IGCSE Biology Paper-3: Specimen Questions with Answers 305 - 305 of 358

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Passage

The diagram shows the male reproductive system.

Using a Label Line

Question 305 (1 of 2 Based on Passage)

Write in Short

Short Answer▾

Choose words from the list to complete each of the spaces in the paragraph. Each word may be used once only and some words may not be used at all.

Gametes are formed by the division of a nucleus, a process called … This process produces a total of … cells from the original cell. Each of these cells has a nucleus described as being … and each nucleus contains … the number of chromosomes present in the original nucleus.

Explanation

Gametes are formed by the division of a nucleus, a process called meiosis. This process produces a total of four cells from the original cell. Each of these cells has a nucleus described as being haploid and each nucleus contains half the number of chromosomes present in the original nucleus.

Significance of Meiosis

  • Meiosis form gametes that are required for sexual reproduction.
  • Meiosis maintains the fixed number of chromosomes in sexually reproducing organisms by having the same during gametogenesis.
  • In meiosis, paternal and maternal chromosomes assort independently. It causes a reshuffling of chromosomes and the traits controlled by them. The variations help the breeders in improving the races of useful plants and animals.
  • Meiosis introduces a new combination of traits or variations.
  • Chromosomal and genomic mutations occur by irregularities of meiotic division. Some of these mutations are useful to the organism.

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