Biology 102 MindTap Questions CH 10 12 & 15

Without taking crossing over into account, how many different potential gametes can be produced by a single human? It is not possible to estimate 64 trillion 8 million 100 billion

8 million

Which of the following describes a microRNA? Small noncoding RNA that silences gene expression RNA that makes up the structure of ribosomes RNA that delivers amino acids to ribosomes RNA that carries the message that guides polypeptide assembly

?

Which of the following is a function of maternal effect genes? Determine the front-to-back polarity of each segment Establish paired segments Determine embryo's head-tail axis Subdivide the embryo

?

How can transcription factors influence the transcription of DNA? Select all that apply. Inhibit transcription by preventing RNA polymerase from binding to promoters Inhibit translation by preventing the binding of mRNA to ribosomes Inhibit transcription by blocking the progress of RNA polymerase along a DNA molecule Enhance transcription by helping RNA polymerase bind to promoters

??

Which of the following affects gene expression without changing the DNA sequence? Gene knockout Base-pair substitution DNA methylation Mutation in regulatory sites

??

Which of the following are examples of epigenetic mechanisms? Select all that apply. Changes in proteins that modify histones DNA methylation Noncoding RNAs Histone modifications

??

Which of the following are stages in the metabolic control of the lac operon? Select all that apply. When lactose is present, it binds to the repressor and causes the repressor to release the operators. RNA polymerase attaches to the accessible promoter and transcribes the genes. In the absence of lactose, a repressor binds to the two operators, preventing RNA polymerase from attaching to the promoter.

??

Which of the following defines a master gene? A regulatory protein that influences transcription by binding directly to DNA A technique of introducing a mutation that disables expression of a gene in an organism A gene encoding a product that affects the expression of many other genes A condensed, inactivated X chromosome in the body cell of a female mammal

??

Which of the following describes a Barr body? A gene encoding a product that affects the expression of many other genes An inactivated X chromosome in a cell of a female mammal A transcription factor that increases the rate of transcription when it binds to a promoter or enhancer A type of master gene that triggers the formation of a specific body part during development

??

Which of the following ensures that most genes on one X chromosome are not expressed in female animal cells? X chromosome inactivation Circadian rhythm Knockout Repressors

??

Which of the following is a function of histones in the process of gene expression? They bind to DNA to increase or decrease transcription. They modify newly transcribed mRNA sequences. They transport mRNA to key regions in the cytoplasm. They wrap or unwind DNA and affect which DNA regions are accessible to RNA polymerase.

??

Which of the following points of gene expression control is located in the cytoplasm? DNA loosening from histones Post-translational modification of polypeptide Post-transcriptional modification of RNA Transcription

??

Which of the following master genes trigger the formation of body parts? Segment polarity genes Structural genes Maternal effect genes Homeotic genes

???

One of the simplest methods of cloning DNA uses a structure that is already adept at copying DNA: a living cell. The following diagram summarizes this DNA cloning process. Select the correct label for each of the components from the dropdown menus provided.

A Chromosomal DNA B Plasmid C Restriction enzymes D DNA ligase E Bacterial cell

In the narrative in the narrative, what causes blindness in affected individuals? A missing copy of the RPE65 gene. A mutation in both copies of the gene RPE65. A virus that deleted the RPE65 gene. A viral infection.

A mutation in both copies of the gene RPE65.

Epigenome

A system of chemical modifications that determines which genes are active in a particular cell and which are not

_______ are transcription factors that increase the rate of transcription when they bind to promoters or enhancers. _______ are transcription factors that slow or stop transcription.

Activators Repressors

Which of the following defines a germ cell? A form of a gene that may encode for different versions of the gene's product A diploid cell that forms when two gametes fuse An immature reproductive cell that gives rise to haploid gametes when it divides A mature, haploid reproductive cell

An immature reproductive cell that gives rise to haploid gametes when it divides

In which stage of meiosis is the chromosome number halved? Telophase I Metaphase I Anaphase I Prophase I

Anaphase I

Which of the following stages of meiosis II involves separation and movement of the sister chromatids toward the spindle poles? Telophase II Metaphase II Anaphase II Prophase II

Anaphase II

Which of the following is an advantage of asexual reproduction over sexual reproduction? Asexual reproduction requires a partner. Asexual reproduction does not require a partner. Asexual reproduction leads to offspring with high genetic diversity. The resulting offspring have no genetic diversity.

Asexual reproduction does not require a partner.

Which of the following are influenced by epigenetics? Select all that apply. Gene sequence Certain cancers Cardiovascular disease Gene activation

Certain cancers Cardiovascular disease Gene activation

Which type of regulator can control gene expression by organizing DNA molecules into active and inactive regions? Chromatin modifications Noncoding RNAs Transcription factors Signaling molecules

Chromatin modifications

______ activate and inactivate regions of DNA.

Chromatin modifications

Which of the following is a cycle of biological activity that is repeated approximately every 24 hours? RNA interference Operon Circadian rhythm Dosage compensation

Circadian rhythm

Which of the following is NOT true of crossing over? Crossing over occurs during prophase I of meiosis. Crossing over can occur multiple times per pair of homologous chromosomes. Crossing over can occur only once per pair of homologous chromosomes. Crossing over increases genetic variation.

Crossing over can occur only once per pair of homologous chromosomes.

Which of the following occur in both mitosis and meiosis? Select all that apply. Cytokinesis Crossing over Separation of homologous chromosomes Separation of sister chromatids

Cytokinesis Separation of sister chromatids

One method of identifying specific chunks of DNA involves chopping up an entire strand of DNA and then inserting each chunk into a different bacterial cell. The bacterial cells divide into small colonies. Each of these colonies contains a different segment of the original DNA strand, so together they are known as a _______. The geneticist takes samples from these colonies and then exposes those samples to radioactively labeled fragments of DNA or RNA known as _______, which are designed to identify the specific desired segment of DNA by binding to it. Once the geneticist finds that particular segment of DNA, he or she clones the bacterial cells carrying it so that many copies of that segment of DNA are available to work with.

DNA Library Probes

To understand how DNA sequencing works, consider the following analogy. Imagine a set of plastic building bricks that snap together end-to-end in a continuous chain. There are only four possible brick colors. These bricks represent ____________

DNA nucleotides

Which statement about the regulation of alternative splicing is NOT correct?

Disruption of the normal splicing process has no effect on diseases such as cancer, cardiovascular disease, and diabetes.

When does independent assortment occur? During metaphase of mitosis During metaphase II of meiosis During fertilization During metaphase I of meiosis

During metaphase I of meiosis

The preceding analogy should walk you through the steps in DNA sequencing and should help you understand how geneticists interpret DNA sequencing. The adjacent image represents what an actual DNA sequencing strip might look like. What is the sequence of this DNA code segment? 1. GAUUACAU 2. GATTACAT 3. TACATTAG 4. UACAUUAG

GATTACAT

In histone modification, histone acetylation is usually associated with which of the following? Gene activation miRNA-related gene silencing Gene silencing DNA methylation

Gene activation

What is your genome?

Genetic code, the sequence of the bases A, T, C, and G in your DNA

In the example in the narrative, gene therapy is used to treat which kind of illness? Genetic disorder Bacterial disease Gene therapy is not used to treat diseases. Viral disease

Genetic disorder

Gametes are ______ cells that have a single set of chromosomes. The number of chromosomes in diploid zygotes is represented as ________

Haploid 2n

In PCR, the entire strand of DNA is mixed with short pieces of single-stranded DNA, called primers, that are complementary to the beginning of the specific DNA sequence the geneticist is trying to isolate. The complete strand of DNA is _______ to break apart the hydrogen bonds connecting the bases in each pair and the mixture is then cooled so the _______ bind to the DNA template. At this point, the DNA polymerase begins to synthesize new strands of DNA starting from the primers. This process is repeated over and over, which not only isolates the desired segment of DNA but copies it repeatedly as well.

Heated Primers

Methyl groups can be added to DNA or _____ to alter gene expression.

Histone Proteins

Which of the following occurs during metaphase I? The spindle separates the homologous chromosomes and moves them toward opposite spindle poles. A complete set of chromosomes cluster at each cell end, and two haploid nuclei are produced. Homologous chromosome pairs are aligned midway between spindle poles. Homologous chromosomes pack tightly, pair up, and swap segments.

Homologous chromosome pairs are aligned midway between spindle poles.

__________ refers to the inheritance pattern of separate chromosomes, while _________ refers to events that happen between homologous chromosomes.

Independant Assortment Crossing Over

The concept that the distribution of one chromosome does not affect the distribution of any other chromosome during meiosis is known as which of the following? Random fertilization Crossing over Independent assortment

Independent assortment

In DNA methylation, methyl groups bind to the gene promoter and do which of the following? Modify histone proteins Form a silencing complex Alter the genetic code in your genome Inhibit gene transcription

Inhibit gene transcription

How does Luxturna treat blindness in patients? Luxturna kills the virus that causes the mutation in the RPE65 protein. Luxturna repairs the mutant copy of the RPE65 gene. Luxturna contains a virus that introduces a nonmutant RPE65 gene, which allows the eyes to function correctly. Luxturna activates host defenses to destroy the RPE65 protein.

Luxturna contains a virus that introduces a nonmutant RPE65 gene, which allows the eyes to function correctly.

In miRNA-related gene silencing, a silencing complex binds to target sites on which of the following? Acetyl groups Methyl groups Messenger RNA (mRNA) microRNA (miRNA)

Messenger RNA (mRNA)

During which phase(s) are chromosomes lined up single-file along the center of the cell? Select all that apply. Metaphase II of meiosis Interphase Metaphase I of meiosis Metaphase of mitosis

Metaphase II of meiosis Metaphase of mitosis

In an operon, ______ are DNA binding sites for repressors. ______ are sites in DNA where RNA polymerase attaches to initiate transcription.

Operators Promoters

Which of the following cell types are able to become any body cell? Select all that apply. Pluripotent embryonic stem cells mESCs Totipotent embryonic stem cells Multipotent embryonic stem cells

Pluripotent embryonic stem cells Totipotent embryonic stem cells

Which of these methods is a relatively simple, quick, and cheap method of identifying, isolating, and copying segments of DNA code and thus is the most widely used procedure today? Polymerase chain reaction DNA library construction Nucleic acid hybridization

Polymerase chain reaction

During which phase of meiosis do homologous chromosomes form pairs? Prophase II Anaphase I Metaphase II Prophase I

Prophase I

During which stage of meiosis does crossing over occur? Prophase II Anaphase II Metaphase I Prophase I

Prophase I

Which of the following stages of meiosis II involves the attachment of spindle microtubules to each sister chromatid? Anaphase II Prophase II Metaphase II Telophase II

Prophase II

Which of the following is an advantage of sexually reproducing populations over asexually reproducing populations? Sexually reproducing populations require partners to reproduce. Sexually reproducing populations do not require partners to reproduce. Sexually reproducing populations produce genetically identical offspring. Sexually reproducing populations are more resilient against the effects of harmful mutations.

Sexually reproducing populations are more resilient against the effects of harmful mutations.

Which of the following best describes anaphase II of meiosis? Homologous chromosomes are pulled apart. Crossing over occurs, during which sections of homologous chromosomes are swapped. Chromosomes line up along the metaphase plate. Sister chromatids are pulled apart.

Sister chromatids are pulled apart.

Epigenetics is a rapidly expanding new field of genetic research. Over the last few decades, geneticists have observed experimental situations where some pressure in the environment affects how genes are expressed. Sometimes, these differences in expression are passed on to offspring. For example, female water fleas (Daphnia) respond to predators by forming spiky, protective "helmets" on their heads. Their offspring are also born with helmets, even if predators are absent. The third-generation offspring also produce helmeted offspring, though the helmets are greatly reduced in size. Which of the following statements correctly describes the epigenetic effect that might be occurring in this scenario? Some sort of chemical trigger created by the predator (such as a pheromone) causes the DNA of the female water fleas to mutate. The mutation causes helmet growth. Some sort of chemical trigger created by the predator (such as a pheromone) affects the molecular structure of the female water flea chromosome, which, in turn, affects which genes are transcribed and makes it more likely for the helmet-growth gene to be expressed. Some sort of chemical trigger created by the predator (such as a pheromone) causes a new gene for helmet growth to be transcribed into the DNA of the female water flea.

Some sort of chemical trigger created by the predator (such as a pheromone) affects the molecular structure of the female water flea chromosome, which, in turn, affects which genes are transcribed and makes it more likely for the helmet-growth gene to be expressed.

Which stage of meiosis I is characterized by the formation of two haploid nuclei? Metaphase I Anaphase I Prophase I Telophase I

Telophase I

Which of the following occurs during metaphase II? Spindle microtubules attach to each sister chromatid as the nuclear envelope breaks up. A nuclear envelope forms around each set of chromosomes to form four haploid nuclei. The chromosomes align midway between spindle poles. The sister chromatids separate and move toward the spindle poles.

The chromosomes align midway between spindle poles.

Which of the following may be influenced by alternative splicing? Select all that apply. The development of cancer Embryonic development Diabetes Cell differentiation

The development of cancer Embryonic development Diabetes Cell differentiation

Which of the following is true for both meiosis and mitosis? The genome is duplicated before mitosis or meiosis occurs. All daughter cells produced are genetically identical. Crossing over occurs, increasing genetic variation. All daughter cells produced are genetically identical to the parent cell.

The genome is duplicated before mitosis or meiosis occurs.

Which of the following is an outcome of crossing over? The formation of a zygote The introduction of novel combinations of alleles in offspring The production of gametes The production of genetically identical offspring

The introduction of novel combinations of alleles in offspring

Which of the following are potential ethical hurdles for the use of gene therapy in humans? Select all that apply. The therapies may not be effective. The therapies may not complete clinical trials. The therapies may be used for non-curative purposes. The therapies may be only accessible to the wealthy.

The therapies may be used for non-curative purposes. The therapies may be only accessible to the wealthy.

what do pluripotent embryonic stem cells (pESCs) do?

They can form any type of cell in the body.

During human fertilization, ___________ fuse to produce a ________

a male gamete and a female gamete zygote

Alternative splicing allows more than one form of a protein to be produced from which of the following?

a single gene

All of your body cells _____. are multipotent embryonic stem cells (mESCs) are pluripotent embryonic stem cells (pESCs) contain the same genetic information express the same genetic information

contain the same genetic information

Cell differentiation is a process that _____. produces totipotent embryonic stem cells (tESCs) creates a zygote can be used to clone an identical individual controls which subset of genes is active in any particular type of cell

controls which subset of genes is active in any particular type of cell

Now, imagine that you add a different type of brick to your collection of building bricks. These new bricks are the same size, shape, and colors as the other bricks, but they are smooth on one end. This means that they can connect to one of the other bricks, but then no other brick can connect to them. Each becomes the end of a chain of bricks. These smooth bricks represent ________

dideoxynucleotides

The ploidy of the cells produced after telophase I is __________ the ploidy of the original cell

different than

You give her the bricks in a darkened room so she cannot see them. Without looking at the bricks, she lines them up by size, from shortest chain to longest chain. Organizing the segments in this way mimics the DNA sequencing technique of ________. Then, she turns on the LED light at the end of each segment. She points out that once the segments have been organized by length, the order that these smooth bricks are in matches the order of the original chain. Therefore, by looking at the glowing end of each of the chain segments, she has figured out what the original order was.

electrophoresis

In the first stage of cellular differentiation, three basic germ layers are formed these are _______

endoderm, mesoderm, and ectoderm

your epigenome turns specific genes on in ____

gene activation

your epigenome turns specific genes off in ____

gene silencing

Since the results of this study show that individuals who have a mutation in either BRCA gene have a _____ risk of developing breast cancer than individuals who do not have a mutation in that gene, you can conclude that mutations in either BRCA gene ______ that gene's control over the normal development of the cell.

higher hinder

Since the mystery gene affected the same body part in all three organisms, you conclude that it is a ______ gene.

homeotic

Before meiosis begins, a diploid cell has two copies of each __________. During anaphase II of meiosis, _________ are separated.

homologous chromosome sister chromatids

The likelihood of any sperm cell reaching and fertilizing any egg cell ___________. This phenomenon is known as ______.

is approximately equal random fertilization

Suppose you are studying a gene that appears to occur in the DNA code of multiple types of animals, but you are not sure what it does. In your study, you specifically are looking at the genetics of cats, alligators, and finches. In one experiment, you remove this mystery gene from the fertilized egg of each of these organisms and observe the results in the developing embryos. This type of experiment is called a _______ experiment.

knockout

The results of your experiment show that removing the gene halted the development of the legs in all three of the animals. You know that more than one gene is involved in the development of the legs of these organisms, so you conclude that this mystery gene is a _______ gene.

master

In sexual reproduction, ________ produces genetically diverse ___________

meiosis haploid gametes

In both mitosis and ________, a spindle forms and separates sister chromatids. While mitosis produces two nuclei, meiosis II produces _________

meiosis II four haploid nuclei

The protein AGO is involved in

miRNA-related gene silencing

During ______ , a diploid cell undergoes genome duplication and a single division producing two _______ daughter cells.

mitosis diploid

Now, say you tell a friend what happened with the smooth bricks. She says that because of the way the smooth bricks have interfered with your building process, she can determine what order the chain of bricks was supposed to be in, without even looking at them. However, she does ask you to label each of the smooth bricks with an LED light matching the color of the brick, so that the only bricks she can identify are the ends of each segment. These LED lights labeling the smooth bricks represent ___________. Intrigued, you accept her challenge.

pigment tracers

Crossing over is an event that occurs during _________. In essence, two homologous chromosomes twist around one another and exchange an identically sized segment of their DNA. By exchanging alleles in this way, crossing over helps to create more variation in the genetic codes of the gametes that result from meiosis.

prophase I of meiosis

Alternative splicing rearranges the information in pre-mRNA by _____.

removing noncoding introns and connecting the protein-coding exons

Mitosis is most similar to the ______ phase of meiosis.

second

Epidermal growth factor is an example of a _________ , a tissue-specific RNA-binding protein.

splice factor

During the first division in meiosis, one diploid cell forms ___________

two haploid cells

In the example in the narrative, researchers used a ________ to insert a _______ of the RPE65 gene into the genome of affected individuals.

virus working copy

Histone modifications

work at the chromatin level of DNA organization. Short extensions of histone proteins (histone tails) may be modified by either methylation (methyl groups) or acetylation (acetyl groups). Histone methylation is usually associated with tightening the histones in a nucleosome, which prevents transcription (gene silencing). Histone acetylation is usually associated with loosening the histones in a nucleosome, which activates transcription (gene activation).

DNA methylation

works at the DNA level. Usually, methyl groups (M) bind to the gene promoter and inhibit gene transcription (gene silencing).

miRNA-related gene silencing

works on mRNA

Every human life begins with one cell, a _____

zygote