Unit 5 - Practice Quiz

1 Which of the following terms describes an organism that lives primarily as a saprophyte but can live as a parasite when the opportunity arises?

2 Which type of pathogen requires a living host to complete its life cycle and cannot be grown on artificial culture media?

3 In the context of variability in fungal pathogens, what is the phenomenon where genetically different nuclei coexist within a common cytoplasm?

4 Which mechanism of variability is unique to fungi that lack a sexual cycle (Fungi Imperfecti), involving the fusion of haploid nuclei within a heterokaryon followed by haploidization?

5 Which enzyme is primarily responsible for the degradation of the plant cuticle during the initial stages of pathogen penetration?

6 Soft rot symptoms in vegetables are primarily caused by the action of which group of enzymes that degrade the middle lamella?

7 Which of the following is considered a Host-Specific Toxin (HST)?

8 What is the primary function of the enzyme Polygalacturonase (PG) in pathogenesis?

9 Which growth regulator is responsible for the 'Bakanae' or 'foolish seedling' disease in rice, characterized by excessive stem elongation?

10 The formation of 'Green Islands' around infection spots in rust and mildew diseases is attributed to the localized accumulation of which growth regulator?

11 Which term describes enzymes that are always produced by the pathogen regardless of the presence of the substrate?

12 Wildfire disease of tobacco is associated with which non-host-specific toxin?

13 Hypertrophy in plant tissues, often seen in tumorous diseases like Crown Gall, refers to:

14 Agrobacterium tumefaciens induces crown gall tumors by transferring T-DNA that codes for the synthesis of which plant hormones?

15 Which enzyme degrades the -1,4-glucosidic linkages in cellulose?

16 Pathogens that kill host tissue in advance of penetration and live on the dead matter are known as:

17 The 'shot-hole' symptom in leaves involves the formation of an abscission layer, often triggered by the production of:

18 Which of the following is a definition of a Vivotoxin?

19 T-toxin, produced by Bipolaris maydis race T, specifically affects maize plants with:

20 Lignin, a complex polymer conferring rigidity to wood, is primarily degraded by which group of organisms?

21 What is the role of Pectin Methyl Esterase (PME) in cell wall degradation?

22 Which mechanism creates variability in bacteria through the uptake of naked DNA from the environment?

23 The phenomenon of Saltation (or sectoral mutation) in fungal cultures refers to:

24 Phaseolotoxin, produced by Pseudomonas syringae pv. phaseolicola, causes halo blight in beans by inhibiting:

25 Fusicoccin, a toxin produced by Fusicoccum amygdali, affects plants by:

26 What is the primary effect of Indole-3-Acetic Acid (IAA) when produced in excess by pathogens like Pseudomonas savastanoi?

27 Which of the following is NOT a cell wall degrading enzyme?

28 The 'Gene-for-Gene' hypothesis, explaining variability and host-pathogen interaction, was proposed by:

29 HC-toxin affects maize by inhibiting which specific enzyme activity?

30 Witches' broom symptoms are typically associated with an imbalance of which plant hormone?

31 Which enzyme breaks down hemicellulose (e.g., xylan) in the plant cell wall?

32 In the context of bacterial variability, Conjugation requires:

33 Phytotoxins that are not specific to a host and can affect a wide range of plants are termed:

34 Which molecule acts as the 'cement' holding plant cells together and is the first target of enzymatic attack by soft-rot pathogens?

35 Abscisic Acid (ABA) generally promotes disease susceptibility by:

36 Tentoxin, produced by Alternaria alternata, induces chlorosis by interfering with:

37 The conversion of indole-3-acetamide (IAM) to indole-3-acetic acid (IAA) in bacteria like Pseudomonas savastanoi is catalyzed by:

38 What is the primary role of phospholipases in pathogenesis?

39 Amylases are enzymes that degrade:

40 Root knot nematodes (Meloidogyne spp.) induce the formation of giant cells. This is an example of pathogen-induced changes in:

41 Transduction as a mechanism of variability involves:

42 Which of the following is an example of a Hemibiotroph?

43 The 'Epinasty' (downward bending of leaves) symptom seen in some wilt diseases is primarily caused by:

44 What is the function of Cutinases during the pre-penetration and penetration phase?

45 Which enzyme splits pectin chains by 'elimination' (trans-elimination) rather than hydrolysis?

46 A pathogen strain that differs from others in pathogenicity (ability to infect specific host varieties) is called a:

47 Which toxin causes 'fire blight' symptoms but is actually a virulence factor rather than a strict phytotoxin?

48 In fungal pathogenesis, oxalic acid acts synergistically with which enzymes?

49 General resistance (Horizontal resistance) is usually effective against:

50 The degradation of the secondary cell wall typically involves the breakdown of: