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

Identify the mismatched pair of disease and its causative agent.

  1. Black root rot of cotton: Thielaviopsis basicola

  2. Black rot of crucifers: Xanthomonas campestris

  3. Gray mold of hemp: Agrobacterium tumefaciens

  4. Downy mildew of mustard: Peronospora parasitica

  5. Bottom rot of lettuce: Rhizoctonia solani
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The most important disease of hemp is gray mold.

Multiple choice

_______ is caused by a bacterium.

  1. Corn smut

  2. Citrus canker

  3. Wheat leaf rust

  4. Red rot of sugarcane

  5. Potato late blight
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Citrus canker is a disease affecting citrus species.

Multiple choice

Which of the following matchings is not correct?

  1. Coffee leaf rust: Hemileia vastatrix

  2. Ergot of rye: Claviceps purpurea

  3. Early blight of potato: Phytophthora infestans

  4. Crown rust of oats: Puccinia coronata

  5. Halo blight of beans: Pseudomonas syringae
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Early blight of potato is caused by the fungus Alternaria solani.

Multiple choice

Wildfire of tobacco is caused by

  1. Agrobacterium rhizogenes

  2. Erwinia carotovora

  3. Pseudomonas syringae

  4. Ralstonia solanacearum

  5. Rhodococcus fascians
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Wildfire of tobacco is caused by Pseudomonas syringae.

Multiple choice

What is “plant pathology“?

Directions: Late in the 19th century, T.J. Burrill, working in Illinois, discovered the fire blight disease in pear caused by a bacterium. This opened a new area of microbiology called “ plant pathology”.

  1. The study of plant hormones.

  2. The study of plant diseases.

  3. The study of water transport in plants.

  4. The study of plant diversity and naming.

  5. The study of heredity in plants.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Plant pathology is the study of plant diseases.

Multiple choice

Transmission of viral diseases of plants by insects was suggested by _________.

Directions: Late in the 19th century, T.J. Burrill, working in Illinois, discovered the fire blight disease in pear caused by a bacterium. This opened a new area of microbiology called “ plant pathology”.

  1. H. Weigmann

  2. Martinus Beijerinck

  3. A Japanese farmer Hashimoto

  4. Emil Hansen

  5. McCoy and Chapin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A Japanese farmer Hashimotom suggested the Transmission of viral diseases of plants by insects.

Multiple choice

Brachymeiosis is a characteristic of ascomycetous fungi. It involves

  1. two reductional and one equational division

  2. two reductional and two equational division

  3. one reductional and two equational division

  4. one reductional and one equational division
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Brachymeiosis is a modified meiotic process in some ascomycetous fungi. Unlike typical meiosis (one reductional, one equational division), brachymeiosis involves two reductional divisions followed by one equational division. This unique pattern results in four nuclei from one diploid cell, but with different chromosome numbers than standard meiosis.

Multiple choice

The zygospores are not generally formed in a culture of Rhizopus developed from a single spore because of

  1. lack of light

  2. shortage of oxygen

  3. absence of plus (+) and (-) strains of mycelium

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rhizopus fungi are heterothallic, meaning they require two opposite mating strains (plus + and minus - strains) to undergo sexual reproduction and form zygospores. When you start a culture from a single spore, you only have one strain present. Without both plus and minus strains coming into contact, sexual reproduction cannot occur and zygospores cannot form. This is a fundamental characteristic of their reproductive biology.

Multiple choice

Black rust of wheat is caused by

  1. albugo

  2. puccinia

  3. xanthomonas

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

Puccinia graminis is an obligate parasite causing black rust of wheat. It is a heteroecious fungus that completes its life history on wheat and barberry plants leaves.

Multiple choice

Which of the following plant diseases is caused by Phytophthora infestans?

  1. Loose smut of wheat

  2. Wilt of Pigeon pea

  3. Blight of Chick pea

  4. Late blight of potato
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Phytophthora infestans is a fungus-like organism (oomycete) that causes late blight of potato, which was responsible for the Irish Potato Famine. Loose smut of wheat is caused by Ustilago tritici, wilt of pigeon pea by Fusarium udum, and blight of chickpea by other pathogens.

Multiple choice

Earcockle disease of wheat is caused by

  1. Puccinia tritici

  2. Corynebacterium tritici

  3. Angunia tritici

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Earcockle disease of wheat is caused by Anguina tritici (a nematode). Puccinia tritici causes stem rust of wheat, not earcockle. Corynebacterium tritici causes bacterial leaf streak. 'Angunia' appears to be a typo for 'Anguina' but given the options, C is clearly intended as the correct answer.