NEMATOLOGY 100 MID-TERM EXAM -- 1 1/2 HOURS
MID-TERM EXAM, 10/25/06 90 minutes
1. (20 points)
You are provided with nematodes extracted from various sources that have been centrifuged and the supernatant water removed. Use a fine pipette to suspend the nematodes in the small volume of liquid in the centrifuge tube and spread it on a microscope slide in a strip about 0.5 cm wide and 3 cm long. Save some of the suspension in the centrifuge tube in case you are not satisfied with the slide that you prepare.
a. Use a binocular microscope to confirm the presence of nematodes in the strip and then kill them with gentle heat.
Apply a long coverslip.
Seal the edge of the coverslip with fingernail polish to prevent the slide from drying out.
Place the slide on the compound microscope and adjust the microscope to provide Köhler illumination.
b. Select a nematode that has the following characteristics:
(i) adult female of the Order Tylenchida.
(ii) good condition with structures of the esophagus and stoma clearly visible.
c. Indicate on your exam sheet the Class and Order of your nematode.
d. Draw and label the component parts of the stylet and esophagus for this type of nematode (either from your specimen, or from your knowledge of anatomy and morphology, or both).
e. From the morphological and anatomical characteristics of the specimen, indicate a probable feeding habit for this nematode and explain why.
f. Call the instructor for examination of your nematode. If there is more than one nematode present in the microscope field, indicate the specimen you wish to have examined. Do not ask or expect the instructor to make the selection.
Only the nematode that you indicate initially will be considered.
Grading:
adult female plant-parasite, good condition…………..…… 8 pts
juvenile, male or non-parasite, good condition……………. 4 pts
correct designation of Class and Order…………………..... 3 pts
reasonable justification of feeding habit designation……... 3 pts
correct drawing and identification of stylet/esophagus…… 6 pts
points off for damage, distortion, dry slides, etc.
2. (10 points)
a. Describe the feeding habits of the sheath nematode, Hemicycliophora arenaria.
b. How are the survival and reproduction of the nematode influenced by environmental conditions?
3. (10 points)
In the lower table, provide information from the upper table for each of the nematodes listed (answer by using the appropriate letter).
|
(i) Order |
(ii) Esophagus type |
(iii) Number of ovaries |
(iv) Virus vector? |
|
| a) Tylenchida | a) tylenchid - butting | a) one | a) yes | a) migratory ectoparasite |
| b) Rhabditida | b) tylenchid - overlapping | b) two | b) no | b) migratory endoparasite |
| c) Triplonchida | c) dorylaimid | c) more than two | c) sedentary endoparasite | |
| d) Dorylaimida |
|
Mesocriconema xenoplax (ring nematode)
|
Tylenchorhynchus claytoni
(stunt nematode)
|
Paratylenchus hamatus
(pin nematode)
|
(i) Order
|
|
|
|
(ii) Esophagus type
|
|
|
|
(iii) Number of ovaries
|
|
|
|
(v) Virus vector?
|
|
|
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(vi) Adult female feeding habit
|
|
|
|
4. (10 points)
a. Describe, with the aid of drawings, the components of the male reproductive system in nematodes.
b. Briefly describe the function of each structure.
5. (5 points)
Briefly describe the excretory systems of a tylenchid and a dorylaimid nematode.
6. (10 points)
List five diagnostic characteristics of the Phylum Nematoda.
7. (5 points)
a. How many Orders are there in the Phylum Nematoda?
b. Name the Orders that contain plant-feeding nematodes.
8. (10 points)
a. What are the functions of a plant root?
b. List the ways in which plant roots may be damaged by, or respond to, plant-parasitic nematodes.
9. (10 points)
Briefly describe a method of separating nematodes from soil that does not require the nematodes to be motile.
10. (10 points)
a. Describe the geographic location and soil conditions that favor the sting nematode, Belonolaimus longicaudatus.
b. What crops or plantings are damaged by this nematode?