Biology

Microbes and Plant Diseases

1,118 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

The causative agent for toxic red tides is

  1. Ceratium furca

  2. Noctiluca scintillans

  3. Neospora

  4. Frenkelia

  5. Besnoitia

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ceratium furca blooms because of coastal eutrophication. Blooms of this species cause toxic red tides (red-brown), damage fish gills and deplete dissolved oxygen causing anoxic conditions.

Multiple choice

Which of the following organisms causes blast disease of rice?

  1. Verticillium species

  2. Magnaporthe grisea

  3. Sclerotinia sclerotiorum

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

Magnaporthe grisea causes rice blast disease. Initial symptoms are white to gray-green lesions or spots with darker borders produced on all parts of the shoot, while older lesions are elliptical or spindle-shaped and whitish to gray with necrotic borders. Lesions may enlarge and coalesce to kill the entire leaf.

Multiple choice

Which of the following pairs is incorrect?

  1. Blight of cassava - Xanthomonas axonopodis

  2. Wilt of carnation - Erwinia tracheiphila

  3. Black wood of grapewine - Phytoplasma

  4. Blight of cotton - Xanthomonas citri
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Erwinia tracheiphila causes wilt of cucurbitaceae. Wilt of carnation is caused by Burkholderia caryophylli.

Multiple choice

Which of the following causes leafy gall disease?

  1. Virus

  2. Bacterium

  3. Fungus

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

Leafy gall disease is a bacterial disease. Rhodococcus fascians is a Gram-positive bacterial phytopathogen that causes leafy gall disease.

Multiple choice

Match the given symptoms with the disease and its causative organism.

A maize plant has the following symptoms:

1. Chlorosis and white streaks on leaves which become necrotic with time, leading to shredded leaf appearance

2. Sterility in adult plants

  1. Diplodia ear rot - Stenocarpella macrospora

  2. Sorghum downy mildew - Peronosclerospora sorghi

  3. Downy mildew - Sclerophthora rayssiae

  4. Philippine downy mildew - Peronosclerospora philippinensis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sorghum downy mildew is caused by Peronosclerospora sorghi. It is diagnosed by chlorosis of the leaves that is followed by white streaking of the leaves. The white streaked areas of leaves become necrotic over time that leads to a shredded leaf appearance. In the maturing plant, the reproductive structures do not form properly or do not form at all. This leads to a sterile plant.

Multiple choice

Which of the following sets contain only fruiting myxobacteria?

  1. Melittangium, Polyangium, Cystobacter

  2. Flexibacter, Sporocytophaga, Cytophyga

  3. Melittangium, Sporocytophaga, Flexibacter

  4. Cystobacter, Polyangium, Cytophyga

  5. Flexibacter, Sporocytophaga, Cystobacter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cystobacter, Melittangium, Polyangium : All are fruiting myxobacteria.