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Describe a laboratory or field experiment for any two of the following: (a) to determine the dry matter content of different potato varieties (b) to determine the hygienic quality of milk (c) to demonstrate soil flocculation (d) to demonstrate the effects of grazing on the botanical composition of grassland. - Leaving Cert Agricultural Science - Question 4 - 2011
Question 4
Describe a laboratory or field experiment for any two of the following: (a) to determine the dry matter content of different potato varieties (b) to determine the ... show full transcript
Worked Solution & Example Answer:Describe a laboratory or field experiment for any two of the following: (a) to determine the dry matter content of different potato varieties (b) to determine the hygienic quality of milk (c) to demonstrate soil flocculation (d) to demonstrate the effects of grazing on the botanical composition of grassland. - Leaving Cert Agricultural Science - Question 4 - 2011
Step 1
(a) to determine the dry matter content of different potato varieties
Answer
To determine the dry matter content of different potato varieties, follow these steps:
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Sample Preparation: Take two or more varieties of potato. Chop them into small pieces and weigh the crucibles where the samples will be placed.
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Drying Process: Place the potato samples in the crucibles in a drying oven set to 100 degrees Celsius. Monitor the weight at regular intervals until the weight loss is calculated.
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Reweighing: After you determine when further weight loss has ceased, reweigh the samples.
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Calculating Dry Matter: Use the formula to calculate the percentage of dry matter: ext{Dry Matter extit{( extperthousand)}} = rac{ ext{New Weight - Old Weight}}{ ext{Old Weight}} imes 100
Step 2
(b) to determine the hygienic quality of milk
Answer
To determine the hygienic quality of milk, follow these steps:
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Sample Collection: Place the milk sample in sterile test tubes. Add 1 ml of resazurin solution to the tube.
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Incubation: Stopper the test tube to prevent contamination and incubate it at a temperature of 37 degrees Celsius for 10 minutes.
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Color Observation: After incubation, check the color change in the medium. The color range should indicate quality:
- Blue: Hygienic (best)
- Pink: Moderately hygienic (poor)
- White: Non-hygienic (worst)
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Control Sample: Use two sterile agar plates—one inoculated with the milk and the other as a control. Incubate both samples at 37 degrees for 24 hours or more. Observe for colony growth in the inoculated plate compared to the control.