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 plant diseases in List I with their casual organisms in List II.

 
List I (Plant diseases) List II (Casual organisms)
1. Loose smut of wheat a. Xylella fastidiosa
2. White rust of crucifers b. Agrobacterium tumefaciens
3. Crown gall c. Ustilago tritici
4. Pierce's disease d. Albugo candida

  1. 1 - a, 2 - b, 3 - c, 4 - d

  2. 1 - c, 2 - d, 3 - b, 4 - a

  3. 1 - c, 2 - b, 3 - a, 4 - d

  4. 1 - b, 2 - c, 3 - d, 4 - a
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Loose smut of wheat is caused by Ustilago tritici (1-c). White rust of crucifers is caused by Albugo candida (2-d). Crown gall is caused by Agrobacterium tumefaciens (3-b). Pierce's disease of grape is caused by Xylella fastidiosa (4-a). Option B matches all pairings correctly.

Multiple choice

Trichosporonosis causes death in patients

  1. having severe anaemia

  2. having haematologic malignance

  3. having severe tuberculosis

  4. having sinus and brain problems
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Trichosporon beigelii or T. captitatum are responsible for rare but growing infections in immune deficit patients. These agents can be insulated from the healthy skin and other sites like food, air, etc. Trichosporonosis frequently causes death in patients having haematologic malignance. Early symptoms involve fever, pneumonia, positive blood cultures and lung or eye infections. Trichosporon sp are vulnerable to Amphotericin B, miconazole but in maximum cases patients with disseminated infections die.

Multiple choice

To which part of the spore structure calcium dipicolinate is associated?

  1. Cortex

  2. Spore coat

  3. Exosporium

  4. Core

  5. Spore cell wall
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Up to 20% of the dry weight of the endospore consists of calcium dipicolinate within the core which is thought to stabilize the DNA. Dipicolinic acid could be responsible for the heat resistance of the spore and calcium may aid in resistance to heat and oxidizing agents.

Multiple choice

Which of the following structure protect spore from the drastic effects of hydrogen peroxide?

  1. S layer

  2. Cortex

  3. Spore coat

  4. Core

  5. Core wall
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 In many species including B. subtilis, the coat is the outermost spore structure and in other species such as the pathogenic organisms B. anthracis and B. cereus, the spore is encased in an additional layer called the exosporium. Both the coat and the exosporium have roles in protection of the spore and in its environmental interactions. The spore coat also protects the spore from some chemicals such as hydrogen peroxide (H2O2) but not others such as organic solvents.

Multiple choice

______ are commonly known as imperfect fungi.

  1. Phycomycetes

  2. Ascomycetes

  3. Basidiomycetes

  4. Deuteromycetes

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Deuteromycetes are commonly known as imperfect fungi because only the asexual or vegetative phases of these fungi are known.

Multiple choice

Mycorrhiza is the term applied to indicate the association of

  1. bacteria with the roots

  2. bacteria with the stem

  3. fungus with the roots

  4. fungus with the stem
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mycorrhiza is a symbiotic association between fungi and plant roots. The fungi help plants absorb nutrients (especially phosphorus) from soil, while receiving carbohydrates from the plant. This mutualistic relationship is crucial for most terrestrial plants. Bacteria-root associations would be called rhizobia, not mycorrhiza.

Multiple choice

Improper handling and storage of cereal grains and oilseeds results in the production of toxins known as aflatoxins which are not generally destroyed by normal cooking process. Aflatoxins are produced by

  1. bacteria

  2. protozoa

  3. moulds

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

The fungus Aspergillus flavus produces toxic aflatoxin. This mould is found in soil and decaying vegetation. It is assumed that the products contaminated with aflatoxin are carcinogenic to humans.