BIO 111-02 Exam 4

In contrast to the leading strand, the lagging strand is synthesized as a series of segments called Okazaki fragments. The diagram below illustrates a lagging strand with the replication fork off-screen to the right. Fragment A is the most recently synthesized Okazaki fragment. Fragment B will be synthesized next in the space between primers A and B. Drag the labels to their appropriate locations in the flowchart below, indicating the sequence of events in the production of fragment B. (Note that pol I stands for DNA polymerase I, and pol III stands for DNA polymerase III.)

1. pol III binds to 3' end of primer B 2. pol III moves 5' to 3' 3. pol I binds to 5' end primer A 4. pol I replaces primer A with DNA 5. DNA ligase links fragments A and B

Indicate at which step of the replication-transcription-translation process each type of RNA first plays a role.

Transcription/RNA processing: mRNA Translation: tRNA, rRNA

Which of the following statements apply to the variation of human skin color? Select all that apply a. Human skin color variation evolved recently in hominid evolution, once some populations of our human ancestors migrated out of Africa. b. Variability in human skin color can be explained by the activity of a single gene. c. Human skin color variation is primarily determined by the type and amount of melanin pigment in the skin. d. Human skin color variation likely evolved in response to differences in the intensity of sunlight around the world. e. The color of human skin and the skin of our closest primate relative exhibits a similar range in variability.

a, c, d, a. Human skin color variation evolved recently in hominid evolution, once some populations of our human ancestors migrated out of Africa. c. Human skin color variation is primarily determined by the type and amount of melanin pigment in the skin. d. Human skin color variation likely evolved in response to differences in the intensity of sunlight around the world.

Imagine a genetic counselor working with a couple who have just had a child who is suffering from Tay-Sachs disease. Neither parent has Tay-Sachs, nor does anyone in their extended families. Which of the following statements should this counselor make to this couple? a. "Because you have had one child with Tay-Sachs, you must each carry the allele. Any child you have has a 25% chance of having the disease." b. "Because no one in either of your families has Tay-Sachs, you are not likely to have another baby with Tay-Sachs. You can safely have another child." c. "Because you have had one child with Tay-Sachs, you must each carry the allele. Any child you have has a 50% chance of having the disease." d. "Because you have had one child with Tay-Sachs, you must both carry the allele. However, since the chance of having an affected child is 25%, you may safely have three more children without worrying about having another child with Tay-Sachs." e. "You must both be tested to see who is a carrier of the Tay-Sachs allele."

a. "Because you have had one child with Tay-Sachs, you must each carry the allele. Any child you have has a 25% chance of having the disease."

DNA replication always begins at an origin of replication. In bacteria, there is a single origin of replication on the circular chromosome, as shown in the image here. Beginning at the origin of replication, the two parental strands (dark blue) separate, forming a replication bubble. At each end of the replication bubble is a replication fork where the parental strands are unwound and new daughter strands (light blue) are synthesized. Movement of the replication forks away from the origin expands the replication bubble until two identical chromosomes are ultimately produced. In this activity, you will demonstrate your understanding of antiparallel elongation at the replication forks. Keep in mind that the two strands in a double helix are oriented in opposite directions, that is, they are antiparallel. Drag the arrows onto the diagram below to indicate the direction that DNA polymerase III moves along the parental (template) DNA strands at each of the two replication forks. Arrows can be used once, more than once, or not at all.

a. ---> b. ---> c. <--- d. <---

A haploid set of unreplicated chromosomes (n = 4) of the fruit fly Drosophila melanogaster has a mass of 0.14 p g. What is the mass of D N A in single Drosophila cell at the end of telophase II? a. 0.14 pg b. 0.28 pg c. 0.42 pg d. 0.56 pg

a. 0.14 pg

A haploid set of unreplicated chromosomes (n = 4) of the fruit fly Drosophila melanogaster has a mass of 0.14 p g. What is the mass of D N A in single Drosophila cell in prophase II? a. 0.14 pg b. 0.28 pg c. 0.42 pg d. 0.56 pg

a. 0.28 pg

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails? a. 1/2 b. 1/16 c. 3/16 d. 3/8

a. 1/2

Manx cats have characteristic stubby tails due to being heterozygous at a single locus. Homozygotes for the Manx allele die before birth with severe spinal deformities. What is the expected phenotypic ratio of live offspring of two Manx cats? a. 2 Manx: 1 normal b. 3 normal: 1 Manx c. 3 Manx: 1 normal d. 2 normal: 1 Manx

a. 2 Manx: 1 normal

Consider the case of dominant epistasis in squash, where YY and Yy = yellow and yy = green. At a second, independently assorting locus, WW and Ww = white, and ww allows for yellow or green.What is the expected phenotypic ratio among the progeny of the cross Yy Ww × Yy Ww? (Note these are white squash.) a. 3 whites: 1 yellow b. all yellow c. all white d. 3 yellows: 1 green

a. 3 whites: 1 yellow

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is ________. a. 3'-UCA-5' b. 3'-ACU-5' c. 5'-TCA-3' d. 3'-UGA-5'

a. 3'-UCA-5'

Two true-breeding stocks of pea plants are crossed. One parent has red axial flowers, and the other has white terminal flowers; all F1 individuals have red axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of plants with white axial flowers? a. 3/16 b. 1/16 c. 1/8 d. 9/16

a. 3/16

As a male, I have 46 chromosomes and ________. a. 44 are autosomes and 2 are sexual chromosomes (X and Y) b. 44 are autosomes and 2 are sexual chromosomes (X and X) c. 46 autosomes d. 46 sexual chromosomes

a. 44 are autosomes and 2 are sexual chromosomes (X and Y)

The DNA double helix is composed of two strands of DNA; each strand is a polymer of DNA nucleotides. Each nucleotide consists of a sugar, a phosphate group, and one of four nitrogenous bases. The structure and orientation of the two strands are important to understanding DNA replication.

a. 5' end b. hydrogen bond c. 3' end d. deoxyribose sugar e. nitrogenous base f. phosphate group g. 3' end h. 5' end

Consider a family in which a man, age 47, has just been diagnosed with Huntington's disease, a late-onset disease that is caused by a dominant autosomal allele (the man is a heterozygote). His daughter, age 25, has a 2-year-old son. No one else in the family has the disease. What is the probability that the daughter will develop the disease? a. 50% b. 0% c. 25% d. 75% e. 100%

a. 50%

When crossing an organism that is homozygous recessive for a single trait with one that is heterozygous for the same trait, what is the chance of producing an offspring with the homozygous recessive phenotype? a. 50% b. 75% c. 0% d. 25%

a. 50%

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? a. 8% b. 16% c. 31% d. 42%

a. 8%

Which of these is currently considered the best definition of a gene? a. A gene codes for either a polypeptide or an RNA molecule. b. A gene codes for a single protein. c. A gene codes for a particular ribozyme. d. A gene codes for a single polypeptide. e. A gene codes for a single enzyme.

a. A gene codes for either a polypeptide or an RNA molecule.

The genetic code is essentially the same for all organisms. Base on this information, one can logically assume which of the following statements to be correct? a. A gene from an organism can theoretically be expressed by any other organism. b. Gene expression differs considerably in different organisms. c. The same codons in different organisms translate into the different amino acids. d. DNA was the first genetic material.

a. A gene from an organism can theoretically be expressed by any other organism.

Which of the following processes only occurs in eukaryotic gene expression? a. A poly-A tail is added to the 3' end of an mRNA, and a cap is added to the 5' end. b. RNA polymerase binds to the promoter c. Transcription can begin as soon as translation has assembled the first few amino acids in the polypeptide. d. mRNA, tRNA, and rRNA are transcribed.

a. A poly-A tail is added to the 3' end of an mRNA, and a cap is added to the 5' end.

What is the difference between heterozygous and homozygous individuals? a. All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ. b. The homozygote will express the dominant trait and the heterozygote will express the recessive trait. c. Heterozygotes carry two copies of a gene while homozygotes only carry one. d. Homozygotes have one chromosome while heterozygotes have two similar chromosomes.

a. All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ.

What determines which base is to be added to an RNA strand during transcription? a. Base pairing between the DNA template strand and the RNA nucleotides. b. The previous base. c. Base pairing between the two DNA strands. d. The order of the chemical groups in the backbone of the RNA molecule.

a. Base pairing between the DNA template and the RNA nucleotides.

The diagram below shows a bacterial replication fork and its principal proteins. Drag the labels to their appropriate locations in the diagram to describe the name or function of each structure.

a. Breaks hydrogen bonds, unwinding DNA double helix. b. Synthesizes RNA primers on leading and lagging strands. c. Replaces RNA primers with DNA nucleotides. d. Catalyzes phosphodiester bond formation, joining DNA fragments. e. Lagging strand f. Leading strand g. Relaxes supercoiled DNA. h. Coats single-stranded DNA i. Synthesizes DNA 5' to 3' on leading and lagging strands.

How is the aging process linked to telomeres? a. Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired. b. When a person ages, they begin to get larger and larger telomeres. c. There is only a link between the aging process and telomeres in naked mole rats - but not in humans. d. When telomeres get too long, a signal is sent to the gene to stop the production of all proteins.

a. Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired.

In E. coli, which of the following enzymes removes the RNA primer from the 5' end of the DNA fragment? a. DNA polymerase I b. ligase c. DNA polymerase III d. helicase

a. DNA polymerase I

Which enzyme in E. coli catalyzes the elongation of a DNA strand in the 5' → 3' direction? a. topoisomerase b. primase c. DNA ligase d. DNA polymerase III

a. DNA polymerase III

Which of the following shows the flow of genetic information? a. DNA to RNA to protein b. protein to RNA to DNA c. RNA to DNA to protein d. DNA to RNA to ribosomes

a. DNA to RNA to protein

For the following question(s), match the key event of meiosis with the stages listed below. I. phrophase I - V. prophase II II. metaphase I - VI. metaphase II III. anaphase I - VII. anaphase II IV. telophase I - VIII. telophase II Synaptonemal complexes form or are still present. a. I. prophase I only b. I. prophase I and IV. telophase I only c. I. prophase I and VIII. telophase II only d. I. prophase I, II metaphase I, III. anaphase I, and IV. telophase I only

a. I. prophase I only

In peas the allele for inflated pods (I) is dominant to that for constricted pods (i), and the allele for green pods (G) is dominant to that for yellow pods (g). A plant of unknown genotype with inflated green pods is crossed with a plant with constricted yellow pods. Among the offspring all 93 plants have inflated green pods. What was the previously unknown genotype? a. IIGG b. IiGg c. IiGG d. IIGg

a. IIGG

In peas the allele for inflated pods (I) is dominant to that for constricted pods (i), and the allele for green pods (G) is dominant to that for yellow pods (g). A plant of unknown genotype with inflated green pods is crossed with a plant with constricted yellow pods. Among the offspring are 49 plants with inflated green pods and 53 plants with constricted green pods. What was the previously unknown genotype? a. IiGG b. IiGg c. IIGg d. IIGG

a. IiGG

What is the function of the release factor in translation? a. It binds to the stop codon in the A site in place of a tRNA. b. It releases the ribosome from the ER to allow polypeptides into the cytosol. c. It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. d. It separates tRNA in the A site from the growing polypeptide.

a. It binds to the stop codon in the A site in place of a tRNA.

Which of the following is a function of a poly-A tail in mRNA? a. It helps protect the mRNA from degradation by hydrolytic enzymes. b. It indicates the site of translational termination. c. It is a sequence that codes for the binding of RNA polymerase to the DNA. d. It adds the modified guanine to the 3' end of the mRNA.

a. It helps protect the mRNA from degradation by hydrolytic enzymes.

Albinism in humans occurs when both alleles at a locus produce defective enzymes in the biochemical pathway leading to the pigment melanin. Given that heterozygotes are normally pigmented, which of the following statements is correct? a. One normal allele produces sufficient melanin as compared to two normal alleles. b. Each defective allele produces a little bit of melanin. c. Two normal alleles are needed for normal melanin production. d. The two alleles are codominant.

a. One normal allele produces sufficient melanin as compared to two normal alleles.

What is the name given to the process in which pre-mRNA is edited into mRNA? a. RNA processing b. gene expression c. polypeptide formation d. transcription e. translation

a. RNA processing

When homologous chromosomes cross over, what is the result? a. Specific proteins break the two strands of non sister chromatids and re-join them. b. Two sister chromatids get tangled, resulting in one altering the sequence of its DNA. c. Two sister chromatids exchange identical pieces of DNA. d. Each of the four DNA strands of a homologous pair is broken, and the pieces are mixed.

a. Specific proteins break the two strands of non sister chromatids and re-join them.

In DNA replication in bacteria, the enzyme DNA polymerase III (abbreviated DNA pol III) adds nucleotides to a template strand of DNA. But DNA pol III cannot start a new strand from scratch. Instead, a primer must pair with the template strand, and DNA pol III then adds nucleotides to the primer, complementary to the template strand. Each of the four images below shows a strand of template DNA (dark blue) with an RNA primer (red) to which DNA pol III will add nucleotides. In which image will adenine (A) be the next nucleotide to be added to the primer? a. T CG GC CG A b. C CG GC CG T c. A CG GC CG G d. G CG GC CG C

a. T CG GC CG A

What is meant by the description "antiparallel" regarding the strands that make up DNA? a. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. b. The twisting nature of DNA creates nonparallel strands. c. Base pairings create unequal spacing between the two DNA strands. d. One strand contains only purines and the other contains only pyrimidines.

a. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

Comparing the leading and the lagging strands of DNA synthesis, how do they differ? a. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. b. The leading strand is synthesized at twice the rate of the lagging strand. c. The leading strand is synthesized in short fragments that are ultimately stitched together, whereas the lagging strand is synthesized continuously. d. The leading strand is synthesized by adding nucleotides to the 3′ end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5′ end.

a. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

Which of the following statements correctly describes how the leading and the lagging strands of DNA formed during DNA replication differ? a. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. b. The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. c. The leading strand is synthesized at twice the rate of the lagging strand. d. The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.

a. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

Suppose that the triplet of nucleotides indicated in bold (AGC) spans two codons, that is, CTA and GCC. If the triplet AGC were deleted from this DNA coding sequence, what effect would it have on the resulting protein? 5'-ATGCTAGCCTATCGTAAC-3' a. The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift. b. All of the amino acids up to the deletion would be altered due to the frameshift. c. All of the amino acids after the deletion would be altered due to the frameshift. d. The entire amino acid sequence would be altered due to the frameshift.

a. The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? a. Traits are inherited in discrete units and are not the results of the "blending" of traits. b. An organism that is homozygous for many recessive traits is at a disadvantage. c. Recessive genes occur more frequently in the F1 generation than do dominant ones. d. There is considerable genetic variation in garden peas.

a. Traits are inherited in discrete units and are not the results of the "blending" of traits.

Which of the following statements most accurately describes transformation in bacteria? a. Transformation is the assimilation of external DNA into a cell. b. Transformation is the infection of cells by a phage DNA molecule. c. Transformation is the creation of a strand DNA from an RNA molecule. d. Transformation is the creation of strand RNA from a DNA molecule.

a. Transformation is the assimilation of external DNA into a cell.

True or False? The same phenotype can be produced by more than one genotype? a. True b. False

a. True

Use the codon table to determine which mRNA triplets code for the amino acid cysteine, Cys. a. UGC b. AGU c. UGU d. UGG e. ACA

a. UGC and c. UGU

Which of the following mutations would MOST likely to have a harmful effect on an organism? a. a single nucleotide insertion downstream of, and close to, the start of the coding sequence b. a single nucleotide deletion in the middle of an intron c. a single nucleotide deletion near the end of the coding sequence d. a deletion of three nucleotides near the middle of a gene

a. a single nucleotide insertion downstream of, and close to, the start of the coding sequence

What enzyme catalyzes the attachment of an amino acid to tRNA? a. aminoacyl-tRNA synthase b. rubisco c. dextrinase d. argininosuccinate lyse e. nuclease

a. aminoacyl-tRNA synthase

Many enzymes are named for the substrate on which they work, either to build or disassemble molecules. Also, enzyme names often end in "-ase." For example, lactase is the enzyme that breaks down lactose. With a name like "telomerase," we can deduce that telomerase is probably: a. an enzyme that regulates the assembly of DNA at the ends of chromosomes b. some type of a nucleotide that codes for protein, perhaps DNA or RNA c. a protein that tells the cell when to divide and produce new cells d. an enzyme that chains sugars together to make starches, to provide food for the cell

a. an enzyme that regulates the assembly of DNA at the ends of chromosomes

Based on the risk factors discussed in the video, which of the following groups would be most likely to develop the bone disease rickets? a. children born to parents with dark skin living far from the equator b. adults with dark skin who live close to the equator c. children born to parents with light skin living close to the equator d. adults with light skin who live far from the equator

a. children born to parents with dark skin living far from the equator

While constructing a Punnett square, the symbols on the outside of the boxes represent ________, while those inside the boxes represent ________. a. gametes; progeny b. progeny; gametes c. parents; gametes d. gametes; parents

a. gametes; progeny

Arrange the following terms in order, from smallest to largest size: nucleosome, metaphase chromosome, histone, 30-nm fiber. a. histone, nucleosome, 30-nm fiber, metaphase chromosome b. nucleosome, histone, 30-nm fiber, metaphase chromosome c. histone, nucleosome, metaphase chromosome, 30-nm fiber d. 30-nm fiber, histone, nucleosome, metaphase chromosome

a. histone, nucleosome, 30-nm fiber, metaphase chromosome

enzyme 1 enzyme 2 A−−−−−−−−−−−→B−−−−−−−−−−→C Examine the simple metabolic pathway above. If A, B, and C are all substances required for growth of the organism that carries out this pathway, a strain that is mutant for the gene encoding enzyme 1 would be able to grow on which of the following media? a. minimal medium supplemented with nutrient B only b. minimal medium with no supplements c. minimal medium supplemented with nutrient A only d. minimal medium

a. minimal medium supplemented with nutrient B only

If you wished to observe chiasmata forming during meiosis, what stage of meiosis would have the best cells to use? a. prophase I b. anaphase I c. prophase II d. anaphase II

a. prophase I

The function of the spliceosome is to ________. a. remove introns and splice together exons b. remove eons and splice together introns c. splice together introns and exons d. remove both introns and exons

a. remove introns and splice together exons

Where does translation take place? a. ribosome b. nucleus c. endoplasmic reticulum d. Golgi apparatus

a. ribosome

When a mutation caused by a nucleotide pair insertion occurs in a protein coding region, which of the following effects is least likely to occur? a. silent b. frameshift c. missense d. nonsense

a. silent

Two plants are crossed, resulting in offspring with a 3:1 ration for a particular trait. What does this suggest about the trait? a. that the parents were both heterozygous for a single trait b. that the parents were true-breeding for contrasting traits c. that the trait shows incomplete dominance d. that a blending of traits has occurred

a. that the parents were both heterozygous for a single trait

A tall, purple-flowered pea plant (TtPp) is allowed to self-pollinate. (The recessive alleles code for short plants and white flowers.) The phenotypic ratio of the resulting offspring is 9:3:3:1. What is the genotype of the plant whose phenotype appeared once out of every 16 offspring (the "1" in the 9:3:3:1 ratio)? a. ttpp b. TTPP c. TTpp d. TtPp

a. ttpp

Which of the following clues would tell you if a cell is prokaryotic or eukaryotic? a. whether or not the cell in compartmentalized by internal membranes b. whether the cell contains DNA or RNA c. the presence or absence of ribosomes d. the presence or absence of a rigid cell wall

a. whether or not the cell in compartmentalized by internal membranes

In certain plants, the tall trait is dominant to the short trait. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? a. 1 b. 0 c. 1/2 d. 1/4

b. 0

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. How many genes must be responsible for these coat colors in Labrador retrievers? a. 1 b. 2 c. 3 d. 4

b. 2

Given a DNA molecule with the sequence of bases 5'-ATTGCA-3', what would be the sequence of the complementary strand? (It will be helpful to draw the DNA molecule when answering the question.) a. 5'-UAACGU-3' b. 3'-TAACGT-5' c. 3'-UAACGU-5' d. 5'-TAACGT-3'

b. 3'-TAACGT-5'

Suppose a double-stranded DNA molecule was shown to have 15% adenine bases. What would be the expected percentage of guanine bases in that molecule? a. 15% b. 35% c. 85% d. not enough information

b. 35%

Hershey and Chase used _____ to radioactively label the T2 phage's proteins. a. 222Ra b. 35S c. 92U d. 14C e. 32P

b. 35S

The nontemplate strand of a portion of a gene reads 5' AGTGGTTCA 3' . What will be the sequence of the resulting transcript for this portion? a. 5' UGACCAAGU 3' b. 5' AGUGGUUCA 3' c. 5' UGAACCAGU 3' d. 5' ACUUGGUCA 3'

b. 5' AGUGGUUCA 3'

The direction of synthesis of an RNA transcript is ________. a. 1' to 5' b. 5' to 3' c. 1' to 3' d. 3' to 5' e. 2' to 4'

b. 5' to 3'

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? a. 64 b. 8 c. 4 d. 16

b. 8

Transcription begins at a promoter. What is a promoter? a. Part of the RNA molecule itself b. A site in DNA that recruits the RNA Polymerase c. A site found on the RNA Polymerase d. The same as a start codon

b. A site in DNA that recruits the RNA Polymerase

Which of these is a tRNA? a. A b. B c. C d. D e. E

b. B

If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants? a. Breed this plant with another plant with much weaker traits. b. Clone the plant asexually to produce an identical one. c. Force the plant to self-pollinate to obtain an identical one. d. Backtrack through her previous experiments to obtain another plant with the same traits.

b. Clone the plant asexually to produce an identical one.

In the diagram below, the blue strands represent ________. a. RNA b. DNA c. transcription factors d. RNA polymerase e. the promoter

b. DNA

Which component is NOT directly involved in translation? a. ribosomes b. DNA c. tRNA d. GTP

b. DNA

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. These results indicate which of the following about the inheritance pattern of fur color in Labrador retrievers? a. Brown is dominant to black. b. Epistasis is involved. c. Black is dominant to brown and yellow. d. Yellow is dominant to black.

b. Epistasis is involved.

True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated. a. True b. False

b. False

True or false? In diploid organisms, a dominant phenotype will only be expressed if the individual is homozygous dominant for that trait. a. True b. False

b. False

Which of the following has the greatest potential as a cancer treatment? a. Find a way to turn on the gene for making telomerase in normal cells, so that the normal cells would soon outnumber the cancer cells. b. Find a way to turn off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone. c. Find a way to turn on the gene for making telomerase in cancer cells, since they will be unable to divide if their telomeres are too long. d. Find a way to turn off the gene for making telomerase in all cells in embryos, so that they never develop cancer.

b. Find a way to turn off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone.

Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA? a. Griffith b. Franklin c. Meselson and Stahl d. Chargaff e. McClintock

b. Franklin

Which of these correctly illustrates the pairing of DNA and RNA nucleotides? a. GTTACG & CAATCG b. GTTACG & CAAUGC c. GTTACG & GTTACG d. GTTACG & ACCGTA e. GTTACG & UAACAU

b. GTTACG & CAAUGC

Using the table on the left, identify a polypeptide sequence if the DNA template strand for an mRNA is: 5′−CTGAGGCATGCC−3′ a. Pro-Tyr-Gly-Val b. Gly-Met-Pro-Gln c. Asp-Ser-Val-Arg d. Met-Pro-Gln

b. Gly-Met-Pro-Gln

Diploid cells may undergo either mitosis or meiosis. Can haploid cells? a. Haploid cells can undergo both mitosis and meiosis. b. Haploid cells can undergo mitosis but not meiosis. c. Haploid cells can undergo meiosis but not mitosis. d. Haploid cells can undergo neither mitosis nor meiosis.

b. Haploid cells can undergo mitosis but not meiosis.

An individual with dark skin will be advised to take capsules with vitamin D if he moves to Northern Europe. This is because: a. It is important to take multivitamins when you're adjusting to a new environment. b. Having more melanin in your skin blocks the sun which is in charge of fixing vitamin D in your bones. c. There is too much sunlight in his new environment so he is better protected.

b. Having more melanin in your skin blocks the sun which is in charge of fixing vitamin D in your bones.

Which of the following happens during meiosis I? a. Sister chromatids are separated. b. Homologous chromosomes of a pair are separated from each other. c. Four daughter cells are formed. d. The chromosome number per cell in conserved.

b. Homologous chromosomes of a pair are separated from each other.

For the following question(s), match the key event of meiosis with the stages listed below. I. phrophase I - V. prophase II II. metaphase I - VI. metaphase II III. anaphase I - VII. anaphase II IV. telophase I - VIII. telophase II Homologous chromosomes are aligned at the equator of the spindle. a. I. prophase I b. II. metaphase I c. IV. telophase I d. VI. metaphase II

b. II. metaphase I

What happens to RNA polymerase II after it has completed transcription of a gene? a. It is degraded. b. It is free to bind to another promoter and begin transcription. c. It begins with transcribing the next gene on the chromosome. d. It joins with another RNA polymerase to carry out transcription.

b. It is free to bind to another promoter and begin transcription.

Where does RNA polymerase begin transcribing a gene into mRNA? a. Transfer RNA acts to translate the message to RNA polymerase b. It starts after a certain nucleotide sequence called a promoter c. It starts at one end of the chromosome d. The ribosome directs it to the correct portion of the DNA molecule e. It looks for the AUG start codon.

b. It starts after a certain nucleotide sequence called a promoter

Why is it more practical to prepare karyotypes by viewing somatic diploid cells rather than haploid gametes? a. Only diploid cells have condensed chromosomes. b. Only diploid cells have all the organism's chromosomes. c. Haploid cells are too small. d. Haploid cells are not easily available.

b. Only diploid cells have all the organism's chromosomes.

Which of the following statements correctly describes one difference between the law of independent assortment and the law of segregation? a. The law of segregation is accounted for by anaphase of mitosis. b. The law of independent assortment explains the segregation of two or more genes relative to one another. c. The law of segregation explains the segregation of two or more genes relative to one another. d. The law of segregation requires having two or more generations to describe.

b. The law of independent assortment explains the segregation of two or more genes relative to one another.

DNA is a self-replicating molecule. What accounts for this important property of DNA? a. Its two strands are held together by easily broken covalent bonds. b. The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C. c. Replication is thermodynamically spontaneous and requires no enzymes.

b. The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C.

Which of the following statements best describes the promoter of a protein-coding gene? a. The promoter is part of the RNA molecule itself. b. The promoter is a non transcribed region of a gene. c. The promoter is a site found on RNA Polymerase. d. The promoter is a site at which only RNA polymerase will bind.

b. The promoter is a nonstranscribed region of a gene.

Which of the following is NOT true about naked mole rats? a. They can survive in burrows with high levels or carbon dioxide. b. Their cells do not produce telomerase. c. They often live for 30 years. d. They seem to be resistant to getting cancer.

b. Their cells do not produce telomerase.

During mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules much have which of the following properties? a. They must be intact for nuclear envelope re-formation. b. They must be removed before sister chromatids or homologous chromosomes can separate. c. They must be removed before meiosis can begin. d. They must persist throughout the cell cycle.

b. They must be removed before sister chromatids or homologous chromosomes can separate.

What was Mendel's explanation for his observation that traits that had disappeared in the F1 generation reappeared in the F2 generation of the pea plants he used in his experiments? a. The mechanism controlling the appearance of traits was different between the F1 and the F2 plants. b. Traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1. c. New mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. d. The traits were lost in the F1 due to dominance of the parental traits

b. Traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1.

Which of the following types of cells would be produced by meiosis? a. a diploid unicellular organism b. a haploid animal cell c. a diploid plant cell d. a diploid animal cell

b. a haploid animal cell

If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following? a. up to 18 genes for that trait b. at most 2 alleles for that gene c. up to 18 chromosomes with that gene d. up to, but not more than, 18 different traits

b. at most, 2 alleles for that gene

To "sequence" DNA means to ________. a. arrange molecules by their relative sizes b. determine the order of bases in a molecule c. allow two strands to base pair with each other d. replicate DNA as accurately as possible

b. determine the order of bases in a molecule

In Meselson and Stahl's experiment proving semi-conservative DNA replication, they showed that after switching bacteria from heavy to light nitrogen and allowing one round of replication, their DNA consisted of only hybrid DNA. What did they observe after the second round of replication? a. only hybrid DNA b. equal amounts of light and hybrid DNA c. equal amounts of light, hybrid and heavy DNA d. three times as much light as hybrid DNA

b. equal amounts of light and hybrid DNA

When a mutation caused by a nucleotide pair substitution occurs in a protein coding region, which of the following effects is least likely to occur? a. silent b. frameshift c. missense d. nonsense

b. frameshift

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant trait. True-breeding red-flowered long radishes are crossed with true-breeding white-flowered radishes. All of the F1 offspring are purple-flowered and long radishes. The flower color trait in radishes is an example of which of the following types of inheritance? a. codominance b. incomplete dominance c. a multiple allelic system d. sex linkage

b. incomplete dominance

Which nucleic acid is translated to make a protein? a. DNA b. mRNA c. rRNA d. tRNA

b. mRNA

Characters in humans such as a person's red and white blood cell counts very quite a bit depending on such factors such as altitude and physical activity. Traits like this are referred to as ________. a. polygenic b. multifactorial c. completely dominant d. recessive

b. multifactorial

Tetracycline antibiotics bind to the A site on the bacterial ribosome and prevent further translation. Where would you expect polypeptides to accumulate on tetracycline-inhibited ribosomes? a. on a tRNA attached to the E site b. on a tRNA attached to the P site c. on a tRNA attached to the A site d. alternating between tRNAs attached to the P site and tRNAs attached to the A site

b. on a tRNA attached to the P site

DNA does not store the information to synthesize which of the following? a. proteins b. organelles c. messenger RNA d. DNA

b. organelles

Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging in breathing difficulties to recurrent infections. Which of the following terms best describes this expression of phenotypes? a. epistasis b. pleiotropy c. multiple alleles d. incomplete dominance

b. pleiotropy

Which of the following describes the ability of a single gene to have multiple phenotypic effects? a. incomplete dominance b. pleiotropy c. epistasis d. multiple alleles

b. pleiotropy

When we see chiasmata under a microscope, that lets us know that which of the following processes has occurred? a. anaphase II b. prophase I c. meiosis II d. separation of homologs

b. prophase I

What are telomeres? a. DNA sequences which code for making proteins that regulate cell division b. regions of DNA at the end of chromosomes which do not code for making proteins c. "junk DNA" present throughout the length of our chromosomes d. protein caps found on the ends of chromosomes

b. regions of DNA at the end of chromosomes which do not code for making proteins

Which of the following molecule(s) help(s) to hold the DNA strands apart while they are being replicated? a. primase b. single-strand binding proteins c. ligase d. DNA polymerase

b. single-strand binding proteins

In his work with pneumonia-causing bacteria and mice, Griffith found that ________. a. the protein coat from pathogenic cells was able to transform nonpathogenic cells b. some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic c. heat-killed pathogenic cells caused pneumonia d. the polysaccharide coat of bacteria caused pneumonia

b. some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic

Prophase I of meiosis is generally the longest phase of meiosis. Why might this be? a. DNA replication b. synapsis and recombination c. independent assortment d. gamete formation

b. synapsis and recombination

Which of the following would typically not be used to clone DNA? a. plasmid vector b. telomerase c. restriction enzyme d. PCR

b. telomerase

Independent assortment of chromosomes during meiosis is a result of ________. a. the random nature of fertilization of ova by sperm b. the random and independent way in which each pair of homologous chromosomes lines up at the c. the relatively small degree of homology shared by the X and Y chromosomes d. the random distribution of the sister chromatids to the two daughter cells during anaphase II

b. the random and independent way in which each pair of homologous chromosomes lines up at the

What is the process called that converts the genetic information stored in DNA to an RNA copy? a. translocation b. transcription c. replication d. translation

b. transcription

Labrador retrievers have black, brown, or yellow fur. Fur color is controlled by two genes, one of which exhibits epistasis. Black (B) is dominant over brown (b) in one gene, and (E) is dominant over (e) in the other gene. The (E) gene is epistatic to the (B) gene. In a cross of a black female with a brown male, results can be all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. In one cross of black × black, the results were as follows: 9/16 black, 4/16 yellow, 3/16 brown. The genotype eebb must result in which of the following? a. a lethal result b. yellow c. black d. brown

b. yellow

Suppose a 100-base-pair DNA molecule consists of 20% cytosine bases. How many total hydrogen bonds are there holding the two strands together? a. 20 b. 60 c. 120 d. 240

c. 120

Two true-breeding stocks of pea plants are crossed. One parent has red axial flowers, and the other has white terminal flowers; all F1 individuals have red axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red terminal flowers? a. 250 b. 65 c. 190 d. 565

c. 190

enzyme 1 enzyme 2 A−−−−−−−−−−−→B−−−−−−−−−−→C Examine the simple metabolic pathway above. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway? a. 0 b. 1 c. 2 d. 3

c. 2

What is the minimum number of amino acyl tRNA synthetases there should be? a. 64 b. 61 c. 20 d. 3

c. 20

Examine the table of codons in the figure above. A possible sequence of nucleotides in the template strand of DNA that would code for polypeptide sequence phe-leu-ile-val would be ________. a. 3'-AAC-GAC-GUC-AUA-5' b. 5'-TTG-CTA-CAG-TAG-3' c. 3'-AAA-GAA-TAA-CAA-5' d. 5'-AUG-CTG-CAG-TAT-3'.

c. 3'-AAA-GAA-TAA-CAA-5'

If one strand is 5'-GCAC-3', the complementary strand must be a. 3'-GCAC-5' b. 3'-ATCG-5' c. 3'-CGTG-5' d. 3'-GTGC-5' e. 3'-CACG-5'

c. 3'-CGTG-5'

At which site do new aminoacyl tRNAs enter the ribosome during elongation? a. B-site b. P-site c. A-site d. E-site

c. A-site

A part of the promoter, called the TATA box, is said to be highly conserved in many different organisms throughout evolution. Which of the following correctly describes why this is the case? a. The sequence evolves very rapidly b. The sequence does not mutate c. Any mutation in the sequence is selected against d. The sequence is found in many but not all promoters

c. Any mutation in the sequence is selected against

The radioactive isotope 32P labels the T2 phage's _____. a. base plate b. protein coat c. DNA d. head e. tail

c. DNA

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? a. DNA contains purines, whereas protein includes pyrimidines. b. DNA contains nitrogen, whereas protein does not. c. DNA contains phosphorus, whereas protein does not. d. DNA contains sulfur, whereas protein does not.

c. DNA contains phosphorus, whereas protein does not.

A student isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. After adding some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has the student probably LEFT OUT of the mixture? a. Okazaki fragments b. DNA polymerase c. DNA ligase d. primase

c. DNA ligase

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? a. DNA ligase works only in the 3′ → 5′ direction. b. The origins of replication occur only at the 5′ end. c. DNA polymerase can join new nucleotides only to the 3′ end of a preexisting strand, and the strands are antiparallel. d. Helicases and single-strand binding proteins work at the 5′ end.

c. DNA polymerase can join new nucleotides only to the 3′ end of a preexisting strand, and the strands are antiparallel.

After mixing a heat-killed, phosphorescent (light-emitting) strain of bacteria with a living, nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observation(s) would provide the best evidence that the ability to phosphoresce is a heritable trait? a. DNA passed from the heat-killed strain to the living strain. b. Protein passed from the heat-killed strain to the living strain. c. Descendants of the living cells are also phosphorescent. d. The phosphorescence in the living strain is especially bright.

c. Descendants of the living cells are also phosphorescent.

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) already in the ribosome. Where does tRNA #2 move to after this bonding of lysine to the polypeptide? a. A site b. exit tunnel c. E site d. P site

c. E site

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? a. Transform bacteria with a recombinant DNA molecule. Cut the plasmid DNA using restriction enzymes. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Extract plasmid DNA from bacterial cells. Use ligase to seal plasmid DNA to nonplasmid DNA. b. Extract plasmid DNA from bacterial cells. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Use ligase to seal plasmid DNA to nonplasmid DNA. Transform bacteria with a recombinant DNA molecule. Cut the plasmid DNA using restriction enzymes. c. Extract plasmid DNA from bacterial cells. Cut the plasmid DNA using restriction enzymes. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Use ligase to seal plasmid DNA to nonplasmid DNA. Transform bacteria with a recombinant DNA molecule. d. Cut the plasmid DNA using restriction enzymes. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Use ligase to seal plasmid DNA to nonplasmid DNA. Extract plasmid DNA from bacterial cells. Transform bacteria with a recombinant DNA molecule.

c. Extract plasmid DNA from bacterial cells. Cut the plasmid DNA using restriction enzymes. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Use ligase to seal plasmid DNA to nonplasmid DNA. Transform bacteria with a recombinant DNA molecule.

The somatic cells of a privet shrub each contain 46 chromosomes. To be as different as they are from human cells, which have the same number of chromosomes, which of the following must be true? a. Privet cells cannot reproduce sexually. b. Privet shrubs must be metabolically more like animals than like other shrubs. c. Genes of privet chromosomes are significantly different from those in humans. d. Genes on a particular privet chromosome, such as the X, must be on a different human chromosome, such as number 18.

c. Genes of privet chromosomes are significantly different from those in humans.

Which of the following statements correctly describes an example of epistasis? a. In Drosophila (fruit flies), white eyes can be due to a combination of multiple genes. b. In cacti, there are several genes for the type of spines. c. In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing. d. Recessive genotypes for each of two genes (aabb) result in an albino corn snake.

c. In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.

D N A replication overall has very high fidelity, but it is not perfect. What is the biological and evolutionary importance of this imperfection? a. It allows for DNA repair to occur. b. It allows for gene cloning. c. It allows for genetic variation. d. It allows for gene editing.

c. It allows for genetic variation.

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following? a. It must be human. b. It must be sexually reproducing. c. Its gametes must have 23 chromosomes. d. It must be an animal.

c. Its gametes must have 23 chromosomes.

If an organism with the genotype AaBb produces gametes, what proportion of the gametes would be Bb? a. 1/2 b. 3/4 c. None d. 1/4

c. None

Which of the following problems during DNA replication is being illustrated with the kids in the video? a. DNA replication is a very random process, and many mistakes are made. b. DNA replication only occurs in cancer cells. c. Nucleotides at the ends of the DNA strands are lost when DNA replicates. d. Within a chromosome, there is more telomerase than there is DNA.

c. Nucleotides at the ends of the DNA strands are lost when DNA replicates.

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? a. Each allele affected phenotype expression. b. No genes interacted to produce the parental phenotype. c. One allele was dominant. d. The traits blended together during fertilization.

c. One allele was dominant.

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA known as pre-mRNA? a. RNA polymerase III b. ligase c. RNA polymerase II d. RNA polymerase I

c. RNA polymerase II

Which cells are most likely to have the gene for making telomerase switched on? a. The nerve cells of a 55 year old man. b. The skin cells of a 28 year old person. c. The cells in a developing embryo. d. The muscle cells of a woman who is 80 years old.

c. The cells in a developing embryo.

Which of the following steps occurs last in the initiation phase of translation? a. The small subunit of the ribosome binds to the 5' cap on the mRNA. b. An aminoacyl tRNA binds to the start codon. c. The large ribosomal subunit joins the complex. d. A peptide bond is formed between two adjacent amino acids.

c. The large ribosomal subunit joins the complex.

Which of the following statements correctly describes one of Chargaff's rules regarding DNA? a. The percentages of adenine and cytosine are roughly equal, as are the percentages of guanine and thymine in the DNA of a given species. b. DNA has a double helical structure. c. The percentages of adenine and thymine are roughly equal, as are the percentages of guanine and cytosine in the DNA of a given species. d. DNA base composition does not vary between species.

c. The percentages of adenine and thymine are roughly equal, as are the percentages of guanine and cytosine in the DNA of a given species.

A eukaryotic mutation upstream of a particular gene has been identified that changes the sequence of the TATA box to GATA. How would you predict that this mutation would affect the transcription of this gene? a. Transcription would proceed normally. b. Transcription factors would bind in the middle of the gene sequence and transcribe the gene from that point. c. Transcription factor binding would be reduced or eliminated, and transcription of the gene would decrease dramatically. d. Transcription factors would bind to the start point in the promoter region.

c. Transcription factor binding would be reduced or eliminated, and transcription of the gene would decrease dramatically.

enzyme 1 enzyme 2 A−−−−−−−−−−−→B−−−−−−−−−−→C Examine the simple metabolic pathway above. A mutation results in a defective enzyme 1. Which of the following results would be a consequence of that mutation? a. an accumulation of B and C and no production of A b. an accumulation of A and B and no production of C c. an accumulation of A and no production of B and C d. an accumulation of B and no production of A and C

c. an accumulation of A and no production of B and C

Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following characteristics? a. binding of ribosomes to mRNA b. attachment of amino acids to tRNAs c. bonding of the anticodon to the codon and the attachment of amino acids to tRNAs d. shape of the A and P sites of ribosomes

c. bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

The elongation of the leading strand during DNA synthesis _______. a. progresses away from the replication fork b. occurs in the 3' → 5' direction c. depends on the action of DNA polymerase d. produces Okazaki fragments

c. depends on the action of DNA polymerase

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of ________. a. complete dominance b. pleiotropy c. epistasis d. incomplete dominance

c. epistasis

What is the name of the process shown in the diagram? a. initiation (of transcription) b. RNA processing c. initiation (of translation) d. elongation e. termination (of translation)

c. initiation (of translation)

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contain ________, which demonstrated that ________ is the phage's genetic material. a. labeled protein; protein b. labeled DNA; labeled protein c. labeled DNA; DNA d. labeled protein; DNA e. labeled DNA; protein

c. labeled DNA; DNA

At what state of mitosis are chromosomes usually photographed in the preparation of a karyotype? a. anaphase b. prophase c. metaphase d. telophase

c. metaphase

At what stage is the independent assortment of chromosomes determined? a. prophase I pairing of homologs b. anaphase II separation of homologs c. metaphase I alignment of paired homologs d. telophase I

c. metaphase I alignment of paired homologs

To visualize and identify meiotic cells at metaphase I with a microscope, what would you look for? a. an uninterrupted spindle array b. sister chromatids of a replicated chromosome grouped at the poles c. pairs of homologous chromosomes all aligned at the cell's center d. individual chromosomes all at the cell's center

c. pairs of homologous chromosomes all aligned at the cell's center

Which of the following processes is an example of a post-translational modification? a. peptide bond formation b. initiation c. phosphorylation d. elongation

c. phosphorylation

Skin color in humans has a wide variety of phenotypes. The expression of this trait is caused by more than two genes. What type of inheritance patter is responsible for this expression? a. codominance b. complete dominance c. polygenic inheritance d. incomplete dominance

c. polygenic inheritance

Which of the following lists of replication enzymes consist only of polymerases? a. helicase, primase, DNA pol III b. ligase, DNA pol I c. primase, DNA pol I, DNA pol III c. DNA pol I, DNA pol III, helicase

c. primase, DNA pol I, DNA pol III

What kind of molecules are transcription factors? a. DNA b. RNA c. proteins d. lipids

c. proteins

Which of the following is not involved in the transmission of genes from parent organism to child? a. DNA b. gametes c. somatic cells d. mitosis e. nucleotides

c. somatic cells

Which of the following events occurs in meiosis but not in mitosis? a. production of daughter cells b. condensation of chromatin c. synapsis of chromosomes d. chromosome replication

c. synapsis of chromosomes

Which of the following characteristics of the structure of DNA was determined directly from X-ray diffraction photographs of crystallized DNA? a. the sequence of nucleotides b. the length of a given DNA molecule c. the double helical structure d. the frequency of A versus T nucleotides

c. the double helical structure

Darker skin is more prevalent in high-UV areas. Dr. Nina Jablonski proposed a hypothesis to explain the selective pressure for darker skin in these environments. On what evidence did she base this hypothesis? a. she discovered that people of African descent have less folate circulating in their blood and that folate is important for human reproduction b. the melanin in darkly pigmented skin protects DNA from UV radiation, and UV radiation can cause skin cancer c. the melanin in darkly pigmented skin protects circulating folate from being destroyed by UV radiation, and folate is important in human reproduction d. people of African descent all have the same version of the MC1R gene, indicating that this gene was under selection

c. the melanin in darkly pigmented skin protects circulating folate from being destroyed by UV radiation, and folate is important in human reproduction

In humans, wavy hair occurs in heterozygotes (HSHC) offspring of people with straight hair (HSHS) and curly hair (HCHC). Which of the following crosses would produce offspring with the ratio of 1 straight:2 wavy:1 curly? a. straight x straight b. curly x wavy c. wavy x wavy d. curly x curly

c. wavy x wavy

In what way does natural selection depend on the specific environment in which an organism lives? a. natural selection is random, and the direction of the selective pressure cannot be predicted based on the environment. b. natural selection produces traits that are always either helpful or harmful, regardless of the environment. c. when the environment changes, traits that were beneficial to an organism may become harmful and vice versa. d. when an organism enters a new environment, it evolves all of the traits it needs to survive there

c. when the environment changes, traits that were beneficial to an organism may become harmful and vice versa.

Which of the following sequences shows a frameshift mutation compared to the wild-type mRNA sequence? a. wild-type: 5'-AUGCAUACAUUGGAGUGA-3' mutant: 5'-AUGCAUACAGAGUGA-3' b. wild-type: 5'-AUGCAUACAUUGGAGUGA-3' mutant: 5'-AUGCAUACGUUGGAGUGA-3' c. wild-type: 5'-AUGCAUACAUUGGAGUGA-3' mutant: 5'-AUGCAUACAUCUGGAGUGA-3' d. wild-type: 5'-AUGCAUACAUUGGAGUGA-3' mutant: 5'-AUGCAUGUGACAUUGGAGUGA-3'

c. wild-type: 5'-AUGCAUACAUUGGAGUGA-3' mutant: 5'-AUGCAUACAUCUGGAGUGA-3'

A haploid set of unreplicated chromosomes (n = 4) of the fruit fly Drosophila melanogaster has a mass of 0.14 p g. What is the mass of D N A in single Drosophila cell at the end of prophase I? a. 0.14 pg b. 0.28 pg c. 0.42 pg d. 0.56 pg

d. 0.56 pg

Two mice are heterozygous for albinism (Aa) . The dominant allele (A) codes for normal pigmentation, and the recessive allele (a) codes for no pigmentation. What percentage of their offspring would have an albino phenotype? a. 100 b. 50 c. 75 d. 25

d. 25

In a long random sequence of A, C, G, or U, how often should a stop codon appear? a. almost never b. 1/3 c. 1/64 d. 3/64

d. 3/64

The template strand of a portion of a gene reads 5' TCATTGCAA 3'. What will be the sequence of the resulting transcript for this portion? a. 5' UCAUUGCAA 3' b. 5' AACGUUACU 3' c. 5' AGUAACGUU 3' d. 5' UUGCAAUGA 3'

d. 5' UUGCAAUGA 3'

In which group(s) of organisms would you expect to see coupled transcription and translation? a. bacteria b. archaea c. eukarya d. A and B e. A, B, and C

d. A and B

Which of the following statements correctly describes a monohybrid cross? a. A monohybrid cross is performed for one generation. b. A monohybrid cross involves a single offspring. c. A monohybrid cross involves a single parent. d. A monohybrid cross involves organisms that are heterozygous for one character.

d. A monohybrid cross involves organisms that are heterozygous for one character.

Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein? a. A frameshift missense mutation will cause an early Stop codon, but a substitution missense might be silent. b. A substitution missense mutation causes the protein to be shorter and thus non-functional. c. A frameshift missense will cause the codons to be out of order, but a substitution missense does not change the order of the codons. d. A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.

d. A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules? a. A=G b. A+T=G+C c. A=C d. A+G=C+T

d. A+G=C+T

The nitrogenous base adenine is found in all members of which of the following groups of molecules? a. proteins, ATP, and DNA b. proteins, triglycerides, and testosterone c. glucose, ATP, and DNA d. ATP, RNA, and DNA

d. ATP, RNA, and DNA

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work? a. The phosphate in normal DNA is naturally radioactive. b. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. c. There is no radioactive isotope of nitrogen. d. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

d. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

What is the 5' --> 3' sequence on the anticodon of the methionine (Met) tRNA? a. AUG b. GUA c. UAC d. CAU

d. CAU

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence ________. a. CAG b. CTG c. GAC d. CUG e. TCG

d. CUG

Which of the following statements correctly defines the process of gene expression? a. Gene expression is the process by which proteins direct the synthesis of DNA. b. Gene expression is the process by which RNA direct the synthesis of DNA. c. Gene expression is the process by which proteins direct the synthesis of RNA. d. Gene expression is the process by which DNA directs the synthesis of proteins.

d. Gene expression is the process by which DNA directs the synthesis of proteins.

A sexually reproducing animal has two unlinked genes, on for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? a. HhTt b. tt c. Hh d. HT

d. HT

Who demonstrated that DNA is the genetic material of the T2 phage? a. Meselson and Stahl b. Darwin and Wallace c. Watson and Crick d. Hershey and Chase e. Franklin

d. Hershey and Chase

Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why? a. It could cause a frameshift nonsense or frameshift missense mutation because it would change the reading frame of the codon triplet. b. It could cause a silent mutation because A and T are complementary to each other so it is not really a substitution mutation. c. It could cause a nonsense mutation because the sequence would no longer be the same, so the protein would be shorter and non-functional. d. It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one.

d. It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one.

What is the main advantage of sexual reproduction over asexual reproduction? a. It is more efficient at producing offspring. b. Two parents can invest resources in offspring. c. It allows for more competition. d. It increases genetic variation among offspring.

d. It increases genetic variation among offspring.

Which of the following statements accurately describes why Taq polymerase is used in PCR? a. Only minute amounts are needed for each cycle of PCR. b. It binds more readily than other polymerases to the primers. c. It has regions that are complimentary to the primers. d. It is heat stable and can withstand the heading step of PCR.

d. It is heat stable and can withstand the heading step of PCR.

Which of the following is NOT true of a codon? a. It may code for the same amino acid as another codon. b. It is the basic unit of the genetic code. c. It never codes for more than one amino acid. d. It is localized at the 5' end of a tRNA molecule.

d. It is localized at the 5' end of a tRNA molecule.

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? a. It unwinds the parental double helix. b. It synthesizes RNA nucleotides to make a primer. c. It catalyzes the lengthening of telomeres. d. It joins Okazaki fragments together.

d. It joins Okazaki fragments together.

Which of the following statements accurately describes melanin's function? a. The more melanin an individual has in his or her skin cells, the more likely he or she is to get mutations in DNA. b. Melanin is a molecule that distinguishes humans from their primate relatives. c. Everyone has the same type of melanin, but the amount varies from person to person. d. Lighter skin has less of the dark-brown eumelanin that protects cells from UV damage.

d. Lighter skin has less of the dark-brown eumelanin that protects cells from UV damage.

The initiator tRNA attaches at the ribosome's ________ site. a. A b. translocation c. E d. P e. Q

d. P

Which of the following statements describes one difference between DNA replication in prokaryotes and DNA replication in eukaryotes? a. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. b. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. c. Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. d. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

d. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

In the diagram below, the gray unit represents ________. a. RNA b. DNA c. transcription factors d. RNA polymerase e. the promoter

d. RNA polymerase

What is meant by translocation? a. The completed polypeptide is rebased from the ribosome. b. The polypeptide chain grows by one amino acid. c. The two ribosomal subunits are joined in a complex. d. The ribosome slides one codon down the mRNA.

d. The ribosome slides one codon down the mRNA.

Privet shrubs and humans each have a diploid number of 46 chromosomes per cell. Why are the two species so dissimilar? a. Privet chromosomes undergo only mitosis. b. Privet chromosomes are shaped differently. c. Human chromosomes have genes grouped together differently. d. The two species have appreciably different genes. e. Privets do not have sex chromosomes.

d. The two species have appreciably different genes.

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis? a. They have half the number of chromosomes and half the amount of DNA. b. They have half the amount of cytoplasm and twice the amount of DNA. c. They have the same number of chromosomes and half the amount of DNA. d. They have half the number of chromosomes and one-fourth the amount of DNA.

d. They have half the number of chromosomes and one-fourth the amount of DNA.

For the following question(s), match the key event of meiosis with the stages listed below. I. phrophase I - V. prophase II II. metaphase I - VI. metaphase II III. anaphase I - VII. anaphase II IV. telophase I - VIII. telophase II Centromeres of sister chromatids disjoin and chromatids separate. a. III. anaphase I b. IV. telophase I c. V. prophase II d. VII. anaphase II

d. VII. anaphase II

What is the direct result of a mutagen? a. problems with mitosis b. decreased permeability of the nuclear envelope c. decreased enzyme activity throughout the cell d. a change in the sequence of DNA e. a reduction in the number of tRNA molecules available for protein synthesis

d. a change in the sequence of DNA

Which of the following descriptions of a nucleotide triplets best represents a codon? a. a triplet that has no corresponding amino acid b. a triplet separated spatially from other triplets c. a triplet at the opposite end of tRNA from the attachment site of the amino acid d. a triplet in the same reading frame as an upstream AUG

d. a triplet in the same reading frame as an upstream AUG

DNA replication overall has very high fidelity. Which of the following phenomena or processes contributes to this high fidelity? a. base pairing b. proofreading c. mismatch pair d. all of the above

d. all of the above

Which of the following are ways in which gametes from one individual diploid cell can be different from one another? a. mutation b. crossing over c. independent assortment d. all of the above

d. all of the above

During a normal translation cycle, where would you expect to find a polypeptide on a ribosome? a. on a tRNA attached to the E site b. on a tRNA attached to the P site c. on a tRNA attached to the A site d. alternating between tRNAs attached to the P site and tRNAs attached to the A site

d. alternating between tRNAs attached to the P site and tRNAs attached to the A site

The backbone of a double stranded DNA molecule consists of which of the following? a. Van der Waals interactions b. hydrogen bonds c. purine-pyrimidine base-pairs d. antiparallel sugar-phosphate polymers

d. antiparallel sugar-phosphate polymers

Which of the following terms best describes the relationship between the newly synthesized RNA molecules and the DNA template strand? a. Permanently base-paired b. Identical c. Covalently bound d. Complementary

d. complementary

Garrod hypothesized that inherited diseases such as alkaptonuria, the ability to metabolize the chemical alkapton, occur because ________. a. metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies. b. certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors. c. many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA. d. genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

d. genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

During DNA replication, which of the following enzymes separates the DNA strands during replication? a. ligase b. DNA polymerase III c. DNA polymerase I d. helicase

d. helicase

Imagine a bacterial cell with a mutation that renders DNA Pol I completely nonfunctional (note that this would be a lethal mutation). What, precisely, would go wrong with replication in this cell? a. inability to unwind double helix b. inability to prime replication c. inability to extend the length of leading and lagging strands d. inability to replace primers

d. inability to replace primers

Human populations in low-UV environments tend to have more lightly pigmented skin. One explanation is that the selective pressure for dark skin decreases as UV intensity decreases. At the same time there is selection for lighter skin to absorb more UV radiation, which is needed for vitamin D production. What evidence supports the vitamin D hypothesis for the evolution of lighter skin tones? a. lightly pigmented people tend to be at higher risk of vitamin D deficiency b. lightly pigmented people cannot synthesize vitamin D in high-UV environments, such as equatorial Africa c. red hair and light skin are typical of people of northern European descent d. indigenous peoples living at high latitudes have darker skin, but they eat foods rich in vitamin D

d. indigenous peoples living at high latitudes have darker skin, but they eat foods rich in vitamin D

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common? a. length and position of the centromere only b. length, centromere position, and staining pattern only c. length, centromere position, staining pattern, and DNA sequences d. length, centromere position, staining pattern, and traits coded for by their genes

d. length, centromere position, staining pattern, and traits coded for by their genes

RNA processing converts the RNA transcript into ________. a. a protein b. DNA c. a eukaryotic cell d. mRNA e. a polypeptide

d. mRNA

Which of the following mechanisms removes nucleotides that are paired incorrectly during DNA replication? a. nucleotide excision repair b. telomerase activity c. chromosomal breakage repair d. mismatch repair

d. mismatch repair

What allows sister chromatids to separate in which phase of meiosis? a. release of cohesin along sister chromatid arms in anaphase I b. crossing over of chromatids in prophase I c. release of cohesin at centromeres in anaphase I d. release of cohesin at centromeres in anaphase II e. crossing over of homologs in prophase I

d. release of cohesion at centromeres in anaphase II

What is the function of topoisomerase? a. adding methyl groups to bases of DNA b. unwinding of the double helix c. elongating new DNA at a replication fork by adding nucleotides to the existing chain d. relieving strain in the DNA ahead of the replication fork

d. relieving strain in the DNA ahead of the replication fork

Which of the following correctly matches each gene tool with its function? a. restriction enzyme: amplify; PCR: cut; CRISPR-cas9: edit b. restriction enzyme: edit; PCR: amplify; CRISPR-cas9: cut c. restriction enzyme: cut; PCR: edit; CRISPR-cas9: amplify d. restriction enzyme: cut; PCR: amplify; CRISPR-cas9: edit

d. restriction enzyme: cut; PCR: amplify; CRISPR-cas9: edit

In eukaryotic cells, transcription CANNOT begin until ________. a. the two DNA strands have completely separated and exposed the promoter b. the DNA introns are removed from the template c. the 5' caps are removed from the mRNA d. several transcription factors have bound to the promoter

d. several transcription factors have bound to the promoter

Which of the following descriptions correctly defines a genome? a. a karyotype b. representation of a complete set of a cell's polypeptides c. the complete set of an organism's polypeptides d. the complete set of an organism's genes

d. the complete set of an organism's genes

Which of the following events in translation is the first to occur in eukaryotes? a. elongation of the polypeptide b. base pairing of activated methionine-tRNA to AUG of the messenger RNA c. binding of the larger ribosomal subunit to smaller ribosomal subunits d. the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

d. the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA? a. RNA processing b. gene expression c. polypeptide formation d. transcription e. translation

d. transcription

What is the correct tRNA anti-codon for the mRNA codon 5'-GCA-3'? a. 3'-UGC-5' b. 5'-CGT-3' c. 3'-CGT-5' d. 5'-CGU-3' e. 5'-UGC-3'

e. 5'-UGC-3'

In which group(s) of organisms would you expect to see polyribosomes? a. bacteria b. archaea c. eukarya d. A and B e. A, B, and C

e. A, B, and C

Which of the following is a normal feature of eukaryotic mRNA? a. 5' cap b. poly-A tail c. 5' UTR d. 3' UTR e. All of the above

e. All of the above

What is a ribozyme? a. an enzyme that holds open the DNA double helix while RNA polymerase adds nucleotides b. a biological catalyst consisting of DNA c. a mutated ribosome d. a DNA sequence near the promoter that assists in the binding of RNA polymerase e. a biological catalyst made of RNA

e. a biological catalyst made of RNA

Polypeptides are assembled from ________. a. hexoses b. glycerol c. nucleotides d. proteins e. amino acids

e. amino acids

In animals, fertilization is to zygote as meiosis is to which of the following? a. mitosis b. diploid c. chromosome d. replication e. gamete

e. gamete

After an RNA molecule is transcribed from a eukaryotic gene, what is removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence? a. silencers; enhancers b. exons; introns c. operators; promoters d. promoters; operators e. introns; exons

e. introns; exons Introns ("intervening sequences") are removed and the exons ("expressed sequences") are spliced together.

In the diagram below, the green unit represents ________. a. RNA b. DNA c. transcription factors d. RNA polymerase e. the promoter

e. the promoter

What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein? a. RNA processing b. gene expression c. polypeptide formation d. transcription e. translation

e. translation

The diagram below shows a replication bubble with synthesis of the leading and lagging strands on both sides of the bubble. The parental DNA is shown in dark blue, the newly synthesized DNA is light blue, and the RNA primers associated with each strand are red. The origin of replication is indicated by the black dots on the parental strands. Rank the primers in the order they were produced. If two primers were produced at the same time, overlap them.

earliest A&H B&G C&F D&E latest

The diagram below shows a double-stranded DNA molecule (parental DNA). Drag the correct labels to the appropriate locations in the diagram to show the composition of the daughter DNA molecules after one and two cycles of DNA replication. In the labels, the original parental DNA is blue and the DNA synthesized during replication is red.

first cycle: both half red, half blue second cycle: half red, half blue; red; half red, half blue; red

As DNA replication continues and the replication bubble expands, the parental double helix is unwound and separated into its two component strands. This unwinding and separating of the DNA requires three different types of proteins: helicase, topoisomerase, and single-strand binding proteins. Sort the phrases into the appropriate bins depending on which protein they describe.

helicase: binds at the replication fork, breaks H-bonds between bases topoisomerase: binds ahead of the replication fork, breaks covalent bonds in DNA backbone single-strand binding protein: binds after replication fork, prevents H-bonds between bases

As the two parental (template) DNA strands separate at a replication fork, each of the strands is separately copied by a DNA polymerase III (orange), producing two new daughter strands (light blue), each complementary to its respective parental strand. Because the two parental strands are antiparallel, the two new strands (the leading and lagging strands) cannot be synthesized in the same way. Drag each phrase to the appropriate bin depending on whether it describes the synthesis of the leading strand, the synthesis of the lagging strand, or the synthesis of both strands.

leading strand: made continuously, only one primer needed, daughter strand elongates toward replication fork lagging strand: made in segments, multiple primers needed, daughter strand elongates away from replication fork both: synthesized by 5' to 3'

A ________ mutation causes a wild-type amino acid to be replaced by a different amino acid.

missense

A ________ mutation causes an early stop codon to occur.

nonsense

A ________ mutation does not change the wild-type amino acid sequence.

silent

Sort each description by the type of RNA it describes.

tRNA: contains an anticodon, has amino acids covalently attached mRNA: contains exons, specifies the amino acid sequence for a protein rRNA: is a component of ribosomes, is the most abundant form of RNA