Meiosis HW

Sexual reproduction results in an increase in genetic diversity because: -during fertilization, the gametes that fuse are random so that a large number of chromosomal combinations are possible in the new organism. -during metaphase I, the bivalents line up in a random orientation so that gametes inherit a random set of maternally and paternally derived chromosomes. -All of these choices are correct. -during prophase I, genes that are paternally and maternally derived recombine so that the gametes have chromosomes that are different from the parents' chromosomes.

All of these choices are correct.

Would genetic recombination result if crossing over occurred between sister chromatids? -No, because sister chromatids are genetically identical or nearly identical. -Yes, because genetic diversity would decrease due to the loss of gene combinations. -Yes, because any rearrangement of DNA produces new combinations of alleles. -No, because many genes are present along the entire length of a chromosome.

No, because sister chromatids are genetically identical or nearly identical.

How must spindle microtubules attach to chromosomes during prometaphase of meiosis I? -Microtubules attach at the centrosomes. -Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids. -Spindle microtubules from one pole attach to one kinetochore, and spindle microtubules from the other pole attach to the other kinetochore in a pair of sister chromatids, just like in mitosis. -Microtubules attach using their minus (slow assembling) ends. -Microtubules attach to the chiasma.

Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids.

Why are the X and Y chromosomes not considered homologous? They do not carry the same set of genes. They do not pair during metaphase in meiosis. They only occur in polar bodies. They are named after two different letters of the alphabet.

They do not carry the same set of genes.

Which of the statements is true about gametes? -They are found in animals but not plants. -They fuse to form a new organism during fertilization. -They are formed by mitotic cell division. -They are genetically identical to other gametes formed during meiosis. -They have the same number of chromosomes as a somatic cell of the same individual.

They fuse to form a new organism during fertilization.

The alignment of chromosomes at metaphase of meiosis II is most similar to the alignment of chromosomes during metaphase of mitosis. false true

True

When do sister chromatids separate in meiosis? metaphase II telophase I anaphase I anaphase II

anaphase II

How does meiosis generate genetic diversity? -synapsis -both crossing over at prophase I and random alignment of homologs at metaphase I -random alignment of homologs at metaphase I only -crossing over in prophase I only

both crossing over at prophase I and random alignment of homologs at metaphase I

A zygote is: diploid. haploid. monoploid. polyploid.

diploid

Crossing over occurs during which step in meiosis? anaphase I prophase II prophase I metaphase I

prophase I