Biology Chapter on Meiosis

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Questions and Answers

What is the basic number of chromosomes called in a cell?

Haploid number

Diploid number

Chromosome set (correct)

Chromosome pair

What type of cell division occurs specifically in reproductive organs to produce gametes?

Meiosis (correct)

Binary fission

Cytokinesis

Mitosis

How many chromosomes does a human gamete contain?

23 (correct)

What is the result of the fusion of male and female gametes during fertilization?

Zygote Signup and view all the answers

Homologous chromosomes are defined as pairs of chromosomes that come from which sources?

One paternal and one maternal gamete Signup and view all the answers

What occurs during anaphase I of meiosis?

Homologous chromosomes move to opposite poles of the cell. Signup and view all the answers

What is the result of telophase I in meiosis?

Two new cells containing the haploid number of chromosomes. Signup and view all the answers

Which of the following accurately describes meiosis II?

Sister chromatids are aligned at the center before being separated. Signup and view all the answers

What is a key difference between spermatogenesis and oogenesis?

Spermatogenesis begins at puberty, while oogenesis begins in utero. Signup and view all the answers

How many possible orientations can 23 pairs of chromosomes create during meiosis?

More than eight million possibilities. Signup and view all the answers

What is the primary purpose of meiosis?

Sexual reproduction Signup and view all the answers

Which phase of meiosis involves the pairing of homologous chromosomes?

Prophase I Signup and view all the answers

How many times does a diploid cell divide during meiosis?

Twice Signup and view all the answers

What occurs during the process known as crossing-over?

Chromosomes exchange segments Signup and view all the answers

What is meant by random assortment during meiosis?

Chromosomes align and distribute randomly to daughter cells Signup and view all the answers

At what stage do cells undergo interphase before meiosis begins?

G2 phase Signup and view all the answers

Which statement is true regarding the cells that undergo meiosis?

They produce haploid cells Signup and view all the answers

What is the role of meiosis in relation to genetic information?

It enhances genetic diversity Signup and view all the answers

Study Notes

Meiosis

Meiosis is a type of cell division that creates new gametes (sex cells).
It occurs in reproductive organs (like testes and ovaries).
Meiosis produces gametes with a haploid number of chromosomes.
In humans, the haploid number is 23 (1n).
A diploid cell (2n) has two sets of chromosomes (46 in humans).
Meiosis involves two divisions, Meiosis I and Meiosis II.
This process reduces the chromosome number from diploid to haploid.

Number of Chromosomes

Each species has a characteristic number of chromosomes in its cells.
Humans have 46 chromosomes (23 pairs), chimpanzees 48, elephants 56, and dogs 78.

Fertilization

Fertilization is the fusion of male and female gametes.
The fusion of the nuclei forms a zygote with a diploid number of chromosomes.
In humans, the zygote has 46 chromosomes (2n).

Homologous Chromosomes

Paired chromosomes are called homologous chromosomes.
One chromosome in each pair comes from each parent.

Meiosis I

Prophase I: Homologous chromosomes pair up, and crossing over occurs (exchange of genetic material between non-sister chromatids).
Metaphase I: Homologous chromosomes line up in the middle of the cell.
Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell.
Telophase I: The chromosomes reach the poles, cytokinesis begins, and two haploid cells are formed.

Meiosis II

Meiosis II is similar to mitosis, but it begins with haploid cells.
Prophase II: Chromosomes condense.
Metaphase II: Chromosomes line up in the middle of each cell.
Anaphase II: Sister chromatids separate and move to opposite poles.
Telophase II: Chromosomes reach the poles, cytokinesis begins, and four haploid cells are produced.

Mitosis vs. Meiosis

Mitosis produces two diploid cells from one diploid cell, maintaining the chromosome number.
Meiosis produces four haploid cells from one diploid cell, reducing the chromosome number by half.
Meiosis produces genetic variation through crossing-over and independent assortment.

Gamete Differences

Spermatogenesis (sperm production) starts at puberty, producing four gametes.
Oogenesis (egg production) begins before birth, but pauses until puberty and produces only one mature ovum (egg) during each cycle, with unequal division of cytoplasm.

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Description

Explore the fascinating process of meiosis, a type of cell division that produces gametes in reproductive organs. Understand the significance of haploid and diploid cells, the concept of homologous chromosomes, and the role of fertilization in forming a zygote. This quiz covers key concepts essential for mastering cellular reproduction.