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Biology 2nd Baccalaureate

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8.2.5. Biological importance of meiosis

Biological importance of meiosis

The meiosis is important for two facts:

  • It produces gametes, haploid sex cells. By meiosis cells are obtained with half of chromosomes somatic cells. In this way, when uniting in fertilization with another gamete, the egg or zygote cell will have the number of chromosomes (diploid) of the species. If there were no meiosis, the number of chromosomes would double with each reproduction.
  • Increases genetic variability. The genetic recombination of prophase I, wherein each gamete contains information from both parents, makes the seed contains a single genetic information. The natural selection (and artificial) determine which changes are beneficial or harmful, favoring the evolution of species.

Questions that have come out in University entrance exams (Selectividad, EBAU, EvAU)

Aragon. June 2013, option B . September 2012, option B, 1

Short development theme. Meiosis: (3 points)

a) Concept and brief description of the stages.

b) Biological significance.

c) Differences between meiosis and mitosis.

Castilla y León, option B, question 2

In relation to meiosis:

a) For a species 2n = 6 make a meiotic metaphase I scheme. (0.5)

b) Why is it said that the first meiotic division is reductional? (0.5)

c) What is the biological significance of meiosis? (0.5)

d) In what cell type does meiosis take place? (0.25)

Cantabria, July 2021, question 11

Use a clear drawing to represent the different stages of meiosis, starting from a hypothetical cell of karyotype 2n = 4. Briefly indicate the two main biological functions of meiosis.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.