Meiosis and Alternation of Generations
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Questions and Answers

What is the primary outcome of Meiosis I?

  • Chromosome number is reduced to half in each daughter cell (correct)
  • Sister chromatids separate to form identical cells
  • Chromatids are replicated to produce diploid cells
  • Crossing over occurs resulting in the creation of new cells

During which phase of meiosis does crossing-over occur?

  • Metaphase I
  • Telophase I
  • Prophase I (correct)
  • Anaphase II

What distinguishes haploid cells from diploid cells?

  • Diploid cells are formed through fertilization, while haploid cells are formed during binary fission.
  • Haploid cells contain one set of chromosomes, while diploid cells contain two sets. (correct)
  • Diploid cells have undergone mitosis, while haploid cells have not.
  • Haploid cells are present only in plants, while diploid cells are found in all organisms.

In the alteration of generations, which phase produces haploid gametes?

<p>Gametophyte phase (B)</p> Signup and view all the answers

Which phase of meiosis II is characterized by the separation of sister chromatids?

<p>Anaphase II (B)</p> Signup and view all the answers

Which of the following best describes polyploidy?

<p>Having multiple sets of chromosomes due to incomplete cell division (D)</p> Signup and view all the answers

What is formed at the end of Telophase II?

<p>Four haploid cells (A)</p> Signup and view all the answers

Which event does NOT occur during Meiosis II?

<p>Crossing-over (A)</p> Signup and view all the answers

What is the primary outcome of meiosis in sporocytes?

<p>Production of haploid spores (C)</p> Signup and view all the answers

Which of the following describes haploid cells?

<p>Cells with one set of chromosomes (B)</p> Signup and view all the answers

In the alternation of generations, what is formed at the end of the gametophyte phase?

<p>Gametes (A)</p> Signup and view all the answers

Which type of organism most prominently exhibits alternation of generations?

<p>Plants (D)</p> Signup and view all the answers

What defines polyploid cells?

<p>Cells containing more than two sets of chromosomes (A)</p> Signup and view all the answers

Which of the following statements is true regarding sporophyte cells?

<p>They contain twice as many chromosomes as gametophyte cells. (C)</p> Signup and view all the answers

What is the role of zygotes in the alternation of generations?

<p>They are the first cell of the sporophyte generation. (B)</p> Signup and view all the answers

Which of the following correctly describes the change from sporophyte generation to gametophyte generation?

<p>Resulting from meiosis (A)</p> Signup and view all the answers

In plants, what occurs during the gametophyte phase of the alteration of generations?

<p>Production of gametes via meiosis (B)</p> Signup and view all the answers

What is the haploid state in the life cycle of plants known as?

<p>Gametophyte (D)</p> Signup and view all the answers

Which statement correctly describes polyploidy in organisms?

<p>Organisms with more than two sets of chromosomes (B)</p> Signup and view all the answers

What is the term for chromosome pairs that are identical in length and gene location?

<p>Homologous chromosomes (A)</p> Signup and view all the answers

What happens during Division I of meiosis?

<p>Homologous chromosomes are separated into different cells (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of asexual reproduction?

<p>Requires fertilization of gametes (C)</p> Signup and view all the answers

Flashcards

Diploid cell

A cell containing two sets of chromosomes (2x).

Haploid cell

A cell containing one set of chromosomes (1x).

Polyploid cell

A cell containing more than two sets of chromosomes.

Gamete

A sex cell (sperm or egg) that contains a single set of chromosomes(haploid).

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Sporophyte

The diploid (2x) phase in the life cycle of a plant that produces spores.

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Gametophyte

The haploid (1x) phase in the life cycle of a plant that produces gametes.

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Alternation of Generations

The life cycle of some plants where there is an alternation between a diploid generation and a haploid generation.

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Meiosis

A type of cell division that produces haploid cells from a diploid cell.

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Meiosis I (Reduction Division)

First stage of meiosis, where the number of chromosomes is reduced by half.

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Meiosis II (Equational Division)

Second stage of meiosis, where chromosome number doesn't change further.

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Prophase I

Chromosomes condense, form homologous pairs, and cross over.

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Crossing Over

Exchange of genetic material between homologous chromosomes.

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Metaphase I

Chromosomes align in pairs at the cell's equator.

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Anaphase I

One chromosome from each pair moves to opposite poles.

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Telophase I

One cell splits into two daughter cells with half the original chromosome number.

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Meiosis Gamete Production

Meiosis results in gametes with half the chromosome number of a parent cell.

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Asexual Reproduction

Production of cells identical in chromosomes to the cells from which they arose.

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Sexual Reproduction

Results in the formation of seeds (in flowering/cone-bearing plants) involving gametes (egg and sperm) fusing to form a zygote.

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Homologous Chromosomes

Chromosome pairs identical in length, DNA amount, genes, and centromere location.

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Meiosis Result

Produces four cells with half the chromosome number of the parent cell; rarely identical to each other or original cell.

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Meiosis DNA Replication

DNA molecules of each chromosome double before meiosis.

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Centromere

Structure holding identical DNA molecules of a chromosome together.

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Mitosis vs. Meiosis

Mitosis produces identical cells while meiosis produces cells with half the chromosomes, creating genetic variation.

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Chromosome Number Reduction

The reduction of chromosome number in reproductive cells during meiosis.

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Study Notes

Meiosis and Alternation of Generations

  • Meiosis is a process that reduces the number of chromosomes in a cell to half.
  • Learning changes everything.
  • Asexual reproduction produces identical cells.
  • Sexual reproduction forms seeds in flowering/cone-bearing plants.
  • Gametes (egg and sperm) unite to form a zygote.

Phases of Meiosis

  • Meiosis I (Reduction Division): Reduces the number of chromosomes to half.
  • Meiosis II (Equational Division): No further reduction in chromosome number.
  • DNA molecules double before meiosis.
  • Each chromosome has identical DNA molecules held together by a centromere.

Alteration of Generations

  • Meiosis results in half the number of chromosome sets in a gamete.
  • Haploid (1x) cell: Cell with one set of chromosomes.
  • Diploid (2x) cell: Cell with two sets of chromosomes.
  • Zygote: Fertilized egg.
  • Polyploid cell: Cell with more than two sets of chromosomes.
  • Triploid (3x) cell: Three sets of chromosomes.
  • Homologous chromosomes cannot pair properly in some cases, which causes unviable gametes.
  • Examples of polyploids include: navel oranges and seedless watermelons.
  • Hexaploid (6x) and Octaploid (8x) are other polyploid examples.

Sporophytes

  • Sporophytes develop from zygotes and produce sporocytes.
  • Sporocytes undergo meiosis to produce haploid spores.

Gametophytes

  • Gametophytes develop from spores.
  • Gametophytes form cells/structures to create gametes.
  • Fertilization fuses gametes to form a zygote.

Organisms with Alternation of Generations

  • Alternation of generations: Life cycle with sexual reproduction between diploid sporophyte and haploid gametophyte phases.
  • This pattern can be seen in protists, fungi, and plants.
  • It's most evident in the plant kingdom.

Rules for Alteration of Generations

  • The first cell of a gametophyte is a spore, and the last is a gamete.
  • A gametophyte cell contains half the chromosomes as the sporophyte.
  • The first cell of a sporophyte is a zygote, and the last is a sporocyte.
  • A sporophyte cell contains twice as many chromosomes as a gametophyte.
  • Changes from sporophyte to gametophyte occur via meiosis.
  • Changes from gametophyte to sporophyte occur via fertilization.

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Chapter 12 Meiosis and Alteration of Generations PDF

Description

This quiz covers the fundamental concepts of meiosis and the alternation of generations in plants. It explores the phases of meiosis, the significance of haploid and diploid cells, and the formation of gametes. Test your understanding of how sexual and asexual reproduction contributes to genetic diversity.

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