MCQs on Division II: Eumycota, Subdivision: Mastigomycotina, Class: Oomycetes
- What is the main characteristic of members of the class Oomycetes?
a) Filamentous hyaline coenocytic mycelium
b) Presence of chitin in the cell wall
c) Sexual reproduction by conidia
d) Presence of septate hyphae
Answer: a - Which of the following is true about the cell wall of Oomycetes?
a) It contains chitin
b) It is made of cellulose
c) It contains glucans and hydroxyproline
d) It is composed of proteins only
Answer: b - Oomycetes produce which type of sexual spore?
a) Zygospores
b) Ascospores
c) Oospores
d) Conidia
Answer: c - The flagella of zoospores in Oomycetes are:
a) Both are whiplash type
b) Both are tinsel type
c) One is whiplash and the other is tinsel type
d) Both are biflagellate but equal in length
Answer: c - In Oomycetes, the asexual reproduction is primarily by:
a) Zoospores
b) Ascospores
c) Conidia
d) Zygospores
Answer: a
MCQs on Order Peronosporales
- Which order includes economically important plant pathogens causing downy mildew and white rust diseases?
a) Chytridiales
b) Peronosporales
c) Basidiomycetes
d) Zygomycetes
Answer: b - The hyphae of Peronosporales are:
a) Septate
b) Aseptate
c) Coenocytic
d) Both b and c
Answer: d - Which of the following is a defining characteristic of Peronosporales?
a) Presence of haustoria in host cells
b) Formation of sexual spores only
c) Ability to form septate hyphae
d) None of the above
Answer: a - Asexual reproduction in Peronosporales is through:
a) Conidia
b) Zoosporangia
c) Zygospores
d) Ascospores
Answer: b - Sexual reproduction in Peronosporales involves the union of which two sex organs?
a) Antheridia and sporangia
b) Oogonia and sporangia
c) Antheridia and oogonia
d) Oogonia and conidia
Answer: c
MCQs on Families within Oomycetes
- Which family in Oomycetes includes genera such as Pythium and Phytophthora?
a) Peronosporaceae
b) Albuginaceae
c) Pythiaceae
d) Sclerophthorae
Answer: c - In the family Albuginaceae, sporangiophores are:
a) Similar to vegetative hyphae
b) Strikingly different from vegetative hyphae
c) Non-existent
d) Septate
Answer: b - Which genus is found in the family Albuginaceae?
a) Phytophthora
b) Pythium
c) Albugo
d) Sclerospora
Answer: c - In the family Peronosporaceae, the sporangiophores are:
a) Non-branching
b) Branching or unbranched
c) Always septate
d) Always hyaline
Answer: b - Which family in Oomycetes is characterized by sporangia produced singly or in clusters at the tip of sporangiophores?
a) Albuginaceae
b) Peronosporaceae
c) Pythiaceae
d) Sclerophthorae
Answer: b
MCQs on Peronosporaceae Classification
- In the Peronosporaceae family, which genus has sporophores that germinate by zoospores and oospores that germinate by a germ tube?
a) Sclerophthora
b) Sclerospora
c) Peronospora
d) Bremia
Answer: a - The genus Peronospora is characterized by:
a) Unbranched sporophores
b) Macronemous sporophores
c) Non-persistent sporophores
d) Poroid spore walls
Answer: b - Which genus in Peronosporaceae has sporangia that germinate by zoospores or a germ tube?
a) Plasmopara
b) Peronospora
c) Pythium
d) Bremia
Answer: b - In the genus Plasmopara, the sporophore branching is at:
a) Right angles
b) Acute angles
c) Obtuse angles
d) Perpendicular angles
Answer: a - Which genus in Peronosporaceae is characterized by tips of branches that are acute and sporangia germinate by zoospores?
a) Peronospora
b) Plasmopara
c) Pseudoperonospora
d) Bremiella
Answer: c
MCQs on Pathogenesis and Symptoms
- Club root of cabbage is caused by which pathogen?
a) Phytophthora infestans
b) Pythium spp.
c) Plasmodiophora brassicae
d) Albugo candida
Answer: c - What are the main symptoms of club root disease in cabbage?
a) Yellowing and wilting
b) Club-shaped roots
c) Leaf curling
d) Necrotic lesions on stems
Answer: b - Which disease is caused by the pathogen Pythium?
a) Club root of cabbage
b) Damping off
c) White rust
d) Downy mildew
Answer: b - The thallus of Plasmodiophora brassicae is described as:
a) Septate
b) Plasmodium
c) Hyphal
d) Conidial
Answer: b - What causes the root enlargement in club root disease?
a) Necrosis
b) Hyperplasia and hypertrophy
c) Waterlogging
d) Root rotting
Answer: b
MCQs on Disease Cycle and Life Cycle
- During the seedling stage, infection by Plasmodiophora brassicae occurs at:
a) The seed coat
b) The root hairs
c) The leaves
d) The stem
Answer: b - The resting spores of Plasmodiophora brassicae can lie dormant in the soil for:
a) Several months
b) Several years
c) Several days
d) Forever
Answer: b - What happens when a zoospore from Plasmodiophora brassicae penetrates the root hair?
a) It produces resting spores
b) It develops into a primary plasmodium
c) It germinates into zoosporangia
d) It initiates spore formation
Answer: b - The plasmodium of Plasmodiophora brassicae cleaves into:
a) Multinucleate portions
b) Zoosporangia
c) Conidia
d) Ascospores
Answer: a - The zygotes produced by the fusion of zoospores in Plasmodiophora brassicae are characterized by:
a) Two flagella
b) Four flagella
c) No flagella
d) Multiple flagella of equal size
Answer: b
31. What is the primary symptom of damping off caused by Pythium aphanidermatum?
a) Yellowing and wilting of older leaves
b) Rapid death and collapse of young seedlings
c) Brown lesions on tubers
d) Root rotting in mature plants
Answer: b) Rapid death and collapse of young seedlings
32. Which of the following is NOT a characteristic of Pythium aphanidermatum?
a) Facultative parasite
b) Hyaline, coenocytic mycelium
c) Presence of haustoria
d) Asexual reproduction via zoospores
Answer: c) Presence of haustoria
33. What type of flagella do the zoospores of Pythium aphanidermatum possess?
a) Both flagella are tinsel type
b) Both flagella are whiplash type
c) One is tinsel type, and the other is whiplash type
d) One is whiplash type, and the other is undifferentiated
Answer: c) One is tinsel type, and the other is whiplash type
34. In Pythium aphanidermatum, where is the oogonium typically formed?
a) At the base of the hyphal branch
b) At the tip of the hyphal branch
c) Inside the vesicle
d) On the sporangium
Answer: b) At the tip of the hyphal branch
35. What is the resting spore in the sexual reproduction of Pythium aphanidermatum?
a) Zoospore
b) Oospore
c) Sporangium
d) Hyphal fragment
Answer: b) Oospore
36. What is the primary method of infection in Pythium aphanidermatum?
a) Direct infection through stomata
b) Infection of young seedlings via zoospores
c) Infection of mature plants via sporangia
d) Infection through infected potato tubers
Answer: b) Infection of young seedlings via zoospores
37. Which of the following diseases is caused by Phytophthora infestans?
a) Powdery mildew
b) Late blight of potato
c) Club root of cabbage
d) Black rot of tomatoes
Answer: b) Late blight of potato
38. What is a key symptom of late blight of potato caused by Phytophthora infestans?
a) Water-soaked lesions on roots
b) Brown to purplish black water-soaked lesions on leaves
c) Yellowing and wilting of entire plant
d) White, cottony growth on stems
Answer: b) Brown to purplish black water-soaked lesions on leaves
39. What is the primary mode of reproduction for Phytophthora infestans?
a) Asexual reproduction via conidia
b) Sexual reproduction through zygotes
c) Asexual reproduction via sporangia
d) Sexual reproduction through oospores
Answer: c) Asexual reproduction via sporangia
40. Where are the sporangia of Phytophthora infestans typically produced?
a) On roots
b) On infected leaves and stems through stomata
c) On the surface of infected tubers
d) In the soil surrounding infected plants
Answer: b) On infected leaves and stems through stomata
41. The pathogen Phytophthora infestans causes which of the following symptoms in potato tubers?
a) Yellow lesions
b) Purplish, slightly sunken lesions leading to dry rot
c) Water-soaked lesions that enlarge slowly
d) Blackened roots
Answer: b) Purplish, slightly sunken lesions leading to dry rot
42. How does Phytophthora infestans spread to new plants?
a) By rain-spread zoospores from sporangia
b) Through wind-spread spores
c) By direct contact with infected roots
d) By insects carrying infected plant material
Answer: a) By rain-spread zoospores from sporangia
43. What type of mycelium does Phytophthora infestans have?
a) Septate, pigmented, and branched
b) Coenocytic, hyaline, and branched
c) Aseptate, unbranched, and transparent
d) Septate, colorless, and unbranched
Answer: b) Coenocytic, hyaline, and branched
44. The zoospores of Phytophthora infestans are
a) Uniflagellate and non-motile
b) Reniform, biflagellate, with one tinsel and one whiplash flagellum
c) Spherical and non-motile
d) Multinucleate and non-motile
Answer: b) Reniform, biflagellate, with one tinsel and one whiplash flagellum
45. Which of the following fungi is responsible for damping off in vegetables like tomato and brinjal?
a) Phytophthora infestans
b) Plasmodiophora brassicae
c) Pythium aphanidermatum
d) Bremia lactucae
Answer: c) Pythium aphanidermatum
46. What is the appearance of the mycelium in Pythium aphanidermatum?
a) Hyaline, septate, and branched
b) Hyaline, coenocytic, and branched
c) Brown, septate, and unbranched
d) Dark, septate, and unbranched
Answer: b) Hyaline, coenocytic, and branched
47. What is the function of the fertilization tube in the sexual reproduction of Pythium aphanidermatum?
a) To attach to the surface of the host cell
b) To transport enzymes for cell wall breakdown
c) To allow the fusion of gametes
d) To release oospores
Answer: c) To allow the fusion of gametes
48. What is the role of oospores in the life cycle of Pythium aphanidermatum?
a) To propagate the asexual cycle
b) To cause disease symptoms in the plant
c) To survive adverse environmental conditions
d) To produce more zoospores
Answer: c) To survive adverse environmental conditions
49. How does Phytophthora infestans affect potato leaves?
a) It causes wilting and yellowing from the edges
b) It forms black, sunken lesions that spread rapidly
c) It forms white, cottony growth on leaf undersides
d) It results in large necrotic patches
Answer: b) It forms black, sunken lesions that spread rapidly
50. Which of the following best describes the sporangium of Phytophthora infestans?
a) Multinucleate, thin-walled, and hyaline
b) Mononucleate, thick-walled, and pigmented
c) Multinucleate, thick-walled, and brown
d) Mononucleate, thin-walled, and orange
Answer: a) Multinucleate, thin-walled, and hyaline
51. What is the primary infection source for Phytophthora infestans?
a) Infected seeds
b) Infected tubers
c) Infected roots
d) Airborne spores
Answer: b) Infected tubers
52. In the life cycle of Pythium aphanidermatum, what does the oospore develop into upon germination?
a) A germ tube or saprophytic mycelium
b) A sporangium
c) A new zoospore
d) A haustorium
Answer: a) A germ tube or saprophytic mycelium
53. Which of the following characteristics is shared by both Pythium aphanidermatum and Phytophthora infestans?
a) Both have septate mycelium
b) Both produce asexual spores called sporangia
c) Both produce sexual spores called conidia
d) Both infect mature plants via tubers
Answer: b) Both produce asexual spores called sporangia
54. What causes the wilting and collapse of seedlings in the case of damping off by Pythium aphanidermatum?
a) Bacterial infection of the roots
b) Water-soaked lesions on the collar region
c) Infection by root-knot nematodes
d) Fungal mycelium blocking the vascular tissue
Answer: b) Water-soaked lesions on the collar region
55. What is the primary purpose of haustoria in Phytophthora infestans?
a) To facilitate nutrient absorption from the host plant
b) To produce zoospores
c) To protect the fungus from environmental stress
d) To produce sporangia
Answer: a) To facilitate nutrient absorption from the host plant
56. Which type of spore is formed during the sexual reproduction of Pythium aphanidermatum?
a) Conidia
b) Oospores
c) Zoospores
d) Sporangia
Answer: b) Oospores
57. What role do pectinolytic enzymes play in the infection process of Pythium aphanidermatum?
a) They promote the production of sporangia
b) They dissolve cell wall components and cause tissue maceration
c) They protect the fungus from host defenses
d) They initiate the germination of zoospores
Answer: b) They dissolve cell wall components and cause tissue maceration
58. What type of spore is produced in the asexual reproduction of Pythium aphanidermatum?
a) Conidia
b) Zoospores
c) Oospores
d) Zygospores
Answer: b) Zoospores
59. Which part of the plant does Phytophthora infestans primarily infect?
a) Roots and root hairs
b) Tubers and aerial parts
c) Flowers and fruits
d) Leaves and stems
Answer: b) Tubers and aerial parts
60. What is the function of the vesicle in the asexual reproduction of Pythium aphanidermatum?
a) To store oospores
b) To hold zoospores until they are released
c) To facilitate the fusion of gametes
d) To protect the pathogen from desiccation
Answer: b) To hold zoospores until they are released
61. What is the appearance of downy mildew caused by fungi?
a) Yellow patches on leaves
b) White downy growth on the lower surface of leaves
c) Brown lesions on the stem
d) Green spots on the flowers
Answer: b) White downy growth on the lower surface of leaves
62. Which of the following is a characteristic of the sporangiophore in Sclerospora?
a) Club-shaped with a swollen head
b) Branched at right angles
c) Branched dichotomously at acute angles
d) Short, stout with upright branches near the end
Answer: d) Short, stout with upright branches near the end
63. What symptom is often seen in severely infected plants with downy mildew caused by Sclerospora graminicola?
a) Necrosis in the root system
b) Green ear symptom, i.e., transformation of floral parts into leaf-like structures
c) Complete defoliation of the plant
d) Wilting of the seedlings
Answer: b) Green ear symptom, i.e., transformation of floral parts into leaf-like structures
64. What is the characteristic appearance of pustules formed by the white rust caused by Albugo candida?
a) Powdery yellowish spots on the upper leaf surface
b) Shiny white or creamy yellow pustules on the lower leaf surface
c) Brown lesions with concentric rings
d) Large, blackened patches on stems
Answer: b) Shiny white or creamy yellow pustules on the lower leaf surface
65. The pathogen Sclerospora graminicola belongs to which family?
a) Peronosporaceae
b) Albuginaceae
c) Pythiaceae
d) Mucoraceae
Answer: a) Peronosporaceae
66. Which of the following genera produces sporangiophores that are branched at right angles and irregularly spaced, causing downy mildew disease?
a) Plasmopara
b) Sclerospora
c) Peronospora
d) Pseudoperonospora
Answer: a) Plasmopara
67. What is the primary mode of infection for the downy mildew caused by Sclerospora graminicola?
a) Direct infection via soil-borne oospores
b) Infected seeds
c) Transmission via wind-borne sporangia
d) Root infection by zoospores
Answer: a) Direct infection via soil-borne oospores
68. Which of the following symptoms is characteristic of the white rust caused by Albugo candida on crucifers?
a) Leaves turn purple
b) Petals become green, and stamens turn into leaf-like structures
c) Formation of large sunken lesions on stems
d) Distorted fruit formation
Answer: b) Petals become green, and stamens turn into leaf-like structures
69. In the sexual reproduction of Sclerospora graminicola, the fertilization tube carries the male nucleus into which part of the fungus?
a) Zoospores
b) Oosphere
c) Sporangium
d) Mycelium
Answer: b) Oosphere
70. What is the type of sexual spore produced by Sclerospora graminicola?
a) Oospore
b) Zoospore
c) Sporangium
d) Conidium
Answer: a) Oospore
71. What is a typical feature of the sporangia produced by Albugo candida?
a) Multinucleate and oval in shape
b) Globose or hexagonal, hyaline, smooth, and thin-walled
c) Irregularly shaped and thick-walled
d) Biflagellate with a tinsel-type flagella
Answer: b) Globose or hexagonal, hyaline, smooth, and thin-walled
72. Which pathogen causes the disease known as white rust of crucifers?
a) Sclerospora graminicola
b) Albugo candida
c) Pythium aphanidermatum
d) Phytophthora infestans
Answer: b) Albugo candida
73. How do the sporangia of Albugo candida disperse to infect new plants?
a) By swimming in water
b) By wind
c) By contact with insect vectors
d) By rain splash
Answer: b) By wind
74. What is the result of severe infection by Albugo candida in flowers?
a) Flowers show malformation and discoloration
b) Complete desiccation of flowers
c) Flowers become enlarged and hypertrophied
d) Flowers turn into leaf-like structures
Answer: a) Flowers show malformation and discoloration
75. What kind of mycelium is found in Albugo candida?
a) Septate and branched
b) Coenocytic and branched
c) Non-septate and unbranched
d) Non-septate and intercellular
Answer: b) Coenocytic and branched
76. Which plant part does Sclerospora graminicola infect primarily?
a) Roots
b) Flowers
c) Leaves and floral organs
d) Stem and nodes
Answer: c) Leaves and floral organs
77. Which structure is responsible for the formation of zoospores in Sclerospora graminicola?
a) Sporangium
b) Oogonium
c) Antheridium
d) Mycelium
Answer: a) Sporangium
78. What is the method of asexual reproduction in Albugo candida?
a) Formation of conidia
b) Formation of sporangia
c) Formation of oospores
d) Formation of gametangia
Answer: b) Formation of sporangia
79. Which of the following describes the sporangiophore of Albugo candida?
a) Club-shaped, short, and non-septate
b) Branched with acute angles
c) Dichotomously branched with long, tapering tips
d) Straight and unbranched
Answer: a) Club-shaped, short, and non-septate
80. In the disease cycle of Sclerospora graminicola, how are oospores primarily dispersed?
a) By wind
b) By water
c) By insects
d) By seed contact
Answer: a) By wind
81. What is the significance of oospores in the life cycle of Sclerospora graminicola?
a) They are the source of primary infection
b) They produce new mycelium in the host plant
c) They help the pathogen survive under adverse conditions
d) They cause the collapse of plant tissues
Answer: c) They help the pathogen survive under adverse conditions
82. Which pathogen is known to cause the “green ear” symptom in pearl millet?
a) Pythium aphanidermatum
b) Sclerospora graminicola
c) Phytophthora infestans
d) Albugo candida
Answer: b) Sclerospora graminicola
83. In Albugo candida, what is the role of the disjunctor or isthmus in the sporangia formation?
a) It holds the sporangia together
b) It releases the zoospores
c) It helps in germination of oospores
d) It aids in fertilization
Answer: a) It holds the sporangia together
84. How do the zoospores of Albugo candida infect the host?
a) By encysting and forming a germ tube
b) By direct penetration of the epidermis
c) By swimming to the roots and infecting them
d) By forming a sexual spore
Answer: a) By encysting and forming a germ tube
85. Which type of gametangial arrangement is found in Albugo candida?
a) Paragynous
b) Monoclinous
c) Diclinous
d) Homothallic
Answer: a) Paragynous
86. What is the color of the oospores produced by Sclerospora graminicola?
a) Yellowish-brown
b) Green
c) Orange
d) Black
Answer: a) Yellowish-brown
87. Which symptom is associated with severe white rust infection on mustard and cauliflower?
a) Purple lesions on leaves
b) Stunting of plant growth
c) Enlarged and hypertrophied flowers
d) Leaf curling and wilting
Answer: c) Enlarged and hypertrophied flowers
88. What is the primary characteristic of the pathogen Sclerospora graminicola?
a) It is an obligate parasite
b) It is a facultative saprophyte
c) It is a free-living organism
d) It is a secondary pathogen
Answer: a) It is an obligate parasite
89. What is the appearance of the mycelium in Albugo candida?
a) Coenocytic and intercellular
b) Septate and hyaline
c) Branched and thick-walled
d) Single-celled and unbranched
Answer: a) Coenocytic and intercellular
90. Which plant part does Albugo candida primarily infect in white rust disease?
a) Root
b) Leaf, stem, and inflorescence
c) Fruit
d) Flower and pollen
Answer: b) Leaf, stem, and inflorescence
