What is the blending theory of inheritance?

A.Mendel's theory of how the traits of parents are passed to offspring through the gametes
B. Darwin's theory of how traits are passed from all parts of the parent's body into the gamete to be transmitted to the offspring
C.The modern theory of how genetic information is passed from parents to offspring
D. An old theory that said that offspring show traits intermediate between those of the parents

D

Which characteristic of pea plants were important in their selection as Mendel's research organism?

A. Peas are easy to cultivate.
B. Pea plants have a short generation time.
C. Pea plants are self-pollinating but can be cross-fertilized easily.
D. Many true-breeding varieties were available.
E. All of the above were important characteristics in Mendel's selection.

E

In a classic Mendelian monohybrid cross between a homozygous dominant parent and a homozygous recessive parent, which generation is always completely heterozygous?

A. F1 generation
B. F2 generation
C. F3 generation
D. P generation

A

If a pea plant shows a recessive phenotype,

A. the genotype may be TT or Tt.
B. the genotype may be Tt or tt.
C. the genotype can only be TT.
D. the genotype can only be tt.
E. the genotype may be TT, Tt, or tt.

D

Women with X-linked disorders always pass the genes for the disorder to ______, while men with X-linked disorders always pass the genes for the disorder to _______.

A. only their daughters; only their daughters
B. both their daughters and sons; only their sons
C. both their daughters and sons; only their daughters
D. both their daughters and sons; their daughters and sons

C

Generally, it is not possible to determine whether nondisjunction failed to occur in oogenesis or spermatogenesis. However, it is possible to assert that _________ resulted in nondisjunction in __________.
A. XXY; oogenesis
B. XYY; spermatogenesis
C. XXX; oogenesis
D. XXY; spermatogenesis
E. XO; oogenesis

B

The F2 offspring of a classic Mendelian monohybrid cross between homozygous dominant and homozygous recessive parents would produce the genotype(s)

A. AA and Aa.
B. Aa and aa.
C. AA, Aa, and aa.
D. AA only.
E. Aa only.

C

The offspring of a monohybrid testcross would have what possible genotype(s)?

A. AA and Aa.
B. Aa and aa.
C. AA, Aa, and aa.
D. AA only.
E. aa only.

B

What are alleles?

A. genes for different traits, such as hair color or eye color
B. alternative forms of a gene for a single trait, such as blue eyes or brown eyes
C. the locations of genes on a chromosome
D. recessive forms of a kind of characteristic carried by genes
E. dominant forms of a kind of characteristic carried by genes

B

If an individual with a dominant phenotype is crossed with an individual with a recessive phenotype, 4 of their 9 offspring show the recessive phenotype. What is the genotype of the first parent?

A. AA
B. Aa
C. aa
D. The answer cannot be determined from this information.

B

Which is NOT true according to Mendel's law of segregation?

A. Each individual contains two factors for each trait.
B. One factor must be dominant and one factor recessive in each individual.
C. Factors separate from each other during gamete formation.
D. Each gamete contains one copy of each factor.
E. Fertilization restores the presence of two factors.

B

Some plants fail to produce chlorophyll, and this trait appears to be recessive. Many plants also self-pollinate. If we locate a pea plant that is heterozygous for this trait, self-pollinate it and harvest seeds, what are the likely phenotypes of these seeds when they germinate?

A. All will be green with chlorophyll since that is the dominant trait.
B. All will be white and lack chlorophyll since this is self-pollinated.
C. About one-half will be green and one-half white since that is the distribution of the genes in the parents.
D. About one-fourth will be white and three-fourths green since it is similar to a monohybrid cross between heterozygotes.
E. About one-fourth will be green and three-fourths white since it is similar to a monohybrid cross between heterozygotes.

D

The most common lethal genetic disease among Caucasians is

A. neurofibromatosis.
B. Tay-Sachs disease.
C. phenylketonuria.
D. albinism.
E. cystic fibrosis.

E

The pedigree chart depicts the inheritance pattern of ____. Circles depict females and squares depict males. Colored shapes represent affected individuals (expressing a trait) and uncolored shapes are unaffected (do not express a trait).

A. an autosomal recessive characteristic with both parents being heterozygous
B. an autosomal dominant characteristic with both parents being homozygous dominant
C. an autosomal recessive characteristic with both parents being homozygous recessive
D. none of the above

A

If the parents are AO and BO genotypes for the ABO blood group, their children could include which of the following genotypes?

A. AO and BO only
B. AO, BO, and AB only
C. AA, BB, and AB only
D. AO, BO, and OO only
E. AO, BO, AB, and OO only

E

Haiti is settled by peoples of both African and European ancestry. A young couple, both with mixed ancestry, marry and have several children. The children vary widely in the amount of skin melanin production, with one child being lighter than both parents, and one being darker. The simple explanation for this is

A. epistasis.
B. multiple alleles are available for the one chromosomal locus that governs skin color.
C. the environment affected the phenotype that developed.
D. polygenic inheritance.
E. gene linkage.

D

Lethal genes (genes that result in the failure to develop a vital organ or metabolic pathway) are nearly always recessive. Animal breeders who discover a unique trait and selectively breed to increase the occurrence of that trait often encounter a noticeable increase in lethal genes. Why?

A. The lethal recessive gene may be incompletely dominant.
B. Spreading the gene among offspring of both sexes will increase the likelihood it will be sex-linked and expressed.
C, The selective-mating of closely related individuals, or inbreeding, increases chances that two recessive genes will "meet" in offspring.
D. "Pleiotropy" - the gene that is being selected for this trait may have the second effect of being lethal.
E. "Epistasis" - selection for the desired trait may result in "uncovering" the lethal gene.

C

Unattached earlobes (EE or Ee) are described in the textbook as dominant over attached earlobes (ee). A couple both have unattached earlobes. Both notice that one of their parents on both sides has attached earlobes (ee). Therefore, they correctly assume that they are carriers for attached earlobes (Ee). The couple proceeds to have four children.

A. They can be certain that three will be heterozygous and one homozygous recessive.
B. If the first three are heterozygous, the fourth must be homozygous recessive.
C. The children must repeat the grandparents' genotype (Ee).
D. All children must have unattached earlobes since both parents possess the dominant gene for it.
E. Two heterozygous, one homozygous recessive and one homozygous dominant is a likely outcome, but all heterozygous, or two, three or all four homozygous are also possible.

E

In 1940, two researchers named Weiner and Landsteiner discovered that about 85 percent of the human population sampled possessed a blood cell protein that had been previously detected in Rhesus monkeys. This blood type was labeled Rh positive, and Rh+ was found to be dominant over the absence of the blood factor (Rh). Under normal Mendelian inheritance, which of the following statements is FALSE?

A. Two Rh+ parents could have an Rh- child.
B. Two Rh- parents could have an Rh+ child.
C. An Rh- child would require that both parents be carriers of at least one Rh- gene.
D. It is possible with just one pair of parents to have children where some siblings are Rh- and some are Rh+.
E. All of the choices are false.

B

Since each child of two heterozygous parents has a 50% chance of receiving a recessive trait from each parent,

A. if the first child is phenotypically recessive, then the next child must be phenotypically dominant.
B. if the first child is phenotypically recessive, then the next child has a 3/4 chance of being phenotypically recessive.
C. if the first child is phenotypically recessive, then the next child has a 1/2 chance of being phenotypically recessive.
D no matter what the first child's phenotype, the next child will have a 1/4 chance of being phenotypically recessive.

D

The ability to roll the edges of the tongue upward in a U-shape has been considered to be an inherited ability. The standard assumption is that tongue-rolling is a dominant allele at a single gene locus. Which of the following would cast doubt on this assumption?
A. A teacher reports that after testing her class on the ability to roll their tongue, with very little effort the non-tongue-rollers can learn to also roll their tongues.
B. A student who can roll his tongue has a mother and father, both of whom cannot.
C. A student who cannot roll his tongue has a mother and father, both of whom can.
D. Two of the above are situations that would cast doubt on this assumption.

D

If the probability of event A is 3/4 and the probability of event B is 1/4, then the probability of both A and B occurring at the same time is

A. 3/4.
B. 1/4.
C. 1 or absolute certainty.
D. 1/2.
E. 3/16.

E

The reason why some individuals who inherit polydactyly (having an extra digit on the hand or feet) but do not express the trait is due to ________.

A. incomplete penetrance
B. incomplete dominance
C. gene linkage
D. pleiotropy
E. none of the answers are correct

A

Computer simulations are sometimes used to demonstrate the outcome of monohybrid fruit fly crosses, where a student can run generation after generation of fruit flies with 100 offspring produced each generation, half male and half female, and a 3-to-1 phenotype ratio (or 75 to 25) in the F1 generation. Compared with real genetics results,

A. rarely would exactly 100 fly offspring be produced or survive.
B. an exact balance between males and females would be rare.
C. a precise 3-to-1 ratio would be uncommon.
D. All of the choices are true.

D

In what kind of classic Mendelian cross would you expect to find a ratio of 9:3:3:1 among the F2 offspring?

A. monohybrid cross
B. dihybrid cross
C. testcross
D. None of the choices is correct.

B

Predicting the outcome of a sex-linked trait
If a woman is a carrier for the color-blind recessive allele and her husband is normal, what are their chances that a son will be color-blind?

A. None since the father is normal.
B. 50% since the mother is the only carrier.
C. 100% because the mother has the gene.
D. 25% because the mother is a hybrid.
E. None since he will also be just a carrier.

B

In pea plants, the gene for round seed (R) is dominant, and wrinkled seeds (r) are recessive. The endosperm of the pea is also either starchy, a dominant gene (S), or waxy (s). What can be said of a fully heterozygous, dihybrid cross?

A. It is impossible to secure offspring that are homozygous for both dominant genes.
B. It is impossible to secure offspring that are homozygous for both recessive genes.
C. It is impossible to secure offspring that are homozygous for one dominant gene such as round seed and homozygous recessive for the other recessive waxy gene.
D. All of these choices are impossible combinations in a dihybrid cross.
E. All of these choices are possible combinations in a dihybrid cross.

E

A testcross involves an individual exhibiting the dominant phenotype but an unknown genotype being crossed with an individual that has a(n) ___________ genotype.

A. homozygous dominant
B. heterozygous dominant
C. homozygous recessive
D. any of the choices

C

If individuals exhibiting a dominant phenotype are crossed and produce only offspring with the dominant phenotype, what would be the logical genotype of the parents?

A. both are homozygous recessive
B. one is heterozygous and one is homozygous dominant
C. both are homozygous dominant
D. both are heterozygous
E. two of the options may be correct

E

Use of a Punnett square
In the use of a Punnett square for genetic results of crossing individuals

A. all different kinds of sperm are lined up either horizontally or vertically.
B. all different kinds of eggs are lined up either horizontally or vertically.
C. the results show the offspring's expected genotypes.
D. All of the choices are correct.
E. Only two of the choices are correct.

D

If a human who is a tongue roller (T) and has unattached ear lobes (E) marries a person who cannot roll their tongue and has attached earlobes, could they produce an offspring that was also a non-tongue roller with attached earlobes? What would be the genotype of the first parent? the second parent?

A. yes; TtEe; tree
B. yes; TtEE; tree
C. no; TTEE; ttee
D. unable to determine from the information given

A

The particulate theory of inheritance

A. preceded Mendel's research by a century.
B. was proposed by Mendel.
C. is based on particles or hereditary units we now call genes.
D. All of the choices are correct.
E. Two of the above.

E

As many as 60% of people in malaria-infected regions of Africa have the sickle-cell allele, but only about 10% of the U.S. population of African ancestry carries the allele. Malaria remains a major disease in central Africa but has not been a serious problem in the U.S. for many generations. What is/are the reason(s) for the difference in the percentages and what is a reasonable statement about future percentages?

A. The presence of malaria in Africa maintains the advantage of the heterozygous sickle-cell trait, and the prevalence of malaria will likely continue to preserve the 60% rate.
B. The U. S. percentage may have always been somewhat lower due to immigration from nonmalaria regions, but changes in sites and rates of immigration could occur.
C. Lack of widespread malaria in the United States would have made both homozygous and heterozygous carriers of sickle-cell undergo several generations of negative selection, and we should expect this to continue unless innovative therapies give all individuals an equal chance of surviving and reproducing.
D. All of the choices are reasonable.

D

Which is associated with the inability to produce factor VIII in the blood?

A. Williams syndrome
B. trisomy 21
C. color-blindness
D. Hemophilia A
E. Duchenne muscular dystrophy

D

When crossing a true-breeding red snapdragon flower with a true-breeding white flower of the same species, we secure all pink offspring. This would seem to support the pre-Mendel view that inheritance is a blending of parental traits. However, Mendel and conventional wisdom agree that "blending" of parental traits is not correct and that particles of inheritance are actually involved because

A. in the case of incomplete dominance, only radioactive isotope tracers can follow the actual hereditary particles
B. under blending theory, over many generations only the average (or pink flowers) would remain; there would be no way to get back to pure red and white
C. it is possible to cross the pink F-1 generation and secure a predictable proportion of pure red and white flowers again, which is not accounted for under the blending theory
D. there is no way to directly prove incomplete dominance is not a case of blending, but we can be sure of genes because of the other cases of dominance, etc., where genes are the only logical explanation.
E. two of the above are true

E

Cystic fibrosis and Niemann-Pick Disease are common autosomal dominant disorders.

FALSE

In a case of incomplete dominance, the phenotypic ratio of the F2 generation is the same as the genotypic ratio.

TRUE

Each gamete carries one factor, now called an allele, for each inherited trait.

TRUE

If an individual is heterozygous for a particular trait, the gametes that individual produces will contain 3/4 dominant and 1/4 recessive alleles.

FALSE

Polygenic traits such as height or weight are often influenced by the environment of the organism.

TRUE

If black fur is produced by a recessive allele, which genotype is most likely to produce a black individual?

A. bb
B. BB
C. Bb
D. Cb

A

If white eyes are produced by a recessive allele, what is the likely genotype of a white-eyed individual?

A. rr
B. Rr
C. RR
D. RB

A

Which allele combination represents a homozygous dominant individual?

A. AA
B. Aa
C. aa
D. none of these are homozygous dominant individuals

A

Which allele combination represents a recessive individual?

A. aa
B. AA
C. Aa
D. None of these represent a recessive individual

A

Pleiotropy typically

A. causes various symptoms to appear even though it only impacts a single gene.
B. causes a single symptom to appear even though it only impacts a single gene.
C. causes various symptoms to appear even though it only impacts multiple genes.
D. causes a single symptom to appear even though it only impacts multiple genes.

A

Which occurrence is when an individual inherits a dominant gene but does not fully express the dominant phenotype?

A. incomplete penetrance
B. incomplete dominance
C. polygenic inheritance
D. pleiotropy

A

Which of the following scenarios would not have been used by Mendel during his research?

A. relied on his memory to remember his data
B. followed the scientific method when designing his experiments
C. used a statistic analysis to determine if his data was valid
D. researched multiple generations of pea plants to help derive his conclusions

A.

Which factor led to Mendel's success as a scientist?

A. applied mathematics to the field of science
B. followed the scientific method very closely
C. kept detailed records of his research
D. all of these factors made Mendel successful

A

Which statement about the blending concept of inheritance is correct?

A. A cross between a tall man and a short woman would always produce children of medium height.
B. A cross between a tall man and a short woman can produce some children that are tall while others are short.
C. A cross between a tall man and a short woman produce tall children who can then produce short grandchildren.
D. Genetic material is unstable which accounts for such a wide diversity in our offspring.

A

Which of the following disorders is not a X-linked trait?

A. hemophilia
B. Muscular dystrophy
C. Adrenoleukodystrophy
D. All of these are X-linked disorders

D

During Mendel's pea plants experiment he discovered that the trait for tallness is dominant to that of shortness. Which of the following statements is correct?

A. Tall = TT or Tt while short = tt
B. Tall = TT or tt while short = Tt
C. Tall = tt while short = TT or Tt
D. None of these statements are correct.

A

When an individual of African descent marries and has children with an individual of European descent their children often have a mid shade of skin color. This can best be described as ___________.

A. X-linked inheritance
B. polygenic inheritance
C. pleiotropic inheritance
D. the dominance of the gene for dark skin tone

B

When a round fruit plant is crossed with a long fruit plant their offspring are oval. What is the best explanation for this scenario?

A. pleiotropic inheritance
B. polygenic inheritance
C. incomplete dominance
D. X-linked inheritance

C

Which of the following is not part of Mendel's law of segregation?

A. Each individual has two factors for each trait.
B. The factors segregate during Meiosis.
C. Each gamete will contain two factors for a trait.
D. Fertilization gives the offspring two factors for each trait.

C