Unit 7: Arbuscular Mycorrhizal Fungi (AMF) - Practice Quiz

1 Which method is commonly used to separate AMF spores from soil particles?

2 What type of sample is usually collected for isolating AMF spores?

3 What is the main purpose of adding water during the initial separation of soil samples?

4 Which tool is commonly used to collect individual AMF spores after sieving?

5 Why are different sieve sizes used during AMF spore isolation?

6 Which solution is often used in density-gradient centrifugation to help recover AMF spores?

7 What should be done with isolated AMF spores before microscopic identification?

8 Which feature is commonly examined when identifying AMF spores?

9 Which instrument is mainly used for observing AMF spore morphology?

10 What is a spore wall in an AMF spore?

11 Which characteristic can help distinguish different AMF species?

12 What does spore pigmentation refer to?

13 Which structure may be observed at the point where an AMF hypha attaches to a spore?

14 Why are AMF spore identification keys used?

15 Which observation is most useful for basic AMF spore identification?

16 What does AMF spore density usually mean?

17 If 60 AMF spores are found in 10 g of soil, what is the spore density?

18 Which counting method is commonly used to estimate AMF spores in a sample?

19 Why should a known amount of soil be used for AMF spore counting?

20 What is the main advantage of counting AMF spores in replicate soil samples?

21 During wet sieving and decanting, a soil suspension is allowed to settle briefly before the supernatant is poured through sieves. Why is the settling period kept short?

22 A researcher passes a soil suspension through sieves with openings of 500, 250, 100, and 45 . Which fractions should be examined to obtain the broadest recovery of AMF spores?

23 After wet sieving, the collected fraction contains many fine clay particles that obscure AMF spores. Which additional procedure is most appropriate?

24 Why should AMF spores recovered by sucrose centrifugation be rinsed promptly with water?

25 Two soil samples are being compared for AMF spore abundance. Which sampling procedure best supports a valid comparison?

26 A compact clay soil forms persistent aggregates during wet sieving. What is the best initial adjustment for improving spore release without damaging spores?

27 Following centrifugation in a sucrose solution, where are intact AMF spores most commonly recovered?

28 Which combination of characters is most useful for morphological identification of an isolated AMF spore?

29 A spherical object recovered from soil has a smooth outline but no visible wall layers or hyphal attachment. What is the most appropriate conclusion?

30 Why are AMF spores commonly mounted in polyvinyl alcohol-lactic acid-glycerol with Melzer's reagent during identification?

31 A spore is gently crushed under a coverslip before microscopic examination. What feature becomes easier to evaluate?

32 Several isolated spores are pale, thin-walled, and lack clearly developed diagnostic structures. What is the most likely identification problem?

33 Two AMF spores have similar color and diameter but differ in the structure of their subtending hyphae. How should this observation be used?

34 Which approach provides the strongest identification when an AMF specimen has ambiguous morphological characters?

35 A researcher counts 160 AMF spores in 80 g of dry soil. What is the spore density per 100 g of dry soil?

36 Only one-quarter of a well-mixed spore suspension is examined, and 45 spores are counted. What is the estimated total number of spores in the suspension?

37 Counts from four equal soil subsamples are 72, 80, 76, and 92 spores. What is the mean count per subsample?

38 Sample X contains 120 spores in 50 g of dry soil, while Sample Y contains 180 spores in 100 g. Which sample has the greater standardized spore density?

39 Repeated counts from the same homogenized soil sample vary widely. Which action would most directly improve the precision of the estimated mean spore density?

40 A 40 g field-moist soil sample contains 25% water by mass and yields 90 spores. What is the spore density per 100 g of dry soil?

41 A soil sample contains many clay particles and organic debris, and the expected AMF spores range from 45 to 180 . Which isolation sequence is most appropriate for maximizing spore recovery while reducing debris?

42 During wet sieving, a researcher discards the material retained on the largest sieve before examining it. Which important bias may result?

43 A sample is processed by centrifugation in 60% sucrose, but the recovered spores are collapsed and difficult to identify. Which procedural change most directly addresses this problem?

44 Two soil samples have identical AMF abundance, but one contains substantially more clay. If both are processed using only wet sieving, what is the most likely outcome?

45 A researcher wants to establish a trap culture from an AMF-containing soil but suspects that the native soil also contains plant pathogens. Which design best preserves the purpose of the culture while reducing pathogen carryover?

46 A sample is intended for both morphological identification and DNA-based confirmation. Which handling practice is most appropriate?

47 A round, brown structure isolated from soil has a thick wall but no visible subtending hypha. Which conclusion is most defensible?

48 Which combination provides the strongest morphological evidence for distinguishing closely related AMF spore taxa?

49 A spore appears smooth in water but shows a laminated wall and a faint reaction in Melzer's reagent. Why should the water-based observation not be used alone for identification?

50 Several isolated structures have similar diameters and colors, but some contain abundant lipid droplets while others are empty and granular. What is the best interpretation?

51 A researcher identifies AMF solely from spores collected after trap culture with a single host. What limitation is most important?

52 An unknown spore has a persistent two-layered wall, a narrow subtending hypha, and surface ornamentation visible only after careful optical focusing. Which identification strategy is most reliable?

53 A 50 g soil sample yields 120 counted spores after extraction. The method recovers 80% of spores, and the researcher wants to report the estimated density per 100 g soil. What is the corrected density?

54 A soil suspension is divided into four equal subsamples. The counted spore numbers are 18, 22, 20, and 40. Which summary best represents the data for a routine abundance estimate?

55 Two treatments produce mean spore densities of 100 and 150 spores per 100 g soil, but the second treatment has much greater extraction variability. Which conclusion is most justified?

56 A counting dish contains many spores concentrated along the edge of the grid. Which procedural adjustment most improves the validity of the count?

57 A study reports 85 AMF spores per 100 g soil, but the authors used 10 g of soil from one composite sample and made no recovery correction. Which limitation most directly affects interpretation?

58 A researcher counts intact, crushed, and empty AMF spores together when comparing treatments. What is the main interpretive problem?

59 A treatment increases spore counts but decreases root colonization in the same experiment. Which explanation is most scientifically defensible?

60 A laboratory compares AMF spore densities across soils with different moisture contents but reports values only on a wet-mass basis. Why is this comparison potentially biased?