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Advantages to using the garden pea for Mendel's experiments included all listed below exceptA) true-breeding varieties were scarce. B) he could expect to observe segregation of traits among the offspring. C) they have relatively short generation time. D) sex organs of the pea are enclosed within the flower. 2
Pea plants canA) self-pollinate, but are not self-compatible B) self-fertilize C) only cross-fertilize D) reproduce without pollination 3
In Mendel's F2 generation, one out of four plants had white flowers becauseA) the trait is sex-linked B) both parents were heterozygous purple C) one parent was homozygous recessive D) both parents were heterozygous white 4
Mendelian inheritance may be difficult to analyze because of all of the following exceptA) formation of Barr bodies B) pleiotropic effects C) continuous variation D) epistasis 5
Klinefelter's syndrome is caused by a nondisjunction resulting in a genotype ofA) YYY B) XYY C) XXX D) XXY 6
In the F2 generation, the 3:1 ratio is really a disguisedA) 1:2:1 B) 2:1:1 C) 1:1:2 D) 4:0 E) 4:1 7
The ratio often referred to the Mendelian ratio isA) 1:3:3:1 B) 9:7 C) 1:3:1 D) 1:1 E) 3:1 8
When Mendel crossed pure-breeding purple and white flowered pea plants, the dominant to recessive ratio in the F1 generation wasA) 3:1 B) 4:0 C) 4:1 D) 4:0 E) 9:3:3:1 9
On which of the following chromosomes are sex-linked traits carried?A) 13 B) 18 C) Y D) 15 E) X 10
The genotype of an individual with Turner syndrome isA) YO B) XXY C) XYY D) XO E) XXX 11
In Mendel's F2 generation of the purple and white flower crossing, the dominant to recessive ratio wasA) 1:3:1 B) 3:1 C) 1:1 D) 9:7 E) 9:3:3:1 12
The name for a chromosome map unit isA) centimorgan B) centistern C) millimendel D) decibarr E) centisutton 13
Which of the following represents a testcross?A) Ww x WW B) ww x WW C) Ww x Ww D) WW x WW E) none of the above 14
A disease caused by an autosomal primary nondisjunction isA) Turner syndrome B) Down syndrome C) Tay-Sachs disease D) Klinefelter syndrome E) PKU 15
A individual who has two of the same allele is said to beA) homozygous B) heteromologous C) homologous D) heterozygous E) diplozygous 16
Which of the following represents a dihybrid?A) WWSs B) WwSS C) WwSs D) WWss E) wwSs 17
Where two alternatives for a trait are tall and short, and tall is dominant, the genotype of a heterozygous individual would be expressedA) sS B) ss C) SS D) Ss E) tall 18
Which of the following chromosomes, if trisomic, cause failure of survival of development?A) X B) 21 C) 11 D) 18 E) 15 19
The appearance resulting from a given gene combination is referred to as theA) genotype B) phenotype C) phototype D) alleleotype E) stereotype 20
Compared to previous geneticists, the unique characteristic of Mendel's work wasA) keeping records of numbers of different progeny B) choosing the garden pea for his experiment C) producing hybrids D) studying more than one generation E) crossing true-breeding plants 21
A modified Mendelian ratio is represented byA) 9:3:3:1 B) 1:3:1 C) 3:1 D) 9:7 E) 1:1 22
The two alternatives for a trait are red and white and red is dominant. However, white is the most common trait. What is the genotype of a homozygous dominant individual?A) RR B) rr C) WW D) ww E) red 23
Where the two alternatives for a trait are broad and narrow, and broad is dominant, the phenotype of a homozygous dominant individual would be expressed asA) BB B) nn C) Bn D) NN E) broad 24
A genetic disorder caused by a dominant allele isA) sickle-cell anemia B) PKU C) Tay-Sachs disease D) hemophilia (royal) E) Huntington's disease 25
Early ideas about heredity includeA) traits can be masked in some generations B) traits were segregated among progeny C) alleles do not influence each other D) traits are transmitted directly E) not all copies of a factor are identical 26
What is the phenotype of a fruit fly whose genotype is g+ g+ vsvs (where g = gray body and vs = vestigial wings; wild type = black body and normal wings)?A) gray body; vestigial wings B) gray body; normal wings C) black body; vestigial wings D) black body; normal wings 27
In garden peas, height is determined by a single gene with tall being dominate to short. If two heterozygous plants are crossed, what proportion of the tall progeny will be homozygous dominant?A) 3/4 B) 2/3 C) 1/2 D) 1/3 E) 1/4 28
In the cross MMnn x mmNN, what proportion of the resulting F1 would be homozygous dominant for both genes?A) none B) 1/16 C) 3/16 D) 9/16 E) all 29
In humans pointed eyebrows are dominant to smooth eyebrows and widow's peak (downward pointed frontal hairline) is dominant to continuous hairline. What phenotypic ratio would you expect in the offspring from a cross between an individual heterozygous for both genes and an individual homozygous recessive for both genes?A) 9:3:3:1 B) 9:3:4 C) 1:1:1:1 D) 1:2:1:2:4:2:1:2:1 E) 9:7 30
Hypertrichosis, hairiness of the pinna of the ear, is inherited as a Y-linked recessive in humans. If a man with hypertrichosis marries a normal woman, what types of children may they have?A) All of their children of both sexes have hypertrichosis. B) All the sons have hypertrichosis, but none of their daughters. C) Half of their sons, but none of their daughters will have hypertrichosis. D) All the daughters have hypertrichosis, but none of their sons. E) None of their children have hypertrichosis. 31
The model for the dihybrid cross of heterozygotes predicts a phenotypic ratio of 9:3:3:1.A) True B) False 32
Epistasis is a genetic condition in which certain alleles of one locus can alter the expression of alleles of a different locus.A) True B) False 33
One gene can have multiple effects on an organism.A) True B) False 34
The genotypes of a husband and wife are IA IB x IA i. Among the blood types of their children, how many different genotypes and phenotypes are possible?A) 2 genotypes; 3 phenotypes B) 3 genotypes; 4 phenotypes C) 4 genotypes; 4 phenotypes D) 3 genotypes; 3 phenotypes E) 4 genotypes; 3 phenotypes 35
A trait caused by a recessive autosomal allele will result in a pedigree that shows affected individuals having at least one affected parent.A) True B) False 36
Down syndrome results from:A) the absence of one chromosome in position 21 B) the presence of an extra chromosome in position 21 C) the absence of both chromosomes in position 21 D) crossing over on the chromosomes in position 21 E) none of the above 37
Which of the following is not a result of nondisjunction of the sex chromosomes?A) Down syndrome B) Barr body C) Turner syndrome D) Klinefelter syndrome E) both a and b