Meiosis and the Sexual Life Cycles Study Module

Genetic diversity requires...

- sexual reproduction - independent assortment - crossing over between nonvoter chromatids of homologous chromosomes - random fertilization

Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8

16

The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?

44

What is the result when a diploid cell undergoes meiosis?

Four haploid cells

Which of the following occurs in meiosis, but not mitosis? a) homologous chromosomes separate b) sister chromatids undergo disjunction c) the nuclear envelope disappears d) the cells fried have the same combination of genes as found in the initial cell e) a spindle apparatus forms

a) homologous chromosomes separate

Which life cycle stage is found in plants but not animals? a) multicellular haploid b) unicellular diploid c) gamete d) zygote e) multicellular diploid

a) multicellular haploid

Which of the following statements about homologous chromosomes is *correct* a) they have genes for the same traits at the same loci b) they are found in animal cells but not in plant cells c) they are found in the cells of human females but not in human males d) they pair up in prophase II e) they are found in haploid cells

a) they have genes for the same traits at the same loci

Somatic cells in animals differ from gametes in that somatic cells....

are all of the cells of the body except for the gametes and their precursors

Sister chromatids differ from non sister chromatids in that sister chromatids...

are the product of the S phase of the cell cycle and are two copies of one chromosome

A clone is the product of...

asexual reproduction and mitosis

Regarding the role of cohesion protein in maintaining cohesion between sister chromatids, which of the following statements is false? a) during meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs and cleavage of cohesions between sister chromatid arms at anaphase I allows homologs to separate b) cleavage of cohesions between sister chromatid arms at anaphase I allows homologs to separate c) during meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms. d) during meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs e) during meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs and during meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms

c) during meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms.

somatic cells in humans differs from gametes in that human somatic cells.....

contain two sets of each of the 23 chromosome types

Which of the following is a function of mitosis in humans? a) production of eggs b) decreasing the number of chromosomes c) production of sperm d) increasing genetic variability e) multiplication of body cells

e) multiplication of body cells

Darwin realized the importance of heritable variation to evolution...

even though he never read any of Gregor Mendel's work

A life cycle in which the only multicellular form is haploid is most typical of ___________.

fungi

Allelic variation is an important source of ____________ in a population

genetic diversity

A pair of genetic structures carrying genes that control the same inherited characters are called....

homologous chromosomes

Characteristic of the bdelloid rotifer is that it....

is an example of an animal that has not reproduced sexually in 40 million years

The major contribution of sex to evolution is that

it provides a method to increase genetic variation

Unless the chromosomes were showed to show band patterns, a karyotype would be least likely to show...

part of a chromosome turned around

How many genes are present in the human genome?

tens of thousands

What is a locus?

the precise location of a gene on a chromosome

regardless of whether an organism is an animal, a plant, a fungus, or an algal cell, all zygotes are ___________ are are formed during the __________ of two gametes

• Diploid • Fertilization • Haploid

The life cycle called __________ in plants has two multicellular stages: the ___________ and the ___________

• alternation of generations • haploid gametophyte • diploid sporophyte

___________ are a group of genetically individuals produced by a process called _____________.

• clones • asexual reproduction

The process called ______________ reduces the chromosome number by _____________--

• meiosis • two consecutive cell divisions

In meiosis, ___________ of ___________ cross over and form ___________.

• nonsister chromatids • homologous pairs • chiasmata

The zipper-like complex that forms in meiosis occurs during __________ and is called the ____________

• prophase I • synaptonemal complex

somatic cells in human contain ____________ set(s) of chromosomes and are therefore termed ___________

• two • diploid

At the end of mitosis, ________________ daughter cells that are genetically ___________ are formed, while at the end of meiosis, _________________ daughter cells that are genetically _____________ are formed.

• two • identical • four • distinct