Meiosis as a reducing cell division

•Diploid set for humans; 2n = 46

•Autosomes; homologous chromosomes, one from each
parent (humans = 22 sets of 2)

•Sex chromosomes (humans have 1 set of 2)

•Female-sex chromosomes are homologous (XX)

1.Male-sex chromosomes are non-homologous (XY)

Ploidy: Number of sets of chromosomes

•Haploid (n)-- one set chromosomes

•Diploid (2n)-- two sets chromosomes

•Most plant and animal adults are diploid (2n)

•Eggs and sperm are haploid (n)

• homologous chromosomes

Humans have 23 pairs of homologous chromosomes

-corresponding

chromosomes, one from each parent,

which contain the same genes

Problem 1: Number of chromosomes
A human cell has 46 total or 23 pairs of chromosomes.
Following mitosis, the daughter cells would each have a total
of ______ chromosomes. After meiosis I, the two daughter
cells would have _____chromosomes, and after
meiosis II ______ chromosomes.

A.

46, 46, 46

B.

46, 23, 23

C.

23, 23, 23

D.

46, 12, 12

Problem 2: Four different cells
The process of meiosis produces four cells with nonidentical
chromosomes. This diversification occurs during:
A.

telophase

I B.

prophase I

C.

metaphase II

D.

prophase II

Problem 3: Mitosis vs. Meiosis
Which of the following is unique to mitosis and not a part
of meiosis?
A.

homologous chromosomes pair forming bivalents

B.

homologous chromosomes cross over

C.

chromatids are separated during anaphase

D.

homologous chromosomes behave independently

Problem 4: Haploid cells
The stage of meiosis where cells become haploid.
A.

prophase I

B.

prophase II

C.

anaphase I

D.

anaphase II

Problem 5: Events of meiosis
One of the earliest events that distinguishes meiosis occurs in
prophase I and involves:
A.

Condensation of chromosomes

B.

Loss of the nuclear membrane

C.

Movement of chromosomes towards the metaphase plate

D.

Pairing of homologous chromosomes

Problem 6: Ocean coral

Coral in the ocean grows by budding, where the new organism
grows out of the old one by mitosis. This form of replication
is an example of:

A.

meiosis to produce a zygote

B.

asexual reproduction

C.

sexual reproduction

D.

gamete formation

Problem 7: Asexual vs. sexual reproduction
Some organisms are capable of asexual or sexual
reproduction. Under favorable conditions,
reproduction proceeds asexually. When conditions
become more stressful reproduction switches to
a sexual mode. Why?
A.

Sexual reproduction is simple and more rapid

allowing larger numbers of offspring to be produced.

B.

Sexual reproduction requires two separate

individuals, who can mutually provide nutrient
support during stress.

C.

Asexual reproduction requires more energy.

D.

Sexual reproduction produces individuals with

new combinations of recombined chromosomes
increasing diversity.

Problem 8: Phases of meiosis
_________________ most closely resembles events
of mitosis except that the cells are ___________.
A.

interphase

, diploidB.meiosis II, diploid

C.interphase, haploidD.meiosis II, haploid