True Biology 111 Exam 4
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
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
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
If a cell at metaphase of mitosis contains 20 sister chromatids, how many chromosomes will be present in a G1 cell?
10
When Mendel crossed yellow-seeded and green-seeded pea plants, all the offspring were yellow-seeded. When he took these F1 yellow-seeded plants and crossed them to green-seeded plants, what genotypic ratio was expected?
1:1
If there are 40 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?
20
Ploidy before replication and after replication
2n=2
What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes
Starting with a fertilized egg (zygote), a series of six cell divisions would produce an early embryo with how many cells?
64
How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
8
Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cacti have dull spines. At the same time, a second gene, N, determines whether or not cacti have spines. Homozygous recessive nn cacti have no spines at all. If cacti heterozygous for both traits, SsNn, were allowed to self-pollinate, the offspring would segregate into which of the following phenotype ratios?
9 sharp-spined:3 dull-spined:4 spineless
Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?
A Cdk is an enzyme that attaches phosphate groups to other proteins.
Which of the following statements describes an example of alternation of generations?
A diploid plant (sporophyte) produces a spore by meiosis that gives rise to a multicellular, haploid pollen grain (gametophyte).
centrosome
A structure in animal cells containing centrioles from which the spindle fibers develop.
What does the G2 checkpoint check for?
Are we ready for mitosis?
Chromosome separation begins at the origin of replication on DNA.
Bacteria only
Where is the mitosis checkpoint?
Before anaphase
Albinism is a recessive trait. A man and woman who both have normal pigmentation have one child out of three who has albinism (without melanin pigmentation). What are the genotypes of this child's parents?
Both parents must be heterozygous.
Which of the following calculations require the use of the addition rule of probability?
Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both.
What happens during G1 and G2
Cell growth
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
DNA in both daughter cells would be radioactive.
Which statement provides the best description of the interphase portion of the cell cycle?
During interphase, a cell is metabolically active
Which of the following statements is true of a species that has a chromosome number of 2n = 16?
Each diploid cell has eight homologous pairs of chromosomes.
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.
The beginning of anaphase is indicated by which of the following processes?
Enzymatic cleavage of cohesin.
Before separation, duplicated chromosomes condense. Nuclear envelope fragments, permitting chromosome separation. Two copies of the duplicated chromosome are attached at their centromeres before separating.
Eukrayotes only
What checkpoint is the most important
G1
What is the main difference between G1 and G2
G2 has twice the amount of DNA that G1 has
What are not part of mitosis
G2, interphase, cytokinesis
What happens during mitosis
Getting the cells ready for them to split
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
How are sister chromatids and homologous chromosomes different from each other?
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.
Which of the following scenarios describes an example of epistasis?
In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.
If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents?
It has half the amount of DNA as the cell that began meiosis
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
Where does the nuclear envelope break down
Prometaphase
scientist isolate 1.5 times the DNA than G1 where in the cell cycle were these cells isolated
The S-phase
Which of the following statements are true of cytokinesis in plant cells? Select the two that apply.
The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I?
The cells have half the number of chromosomes and one-fourth the amount of DNA.
What would you expect to happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cells would enter mitosis.
Once a cell enters mitosis, the molecules that activate division must be turned off. What happens to MPF during mitosis?
The cyclin component of MPF is degraded
Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6,022 yellow and 2,001 green (8,023 total). Which of the following statements correctly describes the relationship of the allele for green seeds to the allele for yellow seeds?
The green allele is recessive to the yellow allele.
Why do neurons and some other specialized cells divide infrequently?
They have entered into G0.
Why is it difficult to observe individual chromosomes with a light microscope during interphase
They have uncoiled to form long, thin strands
A cleavage furrow is ________.
a groove in the plasma membrane between daughter nuclei
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
Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cacti have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce ________.
all sharp-spined progeny
different variants of a gene (A or a)
allele
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
anaphase
Cohesins break down. Kinetochores move toward poles of cell.
anaphase
Homologous chromosomes migrate to opposite poles during _____.
anaphase I
During _____ sister chromatids separate.
anaphase II
In the cells of many eukaryotic species, the nuclear envelope has to disappear to permit which of the following events in the cell cycle?
attachment of microtubules to kinetochores
Replicated chromosomes separate by attaching to some other structural feature of the cell. Chromosomes replicate before cell division.
both bacteria and eukaryotes
Many organisms spend most of their life cycle in the diploid state. If meiosis produces haploid cells, how is the diploid number restored for these types of organisms?
by fertilization
the 'center' of the chromosome that condenses the most
centromere
What is the name of the microtubule organizing center
centrosome
a protein that has a fluctuating concentration and helps regulate the cell cycle
cyclin
two sets of chromosomes (2n), somatic cells are these
diploid
During telophase, the nonkinetochore microtubules
dissasemble
trait that covers up another trait
dominant
During which of the following processes do sister chromatids separate from each other?
during both mitosis and meiosis II
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
phenomenon when one locus affects another locus' phenotype
epistasis
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
one set of chromosomes (n), gametes are these
haploid
different alleles (Aa)
heterozygous
same alleles (AA or aa)
homozygous
Nucleoli are present during _____.
interphase
the largest part of the cell cycle (G1, S, and G2 combined)
interphase
haploid
just mom or just dad
protein complex that forms at the centromere during mitosis
kinetochore
During prophase, the microtubules of the mitotic spindle
lengthen
During anaphase, the nonkinetochore microtubules _______ and move past each other, and the kinetochore microtubules ________
lengthen; shorten
physical location of a gene
locus
Crossing over of chromosomes normally takes place during which of the following processes?
meiosis I
Kinetochores are motionless in relation to poles of cell.
metaphase
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
Asexual reproduction occurs during which of the following processes?
mitosis
diploid
mom AND dad
G1 is associated with which of the following cellular events?
normal growth and cell function
hypothesis that discrete units were inherited
particulate
Which of the following inheritance patterns describes the ability of a single allele to have multiple phenotypic effects?
pleiotropy
Microtubules attach to kinetochores.
prometaphase
Spindle fibers attach to kinetochores during _____.
prometaphase
At which phase of the cell cycle do centrioles begin to move apart in animal cells?
prophase
Chromosomes become visible during _____.
prophase
Cohesins join sister chromatids of duplicated chromosome. Tubulins assemble into spindle microtubules.
prophase
Synapsis occurs during _____.
prophase I
During _____ a spindle forms in a haploid cell.
prophase II
Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant trait. If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F1 will be expected to exhibit which of the following phenotypes?
purple and long
trait that is masked
recessive
Which of the following events occurs during interphase of the cell cycle?
replication of the DNA
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (CRCW) offspring of red (CRCR) and white (CWCW) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?
roan × roan
Movement of the chromosomes during anaphase would be most affected by a drug that prevents which of the following events in mitosis and cell division?
shortening of microtubules
Which of the following phenotypes is an example of polygenic inheritance?
skin pigmentation in humans
Which of the following processes occurs in meiosis but not in mitosis?
synapsis of chromosomes
complex that holds homologous chromosomes together during meiosis
synaptonemal
Cytokinesis often, but not always, accompanies _____.
telophase
Nuclear envelope forms again and mitotic spindle falls apart
telophase
Spindle microtubules disassemble
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 an unknown phenotype against a homozygous recessive
test cross
testing a dominant phenotype with unknown genotype
test-cross
FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in binary fission. Its function is analogous to ________.
the cleavage furrow of eukaryotic animal cells
The decline of MPF activity at the end of mitosis is due to
the degradation of cyclin.
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
During prophase a homologous pair of chromosomes consists of _____.
two chromosomes and four chromatids
