Question

In plants, mosaic formation, leaf rolling and curling, yellowing of plant parts, vein clearing, dwarfing and stunted growth, necrosis etc. are the symptoms of
A. Bacterial diseases
B. Mycoplasmal diseases
C. Viral diseases
D. Fungi diseases

Answer 1

Hint: A plant disease is defined as anything that prevents a plant from performing to its maximum potential. This definition includes abiotic and biotic plant diseases.
Diseases can be bacterial, viral or fungal diseases.

Complete answer:
In plants, various types of organisms cause disease such as bacteria, virus or fungus.
According to the question, mosaic formation is mainly seen in tobacco plant, pumpkin, and potato plant which are generally caused by the tobacco mosaic virus.
Now, what is mosaic formation? Mosaic formation is the presence of some light and dark green patches in the leaves of plants which is mainly caused by the viral diseases.
Leaf rolling is curving the leaves of plants outwards.
Due to some diseases the plant which is mostly green in color gets converted into the yellow color plant.
The growth of the plant stops or the plant may be dwarfed.
Necrosis means cell death, due to viral infections the plant cell death occurs.
All these above symptoms which we see in the plant is due to viral disease.
A viral disease is mainly caused by the tobacco mosaic virus (TMV).
Virus is generally infectious in nature that contains protein coat, genetic material of RNA and DNA.
They are also known as obligate parasites which means they depend upon their host organism to complete their life cycle.

So, the correct option is option C. viral diseases.

Note: Bacterial disease symptoms: the symptoms of bacterial infection are more likely to fungal infections such as
1. Leaf spots
2. Blights
3. Wilts
4. Scabs
5. Cankers
6. Soft rots of roots
7. Storage organs
8. Fruit
9. Overgrowth.