Exam #3
In pea plants, the tall phenotype is dominant to the dwarf phenotype. If a heterozygous pea plant is crossed with a homozygous tall pea plant, what is the probability that the offspring will be dwarf in size?
0
What is the probability that individual III-1 is Ww?
1
D d D 1 2 d 3 4 Which of the boxes marked 1-4 correspond to plants with dark leaves?
1,2,3
A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color blind marries a color-blind male. What is the probability that this couple's first son will be color blind?
1/2
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
1/2
Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as an X-linked recessive allele in humans. A woman whose father suffered from G6PD marries a normal man. What proportion of their sons is expected to be G6PD?
1/2
Albinism is a recessive trait. A man and woman both show normal pigmentation, but both have one parent who has albinism (without melanin pigmentation). What is the probability that their first child will have albinism?
1/4
What is the probability of producing the genotype AABBCC in a cross of individuals who both possess this genotype: AaBbCc?
1/64
White eye color is a sex-linked, recessive characteristic in fruit flies. If a female having white eyes is crossed with a wild-type male, what percentage of the F1 males will have white eyes?
100%
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 producing plants with white axial flowers?
3/16
Referring to the figure, what bases will be added to the primer as DNA replication proceeds?
5 A, G, A, C, G, A, C 3
The following question refers to the pedigree chart in the figure 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 progeny of IV-3 and IV-4 will have the trait?
50%
What is the likelihood that the progeny of IV-3 and IV-4 will have the trait?
50%
How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
8
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
8%
In humans, ABO blood types refer to glycoproteins in the membranes of red blood cells. There are three alleles for this autosomal gene: IA, IB, and i. The IA allele codes for the A glycoprotein, The IB allele codes for the B glycoprotein, and the i allele doesn't code for any membrane glycoprotein. IA and IB are codominant, and i is recessive to both IA and IB. People with type A blood have the genotypes IAIA or IAi, people with type B blood are IBIB or IBi, people with type AB blood are IAIB, and people with type O blood are ii. If a woman with type AB blood marries a man with type O blood, which of the following blood types could their children possibly have?
A and B
Between which two genes would you expect the highest frequency of recombination?
A and G
A black guinea pig crossed with a guinea pig with albinism produced 12 black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?
Albinism is a recessive trait; black is a dominant trait.
A new DNA strand elongates only in the 5' to 3' direction because _____.
DNA polymerase can add nucleotides only to the free 3' end
A gene for the MN blood group has codominant alleles M and N. If both children are of blood type M, which of the following is possible?
Each parent is either M or MN.
A gene for the MN blood group has codominant alleles M and N. If both children in a family are of blood type M, which of the following situations is possible?
Each parent is either M or MN.
Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white. What is the most probable genotype of each parent?
Gg × Gg
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?
HT
Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true?
It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease.
In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?
No replication fork will be formed.
In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?
No replication fork will be formed.
A white-eyed female Drosophila is crossed with a red-eyed male Drosophila. Which statement below correctly describes the results?
None of the females will have white eyes.All of the females will have red eyes because they will inherit the dominant red-eye allele from their male parent.
Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?
One-half of the daughters of an affected father and a carrier mother could have this condition.
If cell X enters meiosis, and nondisjunction of one chromosome occurs in one of its daughter cells during meiosis II, how will this affect the gametes at the completion of meiosis?
One-quarter of the gametes descended from cell X will be n + 1, one-quarter will be n - 1, and half will be n.
You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits?
Red shows incomplete dominance over white.
In DNA replication in E. coli, the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following results would you expect?
Replication would not occur on either the leading or lagging strand.
What is meant by the description "antiparallel" regarding the strands that make up DNA?
The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
Which of the following statements would explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?
The two genes are closely linked on the same chromosome.
Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
XCXc and XCY
Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
XNXn and XNY
Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height?
a combination of polygenic inheritance and environmental factors (Several genes (polygenic inheritance) control height in humans, giving an overall normal distribution. Environmental factors such as nutrition smooth out the curve.)
Mendel's law of independent assortment has its basis in which of the following events of meiosis I?
alignment of pairs of homologous chromosomes along the middle of the cell
From this pedigree, how does this trait seem to be inherited?
an autosomal dominant
Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?
environmental factors such as soil pH affect the phenotype
What can we observe in order to visualize Mendel's Law of Segregation?
homologous chromosomes separating during meiosis I Homologous chromosomes each carry an allele for every gene. Those alleles may be the same or different, but they are segregated during meiosis I and distributed to each gamete.
In general, the frequency with which crossing over occurs between two linked genes depends on what?
how far apart they are on the chromosome The farther apart two genes are, the greater the probability that a crossover will occur between them, and therefore the greater the recombination frequency.
Inheritance patterns cannot always be explained by Mendel's models of inheritance. If a pair of homologous chromosomes fails to separate during meiosis I, select the choice that shows the chromosome number of the four resulting gametes with respect to the normal haploid number (n)?
n + 1; n + 1; n - 1; n - 1
A man who is a dwarf with achondroplasia and normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Dwarfism caused by achondroplasia is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their daughters might be expected to be color-blind with achondroplasia?
none
Which of the following describes the ability of a single allele to have multiple phenotypic effects?
pleiotropy
Which of the following inheritance patterns describes the ability of a single allele to have multiple phenotypic effects?
pleiotropy
Pseudohypertrophic muscular dystrophy is a human disorder that causes gradual deterioration of the muscles. Only boys are affected, and they are always born to phenotypically normal parents. Due to the severity of the disease, the boys die in their teens. Is this disorder likely to be caused by a dominant or recessive allele? Is the inheritance of this trait sex-linked or autosomal?
recessive, sex-linked
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?
roan × roan
Which of the following help(s) to hold the DNA strands apart while they are being replicated?
single-strand DNA binding proteins
In cats, black fur color is determined by an X-linked allele; the other allele at this locus determines orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
tortoiseshell females; black males
Sex determination in mammals is due to the SRY gene found on the Y chromosome. Which of the following situations could allow a person with an XX karyotype to develop a male phenotype?
translocation of SRY to an X chromosome
What name is given to the most common phenotype in a natural population?
wild type
What is the genotype of individual II-5?
ww
