chapter 9- assignment
select all of the following which are true statements regarding meiosis II.
- following meiosis 1, the cells are diploid - DNA is replicated prior to meiosis 1, but not before meiosis 2 - meiosis 2 produces four identical diploid daughter cells
consider a cell that has three pairs of chromosomes. what fraction of the gametes produced from this cell will contain only maternal chromosomes?
1/8
how many bivalents are formed in a cell with 20 chromosomes at the beginning of meisois I?
10
consider a cell that has four pairs of chromosomes. what is the number of possible chromosomes orientations in that cell?
16
in humans, there are 22 pairs of chromosomes called ____, which are the same in both males and females, and one pair of chromosomes called ____, which contain genes that determine gender.
autosomes; sex chromosomes
which of the following events occur during prophase I?
breakdown of the nuclear envelope, condensation of chromosomes, and movement of centrosomes
which of the following statements about crossing-over is true?
crossing-over allows for the reassortment of linked genes
true or false. germ-line cells are haploid but gametes are diploid.
false
what is the name of the process in which haploid gametes fuse to form diploid offspring?
fertilization
following telophase II and cytokinesis, meiosis II results in the formation of four ____ (haploid/diploid) daughter cells.
haploid
sister chromatids divide in _____.
meiosis 2
the nuclear division used in sexual reproduction is called ____ and it serves two major functions: (1) reducing the chromosome number and (2) shuffling the chromosomes and genes to produce genetically different gametes, called ____ (males) and ____ (females).
meiosis; sperm; eggs
random orientation of homologous chromosomes occurs in ____ of meiosis.
metaphase 1
classify the following characteristics depending on if they occur in metaphase I or metaphase II during meiosis. 1. tetrads align at the spindle equator. 2. dyads align at the spindle equator. 3. chromosomes are shuffled into new combinations. 4. homologous chromosomes face opposite spindle poles. 5. sister chromatids face opposite spindle poles.
metaphase 1- 1, 3, 4 metaphase 2- 2, 5
classify the following characteristics depending on if they describe events occurring in mitosis, meiosis I, or meiosis II. 1. results in four genetically diverse haploid nuclei. 2. results in two genetically identical diploid nuclei. 3. crossing-over occurs during synapsis. 4. a diploid number of dyads align at the spindle equator during metaphase. 5. homologous chromosomes pair up during prophase. 6. results in two genetically diverse haploid nuclei. 7. a haploid number of dyads align at the spindle equator during metaphase. 8. tetrads align at the spindle equator during metaphase.
mitosis- 2, 4 meiosis 1- 6, 3, 5, 8 meiosis 2- 1, 7
a cross-over in meiosis is an exchange of genetic material between____.
nonsister chromatids of homologous chromosomes
another level of genetic variation is added by ____, since we can't predict which sperm will fertilize a given egg.
random fertilization
which of the following events occur during anaphase I?
separation of homologous chromosomes
during metaphase II, the ____ aligns the sister chromatids along the metaphase plate.
spindle
meiosis II produces haploid cells because ____.
the chromosomes do not replicate between meiosis 1 and meiosis 2
true or false. at the end of meiosis I, there are two haploid cells, each with two sister chromatids per chromosome.
true
true or false. during metaphase II, sister chromatids attach to the spindle by kinetochore microtubules; each is attached to an opposite pole.
true
true or false. independent assortment occurs during prophase 1.
true
a tetrad is made up of ____.
two homologous chromosomes, each consisting of two chromatids
the sex chromosomes in females are two ____ chromosomes.
x
the sex chromosomes in males are x and ____.
y
