BI107 - Ch. 13

The statement(s) is true for meiosis I only

- Homologous chromosomes synapse and crossing over occurs - Independent assortment of chromosomes occurs - The events during this process cause the majority of genetic recombinations

The word homologous literally means same location. How does this relate to homologous chromosomes?

- Physical appearance of the chromosomes are same - The chromosomes have the same genes in the same location.

During first meiotic division (meiosis I),

- homologous chromosomes separate - the chromosomes number becomes haploid - crossing over between nonsister chromatids of homologous chromosomes occurs - paternal and maternal chromosomes assort randomly

If the liver cells of an animal have 24 chromosomes, the sperm cells would have how many chromosomes?

12

Mitosis and cytokinesis result in the formation of ______; meiosis and cytokinesis result in the formation of ________.

2 diploid cells; 4 haploid cells

At the end of telophase I and cytokinesis there are

2 haploid cells

In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing _____ different gametes.

2^23

A human somatic cell contains _____ chromosomes

46

The order that most logically illustrates a sequence of meiosis is which of the following? 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 homologs; no detachment of the centromere 5. synapsis; chromosomes moving to the middle of the cell in pairs

5-2-4-3-1 5. synapsis; chromosomes moving to the middle of the cell in pairs -> 2. alignment of tetrads at the metaphase plate -> 4. separation of the homologs; no detachment of the centromere -> 3. separation of sister chromatids -> 1. formation of four new nuclei, each with half the chromosomes present in the parental nucleus

Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?

A female somatic cell

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

A gamete from this species has 8 chromosomes.

What is a karyotype?

A method of organizing the homologous chromosomes of a cell in relation to their number, size, and type

You are genetically unique. This is a result of A. sexual reproduction. B. genetic recombination. C. mutation.

All of the above

Which does not produce variation in individuals of a species

Asexual reproduction

Which of the following is FALSE in comparing prophase I of meiosis and prophase of mitosis? A. The chromosomes condense in both. B. Tetrads form in both. C. The nuclear envelope disassembles in both. D. A spindle forms in both. E. Each chromosome has two chromatids in both

B. Tetrads form in both

DNA replication occurs

Before a cell divides

The statement is true for mitosis and meiosis 11

Centromeres uncouple and chromatids are separated from each other

Regions where nonsister chromatids cross are called

Chiasmata

Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?

Crossing over

A karyotype would be least likely to show which of the following? A. an extra chromosome B. part of a chromosome duplicated C. a missing chromosome D. part of a chromosome turned around E. translocation (a part of a chromosome breaks and attach to another chromosome)

D. Part of a chromosome turned around

Cytokinesis is the

Division of cell's cytoplasm

When does a synapsis occur?

During prophase I of meiosis

True or False: The production of identical daughter cells is a functions of meiosis in plants

False

The restoration of diploid chromosome number after having meiosis occurs through

Fertilization

In animals, somatic cells result from mitosis and_____result from meiosis

Gametes

The X and the Y chromosomes are called sex chromosomes because

Genes located on the chromosomes play a role in determining the sex of the individual

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

Haploid, and the chromosomes are composed of two chromatids

During anaphase I

Homologues separate and migrate towards opposite poles

Synapsis of homologous pairs occurs; crossing over may occur

I. Prophase I

Tetrads of chromosomes are aligned at the center of the cell; independent assortment soon follows

II. Metaphase I

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

Metaphase

A DNA molecule is a polymer made of subunits called

Nucleotides

Crossing over occurs during

Prophase I

Synapsis occurs during

Prophase I

The phases of meiosis that cause the most variation in the four resulting daughter cells are

Prophase I and anaphase I

Centrioles separate during

Prophase I and prophase II

During anaphase II

Sister chromatids separate and migrate towards opposite poles.

The diploid stage of a plant that exhibits an alternation of generation is the

Sporophyte

Which of the following events occurs during prophase I of meiosis?

Synapsis and crossing over

Crossing over is

The exchange of homologous portions of nonsister chromatids

The statement(s) is true for mitosis and meiosis I

The process(es) is (are) preceded by a copying (replication) of the DNA.

In a given organism, how do cells at the completion of meiosis compare with cells that are just about to begin (G2 of interphase) meiosis?

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

The statement(s) is true for mitosis only

This occurs when a cell divides to form two cells that are genetically identical

True or False: Synapsis occurs during meiosis but not during mitosis

True

Centromeres of sister chromatids detach and chromatids separate

VIII. Anaphase II

Which of the following is a normal human female?

XX

In animals, meiosis results in gametes, and fertilization results in

Zygotes