Exam 4- Homework Questions
A woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood?
50%
The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
Anaphase
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
anaphase
Homologous chromosomes migrate to opposite poles during _____.
anaphase I
At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.
cytokinesis
A cross between two individuals with black eyes and green skin which results in an individual with orange eyes and white skin is an example of a _____ cross.
dihybrid
Mendel formulated his principles of inheritance based on _____.
observations on the outcomes of breeding experiments. The underlying processes were unknown at the time.
Duplication of the chromosomes to produce sister chromatids _____.
occurs in both mitosis and meiosis
Spindle fibers attach to kinetochores during _____.
prometaphase
Chromosomes become visible during _____.
prophase
Synapsis occurs during _____.
prophase I
During _____ a spindle forms in a haploid cell.
prophase II
Which processes lead to most genetic variation in sexually reproducing organisms?
random fertilization independent orientation of chromosomes in meiosis crossing over
Because it is passed essentially intact from father to son, Y chromosome research has been particularly useful in improving our understanding of __________.
recent human evolution
One version of a gene may encode __________, whereas a different version of the same gene may encode __________.
red eyes; white eyes
Nucleoli are present during _____.
interphase
A fragment of chromosome 21 reattaches to chromosome 21, but in the reverse direction. What is the name given to this change?
inversion
If it weren't for _____, chromosome number would double with every generation of sexual reproduction.
meiosis
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
Looking through a light microscope at a cell undergoing division, you see that the condensed chromosomes have lined up along the midline of the cell. The homologous pairs are NOT joined in tetrads. Each chromosome takes its own place in line, independentof its homolog. You are witnessing _____.
metaphase of mitosis
Which of the following is a correct representation of an event that occurs in mitosis?
metaphase—chromosomes line up on the equatorial plane.
During anaphase II, __________.
sister chromatids separate and migrate toward opposite poles
An example of a cell that is 2n is a __________.
somatic cell
Mitosis occurs in _____; meiosis occurs in _____.
somatic or body cells ... germ cells in the testes or ovaries
Cytokinesis often, but not always, accompanies _____.
telophase
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
telophase I
At the end of _____ and cytokinesis there are four haploid cells.
telophase II
Crossing over of chromosomes during meiosis shuffles parental chromosomes, resulting in a genetically unique child.
-During prophase I of meiosis I, homologous paternal and maternal chromosomes pair up and undergo crossing over. -During meiosis II, sister chromatids separate into four different gametes. -A hybrid chromosome that has crossed over will contain pieces of both the maternal and paternal chromosomes.
In a situation in which genes assort independently, what is the ratio of the gametes produced by an AaBB individual?
1 AB : 1 aB
Black eyes are dominant to orange eyes, and green skin is dominant to white skin. Sam, a MendAlien with black eyes and green skin, has a parent with orange eyes and white skin. Carole is a MendAlien with orange eyes and white skin. If Sam and Carole wereto mate, the predicted phenotypic ratio of their offspring would be _____.
1 black eyes, green skin : 1 black eyes, white skin : 1 orange eyes, green skin : 1 orange eyes, white skin
An individual heterozygous for eye color, skin color, and number of eyes mates with an individual who is homozygous recessive for all three characters; what would be the expected phenotypic ratio of their offspring? [Hint: B = black eyes, b = orangeeyes; G = green skin, g = white skin; C = two eyes, c = one eye]
1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1 black eyes, white skin, one eye : 1 orange eyes, green skin, two eyes : 1 orange eyes, green skin, one eye : 1 orange eyes, white skin, twoeyes : 1 orange eyes, white skin, one eye
Assume that in cattle a spotted coat is dominant to an even coat, short horns are dominant to long horns, and the traits for coat type and horn length assort independently. In a cross between cattle that are each heterozygous for both traits, what proportion of their offspring are expected to have long horns?
1/4
You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half the offspring trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents? A = big apples; a = small apples; R = red apples; r = yellow apples.
AArr and aaRr
In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell culture. What is one explanation that could account for this?
Cancer cells continuously secrete growth factors into the cell culture medium.
In the following cross the genotype of the female parent is BbGg. What is the genotype of the male parent? [Hint: B = black eyes, b = orange eyes, G = green skin, g = white skin]
BBGg
Imagine a particular trait that is determined by a single gene. If this gene is present in two forms, how can you tell which allele is dominant and which is recessive?
Do a test cross between two true-breeding individuals and observe the trait expressed by the F1 plants.
During _____ sister chromatids separate.
During _____ sister chromatids separate.
An insect that has the genotype EeGGcc will have the same phenotype as an insect with the genotype _____.
EEGgcc
Consider the cell cycle shown below. Cells will usually divide if they receive the proper signal at a checkpoint in the __________ phase of the cell
G1
When examining cells in the laboratory, you notice that a particular cell has half as much DNA as the surrounding cells. It appears that this cell's cell cycle halted at checkpoint _____.
G1
Imagine that a deaf male has a child with a hearing female. You know that the male must have the genotype dd, but the female could be either Dd or DD.
Her genotype cannot be determined.
Use the Punnett square from the introduction and the ones you drew for Part A to select the three statements that are true about the inheritance of this form of deafness.
If a deaf child is born to hearing parents, both parents must be Dd. If a deaf man and a hearing woman have a deaf child, the mother's genotype must be Dd. The child of a deaf man and a DD hearing woman will definitely have hearing.
During binary fission, each copy of the duplicating chromosome moves to opposite ends of the cell. What does this achieve?
It ensures that each daughter cell receives one copy of the chromosome.
A BbGg x bbgg cross yields a phenotypic ratio of approximately 5 black eyes, green skin : 5 orange eyes, white skin : 1 black eyes, white skin : 1 orange eyes, green skin. Which of the following best explains these results?
Mendel's law of independent assortment is being violated.
The observed distribution of alleles into gametes is an illustration of _____.
Mendel's laws of segregation and independent assortment
The chromosomes line up in the center of the cell during which phase of mitosis?
Metaphase
How have Mendel's laws fared as we have learned more about cell biology and processes such as meiosis?
Our new knowledge has helped to explain some of the exceptions to Mendel's laws of inheritance.
The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
Prophase
The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?
Telophase
What must happen before a cell can begin mitosis?
The chromosomes must be duplicated.
In a particular species of mammal, black hair (B) is dominant to green hair (b), and red eyes (R) are dominant to white eyes (r). When a BbRr individual is mated with a bbrr individual, offspring are produced in a ratio of 5 black hair and red eyes : 5 green hair and white eyes : 1 black hair and white eyes : 1 green hair and red eyes. Which of these explanations accounts for this ratio?
The genes for hair color and eye color are linked.
Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?
The sequences are identical.
If the gene for seed color that Mendel studied exhibited pleiotropy, how might a green pea be different from a yellow pea?
With pleiotropy, there would be other differences between the peas - for example, green peas may also be larger, ripen earlier, and be more sensitive to frost.
If you are a male, the Law of Independent Assortment indicates that your gametes contain _____.
a random mix of the chromosomes you inherited from each parent
In order to determine the genotype of a MendAlien with black eyes and green skin, you would cross this individual with a(n) _____ individual.
bbgg
What is the genotype of the parent with orange eyes and white skin? (Note: orange eyes are recessive.)
bbgg
A cell replicates its entire chromosomal DNA only __________.
before it is about to divide
Which of the following conditions would prevent cell division due to density-dependent factors?
being completely surrounded by other cells
A phenotypic ratio of 9:3:3:1 in the offspring of a cross indicates that _____.
both parents are heterozygous for both genes
Asexual and sexual reproduction differ in that sexual reproduction _____.
can produce great variation among the offspring
Consider the photograph shown below. You can determine this is a plant cell rather than an animal cell because it has __________.
formed a cell plate
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
Fertilization joins _____ to produce a _____.
haploid gametes ... diploid zygote
Mendel observed that pairs of alleles were separated or segregated in gametes and that they were rejoined in fertilization. We know that pairs of _____ are segregated in _____ and then are rejoined through fertilization.
homologous chromosomes ... meiosis
Place the events of meiosis in the proper order. Rank from the first event to the last event, left to right.
homologous chromosomes pair up nonsister chromatids form chiasmata crossing over occurs homologous chromosomes separate sister chromatids separate four haploid gametes are produced
During anaphase I, __________.
homologous chromosomes separate and migrate toward opposite poles
Cystic fibrosis is inherited in an autosomal recessive pattern. Males who have cystic fibrosis are usually sterile. Furthermore, the disease is often lethal before the age of reproduction. Even though people with the disease rarely reproduce, cases continue to arise because __________.
the harmful allele "hides" inside heterozygous individuals and one-fourth of the offspring of two heterozygotes should be afflicted
Two parents of mixed ethnicity have twins, one of which is born with very light skin and one of which is born with very dark skin. This is because of __________.
the polygenic nature of skin color genes
In a test cross, F2 refers to _____.
the second filial generation, or the "grandchildren" of the original mating pair
During mitosis, the chromosomes move because _____.
they attach to a dynamic, precisely regulated mitotic spindle
As we now understand it, the Law of Independent Assortment applies _____.
to pairs of genes that are on different chromosomes, but NOT to pairs of genes that are close together on the same chromosome
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
During prophase a homologous pair of chromosomes consists of _____.
two chromosomes and four chromatids
At the end of telophase I of meiosis, as cytokinesis occurs, there are __________.
two haploid cells
If the two characteristics that Mendel looked at in his dihybrid cross of smooth yellow peas with wrinkled green peas had been controlled by genes that were located close together on the same chromosome, then the F2 generation __________.
would have deviated from the 9:3:3:1 phenotypic ratio that is predicted by the law of independent assortment
