Practice Chapter 5 Exam PDF

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Practice Chapter 5 Exam...

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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) Mendel's results and conclusions were accurate but are seen differently today because we now realize that A) single-gene traits are usually influenced by the environment and other genes. B) he didn't count enough peas to draw conclusions. C) pea color is actually more complex than the human visual system can perceive. D) pea inheritance is different from human inheritance.

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2) Some combinations of recessive alleles cause problems so severe that a fetus may cease to develop. Such lethal allele combinations appear to alter Mendelian ratios because A) homozygotes for the lethal allele pass it on to half their offspring. B) they do not show a 1:2:1 genotypic ratio. C) homozygotes for the lethal allele do not appear as a progeny class. D) carriers do not constitute a progeny class.

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3) Marbles is a Manx cat whose tail is so short that she appears not to have one. The 3) genotype for short tail in Manx cats is heterozygous (Mm). Cats that are genotype mm have normal length tails, but cats that are genotype MM die before birth due to highly abnormal brains and spinal cords. Marbles has one copy of a dominant ________ allele. A) polymorphic B) lethal C) penetrant D) pleiotropic 4) Hairlessness in dogs is inherited from a single dominant allele. Inheriting two dominant alleles is lethal for an embryo. Ralph and Penelope are both hairless dogs. What is the probability that Penelope will give birth to a puppy with hair? A) 1/3 B) 2/3 C) 3/4 D) 1/4

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5) Hairlessness in dogs is inherited from a single dominant allele. Inheriting two dominant alleles is lethal for an embryo. Penelope, a hairless dog mates with Arnold, a dog with hair. The probability Penelope will have hairless puppies is A) 1/2. B) 1/4. C) 2/3. D) 3/4.

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6) Brittany and Jarod have been trying to have a second child for 10 years. They have one healthy child, but Brittany has had four early, spontaneous abortions. The most likely explanation for the many pregnancy losses is that Brittany and Jarod A) are each heterozygous for lethal alleles of the same gene. B) are each homozygous for lethal alleles of the same gene. C) have different alleles for all of their vital genes. D) are not having sex frequently enough.

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7) Morris is a big, healthy bull. One spring, he fathers ten calves, but five of them are stillborn, their muscles very rigid in a phenotype called "contracture." Farm animals often mate with their close relatives. So, three of the dams (mothers of the stillborns) are also Morris' daughters, and the fourth is his half-sister. The large number of stillborns is most likely due to A) co-dominance between two lethal alleles. B) dominant non-lethal alleles that Morris shares with his mates. C) recessive lethal alleles that occur as new mutations in the doomed offspring. D) lethal alleles that Morris shares with his mates.

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8) Multiple alleles are common because A) RNA is an informational molecule, and many sequences are possible for a particular gene. B) there are many humans on the planet. C) proteins are informational molecules, and many amino acid sequences are possible. D) a gene sequence can vary in different ways and still encode a functional protein.

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9) A gene may have many alleles, but a person has only two alleles for a gene, because A) having more than two alleles is always lethal. B) a gene can be altered in many ways, but a person has only two copies of any gene. C) having more than two alleles unbalances the chromosomes. D) a genotype is haploid because of meiosis.

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10) Different alleles that are both expressed in a heterozygote are A) codominant. B) dominant. C) incompletely dominant. D) homozygous dominant.

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11) Familial hypercholesterolemia illustrates incomplete dominance in humans because A) heterozygotes have an intermediate number of low-density lipoprotein receptors on their kidney cells. B) heterozygotes have the minimal number of high-density lipoprotein receptors on their liver cells. C) homozygous wild type individuals have an intermediate number of low-density lipoprotein receptors on their liver cells. D) heterozygotes have an intermediate number of low-density lipoprotein receptors on their liver cells.

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12) The alleles that control which A, B blood group antigens appear on the surfaces of red blood cells are A) variably expressed. B) incompletely dominant. C) codominant. D) semidominant.

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13) If allele T (long tongue) exhibits incomplete dominance over the recessive allele t (short 13) tongue), a heterozygote for this gene would most likely have A) a tongue that changes length. B) a long tongue. C) a tongue of intermediate length. D) a short tongue. 14) Can a woman with blood type A have a child with blood type O with a man who is AB? 14) A) No, because the child's genotype must be ii. B) Yes, because of codominance between the IA and IB alleles. C) No, because a man with type AB blood could not contribute an i allele. D) Yes, because of epistasis between the I and the H genes. 15) Zuzu is a white cat. She is genotype W w for the "white masking gene" that reduces the number of melanocytes (pigment-containing cells). As a result, her body makes pigment, but it cannot get into the cells where it would color the fur. Zuzu's white masking gene is ________ to the melanin pigment gene because it prevents full expression of the pigment. A) dominant B) pleiotropic C) recessive D) epistatic

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16) Several members of the Fitzsimmons family have polydactyly, and they differ in their 16) numbers of extra fingers and toes. Yet, certain relatives who should have extra digits don't, such as Megan Fitzsimmons. She has two children, a son with two extra fingers and a daughter with an extra toe, and her father has an extra digit on each hand and foot Polydactyly in this family is A) dominant and recessive. B) variably expressive and incompletely penetrant. C) pleiotropic and a phenocopy. D) invariably expressive and completely penetrant. 17) In Addam's family, there is an autosomal dominant condition in which webbing attaches 17) the second toe to the third toe and the second toe is longer than the big toe. Only some of the members who have inherited the mutant allele have a second toe longer than the big toe. In addition, the extent of webbing varies. This phenotype is A) invariably expressive and completely penetrant. B) dominant and recessive. C) both inherited and non-inherited. D) variably expressive and incompletely penetrant.

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18) Epistasis and multiple alleles differ in that A) epistasis is an interaction between two genes, and multiple alleles are variants of the same gene. B) epistasis only occurs in genes that have multiple alleles. C) epistasis affects males and multiple alleles occur in females. D) in epistasis one gene masks another, but one allele cannot mask the effect of another.

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19) Clara has alkaptonuria. Her symptoms include back spasms, dark urine, arthritis, 19) hearing loss, kidney stones, heart valve damage, and darkened ear tips. This condition is therefore A) epistatic. B) genetically heterogenic. C) pleiotropic. D) dominant. 20) In many species, lens crystalline protein aggregates in the eyes to form lenses, yet in other cell types, functions as an enzyme. The gene that encodes this protein is therefore A) eclectic. B) pleiotropic. C) mutant. D) incompletely penetrant.

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21) Of nearly 200 forms of hereditary deafness, 132 are autosomal recessive, 64 autosomal dominant, and 4 X-linked recessive. Hereditary deafness is therefore genetically A) heterosexual. B) heterozygous. C) heterogeneous. D) heterogametic.

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22) A man who has normal hearing and has a recessive deafness allele on chromosome 17 marries a woman who also has normal hearing and also has a recessive deafness allele, but this allele is on chromosome 3. The probability that their children will be deaf due to either of these mutated genes is closest to A) 0%. B) 50%. C) 25%. D) 100%.

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23) A trait caused by an environmental influence that appears to be inherited is A) multigenic. B) incompletely penetrant. C) pleiotropic. D) a phenocopy.

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24) Marfan syndrome can be caused by mutations in either of two genes involved in the disorder, but mutations in one of the genes blocks activity of the other. This means that Marfan syndrome demonstrates A) an acquired phenotype. B) genetic heterogeneity and epistasis. C) variable expressivity and complete penetrance. D) late onset and early onset.

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25) Having a mutation in some mitochondrial chromosomes but not others is called A) heterogeneity. B) heterozygosity. C) heteroplasmy. D) heterogamy.

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26) A mitochondrial trait passes from A) mothers to daughters only. C) fathers to sons only.

26) B) mothers to all children. D) fathers to daughters only.

27) Mitochondrial DNA differs from nuclear DNA in that it A) crosses over within the same strand. B) is poorer at DNA repair. C) is present only in cells of the nervous and muscular systems. D) is inherited from the father only.

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28) Which of the following is an illness caused by a mutation in mitochondrial DNA? A) Hemophilia B) Marfan syndrome C) Duchenne muscular dystrophy D) Leigh syndrome

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29) The mitochondrial genome consists of ________ genes. A) 370 B) 250 C) 37

29) D) 12

30) Mitochondrial disorders tend to cause great fatigue because A) lysosomes dismantle the mitochondria in muscle cells. B) muscle cells are normally filled with mitochondria. C) nerve cells are filled with mitochondria. D) affected cells do not use their mitochondrial DNA.

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31) Mitochondrial disorders are probably very rare because 31) A) they are difficult to diagnose because most physicians have forgotten what mitochondria are. B) they are not inherited from the father. C) the oocytes with harmful mitochondrial mutations do not have sufficient energy to survive. D) people have many mitochondria, so the healthy ones can substitute for the affected ones. 32) In common English, "linkage" refers to one event that tends to occur when another does. In genetics, linkage has a precise meaning. It refers to the transmission of A) two genes on different chromosomes. B) genotype and phenotype to an offspring. C) two genes on the same chromosome. D) two genes that have the same effect.

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32)

33) When researchers analyzed the remains of Tsar Nicholas II of Russia and his family, they found that the suspected Tsar and his living great-grandniece Xenia differed at nucleotide position 16169 in the mitochondrial DNA. Retesting the remains showed that for this site in the mitochondrial genome, the purported Tsar had thymine (T) in some samples and cytosine (C) in others. The most likely cause of this finding is A) the samples were too old. B) incomplete dominance. C) heteroplasmy. D) pleiotropy.

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34) Genes that are situated close on a chromosome A) do not cross over. B) do not affect one another. C) produces Mendelian ratios for crosses tracking two or more genes. D) do not assort independently.

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35) In a heterozygote for two linked genes, both dominant alleles are on one chromosome and both recessive alleles are on another chromosome. The genes are said to be in A) recombination. B) trans. C) repulsion. D) cis.

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36) A, B, and C are linked genes. Recombination between A and B is 3%; between A and C is 6%; and between B and C is 9%. What is the order of these genes on the chromosome? A) B-C-A B) A-C-B C) A-B-C D) B-A-C

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37) Geneticists construct linkage maps of chromosomes by A) correlating a phenotype to an observable chromosomal abnormality. B) calculating the percent recombination between two genes on the same chromosome. C) determining the number of crossovers between genes on different chromosomes. D) observing the number of genes on a chromosome.

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38) LOD (logarithm of the odds) scores are used to indicate linkage between genes. A LOD score of ________ or greater is a strong indicator of linkage. A) 3 B) 0.5 C) 1 D) 2

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39) A and B are linked genes. In a study of 100 offspring, 94 had parental genotypes for A and B, while 6 were recombinants. A and B are ________ map units apart. A) 4 B) 9.4 C) 94 D) 6

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40) A popular research technique used to associate patterns of genetic variation with phenotypes that is based on the concept of linkage, but considering all of the chromosomes at once, is A) genome sequencing. B) genome-wide association studies. C) gene expression profiling. D) assisted reproductive technologies.

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41) Types of genetic markers include A) the proteins produced in a cell. B) places in the genome where a base varies among individuals in a population. C) places in the genome where all people have identical base sequences. D) the types of mRNAs in a cell.

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TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 42) Genetic heterogeneity refers to mutations in different genes that cause the same symptoms.

42)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

43) Children who have AIDS may have parents who have AIDS, but this is a result of viral infection, not inheritance of a mutation. This is an example of A) Codominance B) Phenocopy C) Genetic heterogeneity D) Pleiotropy

43)

44) In meiosis, genes that are found close together on a chromosome A) are usually in trans. B) are usually inherited together. C) usually exhibit crossing over. D) are usually assorted independently.

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Answer Key Testname: UNTITLED4

1) A 2) C 3) B 4) A 5) A 6) A 7) D 8) D 9) B 10) A 11) D 12) C 13) C 14) D 15) D 16) B 17) D 18) A 19) C 20) B 21) C 22) A 23) D 24) B 25) C 26) B 27) B 28) D 29) C 30) B 31) C 32) C 33) C 34) D 35) D 36) D 37) B 38) A 39) D 40) B 41) B 42) TRUE 8

Answer Key Testname: UNTITLED4

43) B 44) B

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