Exam 11: Mendel and the Gene Idea

Cystic fibrosis affects the lungs,the pancreas,the digestive system,and other organs,resulting in symptoms ranging from breathing difficulties to recurrent infections.Which of the following terms best describes this expression of phenotypes?

Characters in humans such as a person's red and white blood cell counts vary quite a bit depending on such factors as altitude and physical activity.Traits like this are referred to as

-The figure above represents a pedigree for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer.Numbers under the symbols are the individuals' age at the time of diagnosis.A slash through the symbol indicates that the individual is deceased.From this pedigree,what is the most likely manner by which this trait is inherited?

-The figure above shows a pedigree chart for a family,some of whose members exhibit the dominant trait,W.Affected individuals are indicated by a dark square or circle. What is the likelihood that the offspring of IV-3 and IV-4 will have the trait?

Which of the following statements correctly describes a monohybrid cross?

-The figure above shows a pedigree chart for a family,some of whose members exhibit the dominant trait,W.Affected individuals are indicated by a dark square or circle. What is the probability that individual III-1 is Ww?

Two true-breeding stocks of pea plants are crossed.One parent has red axial flowers,and the other has white terminal flowers;all F₁ individuals have red axial flowers.The genes for flower color and location assort independently.Among the F₂ offspring,what is the probability of plants with white axial flowers?

-The figure above shows a pedigree chart for a family,some of whose members exhibit the dominant trait,W.Affected individuals are indicated by a dark square or circle. What is the genotype of individual II-5?

Achondroplasia,a form of dwarfism in humans,is caused by a dominant allele.What is the probability of a heterozygous dwarf man and a normal,homozygous woman having a child who is a heterozygous dwarf?

The frequency of heterozygosity for the sickle-cell anemia allele is unusually high,presumably because this reduces the frequency of malaria.Such a relationship is related to which of the following concepts?

-In a particular plant,leaf color is controlled by gene locus D.Plants with at least one D allele have dark green leaves,and plants with the homozygous recessive dd genotype have light green leaves.A true-breeding dark-leaved plant is crossed with a light-leaved one,and the F₁ offspring is allowed to self-pollinate.The predicted outcome of the F₂ is diagrammed in the Punnett square shown in the figure above,where 1,2,3,and 4 represent the genotypes corresponding to each box within the square.Which of the boxes marked 1-4 correspond(s)to plants with dark leaves?

Skin color in humans has a wide variety of phenotypes.The expression of this trait is caused by more than two genes.What type of inheritance pattern is responsible for this expression?

-The figure above represents a pedigree for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer.Numbers under the symbols are the individuals' age at the time of diagnosis.A slash through the symbol indicates that the individual is deceased.The affected woman in generation IV is thinking about her future and asks her oncologist (cancer specialist)whether she can know if any or all of her children will have a high risk of the same cancer.The doctor would be expected to advise which of the following: (I)genetic counseling; (II)prenatal diagnosis when/if she becomes pregnant; (III)testing to see whether she has the allele; (IV)testing to see whether her future spouse or partner has the allele?

Which of the following phases of cell division confirms Mendel's observation of the segregation of alleles in gamete formation?

Gene S controls the sharpness of spines in a type of cactus.Cactuses with the dominant allele,S,have sharp spines,whereas homozygous recessive ss cactuses have dull spines.At the same time,a second gene,N,determines whether or not cactuses have spines.Homozygous recessive nn cactuses have no spines at all.A cross between a true-breeding sharp-spined cactus and a spineless cactus homozygous for dull spines would produce

Which of the following statements correctly describes an example of epistasis?

What was Mendel's explanation for his observation that traits that had disappeared in the F₁ generation reappeared in the F₂ generation of the pea plants he used in his experiments?