Exam 14: Mendel and the Gene Idea

An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a serious disorder that is detectable biochemically in fetal cells.The obstetrician would most reasonably offer which of the following procedures to her patient?

Albinism is an autosomal (not sex-linked)recessive trait.A man and woman are both of normal pigmentation,but both have one parent who is albino (without melanin pigmentation).What is the probability that their first child will be an albino?

The following questions refer to the pedigree chart in the figure below 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?

Use the following information to answer the questions below. Skin colour in a certain species of fish is inherited via a single gene with four different alleles. -One fish of this type has alleles 1 and 3 (S₁S₃)and its mate has alleles 2 and 4 (S₂S₄).If each allele confers a unit of colour darkness such that S₁ has one unit,S₂ has two units,and so on,then what proportion of their offspring would be expected to have five units of colour?

When crossing an organism that is homozygous recessive for a single trait with a heterozygote,what is the chance of producing an offspring with the homozygous recessive phenotype?

Use the following pedigree shown below 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 individual's age at the time of diagnosis. -The affected woman in generation IV is thinking about her future and asks her oncologist (cancer specialist)whether she can know whether 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 counselling 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

Use the following information to answer the questions below. A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative.Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r,respectively.A third gene for the MN blood group has codominant alleles M and N. -Which of the following is a possible genotype for the mother?

When both traits are exhibited in the phenotype,it is said that the alleles display

Use the following information to answer the questions below. Tay-Sachs disease is an inherited genetic disorder in which the gene sequence codes for an enzyme involved in lipid metabolism.Accumulation of lipids in the brain leads to seizures,blindness,loss of neural function,and early death.People can be carriers of this disease and only homozygotic offspring will die from this disorder. -When the enzyme structure of a heterozygote carrier is examined,there is an equal number of functioning and non-functioning enzymes produced.This is an example of

What do we mean when we use the terms monohybrid cross and dihybrid cross?

Use the following information to answer the questions below. 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 colour and location assort independently. -Among the F₂ offspring,what is the probability of plants with white axial flowers?

Which of the following statements is a correct explanation for the observation that all offspring exhibit a phenotype for a particular trait that appears to be a blend of the two parental varieties?

Refer to the following information to answer the questions below. Gene S controls the sharpness of spines in a type of cactus.Cacti with the dominant allele,S,have sharp spines,whereas homozygous recessive ss cacti have dull spines.At the same time,a second gene,N,determines whether or not cacti have spines.Homozygous recessive nn cacti have no spines at all. -If doubly heterozygous SsNn cacti were allowed to self-pollinate,the F₂ would segregate in which of the following ratios?

Use the following information to answer the questions below. A certain (hypothetical)organism is diploid,has either blue or orange wings as the consequence of one of its genes on chromosome 12,and has either long or short antennae as the result of a second gene on chromosome 19,as shown in this figure. -A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene.As cells in her ovaries undergo meiosis,her resulting eggs (ova)may have which of the following?

Visitors at Algonquin Park in Northern Ontario may miss out on the brilliant red colouration of Acer sacchrum in autumn because

Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F₂ generation.The results were as follows: 6022 yellow and 2001 green (8023 total).The allele for green seeds has what relationship to the allele for yellow seeds?

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?

Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility and death,usually from coronary artery disease,at an average age of approximately 13.Patients,who look very old even as children,do not live to reproduce.Which of the following represents the most likely assumption?

Which of the following calculations requires that you utilize the addition rule?

When Mendel crossed yellow-seeded and green-seeded pea plants,all the offspring were yellow seeded.When he took these F₁ yellow-seeded plants and crossed them to green-seeded plants,what genotypic ratio was expected?