midterm revision

Question 1

1. The centromere is a region in which
   A) chromatids are attached to one another.
   B) metaphase chromosomes become aligned.
   C) chromosomes are grouped during telophase.
   D) new spindle microtubules form.

Answer 1

A) chromatids are attached to one another.

Question 2

3. Which of the following statements is not true?
   A) Mitosis produces new nuclei with exactly the same chromosomal endowment as the
   parent nucleus entering mitosis.
   B) Mitosis may occur without cytokinesis.
   C) Mitosis and cytokinesis are required for asexual reproduction.
   D) The mitotic spindles in prokaryotic cells are composed of microtubules.

Answer 2

D) The mitotic spindles in prokaryotic cells are composed of microtubules.

Question 3

4. Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not
   cytokinesis, the result would be a cell with
   A) a single large nucleus.
   B) high concentrations of actin and myosin.
   C) two abnormally small nuclei.
   D) two nuclei.

Answer 3

D) two nuclei.

Question 4

5. The formation of a cell plate is beginning across the middle of a cell and nuclei are reforming at opposite ends of the cell. What kind of cell is this?
A) a plant cell undergoing cytokinesis
B) an animal cell in telophase
C) an animal cell undergoing cytokinesis
D) a plant cell in metaphase

Answer 4

A) a plant cell undergoing cytokinesis

Question 5

6. The correct sequence of steps in the M phase of the cell cycle is
   A) prophase, prometaphase, metaphase, anaphase, telophase.
   B) prophase, metaphase, prometaphase, anaphase, telophase.
   C) prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis.
   D) prometaphase, prophase, metaphase, anaphase, telophase, cytokinesis.

Answer 5

C) prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis.

Question 6

7. Measurements of the amount of DNA per nucleus were taken on a large number of cells
   from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus.
   In which stage of the cell cycle was the nucleus with 6 picograms of DNA?
   A) G0
   B) G1
   C) S
   D) G2

Answer 6

D) G2

Question 7

8. If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will usually
   A) move directly into telophase.
   B) complete the cycle and divide.
   C) exit the cycle and switch to a nondividing state.
   D) show a drop in MPF concentration

Answer 7

B) complete the cycle and divide.

Question 8

9. Cells that are in a non-dividing state are in which phase?
A) G0
B) G2
C) G1
D) S

Answer 8

A) G0

Question 9

10. a protein maintained at constant levels throughout the cell cycle that requires cyclin to
become catalytically active
A. Cdk
B. MPF
C. protein kinase
D. cyclin

Answer 9

10. a protein maintained at constant levels throughout the cell cycle that requires cyclin to
    become catalytically active A

Question 10

11. a protein synthesized at specific times during the cell cycle that associates with a kinase
to form a catalytically active complex
A. Cdk
B. MPF
C. protein kinase
D. cyclin

Answer 10

11. a protein synthesized at specific times during the cell cycle that associates with a kinase
    to form a catalytically active complex D

Question 11

12. a protein complex that acts at the G2 checkpoint to trigger mitosis
A. Cdk
B. MPF
C. protein kinase
D. cyclin

Answer 11

12. a protein complex that acts at the G2 checkpoint to trigger mitosis B

Question 12

13. Which of the following is true concerning cancer cells?
    A) They do not exhibit density-dependent inhibition when growing in culture.
    B) The may be considered immortal.
    C) They are generally not subject to cell cycle controls.
    D) All of the above

Answer 12

D) All of the above

Question 13

14. During prophase a homologous pair of chromosomes consists of
A) four chromosomes and two chromatids.
B) two chromosomes and two chromatids.
C) two chromosomes and four chromatids.
D) one chromosome and two chromatids.

Answer 13

C) two chromosomes and four chromatids.

Question 14

15. Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes
    with the assembly of microtubules, its effectiveness must be related to
    A) disruption of mitotic spindle formation.
    B) inhibition of regulatory protein phosphorylation.
    C) suppression of cyclin production.
    D) myosin denaturation and inhibition of cleavage furrow formation.

Answer 14

A) disruption of mitotic spindle formation.

Question 15

16. Which of the following differentiates between independent assortment and segregation?
    A) The law of segregation requires describing two or more genes relative to one another.
    B) The law of segregation requires having two or more generations to describe.
    C) The law of independent assortment is accounted for by observations of prophase I.
    D) The law of independent assortment requires describing two or more genes relative to one
    another.

Answer 15

D) The law of independent assortment requires describing two or more genes relative to one
another.

Question 16

17. Which of the following statements about genes is incorrect?
    A) Genes correspond to segments of DNA.
    B) Many genes contain the information needed for cells to synthesize enzymes and other
    proteins.
    C) During fertilization, both the sperm and the ovum contribute genes to the resulting
    fertilized egg.
    D) Under normal circumstances, each chromosome contains precisely one gene.

Answer 16

D) Under normal circumstances, each chromosome contains precisely one gene.

Question 17

18. 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 6022 yellow and
    2001 green seeds. The allele for green seeds had what relationship over the allele for yellow
    seeds?
    A) dominant
    B) incomplete dominant
    C) codominant
    D) recessive

Answer 17

D) recessive

Question 18

19. At which stage of mitosis are chromosomes photographed in the preparation of a
karyotype?
A) prophase
B) metaphase
C) anaphase
D) telophase

Answer 18

B) metaphase

Question 19

20. There is good evidence for linkage when
    A) two genes occur together in the same gamete.
    B) a gene is associated with a specific phenotype.
    C) two genes work together to control a specific characteristic.
    D) genes do not segregate independently during meiosis.

Answer 19

D) genes do not segregate independently during meiosis.

Question 20

21. In the cells of many eukaryotic species, the nuclear envelope has to disappear to permit
    which of the following events in the cell cycle?
    A) DNA synthesis
    B) attachment of microtubules to kinetochores
    C) separation of the centrosomes
    D) condensation of the chromosomes

Answer 20

B) attachment of microtubules to kinetochores

Question 21

22. After telophase I of meiosis, the chromosomal makeup of each daughter cell is
    A) diploid, and the chromosomes are composed of a single chromatid.
    B) diploid, and the chromosomes are composed of two chromatids.
    C) haploid, and the chromosomes are composed of a single chromatid.
    D) haploid, and the chromosomes are composed of two chromatids.

Answer 21

D) haploid, and the chromosomes are composed of two chromatids.

Question 22

I. prophase I
II. metaphase I
III. anaphase I
IV. telophase I
V. prophase II
VI. metaphase II
VII. anaphase II
VIII. telophase II
24. Synapsis of homologous pairs occurs; crossing over may occur.
A) I
B) II
C) IV
D) VI

Answer 22

A) I

Question 23

I. prophase I
II. metaphase I
III. anaphase I
IV. telophase I
V. prophase II
VI. metaphase II
VII. anaphase II
VIII. telophase II
23. Tetrads of chromosomes are aligned at the centre of the cell; independent assortment
soon follows.
A) I
B) II
C) IV
D) VII

Answer 23

B) II

Question 24

25. Centromeres of sister chromatids uncouple and chromatids separate.
A) II
B) III
C) IV
D) VII

Answer 24

D) VII

Question 25

26. Which of the following happens at the conclusion of meiosis I?
A) Homologous chromosomes are separated.
B) The chromosome number is conserved.
C) Sister chromatids are separated.
D) Four daughter cells are formed.

Answer 25

A) Homologous chromosomes are separated.

Question 26

27. In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype
AABBCC?
A) 1/32
B) 1/4
C) 1/64
D) 1/8

Answer 26

C) 1/64 (1/4 x ¼ x ¼)

Question 27

28. A plant with purple flowers is allowed to self-pollinate. Generation after generation, it
    produces purple flowers. This is an example of
    A) hybridization.
    B) incomplete dominance.
    C) pure breeding.
    D) the law of segregation.

Answer 27

C) pure breeding.

Question 28

29. A cross between homozygous purple-flowered and homozygous white-flowered pea
    plants results in offspring with purple flowers. This demonstrates
    A) the blending model of genetics.
    B) true-breeding.
    C) dominance.
    D) a dihybrid cross.

Answer 28

C) dominance.

Question 29

30. The F1 offspring of Mendel’s classic pea cross always looked like one of the two parental
    varieties because
    A) one allele was completely dominant over another.
    B) each allele affected phenotypic expression.
    C) the traits blended together during fertilization.
    D) no genes interacted to produce the parental phenotype.

Answer 29

A) one allele was completely dominant over another.

Question 30

31. A 9:3:3:1 phenotypic ratio is characteristic of which of the following?
A) a monohybrid cross
B) a dihybrid cross
C) a trihybrid cross
D) linked genes

Answer 30

B) a dihybrid cross

Question 31

32. P = purple, pp = white. The offspring of a cross between two heterozygous purpleflowering plants (Pp × Pp) results in
    A) all purple-flowered plants.
    B) purple-flowered plants and white-flowered plants.
    C) two types of white-flowered plants: PP and Pp.
    D) all white-flowered plants.

Answer 31

B) purple-flowered plants and white-flowered plants.

Question 32

33. 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 the cross BbTt × BBtt will have black fur and long
    tails?
    A) 1/16
    B) 3/16
    C) 3/8
    D) 1/2

Answer 32

D) 1/2

Question 33

34. In snapdragons, heterozygotes have pink flowers, whereas homozygotes have red or
    white flowers. When plants with red flowers are crossed with plants with white flowers, what
    proportion of the offspring will have pink flowers?
    A) 0%
    B) 25%
    C) 50%
    D) 100%

Answer 33

D) 100%

Question 34

35. Sally has just given birth to a baby girl. The medical professional involved in her care has
    advised Sally that mosaic Down Syndrome is suspected in her baby. Sally had received
    prenatal screening which had suggested a low likelihood of a Down syndrome baby, so the
    diagnosis came as quite a shock. A sample of the baby’s blood has been taken for karyotype
    analysis. If the suspected mosaicism is confirmed, the karyotype analysis is most likely to
    show the following:
    A) Three of chromosome 21 in all 20 cells analysed
    B) Three of chromosome 21 in some of the 20 cells analysed
    C) Three of chromosome 18 in all 20 cells analysed
    D) Three of chromosome 18 in some of the 20 cells analysed

Answer 34

B) Three of chromosome 21 in some of the 20 cells analysed

Question 35

36. Further to the situation described in question 35. above, the baby’s karyotype has indeed
    revealed mosaic Down Syndrome. It is more likely that the molecular event leading to the
    mosaicism was
    A) a non-disjunction during meiosis I in oogenesis
    B) a non-disjunction during meiosis II in oogenesis
    C) a non-disjunction during cell division in the early embryo
    D) a chromosomal duplication during meiosis in oogenesis

Answer 35

C) a non-disjunction during cell division in the early embryo

Question 36

37. In a cell in which n = 3, the independent assortment of chromosomes during meiosis can
    by itself give rise to how many genetically different gametes.
    A) 8
    B) 16
    C) 4
    D) 10

Answer 36

A) 8

Question 37

38. In the following list, which term is least related to the others?
A) hemophilia
B) autosome
C) sex-linked genes
D) color blindness

Answer 37

B) autosome

Question 38

39. A man who carries an X-linked allele will pass it on to
A) all of his daughters.
B) half of his daughters.
C) all of his sons.
D) half of his sons.

Answer 38

A) all of his daughters.

Question 39

40. Which of these syndromes afflicts mostly males?
A) Turner syndrome
B) Down syndrome
C) colour blindness
D) cri du chat syndrome

Answer 39

C) colour blindness

Question 40

41. A man who carries a Y linked allele will pass it on to
A) 50% of his sons
B) 25% of his sons
C) all of his sons
D) 75% of his sons

Answer 40

C) all of his sons

Question 41

42. Punnett squares are used for
    A) determining the DNA sequence of a given gene
    B) predicting the outcome of gene crosses
    C) determining the degree of gene mutation
    D) predicting the sex of offspring

Answer 41

B) predicting the outcome of gene crosses

Question 42

43. The mode of inheritance of cystic fibrosis is
A) Autosomal dominant
B) Autosomal recessive
C) X-linked dominant
D) X-linked recessive

Answer 42

B) Autosomal recessive

Question 43

44. The AB blood group in humans is an example of
A) polygenic inheritance
B) co-dominance
C) epistasis
D) lethal alleles

Answer 43

B) co-dominance

Question 44

45. Patau Syndrome is characterised by
A) Trisomy 18
B) Translocation between chr13 and chr21
C) Trisomy 13
D) Trisomy 21

Answer 44

C) Trisomy 13