Which is not correctly matched ?

Question

Accepted Answer

Option 3 is correctly identified as the incorrect match because Rhizobium is not an asymbiotic nitrogen fixer. Instead, Rhizobium is a symbiotic nitrogen fixer. It forms a mutualistic relationship with leguminous plants, where it resides in root nodules and fixes atmospheric nitrogen into a form that the plant can use. This symbiotic relationship benefits both the plant and the bacteria, as the plant provides carbohydrates to the bacteria, and in return, the bacteria supply the plant with nitrogen compounds necessary for growth.

Now, let's examine why the other options are correctly matched:

1. **Agrobacterium – Ti Plasmid**: Agrobacterium tumefaciens is a bacterium known for its ability to transfer a part of its DNA, known as the T-DNA, into the plant genome. This process is facilitated by the Ti (tumor-inducing) plasmid, which is a large plasmid found in Agrobacterium. The Ti plasmid is widely used in genetic engineering to introduce new genes into plants, making this a correct match.

2. **Cosmid - Vector DNA**: Cosmids are plasmid vectors that contain a small portion of bacteriophage lambda DNA, including the cos site, which allows them to be packaged into lambda phage particles. They are used as cloning vectors in molecular biology to clone large fragments of DNA. Thus, this is a correct match.

4. **Albinism – Autosomal recessive gene**: Albinism is a genetic condition characterized by a lack of melanin pigment in the skin, hair, and eyes. It is caused by mutations in genes involved in melanin production and is inherited in an autosomal recessive manner. This means that an individual must inherit two copies of the mutated gene, one from each parent, to express the condition. Therefore, this is a correct match.

In conclusion, Option 3 is the correct answer because it incorrectly describes Rhizobium as an asymbiotic nitrogen fixer, whereas it is actually a symbiotic nitrogen fixer. The other options are correctly matched based on their scientific definitions and roles.