Chapter 3
Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant allele. The couple has a son with normal hands and feet, but the couple's second child has extra digits. What is the probability that their next child will have polydactyly?
1/2
What genotypic ratio is expected? ___ Ww : ___ ww
1:1
Which types of phenotypic ratios are likely to occur in testcrosses when dealing with two gene pairs for which all the genotypic combinations are of equal viability?
1:1:1:1
What genotypic ratio is expected in the progeny of such a cross? ____ GG : ___ Gg : ___ gg What phenotypic ratio is expected in the progeny of such a cross? ___ Gray : ____ white
1:2:1 3:1
Which types of phenotypic ratios are likely to occur in crosses when dealing with a single gene pair for which all the genotypic combinations are of equal viability? 1:4:6:4:1, 1:1:1:1 2:3, 1:2 1:1, 3:1 9:3:3:1, 27:9:9:9:3:3:3:1 12:3:1, 9:7
1:2:1, 3:1 For a single gene pair if all genotype combinations are viable then they can be 1. Homozygous dominant with both dominant alleles 2. Heterozygous with one dominant and one recessive allele 3. homozygous recessive with both recessive alleles This means that the genotype ratio will be 1:2:1 Since dominant allele gives phenotype hence the homozygous dominant and heterozygous will both have dominant phenotype while the homozygous recessive will give recessive phenotype. Thus, the phenotype ratio will be 3:1
If there are 400 progeny total, what are the expected (theoretical) numbers of progeny in each phenotypic class?
200
Which types of phenotypic ratios are likely to occur in crosses when dealing with three gene pairs for which all the genotypic combinations are of equal viability?
27:9:9:9:3:3:3:1
Tightly curled or wooly hair is caused by a dominant gene in humans. If a heterozygous curly-haired person marries a person with straight hair, what percentage of their offspring would be expected to have straight hair?
50% straight
Given a total of 1024 offspring how many flies of each phenotype would you expect? _____ wildtype : _____ hairy : ____ vestigial : ___ vestigial hairy
576:192:192:64
A recessive allele in tigers causes the white tiger. If two normally pigmented tigers are mated and produce a white offspring, what percentage of their remaining offspring would be expected to have normal pigmentation?
75%
Which types of phenotypic ratios are likely to occur in crosses when dealing with two gene pairs for which all the genotypic combinations are of equal viability?
9:3:3:1
The phenotype of vestigial (short) wings (vg) in Drosophila melanogaster is caused by a recessive mutant gene that independently assorts with a recessive gene for hairy (h) body. Assume that a cross is made between a fly with normal wings and a hairy body and a fly with vestigial wings and normal body hair. The wild-type F1 flies were crossed among each other to produce 1024 offspring. Which phenotypes would you expect among the 1024 offspring? vestigial hairy vestigial hairy wildtype
All GGhh x ggHH Cross : GH Gh gH gh x GH Gh gH gh
Name the single individual whose work in the mid-1800s contributed to our understanding of the particulate nature of inheritance as well as the basic genetic transmission patterns. With what organism did this person work?
Gregor Mendel; Pisum sativum
Assume that in a series of experiments, plants with round seeds (W) were crossed with plants with wrinkled seeds (w) and the following offspring were obtained: 220 round and 180 wrinkled. What is the most probable genotype of each parent?
Ww and ww
Assume that a black guinea pig crossed with an albino guinea pig produced 5 black offspring. When the albino was crossed with a second black guinea pig, 4 black and 3 albino offspring were produced. What genetic explanation would apply to these data?
albino = recessive Black = dominant
In peas, gray seed color (G) is dominant to white (g). For the purposes of this question, assume that Mendel crossed plants with gray seeds with each other and the following progeny were produced: 240 gray and 80 white. What are the most probable genotypes of the parents?
both are Gg
Which of the following groups of scientists were influential around the year 1900 in setting the stage for our present understanding of transmission genetics? Which of the following groups of scientists were influential around the year 1900 in setting the stage for our present understanding of transmission genetics? Watson, Crick, Wilkins, Franklin Hippocrates, Aristotle, Kolreuter deVries, Correns, Tschermak, Sutton, Boveri Beadle, Tatum, Lederberg Darwin, Mendel, Lamarck
deVries, Correns, Tschermak, Sutton, Boveri transmission genetics: Transmission Genetics is the study of traits as they are passed from generation to generation within families. Phenotype is the observation of a particular characteristic. In Transmission Genetics data collected is based on phenotype.
According to Charles Darwin and Alfred Wallace, variations followed a more continuous pattern. According to Mendel's model, variation due to dominance-recessive relationships followed a more ___________ form.
discontinuous
A 9:3:3:1 phenotypic ratio is expected from a dihybrid testcross. True or false
false
A gene can have a maximum of two alleles. true/false
false
Mendel's discoveries were well received and understood by his contemporaries. true/false
false
The nonfunctional form of a gene is called a wild-type allele. true/false
false
What meiotic process, relative to the number of chromosomes of a given species, accounts for a significant amount of genetic variation in gametes?
independent assortment of chromosomes
The Chi-square test involves a statistical comparison between measured (observed) and predicted (expected) values. One generally determines degrees of freedom as ________.
one less than the number of classes being compared
The fundamental Mendelian process that involves the separation of contrasting genetic elements at the same locus would be called ________.
segregation
A 1:1 phenotypic ratio is expected from a monohybrid testcross with complete dominance. true or false
true
Assuming complete dominance, a 3:1 phenotypic ratio is expected from a monohybrid sib or self-cross. True or false
true
Mendel's Law of Segregation is supported by a 1:1 testcross ratio. true/false
true
Mendel's postulate of independent assortment is supported by a 1:1:1:1 testcross ratio. true/false
true
To test Mendel's Law of Segregation, the experimenter needs a minimum of two contrasting forms of a gene.
true
