Deck 2: Chromosomes and Cellular Reproduction

Question 1

Which of the following statements is FALSE?

A) Generally, chromosomes of prokaryotes are circular.
B) Prokaryotes usually have a single molecule of DNA.
C) Generally, chromosomes of eukaryotes are circular.
D) Eukaryotes usually have multiple chromosomes.
E) Eukaryote chromosomes are usually linear.

Answer 1

C

Question 2

A chromosome with a centromere at the very end is called:

A) submetacentric.
B) metacentric.
C) acrocentric.
D) acentric.
E) telocentric.

Answer 2

E

Question 3

In prokaryotes, replication usually begins at a specific place on the chromosome called the:

A) binary fission site.
B) origin of replication.
C) origin of mitosis.
D) anchoring site.
E) kinetochore.

Answer 3

B

Question 4

The process of splitting the cytoplasm, which separates one cell into two, is termed:

A) cytokinesis.
B) mitosis.
C) anaphase.
D) diakinesis.
E) fusion.

Question 5

In tissue from the intestinal epithelium of a frog, the following proportions of cells were found at each stage of the cell cycle: $$\begin{array} { | l | c | } \hline \text { Stage } & \text { Prop ortion of Cells } \\\hline \text { Interphase } & 0.90 \\\hline \text { Prophase } & 0.04 \\\hline \text { Prometaphase } & 0.02 \\\text { Metaphase } & 0.01 \\\text { Anaphase } & 0.02 \\\text { Telophase } & 0.01\end{array}$$ If the entire cell cycle in frog epithelium cells requires 20 hours for completion, what is the average duration of each stage?

A) 18 hours for interphase, 0.4 hour for prophase, 0.2 hour for prometaphase, 0.2 hour for metaphase, 0.2 hour for anaphase, 0.4 hour for telophase
B) 1.8 hours for interphase, 0.8 hour for prophase, 0.2 hour for prometaphase, 0.2 hour for metaphase, 0.2 hour for anaphase, 0.8 hour for telophase
C) 18 hours for interphase, 0.8 hour for prophase, 0.4 hour for prometaphase, 0.2 hour for metaphase, 0.4 hour for anaphase, 0.2 hour for telophase
D) 9 hours for interphase, 0.8 hour for prophase, 0.2 hour for prometaphase, 0.2 hour for metaphase, 0.6 hour for anaphase, 0.4 hour for telophase
E) 18 hours for interphase, 0.8 hour for prophase, 0.6 hour for prometaphase, 0.2 hour for metaphase, 0.2 hour for anaphase, 0.8 hour for telophase

Question 6

Chromosome movement during anaphase is a result of:

A) disassembly of tubulin molecules by molecular motor proteins.
B) kinetochore shortening causing chromosomes to pull apart.
C) metaphasal plate splitting resulting in chromosomal disassembly.
D) the cohesion protein attaching to the centromeres of sister chromatids.
E) cilia movement inside the cellular structure.

Question 7

Which of the following statements is FALSE?

A) Errors in chromosome separation are rarely a problem for an organism.
B) Errors in chromosome separation can result in a miscarriage.
C) Errors in chromosome separation can result in cancer.
D) Errors in chromosome separation can result in a child with severe handicaps.
E) Errors in chromosome separation can cause numerous problems for an organism.

Question 8

In order to be functional, a eukaryotic chromosome requires all of the following EXCEPT:

A) a centromere.
B) origins of replication.
C) a plasmid.
D) telomeres.

Question 9

Which of the following statements is TRUE?

A) Eubacteria are prokaryotes while the archaea are eukaryotes.
B) Archaea are more closely related to eukaryotes than to eubacteria.
C) Eukaryotes are more closely related to eubacteria than to archaea.
D) Viruses are more closely related to prokaryotes than to eukaryotes.
E) Eubacteria, archaea, and eukaryotes are all equally related.

Question 10

If a healthy cell passes the G₁/S checkpoint:

A) it will enter the G₀ stage of the cell cycle.
B) DNA will be replicated.
C) it will not divide.
D) it will proceed immediately to cytokinesis.
E) it will die.

Question 11

In eukaryotes, chromosomes do NOT contain:

A) ribosomes.
B) chromatin.
C) proteins.
D) histones.
E) DNA.

Question 12

Which of the following are NOT prokaryotes?

A) eubacteria
B) archaea
C) viruses
D) ancient bacteria

Question 13

A dividing eukaryotic cell is treated with a drug that inhibits the molecular motors associated with kinetochores. At which cell cycle stage would it stop?

A) G₁
B) S
C) G₂
D) M (metaphase)
E) M (telophase)

Question 14

Which of the following does NOT occur during the G₂ phase of the cell cycle?

A) The G₂/M checkpoint is reached.
B) DNA replication and error checking are completed.
C) The cell completes preparation for mitosis.
D) The cell divides.
E) All of these occur during the G₂ phase of the cell cycle.

Question 15

The attachment point on the chromosome for spindle microtubules is the:

A) telomere.
B) centromere.
C) origin of replication.
D) sister chromatid.
E) allele.

Question 16

Diploid cells are cells with _____ chromosomes.

A) a single set of
B) circular
C) two sets of
D) many sets of
E) three sets of

Question 17

The highly organized internal scaffolding of the nucleus is called the:

A) histone complex.
B) spindle microtubules.
C) nuclear cohesion.
D) nuclear matrix.
E) nuclear envelope.

Question 18

Why are viruses considered to be neither prokaryotic nor eukaryotic?

Question 19

Prokaryotic chromosomes do NOT have telomeres because they:

A) do not go through mitosis.
B) do not go through DNA replication.
C) are in the cytoplasm.
D) are circular.
E) have no centromeres.

Question 20

Which of the following occurs during prometaphase?

A) The chromosomes align in a single plane.
B) DNA is replicated.
C) Microtubules attach to the kinetochores.
D) Mitotic spindles form.
E) The two sister chromatids separate.

Question 21

List two differences and two similarities between mitosis and meiosis.

Question 22

Suppose that a diploid cell contains 8 chromosomes (2n = 8). How many different combinations in the gametes are possible?

A) 2
B) 4
C) 8
D) 16
E) 64

Question 23

The cells illustrated here belong to a species with a diploid chromosome number of four. Each of the following cells is in which stage of mitosis or meiosis?

Question 24

The cells of a mature pea plant have 14 chromosomes. How many chromosomes does a nucleus in the pea endosperm contain?

A) 3¹/₂
B) 7
C) 14
D) 21
E) 30

Question 25

Which of the following processes is unique to plants?

A) meiosis
B) double fertilization
C) crossing over
D) haploid gametes
E) spermatogenesis

Question 26

Explain why mitosis does not produce genetic variation and how meiosis leads to the production of tremendous genetic variation.

Question 27

Which of the following are errors in the accompanying drawing of mitotic anaphase? (Select all that apply.)

A) It appears that homologous chromosomes rather than sister chromatids are separating.
B) Sister chromatids do not have identical alleles for the B gene.
C) Two alleles of the same gene (D and d) are on the same chromosome.
D) No alleles of the A gene are on the homologous chromosome.
E) Genes A and B are on the same chromosome.

Question 28

Describe the difference between G₁ and G₂ of the cell cycle.

Question 29

Microscopy to look at a cell's chromosomes is often done when the cell is in mitotic metaphase. For example, karyotyping (extracting chromosomes from a single cell and photographing them to look for abnormalities) is performed on metaphase, rather than interphase, cells. Why?

Question 30

(a) Draw a pair of acrocentric homologous chromosomes as they would appear in G₂. Indicate centromeres with a small circle, and place the alleles A and a on each of the chromatids. (b) Draw the same chromosomes as they would appear in G₁. Place the alleles A and a on each of the chromatids.

Question 31

Which chromosome in the following figure is MOST likely to be described as acrocentric?

A) (a)
B) (b)
C) (c)
D) (d)
E) Chromosomes (a) and (b) are both acrocentric.

Question 32

The centromere divides a chromosome into two sections or "arms." A chromosome is found to have two arms of equal lengths. Such a chromosome can be BEST described as:

A) telocentric.
B) circular.
C) acrocentric.
D) metacentric.
E) homologous.

Question 33

Describe what is happening to chromosomes during the five substages of prophase I.

Question 34

Somatic cancer cells often are unstable and divide inappropriately (divide when they should not be dividing). In addition such cells often contain losses of some chromosomes and extra copies of other chromosomes. Defects in which of the following may be partially responsible for the aberrant behavior of cancer cells? (Select all that apply.)

A) spindle-assembly checkpoint
B) G₁/S checkpoint
C) homologous chromosome pairing
D) crossing over

Question 35

The following figure shows a chromosomal separation taking place. The letters stand for genes; capital and lowercase letters stand for different alleles. The diploid chromosome number in this organism is four. What process is shown?

A) anaphase of mitosis
B) telophase of meiosis I
C) anaphase of meiosis I
D) telophase of mitosis
E) anaphase of meiosis II

Question 36

List and briefly describe three major cell cycle checkpoints. For each checkpoint, predict the consequences if the checkpoint fails to work properly.

Question 37

In a flowering plant, the male part of the flower (the stamen) produces haploid microspores that divide by _____ to eventually produce sperm.

A) mitosis
B) meiosis
C) gametogenesis
D) spermatogenesis
E) fertilization

Question 38

Describe the difference between the centromere and kinetochore.

Question 39

The cells of a mature pea plant have 14 chromosomes. In a pea plant ovary, how many chromosomes would the nucleus of a megaspore contain?

A) 3¹/₂
B) 7
C) 14
D) 21
E) 30

Question 40

Why is mitosis important within the cell cycle?

Question 41

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?

A) 21
B) 42
C) 84
D) 126
E) 168

Question 42

Write all possible genotypes of each of the cells resulting from mitosis and meiosis of a cell of the genotype shown below.

Question 43

To provide food for the developing embryo, a tissue called endosperm is produced through double fertilization. Endosperm has a ploidy of:

A) 1n.
B) 2n.
C) 3n.
D) 4n.
E) 5n.

Question 44

What might be the result if the breakdown of the shugoshin protein were premature?

A) The cohesion protein would hold the chromosome arms together longer.
B) The separation of homologous chromosomes would occur prematurely.
C) The separation of sister chromatids would occur prematurely.
D) Spindle fibers would not form.
E) Sister chromatids would never separate.

Question 45

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?

A) 21
B) 42
C) 84
D) 126
E) 168

Question 46

What events during sexual reproduction are significant in contributing to genetic diversity?

Question 47

A diploid, eukaryotic cell in interphase has these two pairs of homologous chromosomes with the indicated arrangement of alleles: Draw the chromosomes at the end of telophase of (a) mitosis and (b) meiosis II. Indicate placement of alleles on the chromosomes.

Question 48

Describe the difference between meiosis I and meiosis II.

Question 49

During prophase I of meiosis, crossing over is indicated by what microscopically visible structure?

Question 50

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?

A) 21
B) 40
C) 41
D) 42
E) 84

Question 51

A "mistake" is happening during meiosis I in the following figure. Assume the second meiotic division is normal. How many chromosomes would be expected in the four cellular products of this meiotic event?

A) All four cells would have four chromosomes.
B) All four cells would have three chromosomes.
C) Two cells would have three chromosomes and two cells would have five chromosomes.
D) Two cells would have six chromosome and two cells would have 10 chromosomes.
E) One cell would have three chromosomes, one cell would have five chromosomes, and two cells would have four chromosomes.

Question 52

What is one feature of meiosis that produces genetic variability in gametes? In two or three sentences, explain how this feature causes genetic uniqueness.

Question 53

In a typical flowering plant, a pollen grain that lands on a stigma grows a pollen tube to deliver _____ (how many?) sperm to the ovary. Fusion of a sperm with an egg produces a _____ n cell called a _____.

A) 1; 1; zygote
B) 2; 1; megasporocyte
C) 2; 2; zygote
D) 1; 2; microsporocyte
E) 1; 2; megasporocyte

Question 54

Assume that cells that are about to undergo meiosis are treated with a chemical that blocks crossing over but does not affect the cells in any other way, and four viable cells are produced by the two divisions of meiosis. What will be the consequence of such a treatment?

A) The four products of meiosis will be genetically identical.
B) The four products of meiosis will all be genetically unique.
C) All the chromosomes of two of the products of meiosis will have chromosomes that are paternal in origin but the other two products will have chromosomes that are of both paternal and maternal origins.
D) All the chromosomes of two of the products of meiosis will have chromosomes that are maternal in origin but the other two products will have chromosomes that are of both paternal and maternal origins.
E) Two of the products will be genetically identical but genetically different from the other two products, which will also be genetically identical.

Question 55

Describe the difference between the sporophyte and gametophyte.

Question 56

A geneticist observes 10 pairs of homologous chromosomes at metaphase I of meiosis in a newly discovered species of flowering plant. How many chromosomes should be found in a microsporocyte?

A) 20
B) 10
C) 5
D) 40
E) 2

Question 57

Describe the difference between homologous chromosomes and sister chromatids.

Question 58

Assume that the diploid or 2n number of chromosomes is 18 for a certain species of animal. How many DNA molecules will be found in metaphase II for this species?

A) 9
B) 18
C) 36
D) 72
E) 24

Question 59

Humans have 23 pairs of chromosomes. Rarely, an egg is produced with 46 chromosomes instead of 23. How might such an egg have originated?

A) When the first polar body divides in meiosis II, all the chromatids go to one daughter cell.
B) When the secondary oocyte divides in meiosis II, all the chromatids go to one daughter cell.
C) When the second polar body divides in meiosis II, all the chromatids go to one daughter cell.
D) When the primary oocyte divides in meiosis I, all the chromosomes go to the first polar body.
E) When the secondary oocyte divides in meiosis I, all the chromatids go to the second polar body.

Question 60

A diploid, eukaryotic cell in interphase has these two pairs of homologous chromosomes with the indicated arrangement of alleles: Draw the chromosomes at the end of (a) prophase of mitosis and (b) prophase I (of meiosis I) with the most likely crossing-over events. Indicate placement of alleles on the chromosomes.

Question 61

(a) Compare and contrast spermatogenesis and oogenesis in animals. For each process, be sure to include information about division of the nucleus, allocation of chromosomes to the various products, and division of the cytoplasm. (b) Why is the difference in cytoplasmic division between spermatogenesis and oogenesis important to reproduction, considering the different roles of sperm and eggs in reproduction?

Question 62

(a) Describe the changing role of cohesin during the mitotic cell cycle. (b) Explain the importance of regulation of cohesin activity to normal cell division.