Meiosis

Meiosis starts with _____ cells and produces _____ gametes.

diploid ... haploid

Meiosis II typically produces _____ cells, each of which is _____.

four ... haploid

Without crossing over

genetic recombination could not occur.

At the conclusion of meiosis I, the daughter cells are _____.

haploid and the sister chromatids are joined

Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are

homologous chromosomes

The _____ separate in meiosis I; the _____ separate in meiosis II.

homologous chromosomes ... sister chromatids

In anaphase I, _____.

homologous chromosomes move toward opposite poles

During prophase I of meiosis,

homologous chromosomes stick together in pairs.

Looking through a light microscope at a cell undergoing meiosis, you see that the chromosomes have joined into XX-shaped tetrads. These tetrads are lined up along a plane that runs through the center of the cell. This cell is in _____.

meiosis I

Nondisjunction occurs when

members of a chromosome pair fail to separate.

Crossing over is important because it _____

allows the exchange of genes between homologous chromosomes

Homologous chromosomes migrate to opposite poles during _____.

anaphase I

During _____ sister chromatids separate.

anaphase II

The diploid phase of the human life cycle begins with _____.

fertilization

The function of meiosis is to make _____.

four cells with a haploid number of chromosomes

Meiosis starts with a single diploid cell and produces

four haploid cells.

Fertilization joins _____ to produce a _____.

haploid gametes ... diploid zygote

A cell preparing to undergo meiosis duplicates its chromosomes during

interphase

Both mitosis and meiosis are preceded by

interphase

When we say that an organism is haploid, we mean that _____.

its cells each have one set of chromosomes

If it weren't for _____, chromosome number would double with every generation of sexual reproduction.

meiosis

During _____ chromosomes align single file along the equator of a haploid cell.

metaphase II

Looking through a light microscope at a cell undergoing division, you see that the condensed chromosomes have lined up along the midline of the cell. The homologous pairs are NOT joined in tetrads. Each chromosome takes its own place in line, independent of its homolog. You are witnessing _____.

metaphase of mitosis

After fertilization, the resulting zygote begins to divide by _____.

mitosis

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.

nondisjunction

Duplication of the chromosomes to produce sister chromatids _____.

occurs in both mitosis and meiosis

During meiosis, segments of non-sister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

prophase I

During which stage of meiosis do synapsis and crossing over occur?

prophase I

Synapsis occurs during _____.

prophase I

The correct order of events during meiosis is

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

During _____ a spindle forms in a haploid cell.

prophase II

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

random fertilization, independent orientation of chromosomes in meiosis, and crossing over.

The exchange of parts between non-homologous chromosomes is called _____.

reciprocal translocation

The function(s) of meiosis is/are _____.

reproduction (production of gametes)

In meiosis II, _____.

sister chromatids are separated

During anaphase II, _____.

sister chromatids separate and migrate toward opposite poles

Mitosis occurs in _____; meiosis occurs in _____.

somatic or body cells ... germ cells in the testes or ovaries

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

telophase I

At the end of _____ and cytokinesis there are four haploid cells.

telophase II

Crossing over is _____.

the exchange of homologous portions of non-sister chromatids

Meiosis is typically accomplished in _____.

three steps. All of the chromosomes are duplicated in a diploid cell, and then there are two cell divisions to produce a total of four haploid gametes.

Meiosis I produces _____ cells, each of which is _____.

two ... haploid

Mitosis and cytokinesis result in the formation of _____; meiosis and cytokinesis result in the formation of _____.

two diploid cells ... four haploid cells

At the end of telophase I of meiosis, as cytokinesis occurs, there are _________

two haploid cells

In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes.

5

___________ reproduction, in contrast, generates genetically unique offspring. To accomplish this, an organism must produce ______________ -- sperm and egg -- through the process of ___________

Asexual; gametes; meiosis

____________ reproduction is a means of creating new individuals solely by __________, the form of cell division that creates genetically identical daughter cells.

Asexual; mitosis

Which of the following statements regarding the differences between mitosis and meiosis is false?

Crossing over is a phenomenon that creates genetic diversity during mitosis.

Which of the following statements regarding Down syndrome is false?

Down syndrome is least likely to be seen in the infants of mothers over 40.

Which of the following statements regarding genetic diversity is false?

Genetic diversity is enhanced by mitosis.

Crossing over occurs during _____.

Prophase I

The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two processes differ in the arrangement and behavior of their chromosomes. How?

The pairing up of homologous chromosomes and crossing over only occur during meiosis.

If the diploid number of chromosomes in a certain animal is 6 (2n = 6), there are three sets of two homologous chromosomes each, or three pairs. How do these three pairs align and separate in meiosis?

They align and assort independently to form any of eight different combinations.

Baker's yeast is an organism with 32 chromosomes that can perform asexual or sexual reproduction and exist as both a diploid and haploid cell. After meiosis, how many chromosomes will be present in each cell?

16

Which of the following statements regarding mitosis and meiosis is false?

Mitosis produces daughter cells with half the number of chromosomes as the parent cell; Meiosis provides for asexual reproduction.

Cancer is not usually inherited because

the chromosomal changes in cancer are usually confined to somatic cells.

In many organisms, including humans, chromosomes are found in homologous pairs. Homologous chromosomes _____.

are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes