ASRB NET and ARS: dairy disciplines · India · Agricultural Scientists Recruitment Board (ICAR)
Original practice questions written to the published syllabus · not past papersHow dairy laboratories sample, count, detect and certify: criteria, indicator organisms, rapid methods and lab quality systems.
In the exams: ICAR AICE subject 36 Unit 6 and subject 35b Units 1 and 3; ICAR AIEEA-PG group 16 (enumeration, isolation and identification of pathogens)
ASRB NET and ARS — Dairy Microbiology
Recall of methods, media, standards and calculations at Master's depth.
How our questions for ASRB NET and ARS spread across the units of Microbiological Quality Assurance & Rapid Methods. Difficulty: 10 easy, 16 medium, 5 hard.
| Indicator organisms: coliforms, Enterobacteriaceae, E. coli | 7 | |
| Biosafety levels and good microbiological practice | 7 | |
| Biosensors in dairy safety | 6 | |
| Standard plate count and other enumeration methods | 4 | |
| Detection and isolation of pathogens | 4 | |
| Rapid methods: ATP bioluminescence, PCR, real-time PCR, immunoassays | 3 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Coliforms are defined as Gram-negative non-spore-forming rods that:
A. Ferment lactose with acid and gas within 48 h at 30–37 °C
Lactose fermentation with acid and gas is the defining trait; Enterobacteriaceae are defined by glucose fermentation.
Further reading: ICMSF, Microorganisms in Foods 7, 2nd ed.
Coliform counts in raw milk mainly reflect:
A. Hygiene of milking and equipment
In raw milk they are expected and indicate milking and equipment hygiene.
Further reading: ICMSF, Microorganisms in Foods 7, 2nd ed.
The most probable number method is especially useful for:
B. Low numbers in liquids
MPN estimates concentration statistically from positive tubes at several dilutions; it suits low counts.
Further reading: Wehr and Frank (eds), Standard Methods for the Examination of Dairy Products, 17th ed.
Surface plasmon resonance detects binding by a change in:
B. Refractive index at a metal surface
SPR is an optical label-free method used, for example, for antibiotic residues in milk.
Further reading: Wehr and Frank (eds), Standard Methods for the Examination of Dairy Products, 17th ed.
An amperometric biosensor measures:
D. Current
Amperometric sensors measure current; potentiometric ones measure potential; impedimetric ones measure impedance.
Further reading: Wehr and Frank (eds), Standard Methods for the Examination of Dairy Products, 17th ed.
Salmonella, Listeria monocytogenes and Staphylococcus aureus are handled at:
B. BSL-2
They are risk group 2 agents: disease is possible but treatable and spread is limited.
Further reading: Wehr and Frank (eds), Standard Methods for the Examination of Dairy Products, 17th ed.
A Class II biological safety cabinet protects:
D. The worker, the sample and the environment
Inward airflow and HEPA-filtered downflow protect all three; Class I does not protect the sample.
Further reading: Wehr and Frank (eds), Standard Methods for the Examination of Dairy Products, 17th ed.
A Class III biological safety cabinet is:
A. A sealed, gas-tight glove box
Class III cabinets provide maximum containment for the most dangerous agents.
Further reading: ICMSF, Microorganisms in Foods 7, 2nd ed.
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