Genetics Test Questions

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Genetics Practice Test

Multiple Choice
Identify the choice that best completes the statement or answers the question.

____1.Pea plants were particularly well suited for use in Mendel's breeding experiments for all of the following reasons except that a.|peas show easily observed variations in a number of characters, such as pea shape and flower color.| b.|it is possible to control matings between different pea plants.| c.|it is possible to obtain large numbers of progeny from any given cross.| d.|peas have an unusually long generation time.|

e.|many of the observable characters that vary in pea plants are controlled by single genes.|

____2.What is the difference between a monohybrid cross and a dihybrid cross? a.|A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.| b.|A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny.| c.|A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only one.| d.|A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations.| e.|A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.|

____3.A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates a.|the blending model of genetics.|
b.|true-breeding.|
c.|dominance.|
d.|a dihybrid cross.|
e.|the mistakes made by Mendel.|

____4.The offspring of Mendel's classic pea cross always looked like one of the two parental varieties because a.|one phenotype was completely dominant over another.|
b.|each allele affected phenotypic expression.|
c.|the traits blended together during fertilization.|
d.|no genes interacted to produce the parental phenotype.|
e.|different genes interacted to produce the parental phenotype.|

____5.What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? a.|There is considerable genetic variation in garden peas.|
b.|Traits are inherited in discrete units, and are not the results of "blending."| c.|Recessive genes occur more frequently in the than do dominant ones.| d.|Genes are composed of DNA.|
e.|An organism that is homozygous for many recessive traits is at a disadvantage.|

____6.How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? a.|4|
b.|8|
c.|16|
d.|32|
e.|64|

____7.Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests a.|that the parents were true-breeding for contrasting traits.| b.|incomplete dominance.|

c.|that a blending of traits has occurred.|
d.|that the parents were both heterozygous.|
e.|that each offspring has the same alleles.|

____8.Two characters that appear in a 9:3:3:1 ratio in the generation should have which of the following properties? a.|Each of the traits is controlled by single genes.|
b.|The genes controlling the characters obey the law of independent assortment.| c.|Each of the genes controlling the characters has two alleles.| d.|Four genes are involved.|
e.|Sixteen different phenotypes are possible.|

____9.A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? a.|HT|

b.|Hh|
c.|HhTt|
d.|T|
e.|tt|

____10.It was important that Mendel examined not just the generation in his breeding experiments, but the generation as well, because a.|he obtained very few progeny, making statistical analysis difficult.| b.|parental traits that were not observed in the reappeared in the .| c.|analysis of the progeny would have allowed him to discover the law of segregation, but not the law of independent assortment.| d.|the dominant...
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