7e Biology, (Campbell)
Chapter 21: The Genetic Basis of Development
Chapter Questions
1) A model organism for genetic studies of development should ideally meet certain criteria. Which of these is not one of the criteria? A) readily observable embryos B) short generation times C) relatively small genomes D) the presence of unique features not observed in other organisms E) availability of detailed knowledge concerning the organism's genes Answer: D
Topic: Overview Skill: Knowledge
2) Which of the following are common model organisms in the study of de velopmental genetics? A) Homo sapiens B) Drosophila melanogaster C) Arabidopsis thaliana D) B and C only E) A, B, and C Answer: D
Topic: Overview Skill: Comprehension
3) The nematode Caenorhabditis elegans is used as a model organism for genetic studies. One of the key advantages of using C. elegans for such studies is that A) it is hermaphroditic, making it easy to detect recessive mutations. B) it has a great variety of somatic cells. C) its genome is as large as ours. D) its development is extremely variable. E) morphogenesis and growth occur throughout its life. Answer: A
Topic: Overview Skill: Knowledge
4) Which of the following is (are) involved in embryonic development? A) cell division B) cell differentiation C) morphogenesis D) A and B only E) A, B, and C Answer: E
Topic: Concept 21.1 Skill: Knowledge
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5) One striking difference between development in plants and development in animals is the importance of cell ________ in animal embryos. A) division B) differentiation C) growth D) movement E) death Answer: D
Topic: Concept 21.1 Skill: Knowledge
6) One striking difference between development in plants and development in animals is that in plant development A) growth and morphogenesis continue throughout the life of the plant. B) cell differentiation never stops. C) once a structure develops, it cannot reverse its path. D) cell differentiation is rarely permanent. E) chemical signals play a much greater role than in animal development. Answer: A
Topic: Concept 21.1 Skill: Knowledge
7) What is the term for the physical processes that give rise to the shape of an organism? A) morphogenesis B) differentiation C) totipotency D) pluripotency E) mitosis Answer: A
Topic: Concept 21.1 Skill: Knowledge
8) The perpetually embryonic regions of plants responsible for continual growth and formation of new organs are called the A) stamens. B) nurse cells. C) myoblasts. D) apical meristems. E) anchor cells. Answer: D
Topic: Concept 21.1 Skill: Knowledge
9) "Genomic equivalence" refers to the A) similarity in genomes among all individuals of the same species. B) similarity in genomes between males and females of the same species. C) fact that all the cells of an organism express the same genes, regardless of differences in their genomes. D) fact that all the somatic cells of an organism have identical genomes, regardless of their state of differentiation. E) organizational similarity of the genomes of all living organisms, reflecting their common ancestry. Answer: D
Topic: Concept 21.2 Skill: Comprehension
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10) The process of cellular differentiation is a direct result of A) differential gene expression. B) morphogenesis. C) cell division. D) apoptosis. E) differences in cellular genomes. Answer: A
Topic: Concept 21.2 Skill: Knowledge
11) The fact that plants can be cloned from somatic cells demonstrates that A) differentiated cells retain all the genes of the zygote. B) genes are lost during differentiation. C) the differentiated state is normally very unstable. D) differentiated cells contain masked mRNA. E) differentiation does not occur in plants. Answer: A
Topic: Concept 21.2 Skill: Comprehension
12) "Nuclear transplantation" refers to a(n) A) cloning method involving the transfer of a nucleus from a differentiated cell into an enucleated egg cell or zygote. B) form of gene therapy involving the transfer of nuclei from a healthy individual to th e cells of a patient with a genetic disorder. C) method of creating new species by injecting diploid nuclei into diploid zygotes in order to produce tetraploid embryos. D) method of gene therapy in which nuclei are isolated from cells of an individual wi th a genetic disorder, transfected with recombinant DNA, and reintroduced into the individual's cells. E) experimental method involving transferring nuclei from cells of an organism of one species into cells of an organism from another species, and examining the resulting phenotype. Answer: A
Topic: Concept 21.2 Skill: Knowledge
13) In cloning, the ability of a transplanted nucleus to support development A) is inversely related to the age of the donor. B) depends on the DNA base sequence. C) only occurs in plants. D) depends on the size of the genome. E) depends on the nucleus not changing. Answer: A
Topic: Concept 21.2 Skill: Knowledge
14) A cell that remains entirely flexible in its developmental possibilities is said to be A) differentiated. B) determined. C) totipotent. D) genomically equivalent. E) epigenetic. Answer: C
Topic: Concept 21.2 Skill: Knowledge
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15) Differentiation of cells is not easily reversible because it involves A) changes in the nucleotide sequence of genes within the genome. B) changes in chromatin structure that make certain regions of the genome inaccessible. C) chemical modifications of histones and DNA methylation. D) B and C only E) A, B, and C Answer: D
Topic: Concept 21.2 Skill: Comprehension
16) Why was the cloning of "Dolly" considered a major scientific breakthrough? A) It showed that differentiated adult cells of mammals can dedifferentiate. B) It showed that cells can be arrested in the cell cycle. C) It was the first time a surrogate mother was used successfully. D) It was evidence that DNA methylation regulates gene expression. E) It proved that the pattern of gene expression is controlled at transcription. Answer: A
Topic: Concept 21.2 Skill: Knowledge
17) Despite the extensive success that scientists have had in cloning animals, the process is still quite inefficient and cloned animals often show a variety of defects. This is likely because A) the epigenetic features of the chromatin in differentiated donor nuclei are not completely erased in the cloning process. B) cloned animals only have one parent, and therefore carry a high number of homozygous mutations in their genomes. C) cloned animals have fewer genes than other animals, and often lack proteins required for normal health. D) the surrogate mothers that give birth to cloned animals tend to neglect cloned animals in favor of their own biological offspring. E) scientists usually damage the donor cell nuclei in the process of transplantation. Answer: A
Topic: Concept 21.2 Skill: Comprehension
18) In animals, embryonic stem cells differ from adult stem cells in that A) embryonic stem cells are totipotent, and adult ste m cells are pluripotent. B) embryonic stem cells are pluripotent, and adult stem cells are totipotent. C) embryonic stem cells have more genes than adult stem cells. D) embryonic stem cells have fewer genes than adult stem cells. E) embryonic stem cells are localized to specific sites within the embryo, whereas adult stem cells are spread throughout the body. Answer: A
Topic: Concept 21.2 Skill: Knowledge
19) Which of the following statements is not true about stem cells? A) Stem cells can continually reproduce themselves. B) Stem cells can differentiate into specialized cells. C) Stem cells are found in bone marrow. D) Stem cells are found in the adult human brain. E) Stem cell DNA lacks introns. Answer: E
Topic: Concept 21.2 Skill: Knowledge
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20) What is considered to be the first evidence of differentiation in the cells of an embryo? A) cell division B) the occurrence of mRNAs for the production of tissue-specific proteins C) determination D) changes in the size and shape of the cell E) changes resulting from induction Answer: B
Topic: Concept 21.2 Skill: Comprehension
21) In most cases, differentiation is controlled at the level of A) replication of the DNA. B) nucleosome formation. C) transcription. D) translation. E) post-translational activation of the proteins. Answer: C
Topic: Concept 21.2 Skill: Knowledge
22) Which of the following serve as sources of developmental information? A) cytoplasmic determinants such as mRNAs and proteins produced before fertilization B) signal molecules produced by neighboring cells C) ubiquitous enzymes such as DNA polymerase and DNA ligase D) A and B only E) A, B, and C Answer: D
Topic: Concept 21.2 Skill: Comprehension
23) The MyoD protein A) can promote muscle development in all cell types. B) is a transcription factor that binds to and activates the transcription of muscle -related genes. C) was used by researchers to convert differentiated liver cells into muscle cells. D) B and C only E) A, B and C Answer: D
Topic: Concept 21.2 Skill: Knowledge
24) The gene for which protein would most likely be expressed as a result of MyoD activity? A) myosin B) crystallin C) albumin D) hemoglobin E) DNA polymerase Answer: A
Topic: Concept 21.2 Skill: Comprehension
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25) The general process that leads to the differentiation of cells is called A) determination. B) specialization. C) identification. D) differentialization. E) cellularization. Answer: A
Topic: Concept 21.2 Skill: Knowledge
26) Which of the following statements is false ? A) Induction involves cells communicating with each other. B) Induction usually involves transcriptional regulation. C) Induction can play an essential role in the formation of complex organs. D) Induction may involve stimulating cells to die as well as to divide and grow. E) Induction signals are almost always small carbohydrates. Answer: E
Topic: Concept 21.2 Skill: Knowledge
27) Which of the following is least related to the others? A) cell divis ion B) morphogenesis C) induction D) differentiation E) bacterial transformation Answer: E
Topic: Concept 21.2 Skill: Comprehension
28) Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development? A) morphogenesis B) determination C) induction D) differentiation E) pattern formation Answer: E
Topic: Concept 21.3 Skill: Comprehension
29) Of the approximately 13,700 genes in Drosophila , how many were found to be essential for embryonic development by Christiane Nsslein-Volhard and Eric Wieschaus? A) about 120 genes B) about 240 genes C) about 1,200 genes D) about 6,000 genes E) about 9,000 genes Answer: C
Topic: Concept 21.3 Skill: Knowledge
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30) Which of the following is established prior to fertilization in Drosophila eggs? A) the anterior-posterior and dorsal-ventral axes B) the position of the future segments C) the position of the future wings, legs, and antennae D) A and B only E) A, B, and C Answer: A
Topic: Concept 21.3 Skill: Knowledge
31) The product of the bicoid gene in Drosophila provides essential informat ion about A) the anterior-posterior axis. B) the dorsal-ventral axis. C) the left-right axis. D) segmentation. E) lethal genes. Answer: A
Topic: Concept 21.3 Skill: Knowledge
32) If a Drosophila female has a homozygous mutation for a maternal effect gene, A) she will not develop past the early embryonic stage. B) all of her offspring will show the mutant phenotype, regardless of their genotype. C) only her male offspring will show the mutant phenotype. D) her offspring will the show mutant phenotype only if they are also homozygous for the mutation. E) only her female offspring will show the mutant phenotype. Answer: B
Topic: Concept 21.3 Skill: Application
For the following questions, use the following responses: A. B. C. D. E. homeotic genes segmentation genes egg-polarity genes morphogens inducers
33) Mutations in these genes lead to transformations in the identity of entire body parts. Answer: A
Topic: Concept 21.3 Skill: Knowledge
34) These genes are expressed by the mother, and their products are deposited into the developing egg. Answer: C
Topic: Concept 21.3 Skill: Knowledge
35) These genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo. Answer: B
Topic: Concept 21.3 Skill: Knowledge
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36) These genes form gradients and help establish the axes and other features of an embryo. Answer: D
Topic: Concept 21.3 Skill: Knowledge
37) Gap genes and pair -rule genes fall into this category. Answer: B
Topic: Concept 21.3 Skill: Knowledge
38) The product of the bicoid gene in Drosophila could be considered a A) tissue-specific protein. B) cytoplasmic determinant. C) morphogen. D) B and C only E) A, B, and C Answer: D
Topic: Concept 21.3 Skill: Comprehension
39) The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur? A) The embryo would grow to an unusually large size. B) The embryo would grow extra wings and legs. C) The embryo would probably show no anterior development and die. D) Anterior structures would form in both sides of the embryo. E) The embryo would develop normally. Answer: D
Topic: Concept 21.3 Skill: Application
40) What do gap genes, pair -rule genes, segment polarity genes, and homeotic genes all have in common? A) Their products act as transcription factors. B) They have no counterparts in animals other than Drosophila . C) Their products are all synthesized prior to fertilization. D) They act independently of other positional information. E) They apparently can be activated and inactivated at any time of the fly's life. Answer: A
Topic: Concept 21.3 Skill: Comprehension
41) Which of the following is least related to the others? A) gap genes B) cyclin genes C) pair-rule genes D) segment polarity genes E) segmentation genes Answer: B
Topic: Concept 21.3 Skill: Comprehension
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42) The fasciated mutant in tomatoes A) affects the identity of the floral organs produced by the plant. B) affects the number of floral organs produced by the plant. C) affects the overall height of the plant. D) is an example of an "organ identity gene." E) both A and D Answer: B
Topic: Concept 21.3 Skill: Knowledge
43) One difference between development in plants and development in animals involves pattern form ation because A) pattern formation is continuous in plants and limited to early development in animals. B) pattern formation is continuous in animals and limited to early development in plants. C) pattern formation occurs in all parts of the plant, but is limited to specific locations in animals. D) pattern formation is limited to specific locations in plants, but occurs in all parts of animals. E) both A and C Answer: A
Topic: Concept 21.3 Skill: Knowledge
44) Which of the following is not true co ncerning homeotic genes? A) They are found in all animals, but nothing like them exists in plants. B) A specific 180 -nucleotide DNA sequence is common to all of the genes. C) They were first identified in Drosophila by Edward Lewis. D) The peptide gene product is a regulatory protein that controls transcription. E) A mutation may cause alterations in the identity of body segments. Answer: A
Topic: Concept 21.3 Skill: Knowledge
45) A small, impermeable membrane is placed between the anchor cell and the other vulva precursor cells in a larva of C. elegans. What would you expect the result to be? A) The vulva would continue to develop normally. B) The vulva would not develop at all. C) The outer part of the vulva would develop, but the inner part would not. D) The inner part of the vulva would develop, but the outer part would not. E) Only the posterior part of the vulva would develop. Answer: B
Topic: Concept 21.3 Skill: Application
46) Which of the following involves apoptosis? A) Interactions between muscle cells and bone cells guide the growth of the muscle to a specific location so that it can attach to the bone. B) Cells from the top of the mouth combine wi th cells from the base of the brain to form the pituitary. C) A gonad begins as an undifferentiated organ that can form either an ovary or a testis. The formation depends on the hormonal signals that control the growth of some cells and the death of others. D) If part of the developing spinal cord in a frog embryo is transplanted to under the skin of its back, it will stimulate development of an eye in that location. E) The bones of the spinal column develop from blocks of undifferentiated tissue called somites. Answer: C
Topic: Concept 21.3 Skill: Comprehension
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47) In vertebrates, programmed cell death is essential for all of the following except A) normal development of the nervous system. B) normal operation of the immune system. C) normal morphogenesis of human feet. D) normal removal of damaged cells. E) normal triggering of the signal transduction pathways. Answer: E
Topic: Concept 21.3 Skill: Knowledge
48) The term homeobox refers to A) a group of genes that determine polarity during development. B) peptide sequences of 60 amino acids that turn other genes on or off. C) zones of polarizing activity commonly present during limb formation. D) a specific nucleotide sequence present wit hin certain genes that regulate development. E) glycoproteins that assist cells during morphogenetic movements. Answer: D
Topic: Concept 21.4 Skill: Knowledge
49) Which of the following are true statements about homeobox-containing genes? A) They are found in both plants and animals. B) They are involved in the transcriptional regulation of other genes. C) They encode proteins containing domains called "homeodomains." D) Only B and C are true. E) A, B, and C are true. Answer: E
Topic: Concept 2 1.4 Skill: Knowledge
Media Activity Questions
50) What role does a transcription factor play in a signal transduction pathway? A) By binding to a plasma membrane receptor it initiates a cascade. B) It relays a signal from the cytoplasm to the plasma membrane. C) It activates relay proteins. D) By binding to DNA it triggers the transcription of a specific gene. E) It is a plasma membrane protein that binds signal molecules. Answer: D
Topic: Web/CD Activity: Signal Transduction Pathway
51) The bicoid gene product is directly responsible for ________ in the developing Drosophila embryo. A) the establishment of the right -left axis B) vulval development C) flower development D) the establishment of the anterior -posterior axis E) apoptosis Answer: D
Topic: Web/CD Activity: Bicoid gene in Drosophila Development
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52) The region of a Drosophila embryo with the highest concentration of bicoid protein will develop into the A) head. B) ovaries. C) vulva. D) homeobox. E) abdomen. Answer: A
Topic: Web/CD Activity: Bicoid gene in Drosophila Development
53) The bicoid gene is a type of ________ gene. A) segmentation B) pair-rule C) segment polarity D) egg-polarity E) gap Answer: D
Topic: Web/CD Activity: Bicoid gene in Drosophila Development
54) How does bicoid protein get into a fertilized egg? A) exocytosis B) phagocytosis C) diffusion D) pinocytosis E) receptor-mediated endocytosis Answer: C
Topic: Web/CD Activity: Bicoid gene in Drosophila Development
Self-Quiz Questions
55) Which of the following processes is most directly responsible for the lack of webbing between the fingers of most humans? A) pattern formation B) transcriptional re gulation C) apoptosis D) cell division E) induction Answer: C 56) The criteria for a good model organism for studying development would probably include all of the following except A) observable embryonic development. B) short generation time. C) a relatively small genome. D) preexisting knowledge of the organism's life history. E) a rare pattern of development when compared to most organisms. Answer: E
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57) Totipotency is demonstrated when A) mutations in homeotic genes result in the development of misplaced appendages. B) a cell isolated from a plant leaf grows into a normal adult plant. C) an embryonic cell divides and differentiates. D) replacing the nucleus of an unfertilized egg with that of an intestinal cell converts the egg to an intestinal cell. E) segment-specific organs develop along the anterior-posterior axis of a Drosophila embryo . Answer: B 58) Cell differentiation always involves A) the production of tissue-specific proteins, such as muscle actin. B) the movement of cells. C) the transcription of the myoD gene. D) the selective loss of certain genes from the genome. E) the cell's sensitivity to environmental cues such as light or heat. Answer: A 59) The development of Drosophila is somewhat unusual in that A) the early mitotic divisions proceed without cytokinesis. B) metamorphosis occurs during the larval stage rather than the pupal stage, as with other insects. C) homeotic genes are mutated. D) cell migration within the embryo does not occur. E) the initial cell divisions have lengthy G1 phases. Answer: A 60) In Drosophila, which genes initiate a cascade of gene activation that includes all other genes in the list? A) homeotic genes B) gap genes C) pair-rule genes D) egg-polarity genes E) segment polarity genes Answer: D 61) Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirrorimage duplication of posterior parts. This is evidence that the product of the bicoid gene A) is transcribed in the early embryo. B) normally leads to formation of tail structures. C) normally leads to formation of head structures. D) is a protein present in all head structures. E) leads to progr ammed cell death. Answer: C 62) Homeotic genes A) encode transcription factors that control the expression of genes responsible for specific anatomical structures. B) are found only in Drosophila and other arthropods. C) specify the anterior -posterior axis for each fruit fly segment. D) create the basic subdivisions of the anterior -posterior axis of the fly embryo. E) are responsible for the programmed cell death occurring during morphogenesis. Answer: A
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63) The embryonic development of C. elegans illustrates all of the following developmental concepts except: A) An inducer's effect can depend on its concentration gradient. B) The response of an induced cell involves the establishment of a unique pattern of gene activity. C) The signal transduction pathways activated by inducers are unique to embryonic cells. D) Sequential inductions direct the formation of complex structures in the developing embryo. E) Inducers bring about their effects via the activation or inactivation of genes that code for transcriptional regulators. Answer: C 64) Although quite different in structure, plants and animals share some basic similarities in their development, such as A) the importance of cell and tissue movements. B) the importance of selective cell enlargement. C) the importance of homeobox-containing homeotic genes. D) the retention of meristematic tissues in the adult. E) master regulatory genes that encode DNA-binding proteins. Answer: E
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