Exam #6 Flashcards
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cell?
- 32
- 8
- 60
- 4
32
If there are 20 chromatids in a cell, how many centromeres are there?
- 100
- 20
- 85
- 10
20
In eukaryotic cells, chromosomes are composed of DNA and __.
- and proteins
- and RNA
- only
- and phospholipids
And proteins
Which of the following defines a genome?
- The complete set of an organism’s genes
- A Karyotype
- The complete set of an organism’s polypeptides
- The complete set of a species’ polypeptides
The complete set of an organism’s genes.
Which is the smallest unit containing the entire human genome?
- All of the DNA of one human
- One human chromosome
- One human somatic cell
- The entire human population
One human somatic cell
Which of the following is a true statement about sexual vs. asexual reproduction?
- In sexual repro, individuals transmit 50% of their genes to each offspring
- Sexual repro requires that parents be diploid
- Asexual repro, but not sexual repro, is characteristic of plants and fungi
- Asexual repro produces only haploid offspring
In sexual reproduction, individuals transmit 50 % of their genes to each of their offspring.
What do we mean where we use the terms mono hybrid cross and dihybrid cross?
- mono- single parent dihybrid - two parents
- mono- 9:3:3:1 dihybrid 3:1
- dihybrid - heterozygous for 2 characters ; mono involves one
- mono - progeny dihybrid - two progeny
A dihybrid cross involved organisms that are heterozygous for two characters, and a mono hybrid cross involves only one.
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
- there is considerable genetic variation in garden peas
- genes are composed of DNA
- traits are inherited in discrete units, and are not the results of “blending d”
- recessive genes occur more frequently in the F1 generation than do dominate ones
Traits are inherited in discrete units, and are not the results of “blending” .
Which of the following differentiates between independent assortment and segregation ?
- the law of segregation is accounted for by anaphase of mitosis
- the law of segregation requires describing two or more genes relative to one another
- the law of segregation requires having two or more generations to describes
- the law of independent assortments requires describing two or more genes relative to one another
The law of independent assortment requires describing two or more genes relative to one another.
What is the produced if a cell divides by mitosis but does not undergo cytokinesis?
- one cell with two nuclei, each identical to the nucleus of the parent cell
- two cells, with half of genetic material of the parent cell
- two cells, one of cell containing two nuclei and a second cell with out a nucleus
- one cell with one nucleus containing half of the genetic material of the parent cell
One cell with two nuclei, each identical to the nucleus of the parent cell
Humans produce skin cells by mitosis and gametes by meiosis. The nuclei of skin cells produced by mitosis will have
- 4 times as much DNA as the nuclei of gametes produced by meiosis
- same amount of DNA as the nuclei of gametes “
- twice as much DNA as the “
- half as much DNA “
Twice as much DNA as the nuclei of gametes produced by meiosis.
Compared to most prokaryotic cells, eukaryotic cells typically have
- the same number of DNA molecules and similarly sized genomes
- fewer DNA molecules and smaller genomes
- more DNA molecules and larger genomes
- the same number of DNA molecules but larger genomes
More DNA molecules and larger genomes.
At which phase are centrioles beginning to move apart in animal cells?
PMAT
Prophase
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?
- 50
- 10
- 35
- 200
10
At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?
PMAT
Metaphase
Which of the following is true of a species that has a chromosome number of 2n=16?
Each cell has eight homologous pairs.
Which of these statements is false?
- at sexual maturity, ovaries and testes produced diploid gametes by meiosis
- in humans, the 23rd pair, the sex chromosomes determine gender
- sexual life cycles differ with respect to the relative timing of meiosis and fertilization
- single, haploid sets of chromosomes … Single called zygote
At sexual maturity, ovaries and testies produce diploid gemetes by meiosis .
- it’s haploid
Referring to a plant’s sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?
- gametophyte mitosis
- sporophyte meiosis
- alternation of generations
- sporophyte mitosis
Gametophyte mitosis
Referring to a plant’s sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?
Gametophytes mitosis
Which of the following is an example of alternation of generation?
- a diploid plant ( sporophyte ) produces, by meiosis, a spore that gives rise to a mutlicellular, haploid pollen grain ( gametophyte)
- a diploid cell divides by mitosis to produce two diploid daughter cells, which then fuse to produce a tetrapods cell
- a diploid animal produces gametes by meiosis, and the gametes undergo fertilization to produce a diploid zygote
- a grandparent and grandchild each have dark hair, but the parent has blond hair
A diploid plant ( sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain ( gametophyte).
Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that
- new mutations were frequently generated in the F2 progeny, “reinventing” traits that had been lost in the F1
- the traits were lost in the F1 due to dominance of the parental traits
- traits can be dominate or recessive, and the recessive traits were obscured by the dominant one in the F1
Traits can be dominated or recessive, and the recessive traits were observed by the dominate ones in the F1
Why did the F1 offspring of Mendel’s Classic pea cross always look like one of the two parental varieties ?
- each allele affected phenotypic expression
- no gene integrated to produce the parental phenotype
- one allele was dominate
- the traits blended together during fertilization
One allele was dominant.
Which of the following describes the ability of a single gene to have multiple phenotypic effects?
- epistasis
- pleiotropy
- incomplete dominance
- multiple alleles
Pleiotopy
Which of the following is an example of polygenic inheritance ?
- pink flowers
- skin pigmentation in humans
- the ABO blood group in humans
- white and purple flower color in peas
Skin pigmentation in Humans.
Where do the microtubules of the spindle originate during mitosis in animal cells?
- centromere
- centrosome
- centriole
- chromatid
Centrosome
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
- dynein
- kinetochores
- Golgi- derived vesicles
- centrioles and centromeres
Golgi- derived vesicles
The beginning of anaphase is indicated by which of the following ?
- kinetochores attach to the metaphase plate
- cohesin attaches the sister chromatids to each other
- chromatids lose their kinetochores
- cohesin is cleaved enzymatically
Cohesion is cleaved enzymatically.
During which phase of mitosis do the chromatids become chromosomes ?
PMAT
Anaphase
What is the cleavage furrow?
- a groove in the plasma membrane between daughter nuclei
- a ring of vesicles forming a cell plate
- the separation of dividend prokaryotes
- the metaphase plate where chromosomes attach to the spindle
A groove in the plasma membrane between daughter nuclei
The human X and Y chromosomes
- are called autos omens
- included genes that determine an individual’s sex
- are both present in every somatic cell of males and females alike
- are about the same size and have approximately the same number of genes
Include genes that determine an individual’s sex.
Which of these is a karyotype?
- organized images of a cell’s chromosomes
- a display of all the cell types in an organism
- a natural cellular arrangement of chromosomes in the nucleus
- a display of a cell’s mitotic stages
Organized images of a cell’s chromosomes
Mitosis is commonly found in all of the following except
- a diploid bacteria cell
- a haploid animal cell
- a diploid animal cell
- a diploid plant cell
A haploid animal cell
Which of these is a way that the sexual life cycle increases genetic variation in a species?
- by allowing an increase in cell number
- by conserving chromosomal gene order
- by allowing crossing over
- by increasing gene stability
By allowing crossing over
Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle ?
- ATP as an energy source
- intact centromeres
- synthesis of cohesin
- a kinetochore attached to the metaphase plate
ATP as an energy source
When a cell is in late anaphase of mitosis, which of the following will we see?
- breaking down of the nuclear envelope
- chromosomes clustered at the poles
- individuals chromatids beginning to separate from one another
- clear area in the centers of the cell
A clear area in he center of he cell
Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?
A clear area in the center of the cell
Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?
- G1
- G2
- G0
- S
G1
Which of the following is released by platelets in the vicinity of an injury ?
- protein kinase
- cyclin
- MPF
- PDGF
PDGF
Which of the following triggers the cell’s passage past the G2 checkpoint into mitosis?
- cyclin
- MPF
- Protein kinase
- PDGF
MPF
Which of the following provides an example of epistastsis ?
- recessive genotype for each genes ( aabb) result in an albino corn snake
- in rabbits and many other mammals, one genotype ( ee) prevents any fur color from developing.
- In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combo of other genes
In rabbits and many other mammals, one genotype ( ee) prevents any fur color from developing.
A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following ?
- it gametes must have 23 chromosomes
- it must be an animal
- it must be sexually reproducing
- it must be a primate
It’s gametes must have 23 chromosomes
Which of the following can utilize both mitosis and meiosis in the correct circumstance?
- a diploid cell from a plant stem
- any diploid animal cell
- a plantlike protist
- a haploid animal cell
A plantlike protist
To view and analyze human chromosomes in a dividing cell, which of the following is (are ) required?
- a stain particular to human cells
- a scanning electron microscope
- DNA staining and a light microscope
- fluorescent staining and a transmission electron microscope
DNA staining and a light microscope
After telophase 1 of meiosis, the chromosomal makeup of each daughter cell is
- diploid and the chromosomes are each composed of two chromatids
- tetraploid and the chromosomes are each composed of two chromosomes
- haploid and the chromosomes are each composed of two chromatids
Haploid, and the chromosomes are each composed of two chromatids.
When does the synaptonemal complex disappear?
- late metaphase of meiosis II
- late prophase of meiosis I
- during fertilization or fusion of gametes
- early anaphase of meiosis I
Late prophase of meiosis 1
Density- dependent inhibition is explained by which of the following ?
- As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
- As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor.
- As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing
Which of the following is true concerning cancer cells?
- When they stop dividing, they do so at random points in the cell cycle
- When they stop dividing, they do so at random in the cell cycle; they are not subject to cell cycle controls; and they do no exhibit density-dependent inhibition when growing in culture.
- They are not subject to cell cycle controls.
- They do not exhibit density- dependent inhibition when growing in culture.
When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.
Why do neurons and come other specialized cells divided infrequently ?
- They no longer carry receptors for signal molecules
- They no longer have active nuclei
- They have been shunted into G0
- They show a drop in MPF concentration
They have been shunted in G0
Which of the following most accurately described a cyclin ?
- It is activated to phosphorylate by completing with a Cdk
- It activates a Cdk molecule when it is in sufficient concentration
- It is present in similar concentrations throughout the cell cycle.
- It activates a Cdk when it’s concentration is decreased
It activates a Cdk molecule when it is in sufficient concentration.
All cell cycle checkpoints are similar in which way?
- They utilize same Cdks
- They respond to the same cyclins
- They give the go-ahead signal to progress to the next checkpoint
- They activate or inactivate other proteins
They give the go - ahead to progress to the next checkpoint.
Which of the following happens at the conclusion of meiosis 1?
- Cohesions are cleaved at the centromeres
- The chromosome number per cell is conserved
- Homologous chromosomes of a pair are separated from each other
- Sister chromatids are separated
Homologous chromosomes of a pair are separated from each other.
Which of the following occurs in meiosis but not in mitosis?
- production of daughter cells
- condensation of chromatin
- chromosome replication
Synapsis of chromosomes
