Deck 20: Genes and Development

Question 1

Cellular differentiation progressively restricts cell fate because the unexpressed genes in the cell:

A)become more densely packed with nucleosomes.
B)accumulate point mutations.
C)accumulate deletions.
D)accumulate both point mutations and deletions.
E)undergo irreversible repression.

Answer 1

E

Question 2

If one isolated cells at random from an organism at different times in its development and measured developmental potential as the average number of distinct cell types that the cells could differentiate into, which of the curves shown here would MOST likely result?

A)curve M
B)curve H
C)curve K
D)curve L
E)curve Q

Answer 2

C

Question 3

Many valuable horticultural varieties of plants, including roses, rhododendrons, junipers, geraniums, and so on, are commonly propagated by inducing roots to form on cuttings taken from branch tips. This method involves cutting a few inches from the tip of a branch and inserting the cut end into moist sand or other substrate. Under the right conditions, roots may form from the cut end, giving a new plant generated from the stem cutting. In what way could this phenomenon be used to argue for or against the "genome reduction" hypothesis for cell differentiation?

Answer 3

In order to produce roots, the branch cuttings would have to alter gene expression patterns so that cells previously producing proteins necessary for the branch now produce proteins necessary for root development.

Question 4

Mature cells are terminally differentiated. What could cause this permanent change?

A)epigenetic change
B)changes in gene expression
C)changes in chromosome content
D)changes in cell signaling

Question 5

The early cell divisions of human development differ from other mitotic cell divisions in that:

A)cells do not replicate all chromosomes prior to dividing; this helps the cells differentiate.
B)cells do not grow in size; they subdivide the cytoplasm of the fertilized egg.
C)cells move as they divide.
D)they are unequal; some daughter cells are much larger than others.
E)All of these choices are correct.

Question 6

A small group of cells at the growing tip of a plant is called the meristem. As the meristem divides, the resulting cells are able to differentiate into various cell types found in the stems, leaves, and flowers. What type of stem cell is the meristem?

A)multipotent
B)pluripotent
C)totipotent
D)unipotent
E)omnipotent

Question 7

A researcher isolates stem cells from a developing embryo and finds that they are able to differentiate only into liver cells or pancreatic cells. The isolated stem cells are likely from the:

A)morula.
B)gastrula.
C)ectoderm.
D)mesoderm.
E)endoderm.

Question 8

A researcher isolates stem cells from a developing embryo and finds that they are able to differentiate only into bone cells or red blood cells. The isolated stem cells are likely from the:

A)morula.
B)gastrula.
C)ectoderm.
D)mesoderm.
E)endoderm.

Question 9

The body of the human embryo develops from the _____ of the blastocyst.

A)inner cell mass
B)outer cell mass
C)wall
D)membranes
E)cytoplasm

Question 10

The finding that induced pluripotent stem cells (iPS cells) can be created by activation of a small number of genes implies that:

A)aging can eventually be reversed.
B)dying cells can be revitalized.
C)cancer cells can be killed by targeting these genes.
D)developmental restriction of cell fate is reversible.
E)None of the answer options is correct.

Question 11

During morula development, the divisions are more rapid than in most normal adult cells and the individual cells get progressively smaller. Which stage(s) of the cell cycle are probably truncated (made shorter)?

A)G1 and G2
B)S phase
C)M phase
D)both M phase and S phase
E)All of the stages are truncated.

Question 12

A mutation occurs that causes a defect in the development of skeletal muscle. The mutation would likely have occurred in which of the following kinds of cells in order to produce this defect?

A)ectoderm
B)mesoderm
C)endoderm

Question 13

CopyCat, the first cloned cat, was derived from an ovarian cell from a female calico cat. But CopyCat was not an exact copy, as she herself was not calico. This result implies that, if the donor female were also heterozygous for an X-linked harmful mutation causing muscle degeneration, the probability of a clone being affected is:

A)0)
B)1/4.
C)1/2.
D)3/4.
E)1)

Question 14

Which of the following CORRECTLY matches a cell or group of cells with its ability to differentiate into different specialized cells?

A)fertilized egg: pluripotent
B)mesoderm: pluripotent
C)endoderm: multipotent
D)fertilized egg: multipotent
E)ectoderm: totipotent

Question 15

CopyCat, the first cloned cat, was derived from an ovarian cell from a female calico cat. But CopyCat was not an exact copy, as she herself was not calico. This result implies that:

A)one of the X chromosomes had been lost from the donor nucleus.
B)X-chromosome inactivation did not occur in CopyCat.
C)the inactivated X chromosome in the donor nucleus remained inactivated.
D)ovarian cells do not express coat-color genes.

Question 16

In John Gurdon's nuclear-transfer experiments, do you think he would have had more or less success if he had taken cells from a blastula? From an adult frog?

A)less; less
B)less; more
C)more; less
D)more; more

Question 17

Individual cells in the human blastocyst begin to grow at each cell division after:

A)the inner cell mass forms.
B)the blastocyst forms.
C)the blastocyst reaches the uterus.
D)implantation in the uterine wall.
E)development of the placenta.

Question 18

Each answer option below lists terms that classify cell types according to their developmental potential. Which of the options lists the terms from those capable of differentiating into the greatest number of different specialized cells to those capable of differentiating into the least number of different specialized cells?

A)multipotent, pluripotent, totipotent
B)pluripotent, totipotent, multipotent
C)totipotent, multipotent, pluripotent
D)totipotent, pluripotent, multipotent
E)multipotent, totipotent, pluripotent

Question 19

Many valuable horticultural varieties of plants, including roses, rhododendrons, junipers, geraniums, and so on, are commonly propagated by inducing roots to form on cuttings taken from branch tips. This method involves cutting a few inches from the tip of a branch and inserting the cut end into moist sand or other substrate. Under the right conditions, roots may form from the cut end, giving a new plant generated from the stem cutting. Which of the following hypotheses is the LEAST likely, given the observation of roots forming from a cut stem?

A)genome reduction hypothesis
B)differential gene expression hypothesis
C)differential cell signaling hypothesis
D)epigenetic regulation hypothesis

Question 20

Which of the following CORRECTLY lists the stages of human development in order?

A)fertilized egg, blastocyst, gastrula, morula
B)fertilized egg, blastocyst, morula, gastrula
C)fertilized egg, morula, blastocyst, gastrula
D)fertilized egg, morula, gastrula, blastocyst
E)fertilized egg, gastrula, morula, blastocyst

Question 21

Differentiating cells delete the DNA for genes they do not need.

Question 22

The fertilized egg is totipotent, which means:

A)it only contains genetic material from the female.
B)it forms the membranes that surround and support the developing embryo.
C)it can give rise to a complete organism.
D)the Y chromosome does not create interference to the expression of X-linked genes.
E)it can be removed and donated to a surrogate womb.

Question 23

The fertilized egg is also called a(n):

A)zygote.
B)blastocyst.
C)gastrula.
D)morula.
E)ectoderm.

Question 24

Which of the following cells, or cell types, has the GREATEST developmental potential?

A)fertilized egg
B)inner cell mass
C)gastrula
D)ectoderm
E)nerve cell

Question 25

A cell that has the capacity to differentiate into a limited number of related cell types is a _____ stem cell.

A)multipotent
B)pluripotent
C)totipotent
D)unipotent
E)omnipotent

Question 26

Why has the development of iPS cells been viewed as a major breakthrough in the development of stem cell therapies?

A)It allows us to develop pluripotent stem cells without the ethical issues involved in obtaining them from human embryos.
B)It may ultimately allow us to obtain stem cells from any individual-we can match the patient to the tissue.
C)It is easy and inexpensive.
D)It is a proven technique that we will be able to move into a clinical trial very quickly.
E)It will allow us to "grow" new organs very quickly.

Question 27

In humans, the three germ layers are established when the:

A)blastula forms.
B)inner cell mass of the blastula forms.
C)blastula implants into the uterine wall.
D)cells of the inner cell mass reorganize themselves into the gastrula.
E)gastrula implants into the uterine wall.

Question 28

As cells continue differentiating, they increasingly lose their developmental potential and their fate becomes more restricted.

Question 29

A cell in the epithelium lining the human gut is very different in structure and function from, for example, a white blood cell. How would you describe the genetic basis for this difference?

A)These different cell types express different sets of genes, although their genomes are identical.
B)These different cell types contain different sets of genes as a result of modifications during development.
C)Genes are gradually lost as these cell types differentiate into specialized tissues.
D)The genes evolve as the body develops the specialized tissues needed for full development.

Question 30

An individual that carries an exact copy of the nuclear genome of another individual following a successful nuclear transfer is called a:

A)gastrula.
B)blastoderm.
C)clone.
D)stem copy.
E)pluripotent copy.

Question 31

Human development begins with fertilization, but the fertilized egg does not begin to divide until after it implants in the uterine wall.

Question 32

The goals of regenerative medicine are to:

A)create stem cells for patients using their own adult cells.
B)develop cells, tissues, and organs that can replace damaged ones with minimal or no danger of tissue rejection.
C)create a bank of totipotent stem cells from which new tissues and organs can be generated.

Question 33

Which of the following are multipotent cell types?

A)the fertilized egg
B)cells of the inner cell mass
C)cells of the ectoderm
D)cells of the endoderm
E)cells of the mesoderm

Question 34

Cells differentiate through:

A)growth.
B)timing.
C)gene regulation.
D)the cell cycle.

Question 35

Which of the following CORRECTLY pairs a germ layer with the cells that will form from it?

A)ectoderm: inner layer of the skin, muscles
B)mesoderm: inner layer of the skin, muscles
C)endoderm: epithelial and pigment cells of the skin
D)ectoderm: lining of the digestive tract and lungs
E)mesoderm: lining of the digestive tract and lungs

Question 36

As cells become differentiated, they delete the DNA for genes they no longer need.

Question 37

Cells of the mesoderm are multipotent because they can:

A)give rise to any cell type in the embryo.
B)give rise to any cell type of mesodermal origin.
C)give rise to any cell type of any of the three germ layers.
D)become induced pluripotent stem cells.
E)None of the answer options is correct.

Question 38

Stem cells are cells that are capable of:

A)producing an entire organism.
B)producing the three germ layers.
C)differentiating into different cell types.
D)differentiating into a limited number of different cell types.
E)differentiating into any type of cell.

Question 39

Differentiation refers to the process by which:

A)fertilized eggs undergo multiple rounds of cell division to become embryos.
B)changes in gene expression allow cells to produce the correct proteins at the correct time.
C)cells become progressively more specialized during development.
D)gene regulation determines which proteins are produced in a given cell during development.
E)None of the answer options is correct.

Question 40

An adult cell that is reprogrammed to be pluripotent is called a(n) _____ stem cell.

A)embryonic
B)induced pluripotent
C)germ layer pluripotent
D)pluripotent
E)regenerative pluripotent

Question 41

In human development, the blastocyst, which is a hollow sphere of developing cells, implants in the uterine wall approximately 5 to 6 days after fertilization.

Question 42

Gurdon's nuclear transplantation experiments with clawed toads supports the hypothesis that:

A)differentiation is the result of genes being successively deleted from the genome.
B)differentiation is the result of genes being successively turned on or off.
C)differentiation causes cells to become pluripotent.
D)only nuclei from the blastocyst retain sufficient potency to produce an adult organism.
E)All of these choices are correct.

Question 43

A researcher isolates stem cells from a developing embryo and finds that they are able to differentiate only into liver cells or pancreatic cells. The isolated stem cells are:

A)pluripotent.
B)omnipotent.
C)omniscient.
D)multipotent.
E)impotent.

Question 44

Nanos _____ caudal mRNA translation.

A)promotes
B)inhibits
C)does not affect

Question 45

Which of the following is present at greater levels at the anterior end of a Drosophila embryo than the posterior end?

A)bicoid mRNA
B)nanos RNA
C)hunchback mRNA
D)caudal mRNA

Question 46

The mRNA for caudal and hunchback are distributed evenly throughout the Drosophila embryo, yet the Caudal protein is found only in the posterior portion of the embryo and the Hunchback protein is present in greater amounts anteriorly. This distribution is due to:

A)transcriptional regulation of the hunchback and caudal genes in the zygote.
B)translational regulation of the hunchback and caudal mRNAs in the zygote.
C)transcriptional regulation of the nanos and bicoid genes in the zygote.

Question 47

Regenerative medicine is a field that aims to use the natural processes of cell growth and development to replace diseased or damaged tissue. This approach may be used to treat:

A)influenza.
B)Parkinson's disease.
C)measles.
D)obesity.
E)pregnancy.

Question 48

Which types of cells are MOST likely to support normal development in nuclear transplant experiments?

A)endoderm
B)ectoderm
C)mesoderm
D)blastocyst
E)bone marrow

Question 49

Following implantation, the multiplying cells of the human embryo reorganize to form a gastrula, which contains the three germ layers.

Question 50

Which of the three germ layers gives rise to epithelial cells, pigment cells of skin, and nerve cells in the brain?

A)ectoderm
B)mesoderm
C)endoderm

Question 51

If a Drosophila larva is missing much of its posterior end it is likely due to a mutation in the _____ gene.

A)maternal bicoid
B)zygotic bicoid
C)maternal nanos
D)zygotic nanos

Question 52

In human development, cell rearrangement within the ball of cells leads to a hollow sphere with a "mound" of cells at one pole. This group of cells is called the:

A)mesoderm.
B)blastocyst.
C)neural plate.
D)inner cell mass.
E)gastrula.

Question 53

Bicoid _____ caudal mRNA translation.

A)promotes
B)inhibits
C)does not affect

Question 54

To avoid using controversial embryonic stem cells, scientists have learned to reprogram fully differentiated adult cells and return them to a pluripotent state.

Question 55

Regenerative medicine refers to novel:

A)mechanical artificial organs.
B)electronically controlled artificial organs.
C)apps that remind patients to take medicine.
D)use of stem cells to regrow damaged tissue.
E)All of these choices are correct.

Question 56

An abnormal Drosophila larva that is missing much of its posterior end is likely deficient in _____ function.

A)bicoid
B)nanos
C)hunchback

Question 57

Which of the following transcriptional regulators prevents the expression of its target gene when the amount of the transcription factor gets too high?

A)Hunchback
B)Nanos
C)Caudal
D)Bicoid

Question 58

Cells become differentiated when certain subsets of genes are deleted.

Question 59

In human development, early divisions of the embryo are contained within the egg's outer membrane and thus upon each division, egg cytoplasm is partitioned into smaller and smaller cells which form the morula.

Question 60

The fertilized egg is totipotent, whereas the cells from the inner cell mass, called embryonic stem cells, are pluripotent. Only the embryonic stem cells can give rise to the entire organism.

Question 61

The reason scientists hope to develop personalized stem cell therapies is that these therapies would avoid the problem of:

A)tissue rejection.
B)side effects of medication.
C)the expense of organ transplantation.
D)long wait times associated with organ donation.
E)None of the other answer options is correct.

Question 62

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot6, at various positions along the anterior-posterior axis of an insect embryo. The solid lines portray the levels of two regulatory proteins, A and B, that control translation of the Prot6 mRNA. If both A and B stimulate translation of the Prot6 mRNA, then which graph BEST approximates the expected level of Prot6 across the embryo?

A)graph M
B)graph H
C)graph K
D)graph L
E)graph Q

Question 63

The Bithorax mutation in Drosophila results in a pair of wings developing from what would normally develop as halters. Bithorax is an example of a _____ mutation.

A)segmentation
B)maternal-effect
C)gap-gene
D)homeotic

Question 64

In Drosophila, absence of Bicoid protein results in larvae missing anterior segments and absence of Nanos protein results in larvae missing posterior segments. Suppose you inject Bicoid protein into the posterior region of early embryos lacking Nanos. The expected result would be:

A)larvae like bicoid mutants.
B)larvae like nanos mutants.
C)larvae with two anterior regions.
D)larvae with two posterior regions.
E)None of the answer options is correct.

Question 65

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot3, at various positions along the anterior-posterior axis of an insect embryo. The solid line represents the level of a regulatory protein that controls translation of the Prot3 mRNA. If the regulatory protein stimulates translation of the Prot3 mRNA, then which graph shows the expected level of protein Prot3 across the embryo?

A)graph M
B)graph H
C)graph K
D)graph L
E)graph Q

Question 66

A new mutation is discovered in Drosophila in which alternate larval segments are missing. What kind of gene is it?

A)gap
B)segment-polarity
C)pair-rule
D)None of the other answer options is correct.

Question 67

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot4, at various positions along the anterior-posterior axis of an insect embryo. The solid line represents the level of a regulatory protein that controls translation of the Prot4 mRNA. If the regulatory protein stimulates translation of the Prot4 mRNA, then which graph shows the expected level of Prot4 across the embryo?

A)graph M
B)graph H
C)graph K
D)graph L
E)graph Q

Question 68

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot7, at various positions along the anterior-posterior axis of an insect embryo. The solid lines portray the levels of two regulatory proteins, A and B, that control translation of the Prot7 mRNA. If both A and B stimulate translation of the Prot7 mRNA, then which graph BEST approximates the expected level of Prot7 across the embryo?

A)graph M
B)graph H
C)graph K
D)graph L
E)graph Q

Question 69

Gene regulation during development is _____, which means that _____.

A)restrictive; genes are successively lost over time
B)restrictive; genes lose developmental potential over time
C)hierarchical; genes expressed at each stage control the expression of genes that act later
D)hierarchical; genes are turned on in a specific sequence, starting with totipotent and ending with multipotent
E)combinatorial; genes expressed at each stage control the expression of genes that act later

Question 70

Maternal-effect genes:

A)are expressed by the mother.
B)affect maternal phenotype.
C)affect offspring phenotype.
D)are expressed by the mother and affect maternal phenotype.
E)are expressed by the mother and affect offspring phenotype.

Question 71

Therapies using stem cells are already used in:

A)bone marrow transplantation.
B)treating Parkinson's disease.
C)treating Alzheimer's disease.
D)All three of these choices are correct.

Question 72

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot2, at various positions along the anterior-posterior axis of an insect embryo. The solid line represents the level of a regulatory protein that controls translation of the Prot2 mRNA. If the regulatory protein represses translation of the Prot2 mRNA, then which graph shows the expected level of protein Prot2 across the embryo?

A)graph M
B)graph H
C)graph K
D)graph L
E)graph Q

Question 73

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot5, at various positions along the anterior-posterior axis of an insect embryo. The solid line represents the level of a regulatory protein that controls translation of the Prot5 mRNA. If the regulatory protein represses translation of the Prot5 mRNA, then which graph shows the expected level of Prot5 across the embryo?

A)graph M
B)graph H
C)graph K
D)graph L
E)graph Q

Question 74

In fruit flies (Drosophila), an embryo during gastrulation:

A)begins enclosing nuclei within their own cell membranes.
B)forms its three germ layers.
C)becomes organized into distinct segments.
D)forms three germ layers and becomes organized into distinct segments.
E)begins enclosing nuclei within their own cell membranes, forms three germ layers, and becomes organized into distinct segments.

Question 75

In a Drosophila oocyte, bicoid mRNA produced by the mother is localized at one end of the egg rather than evenly distributed throughout the egg. This is an example of:

A)translational control of gene expression during development.
B)translational control of development.
C)hierarchical control of gene regulation during development.
D)maternal developmental effect.
E)oocyte polarization.

Question 76

Which of the following CORRECTLY orders the sequence in which genes controlling the development of the anterior-posterior axis of Drosophila larvae are expressed?

A)maternal-effect genes, gap genes, pair-rule genes, segment-polarity genes
B)maternal-effect genes, gap genes, segment-polarity genes, pair-rule genes
C)pair-rule genes, maternal-effect genes, segment-polarity genes, gap genes
D)maternal-effect genes, segment-polarity genes, pair-rule genes, gap genes
E)gap genes, pair-rule genes, segment-polarity genes, maternal-effect genes

Question 77

Why does a mutation in a maternal-effect gene affect the offspring of mutant females and not the mutant female herself?

A)because the affected female is heterozygous
B)because the mutant gene product is not needed in development
C)because the mutant gene product results in defective oocytes
D)because the father of the affected offspring is also affected

Question 78

Bicoid protein is a transcription factor that promotes transcription of the hunchback gene. This is an example of:

A)translational control of gene expression during development.
B)translational control of development.
C)hierarchical control of gene regulation during development.
D)maternal developmental effect.
E)oocyte polarization.

Question 79

In Drosophila, absence of Bicoid protein results in larvae missing anterior segments and absence of Nanos protein results in larvae missing posterior segments. Suppose you inject Nanos protein into the anterior region of early embryos lacking Bicoid. The expected result would be:

A)larvae like bicoid mutants.
B)larvae like nanos mutants.
C)larvae with two anterior regions.
D)larvae with two posterior regions.
E)None of the answer options is correct.

Question 80

A new mutation is discovered in Drosophila in which a group of contiguous larval segments are missing. What kind of gene is it?

A)gap
B)segment-polarity
C)pair-rule
D)It is not possible to determine based on the information provided.