Ch. 13

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

16

The diploid number of a roundworm species is 4. Assuming there is no crossover, and there is random segregation of homologues during meiosis, how many different possible combinations of chromosomes might there be in the offspring?

16

A certain gene found in a diploid species is known to have 18 alleles (variants). Any given organism of that species can/must have which of the following? A) 2 alleles for that gene B) up to 18 chromosomes with that gene C) up to 18 genes for that trait D) a haploid number of 9 chromosomes E) up to, but not more than, 18 different traits

2 alleles for that gene

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be

2x.

Columnar aspen, found commonly throughout Canada, although not in the Northwest Territories, can send out underground stems for asexual reproduction. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?

38

7) 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.

Each cell has eight homologous pairs.

Which of the following happens at the conclusion of meiosis I?

Homologous chromosomes are separated

8) 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

II, III, and IV

For the following questions, match the key event of meiosis with the stages listed below. I-Prophase I II- Metaphase I III-Anaphase I IV- Telophase I V-Prophase II VI-Metaphase II VII-Anaphase II VIII-Telophase II Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment.

II-Metaphase I

3) 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.

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

If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents? A) It has half the amount of DNA as the cell that began meiosis. B) It has the same number of chromosomes but each of them has different alleles than another cell from the same meiosis. C) It has half the chromosomes but twice the DNA of the originating cell. D) It has one-fourth the DNA and one-half the chromosomes as the originating cell. E) It is identical in content to another cell from the same meiosis.

It has half the amount of DNA as the cell that began meiosis.

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.

Its gametes must have 23 chromosomes.

34) When we see chiasmata under a microscope, that lets us know which of the following has occurred? A) asexual reproduction B) meiosis II C) anaphase II D) prophase I E) separation of homologues

Prophase I

1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus 2. Alignment of tetrads at the metaphase plate 3. Separation of sister chromatids 4. Separation of the homologues; no uncoupling of the centromere 5. Synapsis; chromosomes moving to the middle of the cell in pairs Which of the steps takes place in both mitosis and meiosis?

Seperation of sister chromatids

What is a major difference between mitosis and meiosis I in a diploid organism? A) Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I. B) Crossing over occurs in mitosis but not in meiosis I. C) DNA replication takes place prior to mitosis, but not before meiosis I. D) Only meiosis I results in daughter cells that contain identical genetic information. E) There are two divisions in meiosis I but only 1 in mitosis.

Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I.

When homologous chromosomes cross over, what occurs? A) Two chromatids get tangled, resulting in one re-sequencing its DNA. B) Two sister chromatids exchange identical pieces of DNA. C) Specific proteins break the two strands and re-join them with their homologues. D) Each of the four DNA strands of a tetrad is broken and the pieces are mixed. E) Maternal alleles are "corrected" to be like paternal alleles and vice versa.

Specific proteins break the two strands and re-join them with their homologues.

26) 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.

The statement is true for meiosis I only.

28) Independent assortment of chromosomes occurs. 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.

The statement is true for meiosis I only.

Chromatids are separated from each other 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.

The statement is true for mitosis and meiosis II.

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

They have half the number of chromosomes and one-fourth the amount of DNA.

Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must have which of the following properties? A) They must persist throughout the cell cycle. B) They must be removed before meiosis can begin. C) They must be removed before anaphase can occur. D) They must reattach to chromosomes during G1. E) They must be intact for nuclear envelope reformation.

They must be removed before anaphase can occur

For the following questions, match the key event of meiosis with the stages listed below. I-Prophase I II- Metaphase I III-Anaphase I IV- Telophase I V-Prophase II VI-Metaphase II VII-Anaphase II VIII-Telophase II Centromeres of sister chromatids disjoin and chromatids separate.

VII-Anaphase II

When an individual chromosome carries DNA from two different parents, it is said to be A) fertilized. B) a mutation. C) a karyotype. D) synapsed. E) recombinant.

recombinant

Meiosis II is similar to mitosis in that A) sister chromatids separate during anaphase. B) DNA replicates before the division. C) the daughter cells are diploid. D) homologous chromosomes synapse. E) the chromosome number is reduced.

sister chromatids separate during anaphase

29) Which of the following occurs in meiosis but not in mitosis? A) chromosome replication B) synapsis of chromosomes C) production of daughter cells D) alignment of chromosomes at the equator E) condensation of chromatin

synapsis of chromosomes

36) 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 centre C) an uninterrupted spindle array D) the synaptonemal complex E) tetrads all aligned at the cell's centre

tetrads all aligned at the cells centre

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.

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

Which of the following is true regarding homologous chromosomes? A) They are identical. B) They each carry copies of the same genes. C) They carry the same alleles. D) They align on the metaphase plate in meiosis II. E) All human chromosomes are homologous in somatic cells.

they each carry copies of the same genes

33) A tetrad includes which of the following sets of DNA strands? A) two single-stranded chromosomes that have synapsed B) two sets of sister chromatids that have synapsed C) four sets of sister chromatids D) four sets of unique chromosomes E) eight sets of sister chromatids

two sets of sister chromatids that have synapsed

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

x

9) 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.

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

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?

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

In meiosis, when are homologous chromosomes are separated? A) anaphase II B) prophase I C) mitosis D) anaphase I E) prophase II

anaphase I

When do centromeres split and sister chromatids migrate to opposite poles in meiosis? A) anaphase I B) telophase I C) anaphase II D) telophase II E) prophase II

anaphase II

Which of the following best describes the frequency of crossing over in mammals? A) ~50 per chromosome pair B) ~2 per meiotic cell C) at least 1-2 per chromosome pair D) ~1 per pair of sister chromatids E) a very rare event among hundreds of cells

at least 1-2 per chromosome pair

How does the sexual life cycle increase the genetic variation in a species?

by allowing crossing over

32) Experiments with cohesins have found that A) cohesins are protected from destruction throughout meiosis I and II. B) cohesins are cleaved from chromosomes at the centromere before anaphase I. C) cohesins are protected from cleavage at the centromere during meiosis I. D) a protein cleaves cohesins before metaphase I. E) a protein that cleaves cohesins would cause cellular death.

cohesins are protected from cleavage at the centromere during meiosis I.

83) Which of the following can occur by the process of meiosis but not mitosis? A) Haploid cells fuse to form diploid cells. B) Haploid cells multiply into more haploid cells. C) Diploid cells form haploid cells. D) A diploid cell combines with a haploid cell. E) Diploid cells multiple into more diploid cells.

diploid cells form haploid cells

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?

either anaphase I or II

If meiosis produces haploid cells, how is the diploid number restored for those organisms that spend most of their life cycle in the diploid state? A) DNA replication B) reverse transcription C) synapsis D) fertilization E) spore production

fertilization

After telophase I of meiosis, the chromosomal makeup of each daughter cell is

haploid, and the chromosomes are each composed of two chromatids.

Homologous chromosomes move toward opposite poles of a dividing cell during A) mitosis. B) meiosis I. C) meiosis II. D) fertilization. E) binary fission.

meiosis I

Crossing over normally takes place during which of the following processes? A) meiosis II B) meiosis I C) mitosis D) mitosis and meiosis II E) mitosis, meiosis I, and meiosis II

meiosis II

When do homologous pairs of chromosomes align opposite of each other at the equator of a cell? A) mitosis metaphase B) meiosis metaphase I C) meiosis telophase II D) meiosis metaphase II E) mitosis telophase

meiosis metaphase I

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?

metaphase

Asexual reproduction occurs during which of the following A) meiosis B) mitosis C) fertilization D) chromosome exchange between organisms of different species E) cytokinesis

mitosis

The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. Diversity in this species may be generated by which of the following? A) crossing over B) independent assortment C) crossing over and independent assortment D) independent assortment and mutations E) mutations, crossing over, and independent assortment

mutations, crossing over, and independent assortment

Which of the following might result in a human zygote with 45 chromosomes? A) an error in either egg or sperm meiotic anaphase B) failure of the egg nucleus to be fertilized by the sperm C) fertilization of a 23-chromosome human egg by a 22-chromosome sperm of a closely related species D) an error in the alignment of chromosomes on the metaphase plate E) lack of chiasmata in prophase I

A) an error in either egg or sperm meiotic anaphase

1) 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.

Clone the plant asexually to produce an identical one.

Which of the following best describes a karyotype? A) a pictorial representation of all the genes for a species B) a display of each of the chromosomes of a single cell C) the combination of all the maternal and paternal chromosomes of a species D) the collection of all the chromosomes in an individual organism E) a photograph of all the cells with missing or extra chromosomes

a display of each of the chromosomes of a single cell

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes? A) 23 B) 46 C) 460 D) 920 E) about 8 million

about 8 million

Autosomes are chromosomes, which are A) involved in sexual identity. B) capable of reproducing themselves. C) involved in the autoimmune responses. D) all chromosomes, except sex chromosomes. E) the only chromosomes that are inherited.

all chromosomes, except sex chromosomes.