Biology Chapter 10

If a cell contains 12 chromosomes at the end of meiosis I, how many chromosomes will the daughter cells contain at the end of meiosis II?

12

If a sperm cell contains 8 chromosomes, it comes from an animal that has ______ chromosomes.

16

If the diploid number of chromosomes for an organism is 52, what will the haploid number of chromosomes be?

26

Sources of genetic variation in a sexually reproducing population include(s) which of the following?

All of the choices are sources of genetic variation. Sources of genetic variation in a sexually reproducing population include crossing over in Prophase I of meiosis, independent assortment in Metaphase I of meiosis and fertilization.

Which of the following is/are true about sexual reproduction?

All of the choices are true about sexual reproduction.

During which stage of meiosis does the homologue separation occur?

Anaphase I

Which of the following is NOT a difference between anaphase I and anaphase II?

Anaphase I occurs in a haploid cell while anaphase II occurs in a diploid cell. It is not true that anaphase I occurs in a haploid cell while anaphase II occurs in a diploid cell.

Another name for a tetrad is a/an

Bivalent

Which of the following events occurs during prophase I but does not occur during prophase of mitosis?

Crossing over

The genus Lacerta is composed of a species of lizards that are female and do not mate. They undergo "endomitosis" where one extra chromosome replication results in a tetraploid cell before meiosis begins. Normal female 2n offspring result without fertilization. What change(s) from regular meiosis (in preparation for fertilization) would be required to produce this system?

Cytokinesis does not follow "endomitosis" that results in a tetraploid cell.

Which of the following statements is correct about the chromosomal position during mitosis and meiosis?

During metaphase of mitosis the duplicated chromosomes are at the metaphase plate while during metaphase I of meiosis the bivalents are present at the metaphase plate.

Which statement is NOT true about homologues in meiosis I?

Each homologue's centromere splits to form two chromosomes.

A change in the chromosome number resulting from nondisjunction is called euploidy.

False A change in the chromosome number resulting from nondisjunction is called aneuploidy.

Primary nondisjunction occurs during meiosis II when the sister chromatids fail to separate and both daughter chromosomes go in the same gamete.

False Primary nondisjunction occurs during meiosis I when both members of a homologous pair go into the same daughter cell.

The correct number of chromosomes in a species is known as aneuploidy.

False The correct number of chromosomes in a species is known as euploidy.

A lattice holds the members of a bivalent together in such a way that the RNA of the non-sister chromatids is aligned.

False. A lattice holds the members of a bivalent together in such a way that the DNA, not RNA, of the non-sister chromatids is aligned.

Only one of the four daughter cells becomes a functional gamete in spermatogenesis.

False. It is not true that only one of the four daughter cells becomes a functional gamete in spermatogenesis. All are functional.

Oogenesis always involves an equal division of cell contents in the formation of an egg and polar bodies.

False. Oogenesis does not involve an equal division of cell contents. The two cells formed are the secondary oocyte, which receives almost all the cytoplasm and a polar body, which is much smaller.

Which is NOT true about daughter cells of mitosis or meiosis?

In meiosis, the daughter cells are genetically identical.

Interkinesis is different from interphase in which way?

Interphase involves DNA replication and interkinesis does not.

What is the importance of crossing-over?

It increases the likelihood that daughter cells contain different genetic material.

Where in the human male does spermatogenesis occur?

Testes

There is a species of desert lizard where only females are known to exist-there are no males known. It is nevertheless necessary for two females to court and for one to assume the posture of a male to stimulate the female to produce eggs. No fertilization can occur, and the eggs develop into female lizards. What is the probable evolutionary mechanism for this occurring?

The desert is relatively uniform and there is little advantage to maintaining variation, but the animal has not been able to completely evolve away from its heritage of sexual reproduction.

Why do polar bodies form?

They allow a reduction in chromosomes while preserving most of the cytoplasm for one egg.

Aneuploidy is a change in the number of chromosomes resulting from nondisjunction during meiosis.

True

Extra copies of sex chromosomes are more easily tolerated in humans than extra copies of autosomes.

True

It is estimated that an average of two or three cross-overs occur per human chromosome.

True

Jacobs Syndrome, XYY, results from nondisjunction during spermatogenesis.

True

Monosomy occurs when an individual has only one of a particular type of chromosome.

True

Sex chromosome aneuploids are better tolerated and have a better chance of producing survivors.

True

The polar body is

a nonfunctional cell rudiment formed at the same time as an egg cell.

To what does the term chiasma refer?

a structure that holds together homologues during crossing-over

At which stage of meiosis is each chromosome composed of a single chromatid?

anaphase II

During which phase of mitosis and meiosis will the state of the chromosome be the same?

anaphase II and Anaphase. It is only during Metaphase II and Metaphase that the state of the chromosomes is the same.

Identify which event will occur during Prophase I of meiosis but does not occur during prophase of mitosis.

bivalents will form

Homologous chromosomes are similar in all of these characteristics EXCEPT

carry the same alleles for all traits. Homologous chromosomes are similar in size, carry genes for the same traits, and are similar in shape and centromere location. They may carry different alleles for a trait.

All of the following are true concerning Down Syndrome EXCEPT

chances of a woman having a child with Down Syndrome decreases with her age.

The overall function of meiosis includes all of the following EXCEPT

growth of the overall individual. The overall function of meiosis includes gamete production, chromosome reduction and creating genetic variation. The function does not include growth of the individual.

In human females, when is meiosis II completed?

immediately after the sperm penetration of the secondary oocyte

During _______________ the homologous chromosome pairs separate in a random fashion leading to genetic diversity among the offspring.

independent assortment

During which stage of meiosis are the bivalents arranged along the equator?

metaphase I

Before the time of Gregor Mendel and genetics, sexual reproduction was thought to produce a blending or equal mixing of the parents' traits. Today we know that

offspring inherit essentially 50% of their genes from each parent, but two sibling offspring may share with each other from zero to 23 chromosomes in common from each parent, and further variation may occur due to crossing-over.

Meiosis occurs during all of the following EXCEPT

pangenesis. Meiosis occurs during gametogenesis, oogenesis, and spermatogenesis.

During which stage of meiosis does crossing-over occur?

prophase I of meiosis I

Species X reproduces asexually by fission and species Y reproduces sexually. Consider that all other relevant characteristics are similar between these species. When the environment changes, then

species Y should have a better chance of surviving than species X. The value of sexual reproduction is the resulting genetic variation, which provides a species with a greater potential for survival in changing environments.

It could be said that males are able to provide gametes with more genetic diversity than females for reproduction. One main reason would be

spermatogenesis in males results in four functional sperm while oogenesis in females results in only one egg and three structures that contain genetic information that is lost when they disintegrate.

Which does NOT occur in meiosis?

two daughter cells at completion. Meiosis produces four haploid daughter cells, includes two nuclear division and the formation of bivalents.

The cell formed through fertilization of an egg by a sperm is called a/an

zygote