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1

1) What do we mean when we use the terms monohybrid cross and dihybrid cross?

A) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.

B) A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.

C) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations.

D) A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.

B) A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.

2

2) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

A) There is considerable genetic variation in garden peas.

B) Traits are inherited in discrete units and are not the results of "blending."

C) Recessive genes occur more frequently in the F1 generation than do dominant ones.

D) Genes are composed of DNA.

B) Traits are inherited in discrete units and are not the results of "blending."

3

3) How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

A) 4

B) 8

C) 16

D) 64

B) 8

4

4) The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?

A) recurrent mutations forming new alleles

B) crossing over during prophase I

C) different possible assortment of chromosomes into gametes

D) the tendency for dominant alleles to segregate together

C) different possible assortment of chromosomes into gametes

5

5) Mendel continued some of his experiments into the F2 or F3 generation to _____.

A) obtain a larger number of offspring on which to base statistics

B) observe whether or not a recessive trait would reappear

C) observe whether or not the dominant trait would reappear

D) distinguish which alleles were segregating

B) observe whether or not a recessive trait would reappear

6

6) Which of the following statements about independent assortment and segregation is correct?

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

B) The law of segregation requires describing two or more genes relative to one another.

C) The law of independent assortment is accounted for by observations of prophase I.

D) The law of segregation is accounted for by anaphase of mitosis.

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

7

7) A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

A) Hh

B) HhTt

C) T

D) HT

D) HT

8

8) Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that _____.

A) new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1

B) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants

C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1

D) members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait

C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1

9

9) The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following?

A) None of the traits obeyed the law of segregation.

B) The diploid number of chromosomes in the pea plants was 7.

C) All of the genes controlling the traits were located on the same chromosome.

D) All of the genes controlling the traits behaved as if they were on different chromosomes.

D) All of the genes controlling the traits behaved as if they were on different chromosomes.

10

10) Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

A) prophase I of meiosis

B) anaphase II of meiosis

C) metaphase II of meiosis

D) anaphase I of meiosis

D) anaphase I of meiosis

11

11) Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

A) synapsis of homologous chromosomes

B) crossing over

C) alignment of tetrads at the equator

D) separation of cells at telophase

C) alignment of tetrads at the equator

12

Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?

A) 2

B) 4

C) 8

D) 16

B) 4

13

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?

A) No genes interacted to produce the parental phenotype.

B) Each allele affected phenotypic expression.

C) The traits blended together during fertilization.

D) One allele was dominant.

D) One allele was dominant.

14

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: 6022 yellow and 2001 green (8023 total). The allele for green seeds has what relationship to the allele for yellow seeds?

A) dominant

B) incomplete dominant

C) recessive

D) codominant

C) recessive

15

Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both of normal pigmentation, but both have one parent who is albino (without melanin pigmentation). What is the probability that their first child will be an albino?

A) 0

B) 1/2

C) 1/4

D) 1

C) 1/4

16

Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both of normal pigmentation and have one child out of three who is albino (without melanin pigmentation). What are the genotypes of the albino's parents?

A) One parent must be homozygous for the recessive allele; the other parent can be homozygous dominant, homozygous recessive, or heterozygous.

B) One parent must be heterozygous; the other parent can be homozygous dominant, homozygous recessive, or heterozygous.

C) Both parents must be heterozygous.

D) One parent must be homozygous dominant; the other parent must be heterozygous.

C) Both parents must be heterozygous.

17

A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?

A) Albino is recessive; black is dominant.

B) Albino is dominant; black is incompletely dominant.

C) Albino and black are codominant.

D) Albino is recessive; black is codominant.

A) Albino is recessive; black is dominant.

18

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.

(a) What is the most probable genotype of each parent?

(b) Based on your answer in (a) above, what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.)

A) (a) GG . gg; (b) genotypic = 3:1, phenotypic = 1:2:1

B) (a) Gg . Gg; (b) genotypic = 1:2:1, phenotypic = 3:1

C) (a) GG . Gg; (b) genotypic = 1:2:1, phenotypic = 2:1

D) (a) gg . Gg; (b) genotypic = 1:2, phenotypic = 3:1

B) (a) Gg . Gg; (b) genotypic = 1:2:1, phenotypic = 3:1

19

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?

A) 1:2:1

B) 3:1

C) 1:1

D) 1:1:1:1

C) 1:1

20

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?

A) 1/16

B) 3/8

C) 1/2

D) 9/16

C) 1/2

21

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

A) 1

B) 1/2

C) 1/4

D) 0

D) 0

22

In the cross AaBbCc . AaBbCc, what is the probability of producing the genotype AABBCC?

A) 1/4

B) 1/8

C) 1/16

D) 1/64

D) 1/64

23

Given the parents AABBCc . AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent with genotype AABBCc?

A) 1/4

B) 3/4

C) 3/8

D) 1

B) 3/4

24

Which of the following is the best statement of the use of the addition rule of probability?

A) the probability that two or more independent events will both occur

B) the probability that either one of two independent events will occur

C) the probability of producing two or more heterozygous offspring

D) the likelihood that a trait is due to two or more meiotic events

B) the probability that either one of two independent events will occur

25

Which of the following calculations require that you utilize the addition rule?

A) Calculate the probability of black offspring from the cross AaBb . AaBb, where B is the symbol for black.

B) Calculate the probability of children with both cystic fibrosis and polydactyly when parents are each heterozygous for both genes.

C) Calculate the probability of each of four children having cystic fibrosis if the parents are both heterozygous.

D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both

D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both.

26

The centromere is a region in which

A) chromatids remain attached to one another until anaphase.
B) metaphase chromosomes become aligned at the metaphase plate.
C) chromosomes are grouped during telophase.
D) the nucleus is located prior to mitosis.
E) new spindle microtubules form at either end.

A) chromatids remain attached to one another until anaphase

27

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
A) 4
B) 8
C) 16
D) 32
E) 64

D) 32

28

If there are 20 chromatids in a cell, how many centromeres are there?
A) 10
B) 20
C) 30
D) 40
E) 80

A)10

29

For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission?

A) Binary fission would not allow for the formation of new organisms.
B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes.
C) Cell division would be faster than binary fission.
D) Cell division allows for lower rates of error per chromosome replication.
E) Binary fission would not allow the organism to have complex cells.

B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes

30

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following?

A) one-twelfth of the genes of the organism
B) two chromosomes, each with six chromatids
C) a single circular piece of DNA
D) two long strands of DNA plus proteins
E) two chromatids attached together at a centromere

D) two long strands of DNA plus proteins

31

At which phase are centrioles beginning to move apart in animal cells?

A) telophase
B) anaphase
C) prometaphase
D) metaphase
E) prophase

E) prophase

32

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the formation of the spindle apparatus, at which stage will mitosis be arrested?

A) anaphase
B) prophase
C) telophase
D) metaphase
E) interphase

D) metaphase

33

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

A) 10
B) 20
C) 30
D) 40
E) 80

A) 10

34

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?

A) centromere
B) centrosome
C) centriole
D) chromatid
E) kinetochore

B) centrosome

35

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect

A) the formation of the mitotic spindle.
B) anaphase.
C) formation of the centrioles.
D) chromatid assembly.
E) the S phase of the cell cycle

A) the formation of the mitotic spindle

36

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?

A) kinetochores
B) Golgi-derived vesicles
C) actin and myosin
D) centrioles and centromeres
E) cyclin-dependent kinases

B) Golgi-derived vesicles

37

In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?

A) seedless plants
B) dinoflagellates
C) diatoms
D) dinoflagellates and diatoms only
E) seedless plants, dinoflagellates, and diatoms

D) dinoflagellates and diatoms only

38

Movement of the chromosomes during anaphase would be most affected by a drug that

A) reduces cyclin concentrations.
B) increases cyclin concentrations.
C) prevents elongation of microtubules.
D) prevents shortening of microtubules.
E) prevents attachment of the microtubules to the kinetochore.

D) prevents shortening of microtubules.

39

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 did the nucleus contain 6 picograms of DNA?

A) G₀
B) G₁
C) S
D) G₂
E) M

D) G₂

40

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G₂?

A) 8; 8
B) 8; 16
C) 16; 8
D) 16; 16
E) 12; 16

D) 16; 16

41

For anaphase to begin, which of the following must occur?

A) Chromatids must lose their kinetochores.
B) Cohesin must attach the sister chromatids to each other.
C) Cohesin must be cleaved enzymatically.
D) Kinetochores must attach to the metaphase plate.
E) Spindle microtubules must begin to depolymerize.

C) Cohesin must be cleaved enzymatically.

42

Why do chromosomes coil during mitosis?

A) to increase their potential energy
B) to allow the chromosomes to move without becoming entangled and breaking
C) to allow the chromosomes to fit within the nuclear envelope
D) to allow the sister chromatids to remain attached
E) to provide for the structure of the centromere

B) to allow the chromosomes to move without becoming entangled and breaking

43

Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?

A) The chromosomes are "reeled in" by the contraction of spindle microtubules.
B) Motor proteins of the kinetochores move the chromosomes along the spindle microtubules.
C) Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles.
D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.
E) The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles.

D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.

44

Which of the following is a function of those spindle microtubules that do not attach to kinetochores?

A) maintaining an appropriate spacing among the moving chromosomes
B) producing a cleavage furrow when telophase is complete
C) providing the ATP needed by the fibers attached to kinetochores
D) maintaining the region of overlap of microtubules in the cell's center
E) pulling the poles of the spindles closer to one another

D) maintaining the region of overlap of microtubules in the cell's center

45

During which phase of mitosis do the chromatids become chromosomes?

A) telophase
B) anaphase
C) prophase
D) metaphase
E) cytokinesis

A) telophase

46

Which of the following was a discovery that had to be made before human chromosomes could be correctly counted?

A) how to use a hypotonic solution to swell nuclei
B) how to visualize sperm nuclei
C) how to visualize chromosomes
D) when to see chromosomes separate from one another
E) when to see chromosomes in pairs

A) how to use a hypotonic solution to swell nuclei

47

Which of the following is (are) required for motor proteins to function in the movement of chromosomes toward the poles of the mitotic spindle?

A) intact centromeres
B) an MTOC (microtubule organizing center)
C) a kinetochore attached to the metaphase plate
D) ATP as an energy source
E) synthesis of cohesin

D) ATP as an energy source

48

What is a cleavage furrow?

A) a ring of vesicles forming a cell plate
B) the separation of divided prokaryotes
C) a groove in the plasma membrane between daughter nuclei
D) the metaphase plate where chromosomes attach to the spindle
E) the space that is created between two chromatids during anaphase

C) a groove in the plasma membrane between daughter nuclei

49

Which of the following proteins are involved in binary fission as well as eukaryotic mitotic division?
A) cyclins
B) Cdks
C) MPF
D) actin and tubulin
E) cohesins

D) actin and tubulin

50

Using which of the following techniques would enable your lab group to distinguish between a cell in G₂ and a cell from the same organism in G₁?

A) fluorescence microscopy
B) electron microscopy
C) spectrophotometry
D) radioactive-labeled nucleotides
E) labeled kinetochore proteins

D) radioactive-labeled nucleotides

51

If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants?

A) Backtrack through her previous experiments to obtain another plant with the same traits.
B) Breed this plant with another plant with much weaker traits.
C) Clone the plant asexually to produce an identical one.
D) Force the plant to self-pollinate to obtain an identical one.
E) Add nitrogen to the soil of the offspring of this plant so the desired traits continue.

C) Clone the plant asexually to produce an identical one.

52

The human genome is minimally contained in which of the following?
A) every human cell
B) each human chromosome
C) the entire DNA of a single human
D) the entire human population
E) each human gene

A) every human cell

53

In the human species, all somatic cells have 46 chromosomes. Which of the following can also be true?
A) A plant species (privet shrubs) has 46 chromosomes per cell.
B) Some adult humans have 69 chromosomes per cell.
C) Some adult humans have 23 chromosomes per cell.
D) A certain fungal species has only one chromosome per cell.
E) A certain bacterial species has 23 chromosomes.

A) A plant species (privet shrubs) has 46 chromosomes per cell.

54

Which of the following is a true statement about sexual vs. asexual reproduction?
A) Asexual reproduction, but not sexual reproduction, is characteristic of plants and fungi.
B) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring.
C) In asexual reproduction, offspring are produced by fertilization without meiosis.
D) Sexual reproduction requires that parents be diploid.
E) Asexual reproduction produces only haploid offspring.

B) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring.

55

Which of the following defines a genome?
A) representation of a complete set of a cell's polypeptides
B) the complete set of an organism's polypeptides
C) the complete set of a species' polypeptides
D) a karyotype
E) the complete set of an organism's genes

E) the complete set of an organism's genes

56

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

B) metaphase

57

The human X and Y chromosomes
A) are both present in every somatic cell of males and females alike.
B) are of approximately equal size and number of genes.
C) are almost entirely homologous, despite their different names.
D) include genes that determine an individual's sex.
E) include only genes that govern sex determination.

D) include genes that determine an individual's sex.

58

Which of the following is true of a species that has a chromosome number of 2n = 16?

A) The species is diploid with 32 chromosomes per cell.
B) The species has 16 sets of chromosomes per cell.
C) Each cell has eight homologous pairs.
D) During the S phase of the cell cycle there will be 32 separate chromosomes.
E) A gamete from this species has four chromosomes.

C) Each cell has eight homologous pairs.

59

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?

I. Alternation of generations
II. Meiosis
III. Fertilization
IV. Gametes
V. Spores

A) I, IV, and V
B) I, II, and IV
C) II, III, and IV
D) II, IV, and V
E) I, II, III, IV, and V

C) II, III, and IV

60

Which of these statements is false?
A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome.
B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY).
C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote.
D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis.
E) Sexual life cycles differ with respect to the relative timing of meiosis and fertilization.

D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis.

61

Referring to a plant's sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?
A) sporophyte meiosis
B) gametophyte mitosis
C) gametophyte meiosis
D) sporophyte mitosis
E) alternation of generations

B) gametophyte mitosis

62

Which of the following is an example of alternation of generations?
A) A grandparent and grandchild each have dark hair, but the parent has blond hair.
B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte).
C) A diploid animal produces gametes by meiosis, and the gametes undergo fertilization to produce a diploid zygote.
D) A haploid mushroom produces gametes by mitosis, and the gametes undergo fertilization, which is immediately followed by meiosis.
E) A diploid cell divides by mitosis to produce two diploid daughter cells, which then fuse to produce a tetraploid cell.

B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte).

63

The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following?
A) mitosis in her ovary
B) metaphase I of one meiotic event
C) telophase II of one meiotic event
D) telophase I of one meiotic event
E) either anaphase I or II

E) either anaphase I or II

64

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following?
A) It must be human.
B) It must be a primate.
C) It must be an animal.
D) It must be sexually reproducing.
E) Its gametes must have 23 chromosomes.

E) Its gametes must have 23 chromosomes.

65

A triploid cell contains three sets of chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following?
A) 63 chromosomes in 31 1/2 pairs
B) 63 chromosomes in 21 sets of 3
C) 63 chromosomes, each with three chromatids
D) 21 chromosome pairs and 21 unique chromosomes

B) 63 chromosomes in 21 sets of 3

66

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?
A) Length and position of the centromere only.
B) Length, centromere position, and staining pattern only.
C) Length, centromere position, staining pattern, and traits coded for by their genes.
D) Length, centromere position, staining pattern, and DNA sequences.
E) They have nothing in common except they are X-shaped.

C) Length, centromere position, staining pattern, and traits coded for by their genes.

67

When does the synaptonemal complex disappear?
A) late prophase of meiosis I
B) during fertilization or fusion of gametes
C) early anaphase of meiosis I
D) mid-prophase of meiosis II
E) late metaphase of meiosis II

A) late prophase of meiosis I

68

A cell divides to produce two daughter cells that are genetically different.
A) The statement is true for mitosis only.
B) The statement is true for meiosis I only.
C) The statement is true for meiosis II only.
D) The statement is true for mitosis and meiosis I.
E) The statement is true for mitosis and meiosis II.

B) The statement is true for meiosis I only.

69

To visualize and identify meiotic cells at metaphase with a microscope, what would you look for?
A) sister chromatids grouped at the poles
B) individual chromosomes all at the cell's center
C) an uninterrupted spindle array
D) the synaptonemal complex
E) tetrads all aligned at the cell's center

E) tetrads all aligned at the cell's center

70

For the following question, match the key event of meiosis with the stages listed below.

I. Prophase I V. Prophase II
II. Metaphase I VI. Metaphase II
III. Anaphase I VII. Anaphase II
IV. Telophase I VIII. Telophase II

40) Centromeres of sister chromatids disjoin and chromatids separate.
A) II
B) III
C) IV
D) V
E) VII

E) VII

71

Independent assortment of chromosomes is a result of

A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
B) the random nature of the fertilization of ova by sperm.
C) the random distribution of the sister chromatids to the two daughter cells during anaphase II.
D) the relatively small degree of homology shared by the X and Y chromosomes.
E) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I, the random nature of the fertilization of ova by sperm, the random distribution of the sister chromatids to the two daughter cells during anaphase II, and the relatively small degree of homology shared by the X and Y chromosomes.

A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.

72

There is a group of invertebrate animals called rotifers, among which a particular group of species reproduces, as far as is known, only asexually. These rotifers, however, have survived a long evolutionary history without evidence of having been overcome by excessive mutations.

61) Assuming that the eggs are diploid, tetraploid, or partially tetraploid, what mechanism may still occur without fertilization?
A) meiosis in each generation
B) meiosis in every second generation
C) independent assortment of maternal and paternal chromosomes
D) meiosis in times of adverse environmental conditions
E) crossing over of homologs

E) crossing over of homologs

73

The somatic cells of a privet shrub each contain 46 chromosomes. To be as different as they are from human cells, which have the same number of chromosomes, which of the following must be true?
A) Privet cells cannot reproduce sexually.
B) Privet sex cells have chromosomes that can synapse with human chromosomes in the laboratory.
C) Genes of privet chromosomes are significantly different than those in humans.
D) Privet shrubs must be metabolically more like animals than like other shrubs.
E) Genes on a particular privet chromosome, such as the X, must be on a different human chromosome, such as number 18.

C) Genes of privet chromosomes are significantly different than those in humans.

74

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8(2n = 8)?
A) 2
B) 4
C) 8
D) 16
E) 32

D) 16

75

If the DNA content of a diploid cell in the G₁ phase of the cell cycle is x, then the DNA content of a single cell at metaphase of meiosis II would be
A) 0.25x.
B) 0.5x.
C) x.
D) 2x.
E) 4x.

C) x.