Mer Scott
Test por , creado hace más de 1 año

• Explain what the sexual cycle is. • Identify the structures of meiosis. • Summarise the order of events in meiosis. • Compare and contrast the events that occur in meiosis and mitosis. • Illustrate how meiosis leads to gametic and zygotic diversity

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Mer Scott
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L20 The sexual cycle, meiosis and the value of sex

L20 The sexual cycle, meiosis and the value of sex

Pregunta 1 de 14

1

Choose the incorrect statement about the sexual cycle.

Selecciona una de las siguientes respuestas posibles:

  • Adult eukaryotic cells are diploid.

  • Cells in the ovaries and testes are the only cells which undergo meiosis.

  • Gametic cells are diploid.

  • The ovum or sperm is haploid.

  • When an adult gametic cell undergoes mitosis, it is still diploid.

Explicación

Pregunta 2 de 14

1

Choose the correct statements.

Selecciona una o más de las siguientes respuestas posibles:

  • Two gametes which are haploid fuse to make a diploid zygote.

  • Meiosis halves the number of of chromosomes going into gametes.

  • Mitosis creates two haploid daughter cells.

  • Meiosis creates four diploid daughter cells.

Explicación

Pregunta 3 de 14

1

Meiosis I separates sister chromatids.

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 4 de 14

1

Choose the incorrect statement about Meiosis I.

Selecciona una de las siguientes respuestas posibles:

  • Crossing over occurs between homologous pairs during metaphase.

  • Four sister chromatids form a tetrad in prophase.

  • Crossing over occurs at a chiasmata, the joining of a locus on each chromatid.

  • In anaphase I, sister chromatids remain attached when the spindles shorten.

Explicación

Pregunta 5 de 14

1

Meiosis I produces two diploid cells.

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 6 de 14

1

Choose the statements about Meiosis II that are false.

Selecciona una o más de las siguientes respuestas posibles:

  • Two haploid cells with doubled chromosomes enter prophase II.

  • Crossing over occurs between sister chromosomes during prophase II.

  • In anaphase II, sister chromatids are pulled apart.

  • At the end of telophase II, two haploid cells are present.

Explicación

Pregunta 7 de 14

1

There are no chiasmata formed in mitosis.

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 8 de 14

1

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:

Selecciona una de las siguientes respuestas posibles:

  • 3pg

  • 6pg

  • 12pg

  • 24pg

Explicación

Pregunta 9 de 14

1

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:

Selecciona una de las siguientes respuestas posibles:

  • chromatid number

  • gene copy number

  • the ratio of maternal to paternal genes

  • all of the above

Explicación

Pregunta 10 de 14

1

In males, diploid spermatocytes undergo meiosis to produce two secondary spermatocytes. These undergo meiosis to form haploid spermatids, or, sperm. Tens of of these can be produced per day.
In females, 500,000 oocytes are present in a six month old fetus. These begin meiosis I but are suspended in until ovulation. After ovulation, meiosis I and produces two haploid cells, one becomes a oocyte and the other becomes the first polar body. The first polar body is suspended in until fertilisation, upon which it completes meiosis II and makes two . The secondary oocyte undergoes meiosis II to produce the fourth polar body, and the , which are both haploid. than 500 ovum will be produced in the female lifespan.

Arrastra y suelta para completar el texto.

    primary
    I
    haploid
    II
    millions
    thousands
    diploid primary
    prophase I
    finishes
    secondary
    metaphase II
    haploid polar bodies
    ovum
    Less

Explicación

Pregunta 11 de 14

1

How can you calculate the possible number of gamete combinations using the haploid number n?

Selecciona una de las siguientes respuestas posibles:

  • 2n

  • 2n^2

  • n^2

  • 2^n

Explicación

Pregunta 12 de 14

1

Because of sexual reproduction, and because human's haploid number is 23 chromosomes, there are approximately 8 million gametic combinations.

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 13 de 14

1

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?

Selecciona una de las siguientes respuestas posibles:

  • 4

  • 8

  • 16

  • 32

Explicación

Pregunta 14 de 14

1

Presence of the sexual cycle in a species has the potential to:

Selecciona una de las siguientes respuestas posibles:

  • decrease competition among offspring

  • allow the species to respond better
    to parasites

  • increase evolutionary flexibility

  • all of the above

Explicación

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