bio chapter 12 – Flashcards
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Which statement is correct concerning the relationship between chromosomes and chromatids?
A replicated chromosome contains two sister chromatids.
A replicated chromosome contains a single chromatid.
An unreplicated chromosome contains two sister chromatids.
An unreplicated chromosome contains a single chromatid.
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A replicated chromosome contains two sister chromatids.
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Which event makes meiosis a reduction division and why?
separation of sister chromatids in meiosis I because it reduces the number of chromatids per chromosome
separation of homologs in meiosis II because it produces 2 haploid (n) daughter cells from a single diploid (2n) parent cell
separation of sister chromatids in meiosis II because it reduces the number of chromatids per chromosome
separation of homologs in meiosis I because it produces 2 haploid (n) daughter cells from a single diploid (2n) parent cell
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separation of homologs in meiosis I because it produces 2 haploid (n) daughter cells from a single diploid (2n) parent cell
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Which form of reproduction results in the highest degree of genetic variation among offspring?
outcrossing
asexual reproduction
bacterial fission
selfing (self-fertilization)
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outcrossing
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Which statement is FALSE concerning gametes produced by meiosis?
Gametes contain nonrandom combinations of maternal and paternal chromosomes.
Gametes contain half as many chromosomes as the parent cell.
Gametes contain a random assortment of maternal and paternal alleles.
Gametes contain a random assortment of maternal and paternal chromosomes.
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Gametes contain nonrandom combinations of maternal and paternal chromosomes.
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art A
What would be the outcome of meiosis I if none of the homologous chromosomes separate at anaphase?
Both daughter cells would be n.
One daughter cell would be 2n; the other would have no chromosomes.
One daughter cell would be 4n; the other would have no chromosomes.
Both daughter cells would be 2n.
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One daughter cell would be 2n; the other would have no chromosomes.
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For species that alternate between sexual and asexual reproduction, which statement is most accurate?
For either type of reproduction to occur, environmental conditions must be stable.
Asexual reproduction is common when environmental conditions are changing rapidly.
Sexual reproduction is common when environmental conditions are changing rapidly.
Sexual reproduction is common when environmental conditions are stable.
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Sexual reproduction is common when environmental conditions are changing rapidly.
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During which phase of meiosis would the cell first become haploid because homologous chromosomes
separate?
telophase II
metaphase I
anaphase II
anaphase I
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anaphase I
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Homologous chromosomes are separated during _____.
anaphase I
mitosis
prophase I
anaphase II
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anaphase I
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What is a major difference between mitosis and meiosis I?
Only meiosis I results in daughter cells that contain identical genetic information.
DNA replication takes place prior to mitosis, but not before meiosis I.
Sister chromatids separate in mitosis, and homologues separate in meiosis I.
Sister chromatids separate in mitosis, and homologues separate in meiosis II.
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Sister chromatids separate in mitosis, and homologues separate in meiosis I.
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Crossover, the exchange of segments of homologous chromosomes, takes place during which of the following processes?
metaphase I
prophase II
synapsis
anaphase I
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synapsis
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The egg of a fruit fly has 4 chromosomes. How many chromosomes are in a somatic cell of a fruit fly?
8
2
16
4
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8
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A non-sex chromosome is _____.
a Y chromosome
an X chromosome
a karyotype
an autosome
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autosome
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If meiosis produces haploid cells, how is the diploid number restored for those organisms that spend most of their life cycle in the diploid state?
fertilization
synapsis
reverse transcription
DNA replication
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fertilization
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Nondisjunction in meiosis produces _____.
diploids
haploids
zygotes
aneuploids
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aneuploids
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An advantage of sexual reproduction is hypothesized to be _____.
reducing genetic diversity
the production of clones
increasing the chance that a parent will transmit all their genes to a an offspring
avoiding the transmission of harmful alleles to offspring
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avoiding the transmission of harmful alleles to offspring
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meiosis
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nuclear division that leads to halving of chromosome
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gene
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section of DNA that influences some hereditary trait in an individual
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allele
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different version of the same gene
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karyotype
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number and types of chromosomes present
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centromere
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connects the sister chromatids together
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chromosome
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structure made up of DNA and proteins; carries gene
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sex chromosome
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chromosome associated with an individual's sex
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autosome
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a non-sex chromosome
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unreplicated chromosome
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a chromosome that consists of a single copy
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replicated chromosome
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a chromosome that has been copied; consists of 2 linear structures joined at the centromere
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sister chromatids
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the chromosome copies in a replicated chromosome
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homologous chromosome
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in a diploid organism, chromosomes that are similar in size, shape, and gene content
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non-sister chromarids
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chromatids belonging to homologous chromosome
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tetrad
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different homologous replicated chromosomes that are joined together
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haploid number
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the number of different types of chromosomes in cell, n
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diploid number
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the number of chromosomes present in a diploid cell, 2n
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ploidy
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the number of each type of chromosome present
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haploid
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having one of each type of chromosome
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diploid
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having 2 of each type of chromosome
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polyploid
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having more than 2 of each type of chromosome
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gametogenesis
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process of forming egg cell or sperm cells from haploid daughter cells
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zygote
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cell that results from fertilization is diploid
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life cycle
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the sequence of events that occurs over the life span of an individual
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prophase 1
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chromosomes condense, spindle appartus forms, nuclear envelope disappear, homologous chromosomes come together, non sister chromatids separate at certain points and stay join at certain points, crossing over occurs
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synapsis
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homologous chromosome come together
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chiasma
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x-shaped structure
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crossing over
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paternal and maternal chromatids break and rejoin at each chiasma
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metaphase 1
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kinetochore microtubules move the homologous chromosomes to the middle of the cell, metaphase plate
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anaphase 1
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homologous chromosome separate and begin to move to the opposite side of the cell
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telophase 1
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homologs finish moving to the poles
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cyokinesis
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2 haploid daughter cell form
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meiosis II: phophase II, metaphase II, anaphase II, telophase II, cytokinesis
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same as mitosis
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synaptonemal complex
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network of protein that holds the non-sister chromatids together
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asexual reproduction
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producing offspring without gametes (egg+ sperm)
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sexual reproduction
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producing offspring with gametes
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genetic recombination
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any change in combination of alleles on a given chromosome
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self-fertilization
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2 gametes produced by the same person to form a diploid offspring
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outcrossing
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gametes from different individuals to form offspring
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nondisjunction
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failure of separation of homologs
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aneuploid
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too many or too little chromosomes in a cell
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monosomy
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having only one copy of a particular type of chromosome
