Questão 1
Questão
Choose the incorrect statement about the sexual cycle.
Responda
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Adult eukaryotic cells are diploid.
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Cells in the ovaries and testes are the only cells which undergo meiosis.
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Gametic cells are diploid.
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The ovum or sperm is haploid.
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When an adult gametic cell undergoes mitosis, it is still diploid.
Questão 2
Questão
Choose the correct statements.
Responda
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Two gametes which are haploid fuse to make a diploid zygote.
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Meiosis halves the number of of chromosomes going into gametes.
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Mitosis creates two haploid daughter cells.
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Meiosis creates four diploid daughter cells.
Questão 3
Questão
Meiosis I separates sister chromatids.
Questão 4
Questão
Choose the incorrect statement about Meiosis I.
Responda
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Crossing over occurs between homologous pairs during metaphase.
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Four sister chromatids form a tetrad in prophase.
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Crossing over occurs at a chiasmata, the joining of a locus on each chromatid.
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In anaphase I, sister chromatids remain attached when the spindles shorten.
Questão 5
Questão
Meiosis I produces two diploid cells.
Questão 6
Questão
Choose the statements about Meiosis II that are false.
Responda
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Two haploid cells with doubled chromosomes enter prophase II.
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Crossing over occurs between sister chromosomes during prophase II.
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In anaphase II, sister chromatids are pulled apart.
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At the end of telophase II, two haploid cells are present.
Questão 7
Questão
There are no chiasmata formed in mitosis.
Questão 8
Questão
If the sperm of a mouse has 3 picograms of DNA,
the amount of DNA in the nucleus of a somatic cell
about to divide by mitosis would be:
Questão 9
Questão
The structures that move to the spindle poles at
anaphase of meiosis I usually differ from those that
move to the poles at anaphase II with respect to:
Questão 10
Questão
In males, diploid [blank_start]primary[blank_end] spermatocytes undergo meiosis [blank_start]I[blank_end] to produce two [blank_start]haploid[blank_end] secondary spermatocytes. These undergo meiosis [blank_start]II[blank_end] to form haploid spermatids, or, sperm. Tens of [blank_start]millions[blank_end] of these can be produced per day.
In females, 500,000 [blank_start]diploid primary[blank_end] oocytes are present in a six month old fetus. These begin meiosis I but are suspended in [blank_start]prophase I[blank_end] until ovulation. After ovulation, meiosis I [blank_start]finished[blank_end] and produces two haploid cells, one becomes a [blank_start]secondary[blank_end] oocyte and the other becomes the first polar body. The first polar body is suspended in [blank_start]metaphase II[blank_end] until fertilisation, upon which it completes meiosis II and makes two [blank_start]haploid polar bodies[blank_end]. The secondary oocyte undergoes meiosis II to produce the fourth polar body, and the [blank_start]ovum[blank_end], which are both haploid. [blank_start]Less[blank_end] than 500 ovum will be produced in the female lifespan.
Responda
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primary
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I
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haploid
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II
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millions
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thousands
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diploid primary
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prophase I
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finishes
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secondary
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metaphase II
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haploid polar bodies
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ovum
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Less
Questão 11
Questão
How can you calculate the possible number of gamete combinations using the haploid number n?
Questão 12
Questão
Because of sexual reproduction, and because human's haploid number is 23 chromosomes, there are approximately 8 million gametic combinations.
Questão 13
Questão
Drosophila males do not undergo crossing over at meiosis. If Drosophila has a diploid number of 8, how many genetically distinct types of gametes can be produced by a male Drosophila?
Questão 14
Questão
Presence of the sexual cycle in a species has the potential to:
Responda
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decrease competition among offspring
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allow the species to respond better
to parasites
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increase evolutionary flexibility
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all of the above