Mycology MCQ Questions (Oomycetes):

Instructions: Choose the best answer for each question.

1. Which of the following is a defining characteristic of Oomycetes?

a) Presence of chitin in cell walls
b) Heterokont flagella on zoospores
c) Homokont flagella on zoospores
d) Exclusively terrestrial habitat

Answer: b) Heterokont flagella on zoospores

2. What type of flagella does a Saprolegniales zoospore possess?

a) One tinsel type
b) One whiplash type
c) Two whiplash type
d) One whiplash and one tinsel type

Answer: d) One whiplash and one tinsel type

3. Which of the following is NOT a major component of Oomycetes cel

l walls?
a) Cellulose
b) Glucans
c) Chitin
d) β(1-3) and β(1-6) glycosidic linkages

Answer: c) Chitin

4. What is the term for an Oomycete with a thallus consisting of a sing

le cell?
a) Eucarpic
b) Holocarpic
c) Diplantic
d) Dimorphic

Answer: b) Holocarpic

5. Which order of Oomycetes is primarily aquatic and often found as s

aprophytes on plant and animal debris?
a) Peronosporales
b) Leptomitales
c) Laginidiales
d) Saprolegniales

Answer: d) Saprolegniales

6. What are the two types of zoospores found in some genera of Sapr
olegniales?
a) Apically flagellated and laterally flagellated
b) Whiplash and tinsel
c) Primary and secondary
d) Pear-shaped and bean-shaped

**Answer: a) Apically flagellated and laterally flagellated **

7. What is the phenomenon of repeated encystment and motility of zo

ospores called?
a) Diplanetism
b) Dimorphism
c) Polyplanetism
d) Heterokont

Answer: c) Polyplanetism

8. What is the primary mode of asexual reproduction in Saprolegniace

ae?
a) Budding
b) Fragmentation
c) Zoosporogenesis
d) Conidiogenesis

Answer: c) Zoosporogenesis

9. What is the function of the gemma in Saprolegniaceae?

a) Asexual reproduction
b) Sexual reproduction
c) Survival under unfavorable conditions
d) Nutrient absorption

Answer: c) Survival under unfavorable conditions

10. In Saprolegnia, how are zoospores released from the sporangium?
a) Through a pore at the tip
b) By rupture of the sporangial wall
c) Through a lateral opening
d) By dissolution of the sporangium

Answer: a) Through a pore at the tip

11. What is the shape of the secondary zoospores in Saprolegnia?

a) Pear-shaped
b) Bean-shaped
c) Spherical
d) Filamentous

Answer: b) Bean-shaped

12. How does zoosporangial development in Achlya differ from that in

Saprolegnia?
a) Zoospores are released directly into the water
b) Zoospores encyst at the mouth of the sporangium
c) No secondary zoospores are produced
d) Zoosporangia develop laterally

Answer: b) Zoospores encyst at the mouth of the sporangium

13. What is the term for a species in which a single strain can produce
both male and female reproductive structures?
a) Heterothallic
b) Dioecious
c) Monoecious
d) Homothallic

Answer: d) Homothallic

14. What is the term for the development of an egg without fertilizatio
n?
a) Parthenogenesis
b) Apogamy
c) Oogamy
d) Anisogamy
Answer: b) Apogamy

15. How many eggs are typically found within an oogonium of Saprole
gniaceae?
a) One
b) Two
c) Many
d) None

Answer: c) Many

16. What structure facilitates the fertilization of the egg by the antheri
dium?
a) Germ tube
b) Flagellum
c) Fertilization tube
d) Conidiophore

Answer: c) Fertilization tube

17. What is the term for an arrangement where the antheridial branche
s arise from the stalk of the oogonium?
a) Androgynous
b) Monoclinous
c) Diclinous
d) Heterothallic

Answer: a) Androgynous

18. What is the function of the preplasm in a multinucleated oogonium

?
a) Formation of the egg wall
b) Providing nutrition to the oospore
c) Initiating germination of the oospore
d) Attracting antheridia

Answer: b) Providing nutrition to the oospore

19. What structure does the oospore germinate to produce?

a) Zoospore
b) Conidium
c) Germ tube
d) Sporangium

Answer: c) Germ tube

20. Which order of Oomycetes is primarily terrestrial and includes pla

nt pathogens?
a) Saprolegniales
b) Leptomitales
c) Peronosporales
d) Laginidiales

Answer: c) Peronosporales

21. What structure in Leptomitales distinguishes them from Saprolegn

iales?
a) Cellulin plugs
b) Apically attached flagella
c) Multiple oospores per oogonium
d) Holocarpic thallus

Answer: a) Cellulin plugs

22. Which order of Oomycetes is primarily parasitic on algae and wate

r molds?
a) Saprolegniales
b) Leptomitales
c) Peronosporales
d) Laginidiales

Answer: d) Laginidiales

This is a sample of 22 questions. You can use these as a starting point and
expand upon them to create a total of 50 questions. Remember to include
questions about the life cycles, specific structures, ecological roles, and ec
onomic importance of Oomycetes.
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Mycology MCQ Questions (Oomycetes) - Continued:
23. What is the primary function of zoospores in Oomycetes?
a) Sexual reproduction
b) Dispersal and colonization of new substrates
c) Survival under unfavorable conditions
d) Nutrient absorption

Answer: b) Dispersal and colonization of new substrates

24. Which of the following statements about Oomycetes is FALSE?

a) They are eukaryotic organisms.
b) They obtain nutrients through absorption.
c) They are closely related to true fungi.
d) They play important roles in aquatic ecosystems.

Answer: c) They are closely related to true fungi.

25. What is the ecological role of saprophytic Oomycetes?

a) Decomposers of organic matter
b) Pathogens of plants
c) Symbionts with algae
d) Predators of small animals

Answer: a) Decomposers of organic matter

26. Which Oomycete disease caused the Irish Potato Famine?

a) Downy mildew of grapes
b) Late blight of potato
c) White rust of crucifers
d) Powdery mildew of roses

Answer: b) Late blight of potato

27. What is the economic importance of Phytophthora infestans?

a) Causes significant losses in potato and tomato crops
b) Degrades wood in buildings
c) Contaminates food products
d) Infects fish in aquaculture

Answer: a) Causes significant losses in potato and tomato crops

28. Which of the following structures is NOT involved in sexual reprod
uction in Oomycetes?
a) Zoosporangium
b) Oogonium
c) Antheridium
d) Oospore

Answer: a) Zoosporangium

29. What is the advantage of having two types of zoospores in some

Oomycetes?
a) Increased genetic diversity
b) Enhanced dispersal and colonization
c) Improved survival under stress
d) All of the above

Answer: d) All of the above

30. Which of the following factors can influence the development of O

omycete diseases?
a) Temperature
b) Humidity
c) Host susceptibility
d) All of the above

Answer: d) All of the above

31. What is a common management strategy for Oomycete diseases?

a) Use of resistant cultivars
b) Application of fungicides
c) Crop rotation
d) All of the above

Answer: d) All of the above

32. Which of the following is NOT a genus within the order Saprolegni
ales?
a) Saprolegnia
b) Achlya
c) Phytophthora
d) Dictyuchus
Answer: c) Phytophthora

33. What structure distinguishes Leptomitales from other Oomycete o

rders?
a) Cellulin plugs at hyphal constrictions
b) Apically attached flagella on zoospores
c) Production of multiple oospores per oogonium
d) Absence of sexual reproduction

Answer: a) Cellulin plugs at hyphal constrictions

34. What is the primary habitat of Laginidiales?

a) Soil
b) Freshwater
c) Marine environments
d) Plant surfaces

Answer: b) Freshwater

35. Which of the following features is characteristic of Peronosporale

s?
a) Often terrestrial and parasitic on vascular plants
b) Zoosporangia can function as conidia
c) Includes significant plant pathogens
d) All of the above

Answer: d) All of the above

36. What is the difference between a zoosporangium and a conidium?

a) Zoosporangia produce zoospores, while conidia are dispersed directly
b) Zoosporangia are asexual, while conidia are sexual
c) Zoosporangia are produced by Saprolegniales, while conidia are produc
ed by Peronosporales
d) There is no difference; the terms are interchangeable

Answer: a) Zoosporangia produce zoospores, while conidia are disper

sed directly

37. Which of the following is an example of a biocontrol agent used ag

ainst Oomycetes?
a) Bacillus thuringiensis
b) Trichoderma harzianum
c) Beauveria bassiana
d) Metarhizium anisopliae

Answer: b) Trichoderma harzianum

38. What are the implications of the fact that Oomycetes are not true f
ungi?
a) Antifungal medications may not be effective against them
b) Different management strategies may be required for their control
c) Their evolutionary history is distinct from that of true fungi
d) All of the above

Answer: d) All of the above

39. What is the role of chemotaxis in the sexual reproduction of Oomy

cetes?
a) Guiding the growth of antheridial branches towards oogonia
b) Initiating the release of zoospores
c) Triggering the germination of oospores
d) Enhancing the dispersal of conidia

Answer: a) Guiding the growth of antheridial branches towards oogon

ia

40. Which of the following environments is LEAST likely to harbor Oo

mycetes?
a) A stagnant pond
b) A decaying log
c) A dry desert soil
d) A field of potatoes

Answer: c) A dry desert soil

41. What is the name of the chemical compound often found in the cel
l walls of Oomycetes but absent in true fungi?
a) Chitin
b) Cellulose
c) Lignin
d) Peptidoglycan
Answer: b) Cellulose

42. What is the term for the thickened, enlarged hyphal segments that
allow Saprolegniaceae to survive harsh conditions?
a) Zoosporangia
b) Oogonia
c) Conidia
d) Gemma

Answer: d) Gemma

43. In what ways do Oomycetes contribute to the cycling of nutrients i

n ecosystems?
a) Decomposing organic matter and releasing nutrients back into the enviro
nment
b) Parasitic interactions with other organisms can influence population dyna
mics
c) Their presence can alter the physical structure of habitats
d) All of the above

Answer: d) All of the above

44. How are Oomycetes classified taxonomically?

a) Kingdom Fungi
b) Kingdom Protista
c) Kingdom Chromista
d) Kingdom Stramenopila

Answer: d) Kingdom Stramenopila

45. Which of the following is a potential area for future research on Oo

mycetes?
a) Development of novel biocontrol strategies
b) Understanding the molecular mechanisms of pathogenesis
c) Exploring the diversity and ecological roles of Oomycetes
d) All of the above

Answer: d) All of the above

46. What is the term for the type of sexual reproduction where the ga
metes are morphologically distinct?
a) Isogamy
b) Anisogamy
c) Oogamy
d) Parthenogenesis

Answer: c) Oogamy

47. How does the presence of cellulin plugs in Leptomitales relate to t

heir ecological niche?
a) Enhances their ability to survive in low-nutrient environments
b) Aids in the dispersal of zoospores
c) Provides structural support for their hyphae
d) Facilitates the formation of fertilization tubes

Answer: c) Provides structural support for their hyphae

48. What is the significance of the discovery that zoosporangia in Per

onosporales can function as conidia?
a) It highlights the adaptability of Oomycetes
b) It demonstrates the importance of asexual reproduction
c) It suggests that these structures are not homologous to those in true fun
gi
d) All of the above

Answer: d) All of the above

49. What is the role of molecular techniques in the study of Oomycete

s?
a) Identifying new species
b) Understanding evolutionary relationships
c) Diagnosing diseases
d) All of the above

Answer: d) All of the above

50. What are the broader implications of studying Oomycetes?

a) Enhancing our understanding of eukaryotic evolution
b) Developing new strategies for disease control
c) Gaining insights into ecological processes
d) All of the above
Answer: d) All of the abov