AP BIOLOGY

CELL DIVISION

THE CELL CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the purpose of crossing-over in meiosis?
A
To create mutations in gametes to increase variation
B
To randomly separate homologous chromosome pairs
C
To reduce the number of chromosomes in gametes by one half
D
To create new combinations of alleles on homologous chromosomes
Explanation: 

Detailed explanation-1: -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-2: -Explanation: When chromatids “cross over, ” homologous chromosomes trade pieces of genetic material, resulting in novel combinations of alleles, though the same genes are still present. Crossing over occurs during prophase I of meiosis before tetrads are aligned along the equator in metaphase I.

Detailed explanation-3: -Crossing over helps to bring about random shuffling of genetic material during the process of gamete formation. This results in formation of gametes that will give rise to individuals that are genetically distinct from their parents and siblings.

Detailed explanation-4: -The exchange of chromosome material results in variation in the offspring. It plays a crucial function in the evolution process. The creation of genetic maps is aided by crossing over frequency. Crossing over is evidence of a chromosome’s linear organization of connected genes.

Detailed explanation-5: -Crossing Over in Prophase 1 The steps in prophase I of meiosis I that lead up to crossing over must also occur in specific order. First, synapsis pairs homologous chromosomes, then interlinking homologous chromosomes form chiasmata, and lastly, crossing over occurs at chiasma crossing points.

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