Chapter 13 - Meiosis and Sexual Life Cycles

DNA was isolated from three different cell types of the same organism, the relative DNA content for each type was determined, and the results were plotted on the graph shown in the figure below. Refer to the graph to answer the following question Which sample of DNA might be from a cell that stopped the process of cell division in G0 phase of the cell cycle prior to meiosis?

I

DNA was isolated from three different cell types of the same organism, the relative DNA content for each type was determined, and the results were plotted on the graph shown in the figure below. Refer to the graph to answer the following question. Which sample of DNA might represent a zygote?

I

Refer to the drawings in the figure below of a single pair of homologous chromosomes as they might appear during various stages of either mitosis or meiosis, and answer the following question. Which diagram represents anaphase I of meiosis?

I

Which of the life cycles is typical for animals?

I only (very left)

DNA was isolated from three different cell types of the same organism, the relative DNA content for each type was determined, and the results were plotted on the graph shown in the figure below. Refer to the graph to answer the following question. Which sample of DNA might represent an animal cell in the G2 phase of the cell cycle prior to meiosis?

II

Which of the following statements is correct in comparing sexual and asexual reproduction?

In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring.

If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents?

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

Which of the following statements is correct regarding the human X chromosomes?

It is present in every somatic cell of males and females.

Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms. Which of the following statements best represents the connection between reproduction and evolution?

Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.

How does natural selection apply to sexual reproduction as opposed to asexual reproduction?

Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction.

Which of the following statements describes a major difference between mitosis and meiosis I in a diploid organism?

Sister chromatids separate in mitosis, while homologous pairs of chromosomes

Which of the following statements describes the chromosomal makeup of each daughter cell after telophase of meiosis I?

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

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I?

The cells have half the number of chromosomes and one-fourth the amount of DNA

Imagine that there are 25 different species of protists living in a tide pool. Some of these species reproduce both sexually and asexually, and some of them can reproduce only asexually. The pool gradually becomes infested with disease-causing viruses and bacteria. Which species are more likely to thrive in the changing environment?

The sexually reproducing species is likely to thrive.

The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. In addition to mutations, how might genetic diversity be generated in this species?

crossing over and random fertilization

During which of the following processes do sister chromatids separate from each other?

during both mitosis and meiosis II

Which of the following processes occurs in a plant's sexual life cycle?

gametophytes produce gametes by mitosis

Asexual reproduction occurs during which of the following processes?

mitosis

Independent assortment of chromosomes is a result of which of the following processes?

the random way each pair of homologous chromosomes lines up at the metaphase

Somatic cells of roundworms have four individual chromosomes per cell. How many chromosomes would you expect to find in an ovum from a roundworm?

two

Which of the following statements defines a genome?

the complete set of an organism's genes and other DNA sequences

Which of the following processes occurs when homologous chromosomes cross over in meiosis I?

corresponding segments of non-sister chromatids are exchanged

Crossing over of chromosomes normally takes place during which of the following processes?

meiosis I

Which processes lead to most genetic variation in sexually reproducing organisms?

1. independent assortment of chromosomes in meiosis 2. crossing over 3. random fertilization

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Normal human gametes carry _____ chromosomes

23

Quaking aspen trees 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

A triploid cell contains three sets of homologous chromosomes. If a cell of a diploid species that normally has 42 chromosomes per cell is triploid, this cell would be expected to have which of the following sets of chromosomes?

63 chromosomes in 3 sets of 21

Which of the following statements describes an example of alternation of generations?

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

Which of these cells is (are) haploid?

C and D

Which of the following processes might produce a human zygote with 45 chromosomes?

An error in either egg or sperm meiotic anaphase

Which of these gametes contains one or more recombinant chromosomes?

B and C

Which of the following processes occur during meiosis but not mitosis?

Diploid cells form haploid cells.

Which of the following statements describes one characteristic of each chromosome in a cell during the entire process of meiosis I?

Each chromosome consists of two sister chromatids joined by a centromere

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

Each diploid cell gas eight homologous pairs of chromosomes

In a life cycle such as that shown in part II of the figure above, if the zygote's chromosome number is ten, which of the following statements will be true?

The sporophyte's chromosome number per cell is ten and the gametophyte's is five.

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 Centromeres of sister chromatids disjoin and chromatids separate.

VII

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes based on the independent assortment of chromosomes during meiosis?

about 8 million

During which of the following phases of meiosis do centromeres split and sister chromatids migrate to opposite poles of the cell?

anaphase

During which of the following phases of meiosis do homologous chromosomes separate?

anaphase I

Many organisms spend most of their life cycle in the diploid state. If meiosis produces haploid cells, how is the diploid number restored for these types of organisms?

by fertilization

During which of the following processes does independent assortment of chromosomes occur?

in meiosis I only

A particular organism has 46 chromosomes in its karyotype. Which of the following statements is correct regarding this organism?

it produces gametes with 23 chromosomes

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?

length, centromere position, staining pattern, and genes controlling the same inherited characters

Human gametes are produced by _______ .

meiosis

Refer to the information and figure below to answer the following question.A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in the figure. A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene. As cells in her ovaries undergo meiosis, which of the following combinations of genes and chromosomes will her eggs have?

one chromosome 12 with one blue gene and one chromosome 19 with one long gene

When chiasmata can first be seen in cells using a microscope, which of the following processes has most likely occurred?

prophase I

Which of the following processes facilitates the fastest way for organisms to adapt to a changing environment?

sexual reproduction

Which of the following processes occurs in meiosis but not in mitosis?

synapsis occurs