The term biotechnology refers to the use of living organisms or their products to modify human health and their human environment. For example, 'test tube' program, synthesis of a gene or correcting a defective gene are all part of the biotechnology. The basis of the modern biotechnology are genetic engineering and maintenance of sterile conditions. Genetic engineering is the technique that alter the chemistry of genetic material i.e. DNA and RNA, then this genetic material is introduced into host organisms, which alter the phenotype of the host organism.
The recognition sequence of the first restriction enzyme isolated was base pair long.

Options

A. four
B. six
C. five
D. two

Explanation

### Step-by-Step Solution:

1. **Understanding Biotechnology**:
- Biotechnology involves the use of living organisms or their products to enhance human health and the environment. It includes various applications such as gene synthesis, gene correction, and test tube programs.

2. **Key Components of Modern Biotechnology**:
- The foundation of modern biotechnology is genetic engineering and the maintenance of sterile conditions. Genetic engineering allows for the alteration of genetic material (DNA and RNA) to modify organisms.

3. **Genetic Engineering Process**:
- Genetic engineering involves changing the nucleotide sequences in DNA and RNA. This altered genetic material is then introduced into host organisms, which leads to changes in their phenotype (observable characteristics).

4. **Role of Restriction Enzymes**:
- Restriction enzymes, also known as restriction endonucleases, are crucial tools in genetic engineering. They act as molecular scissors that cut DNA at specific sequences.

5. **Identifying the First Restriction Enzyme**:
- The first restriction enzyme discovered was EcoRI, which recognizes a specific sequence of DNA. The recognition sequence of EcoRI is 6 base pairs long.

6. **Conclusion**:
- Therefore, the recognition sequence of the first restriction enzyme isolated (EcoRI) is 6 base pairs long.

### Final Answer:
The recognition sequence of the first restriction enzyme isolated was **6 base pairs long**.

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