Biology

Microbes and Plant Diseases

1,145 Questions

Microbes and plant diseases examine the role of fungi, bacteria, and viruses in causing infections in plants and humans. Topics cover symbiotic associations like mycorrhiza, fungal structures, and specific agricultural pathogens. Practice these biology questions to master microbiology concepts for upcoming competitive examinations.

Fungal associationsPlant pathogensMicrobial structuresBacterial infections

Microbes and Plant Diseases Questions

Multiple choice

Which of the following organisms cause yellow vein mosaic of okra?

  1. Bacteria

  2. Fungi

  3. Virus

  4. Protozoa
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yellow vein mosaic of okra (Bhindi) is a viral disease caused by Bhendi yellow vein mosaic virus (BYVMV), a Geminivirus. It is transmitted by the whitefly Bemisia tabaci and causes characteristic yellow mosaic patterns on leaves, vein thickening, and stunted plant growth. Bacterial diseases include citrus canker or blight, fungal diseases include rusts and smuts, and protozoa do not typically affect plants.

Multiple choice

Why is mushroom called 'heterotrophic'?

  1. As it causes diseases.

  2. As it depends on others for food.

  3. As it reproduces though spores.

  4. As it helps to make wine and bread.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mushroom is called 'heterotrophic' as it depends on others for food. Some are saprophytes, and some are parasites.

Multiple choice

Why are fungi called saprophytes?

  1. As they grow on dead or decaying plants.

  2. As they grow on living plants and animals.

  3. As they cause skin infections to human beings.

  4. As they reproduce through spores.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fungi are called saprophytes as they live on dead or decaying plant or animal matter.

Multiple choice

Which of the following is true for Citrus canker?

  1. It is caused by fungus and spread by air.

  2. It is caused by a virus and spread by insects.

  3. It is caused by virus and spread by air.

  4. It is caused by bacteria and spread by air.

  5. It is caused by bacteria and spread by insects.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Citrus canker is caused by bacteria, which spreads through air. 

Multiple choice

Which of the following fungus is the most common in diabetes?

  1. Cryptococcus

  2. Aspergillus

  3. Rhodotorula

  4. Nocardia
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Aspergillus causes opportunistic infection in immunocompromized patients and debilitated hosts like HIV, diabetes and other immunocomprmised. Other opportunistic fungal infection in diabetes is candidiasis.

Multiple choice

Which of the following disease(s) is/are caused by Pseudomonas fuscovaginae in rice? P. Sheath brown rot Q. Grain rot R. Foot rot

  1. Only P

  2. Only Q

  3. Only R

  4. P and Q

  5. Q and R
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sheath brown rot disease of rice is caused by Pseudomonas fuscovaginae, symptoms appearing at seedling and later stages include discoloration and rotting of sheath. After transplanting, infected seedlings initially show yellow-brown discolorations on their lower leaf sheaths. Later the discolorations turn gray-brown to dark brown. Ultimately, rot results in death of the infected seedlings.

Multiple choice

In maize, ___________ is caused by Erwinia and _________ is caused by Pseudomonas syringae.

  1. Stewart’s disease, Holcus spot disease

  2. Seed rot-seedling blight, Anthracnose leaf blight

  3. Black bundle disease, Black kernel rot

  4. Black kernel rot disease, Holcus spot disease

  5. Holocus spot disease, Anthracnose leaf blight
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In maize, Stewart's disease is caused by Erwinia stewartii and Holcus spot disease is caused by Pseudomonas syringae.

Multiple choice

Which of the following statement(s) is/are correct? A. Early blight of tomato disease is caused by Phytophthora infestans. B. Black rust of wheat is caused by Puccinia graminis. C. Loose smut of wheat is caused by Ustilago tritici.

  1. A only

  2. B only

  3. C only

  4. A and B

  5. B and C
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Early blight of tomato and potato disease is caused by Alternaria solani. Phytophthora infestans causes the Late blight of potato disease.Stem black rust of wheat is caused by Puccinia graminis fungus.Loose smut of wheat is caused by fungi, Ustilago species like-U. tritici, U. segatum.