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Which of the following statements are co...

Which of the following statements are correct regarding crossing over?
I. It provides its results as variations, which are new material of evolutionary changes in nature.
II. It helps in the construction of linkage maps.
III. It affords a proof for linear arrangement of genes.
IV. It helps in the cytoplasmic inheritance.

A

I,II and III

B

II and IV

C

III and IV

D

Only IV

Text Solution

AI Generated Solution

The correct Answer is:
To determine which statements regarding crossing over are correct, we will analyze each statement one by one. ### Step 1: Analyze Statement I **Statement I:** It provides its results as variations, which are new material of evolutionary changes in nature. - **Explanation:** Crossing over occurs during meiosis when homologous chromosomes exchange segments of genetic material. This process creates new combinations of alleles, leading to genetic variation in the offspring. These variations are essential for evolution as they provide the raw material for natural selection. **Conclusion:** Statement I is correct. ### Step 2: Analyze Statement II **Statement II:** It helps in the construction of linkage maps. - **Explanation:** Crossing over is used to determine the relative positions of genes on a chromosome. By analyzing the frequency of recombination between genes, scientists can construct linkage maps that show the order and distance between genes on a chromosome. **Conclusion:** Statement II is correct. ### Step 3: Analyze Statement III **Statement III:** It affords a proof for linear arrangement of genes. - **Explanation:** The occurrence of crossing over between genes on a chromosome provides evidence that genes are arranged in a linear sequence. The frequency of crossing over can indicate how far apart genes are from one another, supporting the idea of a linear arrangement. **Conclusion:** Statement III is correct. ### Step 4: Analyze Statement IV **Statement IV:** It helps in the cytoplasmic inheritance. - **Explanation:** Cytoplasmic inheritance refers to the transmission of genes located in the cytoplasm, such as those found in mitochondria or chloroplasts. Crossing over occurs between homologous chromosomes in the nucleus and does not involve cytoplasmic genes. **Conclusion:** Statement IV is incorrect. ### Final Conclusion Based on the analysis: - Statements I, II, and III are correct. - Statement IV is incorrect. Thus, the correct statements regarding crossing over are I, II, and III. ---
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