in combating the disease. The plate shown below shows growth after 48 hours. Examine the key and the diagram before answering the question below. KEY I = Penicillin II = Erythromycin III = Tetracycline The antibiotic that is effective against the bacteria is
- A.
I
- B.
II
- C.
III
- D.
I and II
- E.
I and III
Correct Answer
A. IExplanation
The plate shows growth after 48 hours, indicating that the bacteria are not being inhibited by the antibiotics. However, there is no growth in the area where Penicillin (I) is present, suggesting that this antibiotic is effective in combating the bacteria. Therefore, the correct answer is I.Rate this question:
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- 5.
The molecular biology process in which many copies of a gene can be produced from a single cell of small DNA sample is called
- A.
Gel electrophoresis
- B.
Polymerase chain reaction
- C.
Transcription
- D.
Translation
- E.
Nuclear multiplication
Correct Answer
B. Polymerase chain reactionExplanation
Polymerase chain reaction (PCR) is a molecular biology process that allows for the amplification of a specific DNA sequence. It involves the use of DNA polymerase enzyme to repeatedly copy and amplify the targeted DNA region, resulting in the production of many copies of the gene from a small DNA sample. Gel electrophoresis is a technique used to separate DNA fragments based on their size, while transcription and translation are processes involved in gene expression. Nuclear multiplication is not a recognized term in molecular biology.Rate this question:
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- 6.
The scientist credited for the development of PCR techniques is
- A.
Watson and Crick
- B.
Jochame Hammerling
- C.
Barbara McClintock
- D.
Thomas Chech
- E.
Kary Mullis
Correct Answer
E. Kary MullisExplanation
Kary Mullis is credited for the development of PCR techniques. PCR, or Polymerase Chain Reaction, is a widely used method in molecular biology to amplify a specific DNA sequence. Mullis invented this technique in 1983, which revolutionized the field of genetics and has numerous applications in research, medicine, and forensic science. His invention earned him the Nobel Prize in Chemistry in 1993. Watson and Crick are known for discovering the structure of DNA, Jochame Hammerling for his work on genetics in single-celled organisms, Barbara McClintock for her discovery of genetic transposition, and Thomas Chech is not associated with the development of PCR techniques.Rate this question:
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- 7.
The HIV virus uses which of the cycles of infection below
- A.
Lytic
- B.
Lysogenic
- C.
Prebiotic
- D.
Prokaryotic
- E.
Eukaryotic
Correct Answer
B. LysogenicExplanation
The HIV virus uses the lysogenic cycle of infection. In this cycle, the virus inserts its genetic material into the host cell's DNA and remains dormant for an extended period of time. The viral DNA replicates along with the host cell's DNA, and the virus is passed on to daughter cells during cell division. Eventually, the virus can switch to the lytic cycle, where it becomes active, replicates rapidly, and destroys the host cell.Rate this question:
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- 8.
The conclusion reached in the experiment shown below was that the cellular structure responsible for the characteristic shape of the algal cap was the
- A.
Cytoplasm
- B.
Nucleus
- C.
Cell wall
- D.
Cell membrane
- E.
Cytoplasm and the cell wall
Correct Answer
B. NucleusExplanation
The experiment concluded that the cellular structure responsible for the characteristic shape of the algal cap was the nucleus. This suggests that the shape of the algal cap is determined by the genetic information stored in the nucleus, which controls the synthesis of proteins and other cellular components involved in shaping the cap. The cytoplasm, cell wall, and cell membrane may also play a role in maintaining the shape, but the nucleus is the key structure responsible for determining the shape of the algal cap.Rate this question:
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- 9.
Cells that can differentiate into other body cells are called
- A.
Mitotic cells
- B.
Stem cells
- C.
Gamete cells
- D.
Non cells
Correct Answer
B. Stem cellsExplanation
Stem cells are cells that have the ability to differentiate into various types of specialized cells in the body. They can divide and renew themselves through mitosis, and under certain conditions, they can be induced to become cells with specific functions. This unique characteristic of stem cells makes them crucial in various medical and scientific research, as they hold the potential to treat a wide range of diseases and injuries by replacing damaged or diseased cells. Therefore, stem cells are the correct answer to the question.Rate this question:
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- 10.
Prokaryotes like bacteria shown below reproduce by
- A.
Binary fission
- B.
Binary fusion
- C.
Sex
- D.
They do not reproduce
Correct Answer
A. Binary fissionExplanation
Prokaryotes like bacteria reproduce by binary fission, which is a form of asexual reproduction. In binary fission, the prokaryotic cell divides into two identical daughter cells, each receiving a copy of the genetic material. This process allows bacteria to rapidly reproduce and increase their population size. Binary fusion is not a term used in biology, and sex, which involves the fusion of gametes, is not a common method of reproduction in prokaryotes. Therefore, the correct answer is binary fission.Rate this question:
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- 11.
Identify the phase of mitosis from the picture below:
- A.
Interphase.
- B.
Prophase.
- C.
Metaphase.
- D.
Anaphase.
- E.
Telophase.
Correct Answer
E. Telophase.Explanation
The correct answer is telophase. This phase of mitosis is characterized by the separation of sister chromatids, which move towards opposite poles of the cell. The nuclear envelope reforms around each set of chromosomes, and the spindle fibers disassemble. This marks the end of mitosis and the beginning of cytokinesis, where the cell divides into two daughter cells.Rate this question:
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- 12.
To observe the process of mitosis in plant root cells, a biologist should examine the plant's
- A.
Root hairs.
- B.
Casparian strip.
- C.
Root cap.
- D.
Zone of maturation.
- E.
Apical meristem.
Correct Answer
E. Apical meristem.Explanation
To observe the process of mitosis in plant root cells, a biologist should examine the apical meristem. The apical meristem is a region of actively dividing cells located at the tips of plant roots. It is responsible for the growth of the root and contains cells that undergo mitosis, which is the process of cell division. By examining the apical meristem, the biologist can directly observe the mitotic process in plant root cells.Rate this question:
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- 13.
The exchange of segments of DNA between the members of a pair of chromosomes.
- A.
Ensures that variations within a species never occur.
- B.
Acts as a source of variations within a species.
- C.
Always produces genetic disorders.
- D.
Is called crossing.
Correct Answer
B. Acts as a source of variations within a species.Explanation
The exchange of segments of DNA between the members of a pair of chromosomes acts as a source of variations within a species. This process, known as genetic recombination or crossing over, occurs during meiosis when homologous chromosomes exchange genetic material. This exchange leads to the creation of new combinations of genes, increasing genetic diversity within a population. This variation is important for the survival and adaptation of a species to changing environments.Rate this question:
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- 14.
Which of the following is a characteristic of mitochondria and chloroplast that supports the endosymbiotic theory?
- A.
Both have bacteria-like polysaccharide cel walls.
- B.
Both can reproduce on their own outside of the cell.
- C.
Both contain DNA molecules.
- D.
Both contain endoplasmic reticulum and Golgi bodies .
- E.
Both contain ribosomes that are identical to ribosomes of the eukaryotic cytoplasm.
Correct Answer
C. Both contain DNA molecules.Explanation
Both mitochondria and chloroplasts contain DNA molecules, which is a characteristic that supports the endosymbiotic theory. This theory suggests that these organelles were once free-living bacteria that were engulfed by a host cell, forming a symbiotic relationship. The presence of DNA in mitochondria and chloroplasts is evidence of their bacterial origins, as bacteria also contain DNA. This supports the idea that these organelles were once independent organisms that were incorporated into eukaryotic cells.Rate this question:
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- 15.
Which of the following is a correct statement about mutations?
- A.
They are a source of variation for evolution.
- B.
They drive evolution by creating mutation pressures.
- C.
They are irreversible.
- D.
They occur in germ cells but not in somatic cells.
- E.
They are most often beneficial to the organisms in which they occur.
Correct Answer
A. They are a source of variation for evolution.Explanation
Mutations are changes in the DNA sequence of an organism. They can introduce new genetic variations, which can then be inherited by future generations. This variation is essential for the process of evolution, as it provides the raw material for natural selection to act upon. Mutations can occur randomly and can be caused by various factors such as environmental factors or errors during DNA replication. While some mutations can be harmful or have no effect, others can be beneficial and provide an advantage to the organisms in which they occur. Therefore, the statement "They are a source of variation for evolution" is correct.Rate this question:
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- 16.
Which of the following statements concerning a gene is correct?
- A.
A gene can code for a specific protein.
- B.
A gene can exist in alternate forms called introns.
- C.
A gene undergoes crossing-over during DNA replication.
- D.
A gene that is very similar in sequence in a human and in a bacterium is probably a recent mutation.
- E.
A gene that is expresses in every offspring of every generation is recessive.
Correct Answer
A. A gene can code for a specific protein.Explanation
A gene can code for a specific protein. Genes are segments of DNA that contain the instructions for building proteins. Proteins are essential molecules that perform various functions in the body. Genes provide the information needed to assemble the amino acids in the correct order to form a specific protein. This process is known as protein synthesis or gene expression. Therefore, the statement that a gene can code for a specific protein is correct.Rate this question:
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- 17.
The mRNA codons and the amino acids for which they code are? GGG= glycine ACU= threonine CCC= proline AAA= lysine The sequence GGGACUCCC arranges the amino acids in the order. glycine--threonine--proline Wich DNA sequence would substitute lysine for threonine.?
- A.
CCCATTGGU
- B.
CCCATAGGG
- C.
CCCAATGGG
- D.
CCCTTTGGG
- E.
GGGAUAGGG
Correct Answer
D. CCCTTTGGGExplanation
The DNA sequence CCCTTTGGG would substitute lysine for threonine. This is because the codon ACU codes for threonine, and the codon AAA codes for lysine. By changing the ACU codon to AAA, the amino acid threonine is replaced with lysine in the sequence.Rate this question:
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- 18.
The maximum number of RNA codons comprising the genetic code is.
- A.
2
- B.
16
- C.
64
- D.
128
- E.
256
Correct Answer
C. 64Explanation
There are a total of 64 RNA codons in the genetic code. Codons are three-letter sequences of RNA nucleotides that determine the specific amino acid to be added during protein synthesis. Since there are four different RNA nucleotides (A, U, G, and C), and each codon is made up of three nucleotides, there are 4^3 = 64 possible combinations. Therefore, the maximum number of RNA codons in the genetic code is 64.Rate this question:
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- 19.
Using radioactive tracers (shown below) to determine the interactions of bacteriophages and their host bacteria Hershey and Chase demonstrated without question that
- A.
Genes are compose of protein molecules
- B.
DNA and proteins are actually the same molecules located in different parts of the cells.
- C.
Bacteria injects their DNA into the cytoplasm of bacteriophages.
- D.
DNA is the molecule that stores genetic information in the cells.
Correct Answer
D. DNA is the molecule that stores genetic information in the cells.Explanation
Hershey and Chase used radioactive tracers to determine the interactions of bacteriophages and their host bacteria. This experiment conclusively showed that DNA is the molecule that stores genetic information in cells. This is because when the bacteriophages infected the bacteria, only the radioactive DNA was found inside the bacteria, not the radioactive proteins. This demonstrated that DNA, not proteins, is responsible for carrying and transmitting genetic information.Rate this question:
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- 20.
Cancer cells that spread are called
- A.
Benign
- B.
Malignant
- C.
Somatic
- D.
Gametic
Correct Answer
B. MalignantExplanation
Malignant cells are cancer cells that have the ability to invade nearby tissues and spread to other parts of the body through the bloodstream or lymphatic system. Unlike benign cells, which are non-cancerous and do not spread, malignant cells can form tumors and metastasize, causing harm to the body. Therefore, the correct answer is "malignant."Rate this question:
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- 21.
Acetabularia mediterranea is mostly closely related to
- A.
Mediterranea crassa.
- B.
Mediterranea crenulata.
- C.
Crenulata crenulata.
- D.
Crenulata acetabularia.
- E.
Acetabularia crenulata.
Correct Answer
B. Mediterranea crenulata.Explanation
Acetabularia mediterranea is mostly closely related to Mediterranea crenulata.Rate this question:
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- 22.
Molecules of DNA are composed of long chains of
- A.
Amino acids.
- B.
Fatty acids.
- C.
Monosaccharides.
- D.
Nucleotides.
Correct Answer
D. Nucleotides.Explanation
DNA molecules are composed of long chains of nucleotides. Nucleotides are the building blocks of DNA and consist of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). These nucleotides are joined together through phosphodiester bonds to form a long chain, which makes up the DNA molecule. Amino acids are the building blocks of proteins, fatty acids are components of lipids, and monosaccharides are the building blocks of carbohydrates, but they are not the components of DNA molecules.Rate this question:
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- 23.
The entire molecule shown in the diagram is called a(n)
- A.
Amino acids.
- B.
Nucleotide.
- C.
Polysaccharide.
- D.
Pyrimidine.
Correct Answer
B. Nucleotide.Explanation
The correct answer is nucleotide. A nucleotide is a molecule that is composed of a sugar, a phosphate group, and a nitrogenous base. The diagram shows a molecule that has all these components, indicating that it is a nucleotide. Amino acids are the building blocks of proteins, polysaccharides are large carbohydrates, and pyrimidine is a type of nitrogenous base found in nucleotides.Rate this question:
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- 24.
Retrovirus such as HIV are capable of replicating
- A.
DNA from RNA
- B.
DNA from DNA
- C.
RNA from DNA
- D.
RNA from RNA
- E.
Neither DNA nor RNA
Correct Answer
A. DNA from RNAExplanation
Retroviruses, such as HIV, have a unique enzyme called reverse transcriptase that allows them to replicate DNA from RNA. This process is known as reverse transcription. The retrovirus uses its RNA genome as a template to synthesize a complementary DNA strand, which is then integrated into the host cell's DNA. This allows the retrovirus to hijack the host cell's machinery and produce more viral particles. Therefore, the correct answer is DNA from RNA.Rate this question:
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- 25.
Waston and Crick built models that demonstrated that
- A.
DNA and RNA have the same structure.
- B.
DNA is made of two strands that twist into a double helix.
- C.
Guanine forms hydrogen bonds with adenine.
- D.
Thymine forms hydrogen bonds with cytosine.
Correct Answer
B. DNA is made of two strands that twist into a double helix.Explanation
The correct answer is "DNA is made of two strands that twist into a double helix." This is because Watson and Crick's model of DNA structure, based on X-ray crystallography data from Rosalind Franklin, revealed that DNA consists of two strands that are twisted around each other to form a double helix shape. This discovery was a crucial breakthrough in understanding the structure and function of DNA.Rate this question:
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- 26.
Homologous chromosomes are pairs of chromosomes containing genes that code for
- A.
Different traits.
- B.
Same traits.
- C.
DNA.
- D.
Cytosol.
Correct Answer
B. Same traits.Explanation
Homologous chromosomes are pairs of chromosomes that have the same genes in the same order, although they may have different alleles for those genes. This means that they code for the same traits, although there may be variations in the specific expression of those traits due to the presence of different alleles. Therefore, the correct answer is "same traits."Rate this question:
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- 27.
Griffith's transformation experiments shown below
- A.
Changed proteins into DNA.
- B.
Caused non-harmful bacteria to become deadly.
- C.
Resulted in DNA molecules becoming proteins.
- D.
Were design to show the effect of heat on bacteria.
Correct Answer
B. Caused non-harmful bacteria to become deadly.Explanation
Griffith's transformation experiments involved injecting non-harmful bacteria with a heat-killed strain of deadly bacteria. The results showed that the non-harmful bacteria were able to acquire the ability to cause disease and become deadly themselves. This discovery demonstrated the concept of bacterial transformation, where genetic material can be transferred between bacteria, leading to a change in their characteristics. The experiments did not involve changing proteins into DNA, resulting in DNA molecules becoming proteins, or showing the effect of heat on bacteria.Rate this question:
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- 28.
A strand of DNA has the following sequence of bases: ATC GTC TTC AAG What sequence of bases will make up the other strand of DNA?
- A.
TAG CAG AAG TTC
- B.
UUC AAG CAG UAG
- C.
UAG CAG AAG UUC
- D.
GTC ATC AAG TTC
Correct Answer
A. TAG CAG AAG TTCExplanation
The other strand of DNA will have a complementary sequence of bases. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Therefore, the complementary sequence to ATC GTC TTC AAG is TAG CAG AAG TTC.Rate this question:
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- 29.
Chromatids are
- A.
Dense patches within the nucleus.
- B.
Bacterial chromosomes.
- C.
Joined strands of duplicated genetic material (chromosome)
- D.
Prokaryotic nuclei.
Correct Answer
C. Joined strands of duplicated genetic material (chromosome)Explanation
Chromatids are joined strands of duplicated genetic material (chromosome). During the process of cell division, the DNA in a chromosome is replicated, resulting in two identical chromatids that are held together by a structure called the centromere. These chromatids are then separated during cell division to form two daughter cells, each with a complete set of genetic material. Therefore, chromatids represent the duplicated form of a chromosome and are essential for the accurate distribution of genetic material to daughter cells.Rate this question:
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- 30.
The point at which two chromatids are attached to each other in a chromosome is called a(n)
- A.
Chloroplast.
- B.
Centromere.
- C.
Gamete.
- D.
Centriole.
Correct Answer
B. Centromere.Explanation
The point at which two chromatids are attached to each other in a chromosome is called a centromere. This structure plays a crucial role in the separation of chromatids during cell division. It serves as an attachment site for the spindle fibers, which pull the chromatids apart during mitosis or meiosis. The centromere also helps to ensure that each daughter cell receives the correct number of chromosomes. Chloroplasts are organelles involved in photosynthesis, gametes are reproductive cells, and centrioles are involved in cell division, but none of these options are directly related to the attachment point of chromatids in a chromosome.Rate this question:
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- 31.
The non-coding portions of DNA that are separated from the portions of DNA actually used during transcription are called
- A.
Mutons
- B.
Exons
- C.
Introns
- D.
Exposons
Correct Answer
C. IntronsExplanation
Introns are the non-coding portions of DNA that are separated from the portions of DNA actually used during transcription. During the process of transcription, introns are removed from the pre-mRNA molecule and the remaining coding portions, called exons, are spliced together to form the mature mRNA molecule. This allows for the production of different protein variants through alternative splicing, where different combinations of exons can be included or excluded. Mutons, exposons, and exons are not correct terms for this concept.Rate this question:
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- 32.
Many biologists believe that having the genes of eukaryotic cells interrupted by introns
- A.
Prevents the code from being corrected.
- B.
Ensured severely damaging mutations.
- C.
Ensures that replication occurs correctly.
- D.
Provides evolutionary flexibility.
Correct Answer
D. Provides evolutionary flexibility.Explanation
Having the genes of eukaryotic cells interrupted by introns provides evolutionary flexibility. Introns are non-coding sequences within genes that are removed during RNA processing. This allows for alternative splicing, where different combinations of exons can be joined together to produce different protein isoforms. This flexibility in gene expression and protein production allows for adaptation to changing environments and evolutionary innovation.Rate this question:
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- 33.
The portions of DNA molecules that actually code for the production of proteins are called
- A.
Mutons
- B.
Exons
- C.
Introns
- D.
Exposons
Correct Answer
B. ExonsExplanation
Exons are the portions of DNA molecules that code for the production of proteins. They contain the genetic information necessary for the synthesis of functional proteins. Mutons, introns, and exposons are not the correct terms for the coding regions of DNA. Mutons are hypothetical units of mutation, introns are non-coding regions of DNA, and exposons are not a recognized term in molecular biology. Therefore, the correct answer is exons.Rate this question:
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- 34.
The lac operon is shut off when
- A.
Lactose is present.
- B.
Lactose is absent.
- C.
Glucose is present.
- D.
Glucose is absent.
Correct Answer
B. Lactose is absent.Explanation
The lac operon is a genetic system in bacteria that controls the expression of genes involved in lactose metabolism. It consists of three main components: the promoter, the operator, and the genes coding for lactose-metabolizing enzymes. When lactose is absent, a repressor protein binds to the operator, preventing the transcription of the genes. This effectively shuts off the lac operon. In the presence of lactose, the repressor protein is unable to bind to the operator, allowing the genes to be transcribed and lactose to be metabolized. Therefore, the correct answer is lactose is absent.Rate this question:
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- 35.
Refer to the illustration below. Where on the lac operon does transcription take place?
- A.
Promoter (p)
- B.
Operator (o)
- C.
Gene (z)
Correct Answer
C. Gene (z)Explanation
Transcription is the process of synthesizing RNA from a DNA template. In the lac operon, transcription takes place on the gene (z). The promoter (p) is the region where RNA polymerase binds to initiate transcription, and the operator (o) is the region that controls the access of RNA polymerase to the gene. However, the actual synthesis of RNA occurs on the gene (z) itself.Rate this question:
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- 36.
The function of an operator is to?
- A.
Regulate access of RNA polymerase to specific genes.
- B.
Turn on and off the molecules of tRNA.
- C.
Control the process of transcription within the nucleus.
- D.
Generate amino acids for protein synthesis.
Correct Answer
A. Regulate access of RNA polymerase to specific genes.Explanation
The function of an operator is to regulate access of RNA polymerase to specific genes. An operator is a region of DNA that controls the activity of genes by acting as a switch. It can either block or allow RNA polymerase, the enzyme responsible for transcription, to bind to the promoter region of a gene. By controlling the access of RNA polymerase, the operator determines whether a gene is turned on or off, thereby regulating gene expression. This mechanism plays a crucial role in the control of transcription within the nucleus. It does not directly involve the molecules of tRNA or the generation of amino acids for protein synthesis.Rate this question:
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- 37.
Refer to the illustration below. To which portion of the lac operon does the repressor bind?
- A.
Promoter (p)
- B.
Operator (o)
- C.
Gene (z)
Correct Answer
B. Operator (o)Explanation
The lac operon is a segment of DNA that controls the expression of genes involved in lactose metabolism. It consists of three main components: the promoter (p), the operator (o), and the gene (z). The promoter is responsible for initiating transcription, while the gene contains the coding sequence for the enzyme beta-galactosidase. The operator acts as a regulatory region that can bind to the lac repressor protein. The lac repressor binds to the operator, preventing RNA polymerase from transcribing the gene. Therefore, the correct answer is the operator (o) because it is the portion of the lac operon where the repressor binds.Rate this question:
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- 38.
Cells must control gene expression so that
- A.
Their genes will only be expressed when needed.
- B.
Their genes will always be expressed.
- C.
Their genes will never be expressed.
- D.
Genetic disorders can be corrected.
Correct Answer
A. Their genes will only be expressed when needed.Explanation
Cells must control gene expression so that their genes will only be expressed when needed. This is important for maintaining proper cellular function and responding to changes in the environment. If genes were always expressed, it could lead to unnecessary protein production and waste of resources. On the other hand, if genes were never expressed, essential proteins would not be produced, leading to cellular dysfunction. By tightly regulating gene expression, cells can ensure that the right genes are expressed at the right time and in the right amount, allowing for proper development, growth, and response to stimuli.Rate this question:
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- 39.
A repressor protein
- A.
Prevents DNA synthesis.
- B.
Blocks movement of RNA polymerase.
- C.
Attaches to ribosome during translation.
- D.
Destroys amino acids before protein synthesis occurs.
Correct Answer
B. Blocks movement of RNA polymerase.Explanation
A repressor protein is a type of regulatory protein that binds to specific DNA sequences and prevents the movement of RNA polymerase, which is responsible for synthesizing RNA from DNA. By blocking the movement of RNA polymerase, the repressor protein inhibits the transcription process and prevents the synthesis of RNA molecules. This regulation mechanism helps control gene expression and ensure that certain genes are not expressed when they are not needed.Rate this question:
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- 40.
Using the DNA fingerprinting shown below which suspect most likely matchs the sample taken from the crime scene
- A.
Suspect A
- B.
Suspect B
- C.
No suspect matches the DNA fingerprint
Correct Answer
B. Suspect BExplanation
Based on the given information, it is stated that no suspect matches the DNA fingerprint. Therefore, the correct answer is Suspect B because it is the only option given that does not match the DNA fingerprint.Rate this question:
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- 41.
At the very beginning of the translation, the first tRNA molecule
- A.
Binds to the ribosome's A site.
- B.
Attaches directly to the DNA codon.
- C.
Connects an amino acid to its anticodon.
- D.
Attaches to the P site of the ribosome.
Correct Answer
A. Binds to the ribosome's A site.Explanation
During the process of translation, the first tRNA molecule binds to the ribosome's A site. The A site is one of the three binding sites on the ribosome, along with the P site and E site. The A site is responsible for holding the incoming tRNA molecule, which carries the specific amino acid that corresponds to the codon on the mRNA strand. This binding is necessary for the formation of the polypeptide chain during protein synthesis.Rate this question:
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- 42.
The anticodons on the tRNA molecule for the codons in the mRNA: CUCAAGUCCUUC would be
- A.
GAG--UUC--AGG--AAG.
- B.
GAG--TTC--ACG--AAG.
- C.
CUC--GAA--CGU--CUU.
- D.
CUU--CGU--GAA--CUC.
Correct Answer
A. GAG--UUC--AGG--AAG.Explanation
The anticodons on the tRNA molecule for the codons in the mRNA sequence "CUCAAGUCCUUC" would be "GAG--UUC--AGG--AAG". This is because in the genetic code, the codon "CUC" in the mRNA corresponds to the anticodon "GAG" on the tRNA. Similarly, "AAG" in the mRNA corresponds to "UUC" on the tRNA, "AGG" corresponds to "AGG" on the tRNA, and "CUU" corresponds to "AAG" on the tRNA. Therefore, the correct answer is "GAG--UUC--AGG--AAG".Rate this question:
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- 43.
Which of the following would represent the strand of DNA from which the mRNA:CUCAAGUCCUUC strand in the diagram was made?
- A.
CUCAAGUGCUUC
- B.
GAGUUCACGAAG
- C.
GAGTTCAGGAAG
- D.
AGACCTGTAGGA
Correct Answer
C. GAGTTCAGGAAGExplanation
The given mRNA sequence is CUCAAGUCCUUC. To determine the DNA strand from which this mRNA was made, we need to find the complementary DNA sequence. The complementary DNA sequence is obtained by replacing each nucleotide in the mRNA with its complementary base. In this case, C pairs with G, U pairs with A, and A pairs with T. Therefore, the complementary DNA sequence would be GAGTTCAGGAAG. This is the same as the third option provided, so the correct answer is GAGTTCAGGAAG.Rate this question:
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- 44.
Refer to the illustration below. What is the portion of the protein molecule coded for by the piece of mRNA that is:CUCAAGUCCUUC
- A.
Ser-- Tyr--Arg--Gly
- B.
Val--Asp-- Pro--His
- C.
Leu--Lys--Ser---Phe
- D.
Pro--Gli--Leu--Val
Correct Answer
C. Leu--Lys--Ser---PheExplanation
The given piece of mRNA sequence, CUCAAGUCCUUC, codes for the amino acid sequence Leu--Lys--Ser---Phe. This is determined by using the codon chart, which matches each three-letter mRNA codon to the corresponding amino acid. The codons CUC, AAG, UCC, and UUC correspond to the amino acids Leu, Lys, Ser, and Phe, respectively. Therefore, the portion of the protein molecule coded for by this mRNA sequence is Leu--Lys--Ser---Phe.Rate this question:
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- 45.
Each nucleotide triplet in mRNA that specifies a particular amino acid is called a(n)
- A.
Mutagen .
- B.
Codon.
- C.
Anticodon.
- D.
Exon.
Correct Answer
B. Codon.Explanation
A nucleotide triplet in mRNA that specifies a particular amino acid is called a codon. Codons are the basic units of the genetic code and they determine the sequence of amino acids in a protein. Each codon corresponds to a specific amino acid or a stop signal, and they are read by the ribosome during protein synthesis. Mutagens are substances that can cause changes in the DNA sequence, while anticodons are found in tRNA and are complementary to codons. Exons are the coding regions of genes that are expressed in the final protein product.Rate this question:
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- 46.
During transcription, the genetic information for making a protein is "rewritten" as a molecule of
- A.
Messenger RNA.
- B.
Ribosomal RNA.
- C.
Transfer RNA.
- D.
Translation RNA.
Correct Answer
A. Messenger RNA.Explanation
During transcription, the process by which genetic information is copied from DNA to RNA, the genetic information for making a protein is "rewritten" as a molecule of messenger RNA (mRNA). This mRNA molecule carries the genetic instructions from the DNA to the ribosomes, where it serves as a template for protein synthesis during translation. Ribosomal RNA (rRNA) and transfer RNA (tRNA) are also involved in protein synthesis, but they do not carry the genetic information for making a protein. Translation RNA is not a term used in biology, so it is not the correct answer.Rate this question:
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- 47.
The enzymes responsible for adding nucleotides to the exposed DNA template bases are
- A.
Replicases.
- B.
DNA polymerases.
- C.
Helicases.
- D.
None of the above.
Correct Answer
B. DNA polymerases.Explanation
DNA polymerases are enzymes responsible for adding nucleotides to the exposed DNA template bases during DNA replication. These enzymes are involved in the process of synthesizing a new DNA strand by adding complementary nucleotides to the template strand. Helicases, on the other hand, are responsible for unwinding the DNA double helix, while replicases are enzymes involved in the replication of RNA viruses. Therefore, the correct answer is DNA polymerases.Rate this question:
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- 48.
The enzymes that unwind DNA are called
- A.
Double helixes.
- B.
DNA helicases.
- C.
Forks
- D.
Phages.
Correct Answer
B. DNA helicases.Explanation
DNA helicases are enzymes that play a crucial role in DNA replication and repair by unwinding the double helix structure of DNA. They bind to the DNA molecule and use energy from ATP hydrolysis to separate the two strands, creating a replication fork. This allows other enzymes and proteins to access the DNA strands and perform their respective functions. Therefore, DNA helicases are responsible for the unwinding process and are commonly referred to as the enzymes that unwind DNA.Rate this question:
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- 49.
RNA differs from DNA in that RNA
- A.
Is a single-stranded.
- B.
Contains a different sugar molecule.
- C.
Contains the nitrogen base uracil.
- D.
All of the above.
Correct Answer
D. All of the above.Explanation
RNA differs from DNA in multiple ways. Firstly, RNA is a single-stranded molecule, whereas DNA is double-stranded. Secondly, RNA contains a different sugar molecule called ribose, while DNA contains deoxyribose. Lastly, RNA contains the nitrogen base uracil instead of thymine, which is found in DNA. Therefore, the correct answer is "All of the above" as all the statements are true regarding the differences between RNA and DNA.Rate this question:
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- 50.
The function of rRNA is to
- A.
Synthesize DNA.
- B.
Synthesize mRNA.
- C.
Form ribosomes.
- D.
Transfer amino acids to ribosomes.
Correct Answer
C. Form ribosomes.Explanation
rRNA, or ribosomal RNA, is responsible for forming ribosomes. Ribosomes are cellular structures that play a crucial role in protein synthesis. They are composed of rRNA and proteins, and they provide the site where mRNA (messenger RNA) is translated into proteins. Therefore, the correct answer is that the function of rRNA is to form ribosomes.Rate this question:
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Mar 21, 2023Quiz Edited by
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Mar 03, 2011Quiz Created by
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