AP BIOLOGY

CELL DIVISION

MEIOSIS AND GENETIC VARIATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What causes genetic variation/diversity in meiosis?
A
chromosomes lining up
B
crossing over of chromosomes
C
separation of chromosomes
D
chromosomes pulling apart
Explanation: 

Detailed explanation-1: -Specifically, meiosis creates new combinations of genetic material in each of the four daughter cells. These new combinations result from the exchange of DNA between paired chromosomes. Such exchange means that the gametes produced through meiosis exhibit an amazing range of genetic variation.

Detailed explanation-2: -During meiosis, homologous chromosomes (1 from each parent) pair along their lengths. The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation.

Detailed explanation-3: -This process, also known as crossing over, creates gametes that contain new combinations of genes, which helps maximize the genetic diversity of any offspring that result from the eventual union of two gametes during sexual reproduction.

Detailed explanation-4: -Crossing over is important for the normal segregation of chromosomes during meiosis. Crossing over also accounts for genetic variation, because due to the swapping of genetic material during crossing over, the chromatids held together by the centromere are no longer identical.

Detailed explanation-5: -Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism’s offspring).

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