Bio Exam 4
A cell at the beginning of meiosis has 30 chromosomes. This cell has ______ chromatids. At the end of meiosis, each of its "daughter cells" will have _____ chromosomes.
60, 15
Here are Mendel's four hypotheses. 1.Alternative versions of heritable "factors" (i.e., alleles) account for variations in inherited characters 2.An organism inherits two alleles, one from each parent 3.If the two alleles at a locus differ, then one (the dominant allele) determines the organism's appearance. 4.The "law of segregation" Though Mendel didn't know about "ploidy" per se, two of these hypotheses together constitute the idea of alternations between haploid and diploid in sexual life cycles. Specifically, #______ is similar to saying meiosis makes haploid gametes, and #_______ is similar to saying fertilization makes a diploid zygote. C.4, 2
-Law of segregation: similar to saying meiosis makes haploid gametes -an organism inherits two alleles, one from each parent is similar to saying fertilization makes a diploid gametes
A cell at the end of S phase has 48 chromatids. At the end of mitosis each cell produced would have _____ chromosomes and ______ chromatids.
24, 24 (there are no sister chromatids at end of mitosis)
A cell at the beginning of meiosis has 36 chromosomes. This cell has _____ chromatids. At the end of meiosis, each of its "daughter cells" will have _____ chromosomes.
72, 18
A cell in G1 of the cell cycle has 48 chromosomes. At the end of G2, this cell would have _____ chromatids and ____ chromosomes.....
96, 48
Which of the followinf is true of a species that has a chromosome number of 2n=16? A) each cell has eight homologous paris B) during the S phase of the cell cycle there will be 32 separate chromosomes C) the species has 16 sets of chromosomes per cell D) a gamete from this species has four chromosomes
A) each cell has 8 homologous pairs
Most of the cells in your body are diploid. How did they become this way? A)each of us is a product of sexual reproduction, having one set of genes from our mother and one set of genes from our father B)The number of chromosomes inside cells is doubled each time mitosis happens, so cells wind up with multiple copies of the genome C)the number of chromosomes inside cells is cut in half each time mitosis happens, so cells have to have two sets at all times to be ready for the next mitosis D)at any given time, most cells in your body are stopped between S phase and G2 phase, so they have two copies of everything
A)each of us is a product of sexual reproduction, having one set of chromosomes
During which of the following does the separation of homologous chromosomes occur? A)Mitosis only B) Meiosis I only C) meiosis II only D) Mitosis and Meiosis I E) Mitosis and Meiosis II
B) Meiosis I only
Mendel didnt know about genes of chromosomes per say. In modern terms mendels "law of segregation" can be phrased as stating that TWO alleles an individual possesses for a given gene SEPARATE during gamete formation. If a cell in G1 phase possesses exactly TWO alleles for a given gene, the cell must be A. Diploid B. Haploid C. could be either A or B D. not enough information to choose between A and B
A. Diploid -G1 phase: DNA duplication has no occurred
When purple flowers are crossed with each other, as in the F1generation, what does the hypothesis of blending inheritance predict their offspring (the "F2 generation") should look like? A.all purple B.all white C.purplish white
A. all purple
A cell at the very beginning of meiosis has a total of 4 chromatids. What is "n" for the cell? A.1 B.2 C.4 D.8 E. Can not be determined from information provided
A.1 -there are two chromosomes (2n), but the make ONE pair of homologous chromosomes
Chemotherapy drugs stop the cell cycle . Why are stomach upset, hair loss, and immune system depression all common side effects of chemotherapy? A)cells in these tissues are more sensitive to toxins than others B) compared to other tissues, cells in these tissues are marked by higher rates of cell division C) cells in these tissues are generally not replaced after being damaged D)all of the above
B) Compared to other tissues, cells in these tissues are marked by higher rates of cell division -constant division causes chemotherapy drugs to treat them as if they were cancerous
Which of the following is TRUE about meiosis and sexual life cycles? a) the haploid stage in sexual life cycle is always just a unicellular gamete B)meiosis halves the number of chromosomes; fertilization restores the diploid number of chromosomes C)meiosis is unique to sexually reproducing animals D)all diploid organisms reproduce strictly sexually
B)meiosis halves the number of chromosomes ; fertilization restores the diploid number of chromosomes
Which if the following about interphase is false? A)DNA is replicated during interphase B)very few of our cells are are in interphase at any one time C)cells can remain in the interphase until their demise D)growth of the cell happens during interphase E)cells can halt their progress in the cell cycle by going from G1 to G0 (neurons)
B)very few of our cells are are in interphase at any one time
In science, what does it mean when observations contradict the predictions of a hypothesis? A)we should double-down on our efforts to find data supporting the hypothesis B)we should consider alternative hypotheses (if we weren't already) C)we should manipulate our data to make it look like we found support for the hypothesis D)we should ignore the observations, because our hypothesis must be correct E)we should ignore science, because we don't like what it is telling us
B)we should consider alternative hypotheses (if we weren't already)
Practice making a punnett square. Suppose there are two alleles of a gene, called A and a, and A is dominant to a. In a cross, Aa x Aa, among the offspring there are _____ possible genotypes and _____ possible phenotypes _____ possible phenotypes. A. 4,3 B. 3, 2 C. 2, 1 D. 1, 2 E. 2,4
B. 3, 2
At the end of the G2 phase, a skin cell (in some species of mammal) has 16 chromatids total. How many chromosomes will each cell produced from this cell have after mitosis and cytokinesis are complete? A.4 B.8 C. 16 D. 32 E. not enough information given
B. 8 -2 cells with a one chromatid chromosomes
If any organism has a diploid number of 6 chromosomes, how many different combinations of maternal and paternal chromosomes are possible in its gametes? A. 6 B. 8 C. 12 D. 16 E. 3
B. 8 -haploid 3, use 2^n rule
Mendel didnt know... If the two alleles an individual possesses for a given gene "segregate" (i.e., separate) during gamete formation, what is happening at the chromosomal level during the process of this separation? A.diploid cells are arising from haploid ones B. Haploid cells are arising from diploid ones C. Could be either A or B D.not enough information to choose between A and B
B. Haploid cells are arising from diploid ones -in meiosis I when chromosomes move into separate cells
Below is a picture of a child skin cell, showing 6 of the cell's chromosomes, all of which have been replicated. 3 chromosomes were inherited from the child mom and 3 from the dad. Which of the following best describes a pair of homologous chromosomes? A. any pair consisting of two chromosomes inherited from one parent B. A pair consisting of chromosomes inherited one each from different parents C. two chromosomes, one inherited from each parent, that have the same genes as eachother D.Any two chromosomes having different genes E. There are no homologous chromosomes in this cell
B. a pair consisting of chromosomes inherited one each from different parents
Podophyllotoxin from American and Himalayan mayapples prevents DNA replication. In which part of the cell cycle would a cell be staled by podophyllotoxin? A) mitosis B) Cytokinesis C) S phase D) G2 E)G1
C) S phase- where DNA replication occurs
Who has the highest percentage of cells in the S phase? A) a body builder B)an adult cancer patient C)a fetus D) a sumo wrestler E)your professor
C) a fetus-most cells in the body are going through replication
In science, what is the difference between an "observation" and a "prediction"? A) no difference: they are the same thing B) predictions are true statements; observations are subjective interpretations C) predictions are what you expect if a given hypothesis is correct; observations are what you actually find or measure D) predictions are used to judge whether or not an observation is valid
C) predictions are what you expect if a given hypothesis is correct; observations are what you actually find or measure
Which process in the cell cycle is most directly blocked by Vinca alkaloids A)chromosome condensation B)degradation of nuclear membrane C)attachment of spindle to chromosomes D)separation of sister chromatids E)cytokinesis
C)attachment of spindle to chromosomes- (prometaphase)
In the previous question, the expected ratio of the different possible phenotypes in the offspring of that cross is A. 4:1 B. 1:2:1 (genotype) C. 3:1 D. 2:1:1 E. 1:0
C. 3:1
Why does each parent in the P generation make only one kind of gamete A. because only one gamete is produced during the two rounds of meiosis B. because we are only going to look at one offspring C. because each parent is homozygous for both genes D. because mutations happened E. because only dominant alleles are passed on to gametes
C. Because each parent is homozygous for both genes
Mendel didnt know... Mendels "law of segregation" finds its mechanistic basis most clearly in the behavior of chromosomes during.. A. S phase of Interphase B. Mitosis C.Meiosis I D. Meiosis II E. All of the above
C. Meiosis I
Which of Mendel's four hypotheses can, on its own, directly explain why there are NO white flowers in the F1 generation and why the purple F1's look just as purple as the purple plants in the parental ("P") generation? A. alternative versions of heritable "factors" (i.e. alleles) account for variations in inherited characters B.For each character an organisms inherits two alleles, one from each parent C. If the two alleles at a locus differ, then one (the dominant allele) determines the organisms appearance and D. the "law of segregation"
C. if the two alleles at a locus differ, the one (the dominant allele) determines the organisms appearance and the other (recessive allele) has no noticeable effect on appearance
A purple flower is crossed with a white flower. What does the hypothesis of blending inheritance predict that their offspring should look like? A. all purple B. all white C. purplish-white
C. purplish-white
P generation of experiment: True breeding yellow round crossed with true breeding green wrinkled: what are the genotypes of (1) yellow round and (2)green wrinkled in the P generation? A.Yellow round = yr Green wrinkled = YR B.Yellow round = Yr Green wrinkled = yR C.Yellow round = YYRR Green wrinkled = yyrr D. Yellow round = YYrr Green wrinkled = yyRR E. None of the above
C. yellow round YYRR Green wrinkled yyrr
Which of the following could be ways that keep the cell from passing the G2 checkpoint? A) Degrading (breaking down) cyclin proteins during G2 B)producing proteins that inhibit the formation of "mitosis promoting factor" C) Producing proteins that help cyclin and CDK come together D) A &B E) A, B, &C
D) A & B
***At the very beginning of meiosis, a cell in your ovary/testes has 46 chromosomes. AT the end of meiosis 1 (but before meiosis 2), this cell will have given rise to two cells that are each _____ and each have ______ chromosomes and _________ chromatids. A)Diploid, 46, 46 B)Haploid, 46, 92 C) Diploid, 23, 46 D) Haploid 23, 46 E) Haploid, 92, 92
D)Haploid 23, 46
In science, what is required to test a hypothesis? A)gathering data that support the hypothesis B)making a strong argument (without data) for why the hypothesis should be true (or false) C)asking people to vote on whether or not they think the hypothesis is true D)gathering data and checking whether the data are consistent with or contradict predictions of the hypothesis E)getting a politician and news media to endorse the hypothesis
D)gathering data and checking whether the data are consistent with or contradict predictions of the hypothesis
Chromosomes are duplicated in _____, and the duplicates are separated during _______. A. S phase; G2 phase B. G2 phase, interphase C. Mitosis, cytokinesis D. S phase, mitosis E. Cytokinesis; mitosis
D. S phase, mitotic phase
Suppose you were building a picture or a physical model of a cell in order to demonstrate the principle of independent assortment. What is the SMALLEST number of chromosomes you could put inside your model cell in order to do this? A.1 B.2 C.3 D. 4 E. 6
D.4 -2 chromosomes- only one homologous pairs, with 4 chromosomes- 2 homologous pairs -8 sister chromatids
If an adult human loses an arm in an accident, it does not re-grow. Why not? A. Cell division does not occur in adults B. Damaged tissues are not repaired in adults C. Old cells in your organs are never replaced by newer cells D. Developmental processes for growing limbs are not reactivated when a limb is lost later in life E.When the person's arm is lost, so are the persons genes for gorwing an arm
D.Developmental processes for growing limbs are not reactivated when a limb is lost later in life
Which of the following can NOT contribute to genetic variation in offspring arising from sexual reproduction? A) crossing over during meiosis in the parents B) independent assortment during meiosis in the parents C) random fertilization D) errors during DNA replication replication before meiosis E) mutations in DNA caused by UV rays hitting a parent's dividing skin cells
E) mutations in DNA caused by UV rays hitting a parent's dividing skin cells
During which of the following does the separation of sister chromatids occur? A)mitosis only B) meiosis I only C) Meiosis II only D)Mitosis and Meiosis I E)Mitosis and Meiosis II
E)Mitosis and Meiosis II
Horses have 64 chromosomes per diploid cell. When horse parents have foals via sexual reproduction, those babies also have 64 chromosomes per diploid cell. How is this possible?
Meiosis makes horse gametes with 32 chromosomes each, then fertilization makes a horse zygote with 64 chromosomes
Suppose at the beginning of S phase, a skin cell (in some species of mammal) has * chromosomes total, how many chromosomes will each cell produced from this cell have after mitosis and cytokinesis is complete? A.4 B.8 C.16 D.32 E. not enough information given
b. 8
Two brown haired parents have a child with bright red hair. which of the following is the best explanation for this observation?
each parent has one allele for brown hair and one allele for red hair, and the brown allele is dominant