Question

Which of the following microbes transform normal plant and animal cells to cancerous cells respectively?
A.Retrovirus and rhizobium
B.Escherichia coli and Agrobacterium tumefaciens
C.Agrobacterium tumefaciens and retrovirus
D.Agrobacterium tumefaciens and a rhizogenes

Answer 1

Hint: Tumor formation occurs when the pathogen interferes with genetic makeup of the host.

Complete step by step answer:
-Agrobacterium tumefaciens is a pathogen of several dicot plants. It is able to deliver a piece of its own DNA known as the T-DNA to transform the normal plant cells into a tumor. They also direct these cells to produce the chemicals required by pathogens for its survival. Similarly, retroviruses that infect animal cells have the ability to produce cancerous cells from normal cells.
-The transfer DNA (T-DNA) is the piece of DNA transferred by the tumor-inducing (Ti) plasmid of some species of bacteria such as Agrobacterium tumefaciens and Agrobacterium rhizogenes (Ri plasmid). The T-DNA is transferred from the bacterium into the host plant's nuclear DNA genome to control it for its survival and needs.
-A retrovirus is a type of virus that inserts a copy of its RNA genome into the DNA sequence of the host cell that it invades, thus changing the genome of that cell. It uses the enzyme reverse transcriptase to convert its RNA into a DNA.

Hence correct option is C

Note:
-Rhizobium is a genus of bacteria that are associated with the formation of root nodules on leguminous plants. These bacteria live in symbiosis (living together with mutual benefits) with legumes. They take in nitrogen from the atmosphere and pass it on to the plant, allowing it to grow in soil low in nitrogen. Thus, its primary function is to convert atmospheric nitrogen into compounds absorbable by plants from the soil.
-Escherichia coli (E. Coli) is a Gram-negative, facultative, anaerobic, rod-shaped, and coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms, they are pathogenic when present in high concentrations.