Biology Ch 2

Asexual reproduction __________.

can produce offspring genetically identical to the one single parent.

Chromosomes become visible during _____.

prophase (The chromatin fibers become discrete chromosomes.)

Synapsis occurs during _____.

prophase I; the pairing of homologous chromosomes.

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

centromere is____.

the point of attachment between two duplicated chromosomes.

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

two ... haploid

During prophase a homologous pair of chromosomes consists of _____.

two chromosomes and four chromatids.

The first step of bacterial replication is _____.

DNA replication (The DNA must be copied in order to proceed).

Nucleoli are present during _____.

Interphase

Which of the following statements is correct?

Meiosis results in gametes that are used in reproduction. (egg & sperm)

Spindle fibers attach to kinetochores during _____.

Prometaphase (Attachment of spindle fibers to kinetochores is one of the events of prometaphase).

During _____ a spindle forms in a haploid cell.

Prophase II

Cytokinesis often, but not always, accompanies _____.

Telophase

Which of the following statements applies to sexually reproducing species but not asexually reproducing species?

Two kinds of cell division are required. (mitosis for growth and maintenance and meiosis for reproduction. Only one kind of cell division (mitosis) is required for asexual reproduction.)

Centromeres divide and sister chromatids become full-fledged chromosomes during _____.

Anaphase (sister chromatids separate and migrate to opposite poles).

Which of these gametes contains one or more recombinant chromosomes?

B and C; composed of material derived from both parents (Each of the chromosomes in gametes B and C are composed of material derived from both parents.)

Which of these cells is (are) haploid?

C and D Once meiosis I is completed, cells are haploid.

Most of an organism's DNA is carried by its __________.

Chromosomes (chromosomes carry most of its DNA, but some is found on small DNA molecules in mitochondria and chloroplasts).

Bacteria divide by

binary fission

1. Sexual reproduction requires the cellular process of __________ followed by __________.

- meiosis ... fertilization (Meiosis produces gametes, and a gamete from one individual unites with a gamete from another individual during fertilization).

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?

- the amount of DNA present - whether the DNA is housed in a nucleus or not - whether the DNA is linear or circular

If the hypothetical organism has 5 chromosomes in one of its gametes, then it must have ____ chromosomes in a body cell.

10 (Just before mitosis, the chromosomes in a body cell are duplicated, but the sister chromatids remain joined together. So, you will see 10 (duplicated) chromosomes in a typical body cell.)

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

16 (16 is half of 32).

Normal human gametes carry _____ chromosomes.

23. This is the number of chromosomes in a single set of human chromosomes.

Gametes are produced by _____.

meiosis. Meiosis produces haploid gametes from a diploid parental cell.

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

metaphase II

Homologous chromosomes migrate to opposite poles during _____.

anaphase I (sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles).

During _____ sister chromatids separate.

anaphase II

What name is given to this process?

asexual reproduction

Replication of chromosomal DNA occurs _________.

before a cell divides (This ensures that genetic material is appropriately distributed to the daughter cells)

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

four ... haploid

Mitosis goes on continuously in most parts of the body, whereas meiosis takes place only in the___.

gonads

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

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