Genetics Exam 1 Practice
If a heterozygote is testcrossed, assuming Mendel's first Principle, the expected genotypes are in a 1:1 ratio. True False
True
In plants, the haploid cells/gametes often undergo mitotic cell divisions True False
True
Anaphase I
homologous chromosomes separate and go toward opposite poles
A chromosome may contain one or two chromatids in different phases of the mitotic or meiotic cell cycle. T or F
true
Nondisjunction is viewed as a major cause of aneuploidy. T or F
true
The synaptomenal complex is formed?
Meiosis 1, Prophase 1 in Pachenyma
In a mating between individuals with the genotypes IAIB X IOIO, what percentage of the offspring are expected to have the O blood type? A. 50% B. 20% C. 10% D. 5% E. 0%
0%
Two organisms with genotypes of two traits of TTbb and ttBB are crossed. Assuming Mendel's second principle, what is the probability of obtaining an organism with genotype TtBb or an organism with TtBB ? 9/16 3/4 1/16 0 1
1
Interference Number equation
1- observed crossed over/ expected cross over
What is the probability of an affected Dad and a carrier Mum, having a carrier child ? 3/4 ¼ 1/2 1 None of the above
1/2
Oogonium to Ovum
1. Growth and maturation to primary oocyte 2. Meiosis I to secondary oocyte and first polar body 3. Meiosis II ootid and second polar body 4. differentiation to ovum
spermatogonia to spermatozoa
1. growth and maturation to primary spermatocyte Meiosis 1 to secondary spermatocytes Meiosis II to 4 spermatids differentiation to 4 spermatozoa
What is the probability of a carrier Dad and a carrier Mum, having a carrier child first and then an affected/ diseased child ? 3/4 1/8 1/4 3/12 None of the above
1/8
Phenotypically wild-type F1 female Drosophila, whose mothers had light eyes (lt) and fathers had straw (stw) bristles, produced the following offspring when crossed to homozygous light-straw males: Phenotype Number light-straw 22 wild-type 18 light 990 straw 970 Total: 2000 Compute the map distance between the light and straw loci. A. 2 mU B. 4 cM C. 10 mU D. 30 cM E. all of the above
2 mU
Which of following algebraic expressions would be used to denote a trisomic organism? 3n 2n - 1 2n + 1 2n + 2
2n+1
A plant Aabb is selfed, what are the expected genotypes in the next generation, assuming Mendel's second principle. 3/4 A-bb, ¼ aabb A-bb 9/16 A-bb, 3/16 A-B-,3/16aaB-, 1/16aabb AaBB AAB-
3/4 A-bb, ¼ aabb
Genes A and B are 20 cM apart and are in repulsion. Suppose that a double heterozygote is test-crossed, what percentage of offspring would have the aaBb phenotype? 12% 20% 30% 40% 24%
40%
Gene A is 10 mU from Gene B on chromosome 2, and the alleles are in coupling. An individual with the genotype AaBb is testcrossed. What fraction of the offspring would be expected to have genotype aabb? 10% of the offspring 20% of the offspring 30% of the offspring 45% of the offspring none of the answers are correct
45% of the offspring
AaBb x AaBb Cross
9/16 A-B 3/16 aaB- 3/16 A-bb 1/16 aabb
If the Rf value between two alleles/genes is 0.5, which of the following is true; these genes may show Mendels' 2nd principle these genes may be linked these genes are in coupling A and C A and B
A and B
What is Coupling?
A-B a-b
What is Repulsion
A-b a-B
Assume that a cross is made between two organisms that are both heterozygous for a gene that shows incomplete dominance. What phenotypic and genotypic ratios are expected in the offspring? A. 1:2:1 B. 1:1:1:1 C. 9:3:3:1 D. 1:2:2:4:1:2:1:2:1 E. 3:1
A. 1:2:1
In peas, gray seed color is dominant to white. For the purposes of this question, assume that Mendel crossed gray seeded plants and the following progeny were produced: 320 gray and 80 white. What is the most probable genotype of each parent? G = gray and g = white A. Gg X Gg B. Gg X GG C. GG X GG D. GG X gg E. none of the above
A. Gg X Gg
Assume that a cross is made between AaBb and aabb plants and that all the offspring are either AaBb or aabb. These results are consistent with ________. A. complete linkage B. alternation of generations C. codominance D. incomplete dominance E. hemizygosity
A. complete linkage
________is the term given to one gene affecting/influencing many different traits while _________ is the term given to more than one gene interacting to affect/ influence one trait A. pleiotrophy :epistasis B. sex-limited: sex influenced C. co-dominance: variable expressivity D. linkage: non linkage E. epistasis:pleiotrophy
A. pleiotrophy :epistasis
In a mating between individuals with the genotypes IAIO X IOIO, what percentage of the offspring are expected to have the O blood type? A. 50% B. 20% C. 10% D. 5% E. 0%
A. 50%
Assume that you have a garden and some pea plants have solid leaves and others have striped leaves. You conduct a cross and obtain the results given in the table. Progeny Solid / striped 55 / 60 What are the possible genotypes of the parents of the cross? S (solid) is dominant to s(striped) A. Ss X ss B. SS X SS C. ss X ss D. Ss X Ss E. SS X ss
A. Ss X ss
The centrosomes/centioles produce _____ A. microtubules B. anaphase I C. prophase D. prophase II E. none of the answers are correct
A. microtubules
A bald woman parents children with a man who is nonbald. Which of the following would be true of their children? All would be bald. All of the females would be nonbald, all males would be bald. All of the males would be nonbald, all of the males would be bald. ½ of females would be bald and ½ of the females would be bald. All would be nonbald.
All of the females would be nonbald, all males would be bald.
If two parents have genotypes AO and BO, the following blood phenotype is not possible in their children. A B O AB All of these phenotypes are possible
All of these phenotypes are possible
When does sister chromatids separate in Mitosis? When does sister chromatid separate during meiosis
Anaphase, anaphase II
What is the probability of a carrier Dad and a carrier Mum, having a carrier child first and then an affected/ diseased child ? A. 3/4 B. 1/8 C. 1/4 D. 3/12 E. none of the above
B. 1/8
The house fly, Musca domestica, has a haploid chromosome number of 6. How many chromatids should be present in a diploid, somatic, metaphase cell? A. 12 B. 24 C. 6 D. 18 E. 48
B. 24
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? A. 25% straight B. 50% straight C. 75% straight D. 100% straight E. It is impossible to predict the outcome.
B. 50% straight
Assume that two genes are 40 map units apart on chromosome II of Drosophila and that a cross is made between a doubly heterozygous female and a homozygous recessive male. What percent of parentals would you expect in the offspring of this type of cross? A. 30 B. 60 C. 10 D. 100 E. 40
B. 60
In pigs, the mutant alleles; br (brown), an (anther ear), and f (funny nose) are all recessive to their wild type alleles br+, an+, f+. Pigs were bred to produce heterozygotes for all three traits. A farmer then mated a triple heterozygote pig with a homozygous recessive pig. The pigs had the big big litter below. wildtype 402 funny nose 29 brown 6 brown and funny nose 72 anther ear 60 anther ear and funny nose 4 brown and anther ear 13 brown, anther ear, funny nose 387 What is the sequence of these genes? A. br an f B. an br f C. f an br D. an f br E. none of the above
B. an br f
If the Rf between two genes in repulsion is 0 this means that: A. they are on different chromosomes B. they are very close together C. they show complementation D. they are the same gene E. all of the above
B. they are very close together
How many different gametes will be expected from an individual with the genotype PpCcTTRr, assuming Mendel's principles ? A. 4 B. 8 C. 4 D. 61 E. none of the above
B. 8
A condition in which one gene pair masks the expression of a another gene pair is called ________. A. codominance B. epistasis C. dominance D. recessiveness E. additive alleles
B. epistasis
In pigs, the mutant alleles; br (brown), an (anther ear), and f (funny nose) are all recessive to their wild type alleles br+, an+, f+. Pigs were bred to produce heterozygotes for all three traits. A farmer then mated a triple heterozygote pig with a homozygous recessive pig. The pigs had the big big litter below. wildtype 402 funny nose 29 brown 6 brown and funny nose 72 anther ear 60 anther ear and funny nose 4 brown and anther ear 13 brown, anther ear, funny nose 387 How would you calculate the interference value A. Number of expected double crossovers/ number of observed double crossovers B. Number of observed double crossovers/ number of expected double crossovers C. I - Number of observed double crossovers/ number of expected double crossovers D. I - Number of expected double crossovers/ number of observed double crossovers E. none of the above
C. I - Number of observed double crossovers/ number of expected double crossovers
Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with ________. A. sex-linked inheritance with 30% crossing over B. linkage with 50% crossing over C. linkage with approximately 33 map units between the two gene loci D. independent assortment E. 100% recombination
C. linkage with approximately 33 map units between the two gene loci
Assume that a dihybrid cross (AaBb X AaBb) is made in which the gene loci are autosomal, independently assorting, and incompletely dominant. What phenotypic ratio would you expect from such a cross? Just provide the ratio, not the phenotypes. A. 1:2:1 B. 1:1:1:1, C. 1:2:1:2:4:2:1:2:1 D. 1:2:2:4:1:2:1:2:1, 1:2:1 E. 3:1,
C. 1:2:1:2:4:2:1:2:1
If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism? A. 8 B. 16 C. 32 D. 64 E. 128
C. 32
In a cross between a TtYyRr plant and a TtYyrr plant, which of the following genotypes is not possible ? Assume Mendel's second principle. A. TtYyRr B. TtyyRr C. TtYyRR D. ttyyRr E. ttYyRr
C. TtYyRR
What is a simple definition of an allele? A. a protein B. a nucleotide C. a form of a gene D. a sugar E. none of the above
C. a form of a gene
Which phenotypic ratio is likely to occur in crosses of two completely dominant, independently segregating gene pairs when both parents are fully heterozygous? A. 3:1 B. 1:0 C. 9:3:3:1 D. 1:1:1:1 E. none of the above
C. 9:3:3:1
What does interference tell us?
Certain amount of cross over that were suppose to occur did not occur
Choose from the following answers. You may use any answer more than once. The homologous chromosomes separate and are pulled to opposite poles of the cell. The sister chromatids separate and go towards opposite poles of the cell. The plasma membrane has completely broken down. The synatonemal complex is formed. The nuclear membrane reforms. A. none of the answers are correct B. anaphase I C. prophase II D. metaphase II E. pachytena/e
Correct D. anaphase I Correct B. none of the answers are correct Correct B. none of the answers are correct Correct C. pachytena/e Correct B. none of the answers are correct
Assume that genes (Cc and Dd) coding for two traits are located on the same chromosome pair. The alleles are in coupling on the chromosomes. Which of the following would be an example of a recombination /crossing over between these two homologues? A. alleles C and D together on one chromosome B. alleles c and C together on one chromosome C. alleles d and D together on one chromosome D. alleles c and D together on one chromosome E. none of the above
D. alleles c and D together on one chromosome
The phenomenon in which one crossover decreases the likelihood of crossovers in nearby regions is called ________. A. chiasma B. negative interference C. reciprocal genetic exchange D. positive interference E. mitotic recombination
D. positive interference
Given the following sequence of genes on a chromosome, determine what change in chromosome structure occurred. (the * indicates the centromere) before A B C D * E F G H after A B G F E * D C H A. reciprocal translocation B. duplication C. paracentric inversion D. gene deletion E. none of the answers are correct
E none Pericentric inversion
The end result of meiosis in human females is ______. A. one egg and 4 polar bodies B. three haploid cells C. four diploid cells D. four eggs E. none of the answers are correct
E. none of the answers are correct
If a double crossover occurs between two genes A and B in a double heterozygote that shows coupling, then the genotype of some gametes could be : A. AB B. Ab C. ab D. aB E. two of the above
E. two of the above
To help in describing the variation in height between two populations that have the same mean height, which of the following are true: A. Calculating the variance would be helpful B. Calculating the SD would be helpful C. Calculating the Chi-square value would be helpful D. 30% of the population fall within 2 SD of the mean E. two of the above
E. two of the above
Chiasmata form during _____ A. S phase B. anaphase I C. prophase D. prophase II E. none of the answers are correct
E. none of the answers are correct
In a Chi-square analysis, what condition/s causes one to reject (fail to accept) the null hypothesis? A. when the probability value is less than 0.05 B. when the probability value is greater than 0.05 C. when the probability value is greater than 0.01 D. when the probability value is less than 0.01 E. two of the above
E. two of the above
Which of the following is not correctly matched to its chromosome condition? Down syndrome - trisomy 21 Edward syndrome - trisomy 15 Kleinfelter syndrome - XXY Jacobs syndrome - XYY
Edward syndrome - trisomy 15
During meiosis, chromosome number reduction takes place in anaphase II. T or F
False
If alleles of genes are in repulsion then the Rf value is always 0.3. T or F
False
In the inheritance of an autosomal dominant trait that is a disease, homozygosity for the dominant allele is usually incompletely dominant. True False
False
The cross GEge X gege produces the following progeny: GEge 404, gege 396, gEge 97, Gege 103. From these data, one can conclude that the G and E loci assort independently. True False
False
The term genome size always refers to the diploid content. True False
False haploid content
In birds the female is the homogametic sex True False
False Female heterogametic
In plant cells all the DNA is located in the nucleus and chloroplast only. True False
False also in mitochondria
A negative interference value indicates that the first crossover event prevented the occurrence of additional crossover events in the region. True False
False this is positive
Relationship between distance apart and crossing over?
Genes closer together crossing over is less compared to further apart. Greater the distance more the crossing over
Mendelian Genetics
How traits are passed on/inherited from one generation to the next from parent to offspring
What is the expected phenotypic ratio of the offspring when a triple heterozygote in coupling is testcrossed, assuming the genes are linked and no crossing over occurs. 1:1:1:1:1:1:1;1 9:3:3:1 1:1:1:1 1:1 Impossible to predict
Impossible to predict because we have no idea the distance between the genes
In a Chi-square test, as the value of the χ2 increases, the likelihood of rejecting the null hypothesis ________. Selected Answer: A. Decrease B. Increase
Increase
What is a distinguishing feature of the inheritance of a holandric trait? It is passed from mother to son only More females than males are affected It is passed from fathers to sons only It is passed from fathers to daughters only None of the above
It is passed from fathers to sons only
What is the Forked line Approach? A. It is used in gene mapping B. It uses the product rule of Probability C. It is a method of calculating coefficient of coincidence D. It is used in the empirical approach E. It uses the Binomial Expansion Equation
It uses the product rule of Probability
Assume that a Chi-square test provided a probability value of 0.02. Should the null hypothesis be accepted? Yes or No
No
Does the Plasma membrane every break down?
No
Gametogenesis in human females is different than that in males because: In males only, meiosis is followed by mitosis The complete meiotic cell cycle continues throughout the life of every human female Males are born with their full complement of sperm Females are born with their haploid eggs already formed None of the above are correct
None of the above are correct
Human ____ pass their _____ to ____ only. females/ autosomes/ sons males/ X chromosome/ sons males/ y chromosome/ daughters females/ X chromosomes/ sons none of the answers are correct
None of the answers are correct
What is distance apart based on?
Percentage of progeny showing recombination/ divid by 100 and get map units or centimorgan
When does the nuclear membrane reform?
Telophase, Telophase I and Telophase II
A 1:1 phenotypic ratio is expected if a monohybrid (heterozygote) is testcrossed and it shows complete dominance. T or F
True
Positive interference occurs when a crossover in one region of a chromosome reduces crossovers in nearby regions. T or F
True
The chromatids of a chromosome separate during anaphase. T or F
True
The meiotic cell cycle involves two cell divisions but only one DNA replication T or F
True
To test Mendel's Law of Segregation, the experimenter needs a minimum of two contrasting forms of a gene. T or F
True
If a crossover occurs between two genes A and B in a double heterozygote AaBb that shows repulsion, then the genotype of some gametes could be: AB Ab ab aB all of the above
all of the above
The high incidence of ------- children born to--------- is correlated with --------- Kleinfelter: older mothers: arrested Meiosis I Turner; older fathers: problems during oogenesis Jacobs: older fathers: arrested mitosis Down: older mothers: problems during mitosis all of the answers are incorrect
all the answers are incorrect down, older mothers, during meiosis
Which of the following describes an organism with two complete sets of chromosomes from two different species? tetraploid euploid allohaploid allotetraploid
allotetraploid
Humans can survive if their cells are aneuploid, and they have an extra _________, but they cannot survive if they are monosomic for an/a __________ . A. autosome: autosome B. sex chromosome: sex chromosome C. autosome: sex chromosome D. none of the above
autosome: autosome
In testcross experiments, the frequency of recombination between genes a and b is 0.5; between b and c, 0.2; between a and c, 0.3; and between b and d, 0.1. What is a possible order of the three genes? c-b-d-a d-b-c-a a-d-c-b c-a-b-d none of the above
d-b-c-a
null hypothesis
genes are on completely different chromosomes
Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with ________. sex-linked inheritance with 30% crossing over linkage with 50% crossing over linkage with approximately 33 map units between the two gene loci independent assortment 100% recombination
linkage with approximately 33 map units between the two gene loci
The phenomenon by which a heterozygote has an advantage over either homozygote is : called co-dominance called eigenesis/epigenetics called incomplete penetrance called epistasis none of the above
none of the above heterozygote advantage or over dominance
The failure of chromosomes to separate during _______ is called __________. Synapsis: non-disjunction Meiosis: maternal effect Cytokinesis: non-disjunction Interphase : non-disjunction none of the above
none of the above meiosis/non disjunction
What is the probability of two brown eyed heterozygous parents having 3 out of 4 children with blue eyes. Brown is dominant to blue. 3/4 1/8 1 1/2 None of the above
none of the above 1/4*1/4*1/4*3/4= 3/256+ 3/256+ 3/526+ 3/256= 12/256
The general purpose of the kinetochore is to __________. provide a link between non-sister chromatids in mitosis to enable the reformation of the cell wall during cytokinesis to separate the sister chromatids during metaphase I to attach to the astral/aster microtubules none of the answers are correct
none of the answers are correct Attaches microtubules from centrosomes to centromere
The centromere is _________while the centrosome is ____________. found in the nucleus/ part of the chromosome found in the cytoplasm/ part of the tetrad important in telophase/ a producer microtubules part of the chromosome/ replicated in interphase
part of the chromosome/ replicated in interphase
________ is the term given to one gene affecting/influencing many different traits while _________ is the term given to more than one gene interacting to affect/ influence one trait. pleiotrophy :epistasis sex-limited: sex influenced co-dominance: variable expressivity linkage: non linkage epistasis:pleiotrophy
pleiotrophy :epistasis
Which of the following contain genetic material that is always 100% identical? homologous chromosomes sister chromatids X and Y chromosomes A and B A and C
sister chromatids
If the calculated Rf value from a dihybrid testcross was less than 0.5, then the genes are linked the genes are in coupling the genes might not be linked the genes are x-linked two of the above
the genes are linked
If the age of onset of a disease ranges from 10 to 20 years, this is called --------, and an example is ------------------ . lethal alleles, sickle cell anemia co-dominance, cystic fibrosis variable expressivity, Huntington's Disease sex-influenced inheritance, sickle cell anemia None of the above
variable expressivity, Huntington's Disease
In Mendel's classic dihybrid crosses, the 9:3:3:1 ratio of phenotypes were seen: when the pure-breeding parents were selfed when the heterozygous parents were cross fertilized when the heterozygous F1 plants were selfed none of the above
when the heterozygous F1 plants were selfed
