A phenomenon which results in alteration of DNA sequences and consequently results in changes in the genotype and the phenotype of an organism is

Options

A. Independent assortment
B. Random gametic fusion
C. Mutation
D. Crossing over

Answer

To answer the question regarding the phenomenon that results in alteration of DNA sequences, leading to changes in the genotype and phenotype of an organism, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a phenomenon that alters DNA sequences, which in turn affects the genotype (the genetic makeup) and phenotype (the observable traits) of an organism.

2. **Identifying the Options**: The options provided are:
- a. Independent assortment
- b. Random gametic fusion
- c. Mutation
- d. Crossing over

3. **Analyzing Each Option**:
- **Independent Assortment**: This refers to the way genes segregate independently during gamete formation. It does not involve changes to DNA sequences.
- **Random Gametic Fusion**: This is the random combination of gametes during fertilization. It does not change the DNA sequence itself.
- **Mutation**: This is a direct alteration in the DNA sequence, which can occur through mechanisms like insertion, deletion, or substitution of nucleotide bases. This change in the DNA can lead to changes in the genotype and subsequently the phenotype.
- **Crossing Over**: This occurs during meiosis where homologous chromosomes exchange genetic material. While it creates genetic diversity, it does not alter the DNA sequence of an individual organism.

4. **Conclusion**: The only option that directly results in an alteration of DNA sequences is **c. Mutation**. This process leads to changes in both genotype and phenotype.

### Final Answer:
The phenomenon which results in alteration of DNA sequences and consequently results in changes in the genotype and the phenotype of an organism is **c. Mutation**.

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