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When the cystic fibrosis gene was discovered in 1989,only one mutation was described,and a diagnostic test was developed to detect it.Over the years,as more mutations were discovered,they were added to the test panel.Today,most pregnant women are offered a CF test that detects 100 or so alleles,although more than 1600 mutations have been discovered.Which of these is reflected by the given facts?


A) The presence of multiple alleles
B) The presence of pleiotropy
C) The presence of phenocopy
D) The presence of lethal alleles

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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) A-B-C
B) A-C-B
C) B-C-A
D) B-A-C

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Two different alleles for the same mitochondrial gene is called


A) heterogamy.
B) heteroplasmy.
C) heterogeneity.
D) heterozygosity.

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Mitochondrial disorders are probably very rare because


A) people have many mitochondria,so the healthy ones can substitute for the affected ones.
B) the oocytes with harmful mitochondrial mutations do not have sufficient energy to survive.
C) they are difficult to diagnose because most physicians have forgotten what mitochondria are.
D) they are not inherited from the father.

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Several members of the Fitzsimmons family have polydactyly,and they differ in their 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) variably expressive and incompletely penetrant.
B) invariably expressive and completely penetrant.
C) pleiotropic and a phenocopy.
D) dominant and recessive.

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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) repulsion.
C) cis.
D) trans.

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Genes that are situated close on a chromosome 2-14-2013


A) do not affect one another.
B) do not cross over.
C) do not assort independently.
D) produces Mendelian ratios for crosses tracking two or more genes.

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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 affects males and multiple alleles occur in females.
C) epistasis only occurs in genes that have multiple alleles.
D) in epistasis one gene masks another,but one allele cannot mask the effect of another.

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Mitochondrial disorders tend to cause great fatigue because


A) nerve cells are filled with mitochondriA.
B) muscle cells are normally filled with mitochondria.
C) affected cells do not use their mitochondrial DNA.
D) lysosomes dismantle the mitochondria in muscle cells.

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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) 3/4
B) 1/3
C) 2/3
D) 1/4

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Clara has alkaptonuria.Her symptoms include back spasms,dark urine,arthritis,hearing loss,kidney stones,heart valve damage,and darkened ear tips.This condition is therefore


A) genetically heterogenic.
B) pleiotropic.
C) dominant.
D) epistatic.

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Some combinations of recessive alleles cause problems so severe that a may fetus cease to develop.Such lethal allele combinations appear to alter Mendelian ratios because


A) carriers do not constitute a progeny class.
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) homozygotes for the lethal allele pass it on to half their offspring.

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A and B are linked genes.A heterozygote for both genes would show which configuration if the genes are in cis?


A) AaBb\frac { A a } { B b }
B) ABab\frac { A B } { a b }
C) AbaB\frac { A b } { a B }
D) BbBB\frac { B b } { B B }

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The mitochondrial genome consists of _____ genes.


A) 12
B) 37
C) 250
D) 370

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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) variable expressivity and complete penetrance.
B) an acquired phenotype.
C) late onset and early onset.
D) genetic heterogeneity and epistasis.

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Familial hypercholesterolemia illustrates incomplete dominance in humans because


A) heterozygotes have an intermediate number of low-density lipoprotein receptors on their liver cells.
B) homozygous wild type individuals have an intermediate number of low-density lipoprotein receptors on their liver cells.
C) heterozygotes have an intermediate number of low-density lipoprotein receptors on their kidney cells.
D) heterozygotes have the minimal number of high-density lipoprotein receptors on their liver cells.

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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) 6
C) 9.4
D) 94

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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) 100%.
B) 50%.
C) 25%.
D) 0%.

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Geneticists construct linkage maps of chromosomes by


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

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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) recessive lethal alleles that occur as new mutations in the doomed offspring.
B) dominant alleles that Morris shares with his mates.
C) multiple lethal alleles that Morris shares with his mates.
D) co-dominance between two lethal alleles.

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