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

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

A five year old child was diagnosed with bronchial eosinophilia. Which of the following statements about bronchial eosinophilia due to Aspergillus fumigatus is true?

  1. Patients usually have chronic asthma.

  2. Fungus is nearly always seen on the chest X-ray.

  3. Serum IgE levels are usually low or normal.

  4. Precipitating antibodies to Aspergillus fumigatus are rarely found.

  5. Eosinophils are never found in mucus plugs.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In contrast to pneumonic eosinophilias, which often progresses to pulmonary fibrosis, bronchial aspergillosis is present with asthma.

Multiple choice

Soft rot of apples are caused by

  1. puccinia recondita

  2. penicillium expansum

  3. ustilago hordi

  4. fusarium moniliform

  5. NA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is the correct answer as it will cause soft rot of apples.

Multiple choice

Which of the following statement(s) is/are false regarding ‘African daisy plant’?

  1. Downy mildew disease is caused by Cercospora gerberae.
  2. Nectria canker disease is caused by Erysiphe cichoracearum.
  3. Sclerotium rolfsii causes ‘Southern blight’ disease.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 2 and 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Downy mildew disease of African daisy plant is caused by fungus- Plasmopara majewskii. Cercospora gerberae causes Cercospora leaf spot disease in African daisy plant. Nectria canker disease is caused by Haematonectria haematococca fungus in African daisy plant. Powdery mildew is caused by the fungal pathogen Erysiphe cichoracearum in African daisy plant. Southern blight disease is caused by Sclerotium rolfsii in African daisy plant. Hence, 1 and 2 are false statements.

Multiple choice

The fungus(fungi) responsible for ‘bird’s eye rot’ in grapes is/are A. Mycosphaerella angulata B. Elsinoe ampelina C. Sphaceloma ampelinum

  1. Only A

  2. Only B

  3. Only C

  4. A and B

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

The causing fungal pathogens responsible for bird’s eye rot are Elsinoe ampelina and Sphaceloma ampelinum.
Angular leaf spot of grapes is caused by the fungus Mycosphaerella angulata. Hence, the correct answer is Elsinoe ampelina and Sphaceloma ampelinum.

Multiple choice

Which of the following statements is/are not true?

  1. Leaf streak disease of maize is caused by Stenocarpella macrospora
  2. Stem rot of potato is caused by Sclerotium rolfsii.
  3. Athelia arachnoidea causes crater rot in carot.
  4. Cercospora brachypus causes noble rot disease in grapes.

  1. Only 1

  2. 1 and 2

  3. 2 and 3

  4. 3 and 4

  5. Only 4
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

1) Leaf streak disease is caused by the fungus Stenocarpella macrospora in maize. 2) The causing fungal pathogen for stem rot of paotato is Sclerotium rolfsii. 3) Athelia arachnoidea causes crater rot in carot. 4) Grey rot or noble rot disease is caused by Botrytis cinerea in grapes. Mycosphaerella angulata and Cercospora brachypus cause angular leaf spot in grapes. Hence, only statement 4 is false.

Multiple choice

Match the almond diseases in List-A with causing fungal pathogens in List-B ||| |---|---| |List-A |List-B| |A. Armillaria root rot|1. Venturia carpophila| |B. Green fruit rot|2. Rhizomorpha subcorticalis| |C. Hull rot|3. Rhizopus sp| |D. Scab|4. Botrytis cinerea|

  1. A - 2, B - 4, C - 3, D - 1

  2. A - 3, B - 1, C - 4, D - 2

  3. A - 2, B - 4, C - 1, D - 3

  4. A - 1, B - 3, C - 2, D - 4

  5. A - 2, B - 1, C - 3, D - 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Armillaria root rot is caused by the fungi- Armillaria mellea and Rhizomorpha subcorticalis in almond. Green fruit rot disease of almond is caused by Botrytis cinerea, Botryotinia fuckeliana and Monilinia fructicola. Hull rot disease of almond is mainly caused by Rhizopus sp. Venturia carpophila and Cladosporium carpophilum cause Scab disease of almond. Hence, the sequence of codes A - 2, B - 4, C - 3, D - 1 is correct.

Multiple choice

Which among the following statements is/are not true?

  1. The causing agent for areolate leaf spot in citrus is Nematospora coryli.
  2. Nectria canker disease is caused by Erysiphe cichoracearum.
  3. Glomerella cingulata causes bitter rot in peanut.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 2 and 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  1. The causative agents for areolate leaf spot in citrus are- Thanatephorus cucumeris, Pellicularia filamentosa and Rhizoctonia solani. Dry fruit rot is caused by Nematospora coryli in citrus.
    1. Nectria canker disease is caused by Haematonectria haematococca fungus in African daisy plant. Powdery mildew is caused by the fungal pathogen Erysiphe cichoracearum in African daisy plant.
    2. Bitter rot of peanut is caused by the fungal pathogen Glomerella cingulata. Hence, 1 and 2 both are false statements.
Multiple choice

The fungus responsible for ‘loose smut’ of barley is/are: A. Ustilago tritici B. Ustilago segetum C. Pyrenophora wirreganensis

  1. Only A

  2. Only B

  3. Only C

  4. A and B

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

Infected heads emerge as a mass of dark brown powdery spores is called loose smut. Fungus Ustilago tritici causes loose smut disease in barley. Covered smut is caused by the fungus Ustilago segetum var. hordei in which the heads that emerge are dark in colour and smut balls take the place of the grain. Wirrega blotch of leaf is caused by the fungus Pyrenophora wirreganensis.

Multiple choice

Match the diseases of fruit crops in column-I with fungal pathogens in column-II. ||| |---|---| |Column- I |Column-II| |A. Leaf spot of cherries and palms|1. Cerecosoridium viticola| |B. Brown leaf spot of grapes|2. Taphrina deformans| |C. Citrus greasy leaf spot|3. Blueriella sp.| |D. Leaf curl of peach and apricot|4. Mycosphaerella musicosa| | |5. Mycosphaerella citri|

  1. A - 3, B - 1, C - 5, D - 2

  2. A - 5, B - 1, C - 4, D - 2

  3. A - 3, B - 4, C - 5, D - 2

  4. A - 2, B - 3, C - 4, D - 1

  5. A - 1, B - 4, C - 5, D - 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Leaf spot of cherries and palms is caused by Blueriella sp. Brown leaf spot of grapes is caused by Cerecosoridium viticola. Citrus greasy leaf spot is caused by the fungus Mycosphaerella citri. Banana leaf spot is caused by Mycosphaerella musicosa. Taphrina deformans causes leaf curl of peach and apricot. Hence, the correct sequence of codes is A - 3, B - 1, C - 5, D - 2.