Introductory Plant Pathology MCQs

1. Which of the following statements best defines “biotrophs” in plant pathology?
(A) Organisms that can only grow and reproduce in dead plant tissue.
(B) Organisms that require living host tissue for their nutrition.
(C) Organisms that can survive independently of plant hosts.
(D) Organisms that infect both plant and animal hosts.

2. Which of the following is the primary characteristic of a necrotrophic pathogen?
(A) It only affects plants in specific environmental conditions.
(B) It relies on living plant tissue for survival and reproduction.
(C) It kills plant cells and tissues to obtain nutrients.
(D) It produces systemic symptoms across the entire plant.

3. Which of the following is NOT a method of pathogen entry into plants?
(A) Natural openings like stomata and lenticels
(B) Mechanical injury to the plant surface
(C) Through the vascular system without physical wounds
(D) Through the cuticle layer only during rainstorms

4. What is the primary function of the appressorium in plant pathogenic fungi?
(A) To produce reproductive spores for further infections.
(B) To anchor the fungus to the plant tissue.
(C) To penetrate the plant cell wall.
(D) To spread the infection across the plant’s vascular system.

5. Which of the following best describes the term “host specificity” in plant pathology?
(A) The ability of a pathogen to infect a wide range of plant species.
(B) The tendency of a pathogen to infect only one species or a group of closely related species.
(C) The ability of a pathogen to survive in the environment without a host.
(D) The resistance of a plant species to most pathogens.

6. Which of the following is the primary cause of the disease “Powdery mildew” on plants?
(A) A virus
(B) A fungus
(C) A bacterium
(D) A nematode

7. What is the significance of the “disease triangle” in plant pathology?
(A) It is used to calculate the economic impact of plant diseases.
(B) It emphasizes the interaction between the host, pathogen, and environment in the development of disease.
(C) It predicts the spread of a plant disease across large geographic regions.
(D) It helps identify the genetic resistance of plants to specific pathogens.

8. Which of the following is a common method used to control fungal plant pathogens in agriculture?
(A) Applying antibiotics to infected crops
(B) Using crop rotation with non-host plants
(C) Increasing the soil pH
(D) Installing humidity control systems in greenhouses

9. Which of the following is the most common mode of transmission for bacterial pathogens in plants?
(A) Airborne spores
(B) Root-to-root contact
(C) Through insect vectors and mechanical injury
(D) Via soil water movement only

10. What is the function of “hypersensitive response” (HR) in plants during pathogen infection?
(A) It enhances the growth of plant tissues to limit pathogen access.
(B) It induces rapid cell death at the site of infection to restrict pathogen spread.
(C) It produces systemic acquired resistance throughout the plant.
(D) It increases the susceptibility of the plant to future infections.

11. Which of the following plant diseases is caused by a virus transmitted by aphids?
(A) Late blight
(B) Tobacco mosaic virus (TMV)
(C) Cucumber mosaic virus (CMV)
(D) Wheat rust

12. Which of the following is a key characteristic of an effective plant disease resistance gene (R gene)?
(A) It produces antimicrobial compounds that kill the pathogen.
(B) It triggers a plant immune response upon recognition of a specific pathogen.
(C) It limits the reproduction of the pathogen inside the host plant.
(D) It prevents pathogens from entering plant tissues.

13. What is the role of “mycorrhizal fungi” in plant pathology?
(A) They cause diseases by infecting plant roots.
(B) They enhance plant growth by facilitating nutrient uptake and act as a defense mechanism.
(C) They are the primary pathogens of root rot.
(D) They help in the spread of viral diseases.

14. Which of the following is the best method to manage bacterial wilt disease caused by Ralstonia solanacearum?
(A) Use of resistant crop varieties
(B) Applying chemical pesticides directly to the soil
(C) Increasing irrigation in affected fields
(D) Burning infected plants and rotating crops

15. Which of the following methods is most commonly used for diagnosing plant diseases in the field?
(A) Electrophoresis of plant tissues
(B) Molecular identification using PCR techniques
(C) Visual inspection of symptoms and signs
(D) Genetic modification of the plant