Genetics Exam Ch 2 - Ch 7
Which of the following occur in the g2 phase of the cell cycle?
*The G2/M checkpoint is reached *SNA replication and error checking is completed *The cell completes preparation for mitosis
Pea plants have seven different types of chromosomes. A chromosome with a centromere at the very end is called
telocentric
the sex determination system used by Drosophila is called
the X:A sex determination system
Species in which individuals have only male or only female reproductive structures are called
Dioecious
Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. What is his genotype?
Heterozygous
Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB phenotype from a cross aabb x AABB
1 (100%)
Which of the following are true about probability
*The probability of a woman giving birth to three girls in a row ins 1/8 *The chi-square test is used to determine if observed outcomes are consistent with expected outcomes *The probability of two or more independent events occurring together is calculated by multiplying their independent probabilities *Branched diagrams are used for determining probabilities of various phenotypes or genotypes for genetic cross involving more than one gene pair
If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype?
0%
If a male bird that is heterozygous for a recessive Z-linked mutation is crossed to a wild type female, what proportion of the progeny will be mutant males?
0%
A chi-square test was performed and indicated that the observed number of offsprings were significantly different from expected. Which of the following P-values would support this conclusion?
0.024 (less than 0.05
In animals, the inability to make the pigment melanin results in albinism, a recessive condition. Two unaffected parents, who have decided to have three children, have a first child that has albinism (genotype aa). What is the probability that the second and third children will also have albinism?
1/16
Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining wrinkled, green seed in the F2?
1/16
Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AABB zygote from a cross AaBb x AaBb
1/16
Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. The man has fathered a child with a woman that does not have freckles what is the probability that their child have freckles?
1/2
Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AABb individual?
1/2
a couple has 6 daughters and is expecting seven child. What is the probability that this child is a boy?
1/2
Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AaBb individual?
1/4
Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AaBa zygote from a cross AaBb x AABB
1/4
A woman has normal vision although her maternal grandfather (her mother's father) had red-green colorblindness, a sex-linked recessive trait. Her maternal grandmother and the woman's own father are assumed to not possess a copy of the mutant allele. The woman marries a man with normal vision although his father was colorblind. What is the probability that the first child of this couple will be colorblind?
1/8
Joan is phenotypically normal but had a child with the autosomal recessive disease cystic fibrosis (CF) from a previous marriage. Joan's father has hemophila A, a sex-linked recessive condition where the blood fails to clot properly. Her father has survived due to recent treatment advances. Joan now intends to marry Bill, who is also phenotypically normal but who has a sister, Jill, with CF. Bill's parents are phenotypically normal, and there is no history of hemophilia A in his family. Assume that Joan and Bill do marry and have a child. What is the probability that this child will have CF, but will not have hemophilia A ? (Hint: This problem requires that you utilize concepts from Chapter 3 as well as Chapter 4.)
1/8
Suppose that a diploid cell contains 8 chromosomes (2n = 8). How many different combinations in the gametes are possible?
16
a diploid somatic cell from a rat has a total of 42 chromosomes (2n=42). As in humans, sex chromosomes determine sex: XX in females and XY in males. what is the total number of telomeres in a rat cell in G2?
168
A pollen grain that lands on a stigma grows a pollen tube to deliver _____ (how many?) sperms to the ovary. Fusion of a sperm with an egg produces an _____ n cell called a _____
2 2 zygote
A diploid somatic cell from a rat has a total of 42 chromosomes (2n=42). As in humans, sex chromosomes determine sex: XX in females and XY in males. what is the total number of chromosomes in a polar body cell from a rat?
21
Pea plants have seven different types of chromosomes. A nucleus in the pea endosperm contains how many chromosomes?
21
A woman is phenotypically normal, but her father had the sex-linked recessive condition of red-green colorblindness. If she has children with a man with normal vision, what is the probability that their first child will have normal vision and their second child will be colorblind?
3/16
Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining yellow seed in the F2?
3/4
to provide foos for the developing embryo, a tissue called endosperm is produced through double fertilization. Endosperm has a pointy of
3n
A diploid somatic cell from a rat has a total of 42 chromosomes (2n=42). As in humans, sex chromosomes determine sex: XX in females and XY in males. what is the total number of chromosomes present in the cell during metaphase I of meiosis?
42
in mendels peas, yellow seeds are dominant to green. A pure-breeding yellow plant is crossed with a pure-breeding green plant. All of the offsprings are yellow. If one of these yellow offsprings are crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?
50%
Pea plants have seven different types of chromosomes. The nucleus of a megaspore in a pea ovary contain how many chromosomes?
7
Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining round, yellow seed in the F2?
9/16
Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB phenotype from a cross AaBb x AaBb
9/16
Red-green color blindness is X-linked recessive. A woman with normal color vision has a father who is color blind. The woman had a child with a man with normal color vision. Which phenotype is not expected?
A color blind female
Human females with XY chromosomes and a phenotype that includes the absence of an uterus and ovaries and the presence of testes ar elikely to have which of the following mutations?
A mutation in the androgen receptor gene
Why was the pea plant an idea plant for Mendel to use?
Simple traits that are easy to identify
is an organism of genotype Aa is used for a test cross, what is the genotype of the individual used in the cross?
Aa
Which of the following crosses would produce a 3:1 ratio of phenotypes in the next generation
Aa x Aa
which of the following crosses would produce a 1:1 ratio of phenotypes in the next generation?
Aa x aa
a diploid somatic cell from a rat has a total of 42 chromosomes (2n=42). As in 5. The figure shows a chromosomal separation taking place. The letters stand for genes; capital and lowercase stand for different alleles. The diploid chromosome number in this organism is four. What process is shown?
Anaphase of meiosis II
In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats. This same female was then mated with a brown, spotted male. Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the female?
BBSs
In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats. This same female was then mated with a brown, spotted male. Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted. which could be the genotype of the black, solid male?
BbSS
if a healthy cell passes G1/S checkpoint
DNA will be replicated
in a germ-line cell from a female grasshopper (XX-XO sex determination system), when do the homologous X chromosomes segregate?
During meiosis I, anaphase
Gregor Mendel carried out a cross between two pea plants by taking pollen from a plant that was homozygous for round seeds and dusting the pollen onto the stigma of a plant homozygous for wrinkled seeds. Which of the following would be the reciprocal cross that Mendel had carried put for this experiment?
Homozygous round stigma pollinated with homozygous wrinkled
which of the following statements about C inactivation in mammalian females is false?
Inactivation is though to be initiated by expression of the Xist gene on the X that will remain active
what is the apparent purpose for X inactivation in humans and other mammals?
It allows for the levels of expression of genes in the X chromosome to be similar in males and females
What is the role of the SRY gene in humans?
It is located on the Y chromosome and initiates the developmental pathway toward the male phenotype.
What is the expected outcome for a human embryo with the XXXY chromosome constitution?
It would likely develop a into a sterile male with reduced testes
a diving eukaryote cell is treated with a drug that inhibits the molecular motors associated with kinetochores. At which cell cycle stage would it stop?
M (metaphase)
With of the XX-XO sex determination system, generally
Male offspring have one X chromosome , and it is inherited from his mother
An XXY chromosome constitution produces ________ development in humans and _________ development in fruit flies.
Male; Female
in which of the following organism is gender/sex determined by the temperature during embryonic development?
Many turtles and alligators
Which of the following occur during pro metaphase?
Microtubules attach to the kinetochores
in humans there is a genetic disorder that results from a dominant mutation present in a gene located in the pseudoautosomal region of the Y chromosome and on the X chromosome. Which of the following statement is correct?
Non is correct
the highly organized internal scaffolding of the nucleus is called the
Nuclear matrix
Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. What is the genotype of the F1 progeny?
RrYy
Normal males (XY) and Klinefelter males (XXY) both possess only one active X chromosome. Nonetheless there are clearly phenotypic differences between the two. What is the most reasonable explanation as to why such differences exist?
Some genes remain active on inactive chromosomes so XXY males would produce have higher expression levels for these genes compared to xY males
Familial vitamin-D-resistant rickets is an X-linked dominant condition in humans. If a man is afflicted with this condition and his wife is normal, it is expected that among their children, all the daughters would be affected and all the sons would be normal. In families where the husband is affected and the wife is normal, this is almost always that outcome among their children when such families have been studied. Very rarely an unexpected result occurs in such families where a boy is born with the disorder. If the chromosomes of such unusual boys are examined, what might be expected to be found?
Some of the boys are XXY
which statement best summarize our current understanding of the origin of the Y chromosome?
The Y chromosome is thought to have been derived along with the X chromosome from a pair of autosomes
In poodles, black fur is dominant to white fur. A black poodle is crossed with a white poodle. In a litter of four, all of the puppies are black. What is the best conclusion?
The black poodle is probably homozygous.
In Labrador retrievers, black coat color is dominant to brown. Suppose that a black lab is mated with a brown one and the offspring are for black puppies and 1 brown. What can you conclude about the genotype of the black parent
The genotype must be Bb
Honeybees have a haplo-diploid sex determination system where females develop from a fertilized egg (they are diploid, having one allele from the female queen and one allele from the male), and males develop from unfertilized eggs (they are haploid, having only one allele from the queen). Assuming that the queen is heterozygous for a particular gene, what is the probability that a female will inherit the recessive allele from her mother? What is the probability that a male will inherit a recessive allele from his mother?
The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 50%.
In which of the following individuals would you expect to find two Barr bodies in their somatic cells?
XXX
What is the sex chromosome constitution of a male duck-billed platypus?
XXXXXYYYYY
Which of the following human genotypes is associated with Klinefelter syndrome?
XXY XXXY XXXXY
in which of the following phenotypic females do testes develop?
XY with the X-linked recessive condition of androgen insensitivity syndrome
Which of the following chromosome constitutions would never lead to a viable human baby being born?
YY
In Mendels peas, purple flower color is dominant to white. From which of the following descriptions can you not infer the genotype completely?
purple
A female with androgen-insensitivity syndrome, a sex-linked recessive condition, has
a pair of testes that produce testosterone
True statement about test cross
a test cross can be used to determine wether an individual is heterozygous or homozygous
In eukaryotes, chromosomes do not contain
ribosomes
Genes come in different variations called:
alleles
True statement about prokaryotes and eukaryotes
archaea are more closely related to eukaryotes than they are to eubacteria
prokaryotic chromosomes do not have telomers because they
are circular
In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats. This same female was then mated with a brown, spotted male. Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the brown, spotted male?
bbss
The ability to curl one's tongue into a U-shape is a genetic trait. Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers. Using C and c to symbolize the alleles that control this trait, what is the genotype of a noncurler?
cc (lowercase)
the attachment point on the chromosome for spindle microtubules is the
centromere
in order to be functional, an eukaryotic chromosomes require al of the following:
centromere origin of replication telomeres
interactions among the human ABO blood group alleles involve ___________ and _____________-
co-domiance; complete dominance
The process of splitting the cytoplasm, which separates the cell into two is called
cytokinesis
Chromosome movement during anaphase is a result of:
disassembly of tubular molecules by molecular motor proteins
The Lyon hypothesis helped us to understand which phenomenon in mammals?
dosage compensation between males and females
what process is unique to plants?
double fertilization
False statement for chromosome separation
error in chromosome separation are rare for an organism
False statement about cells eu y pro
eukaryotes chromosomes are circular. THEY ARE LINEAR
which of the following was not one of mendels conclusions based on his monohybrid crosses?
genes are carried on chromosomes
Human males, with XY chromosomes are _____ and produce two different kinds of gametes, whereas females with XX chromosomes are _____ and produce only one kind.
heterogametic homogametic
A Barr body is a(n)
inactivated X chromosome, visible in the nucleus of a cell that is from a female mammal.
the R locus determines flower color in a new plant species. Plants that are genotype RR have red flowers, and plants that are phenotype rr have white flowers. However, Rr plants have pink flowers. What type on inheritance does this demonstrate for flower color in these plants?
incomplete dominance
In a germ-line cell from a human male that is dividing, when do the X and Y chromosomes segregate?
meiosis I anaphase
In a flowering plant, the male part of the flower (the stamen) produces helped microspores that divide by ______ to produce sperm
mitosis
Species in which an individual organism has both male and female reproductive structures are called
monoecious
How many Barr bodies would you predict in cells?
one per somatic cell
in prokaryotes, replication usually begins at a specific place at the chromosome called the
origin of replication
In species of birds, males are the homogametic sex and females the heterogametic sex. Which if the following is true in this system of sex determination?
the gender of the offspring is determined by the female parent
what might be the result if breakdown of the shugoshin protein were premature?
the separation of sister chromatids would occur prematurely
in a cross between pure-breeding tall plants and pure-breeding short plants, all of the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio 3 tall : 1 short. Which of the following is not a valid conclusion from these results?
the tall and short traits assort independently of each other in this cross
diploid cells are cells with
two sets of chromosomes
which is not a eukaryote
viruses