RRB LA UT16 – Histopathology Practice Test 1: Tissue Fixation & Fixatives

About this Assessment

About This Practice Test:
This targeted 30-question bilingual (English and Hindi) online practice test evaluates fundamental knowledge in Histotechnology and Diagnostic Tissue Fixation. Designed strictly according to the RRB Paramedical Category (Laboratory Assistant Grade II, CEN 05/2026) CBT standards and standard MLT curriculum, this test covers chemical mechanisms of fixatives, fixative formulations, fixation artifacts, and tissue preservation standards.

Syllabus Covered:
– Fundamentals of tissue fixation: Aims, autolysis vs. putrefaction, physical vs. chemical fixation, and fixative-to-tissue ratio (commonly at least 10:1; many routine protocols use approximately 10:1 to 20:1)
– Aldehyde fixatives: 10% Neutral Buffered Formalin (4% formaldehyde), phosphate buffering system (pH 6.8 to 7.2), methylene bridge formation, and role of methanol stabilizer
– Compound fixatives and applications:
* Bouin’s fluid (saturated picric acid, 40% formaldehyde, glacial acetic acid) and handling protocols
* Zenker’s fluid and Helly’s fluid (Zenker-formol) formulations
* Carnoy’s rapid nuclear fixative (alcohol, chloroform, acetic acid) and RBC lysis
* B5 fixative for bone marrow trephine biopsy and Baker’s formal-calcium for phospholipids
– Histological fixation artifacts:
* Acid hematin (formalin pigment) formation and removal via alcoholic picric acid
* Mercury pigment deposits and dezenkerization (alcoholic iodine and sodium thiosulfate)
* Chrome oxide precipitate prevention by thorough water washing
* Air-drying artifacts, autolytic necrosis, inadequate fixation, and prolonged-fixation consequences
– Specialized techniques: Glutaraldehyde and Osmium tetroxide for electron microscopy (TEM), microwave-assisted rapid fixation, and routine fixation considerations for bone marrow trephine core biopsies (NBF and protocol-dependent alternatives such as AZF/B5)

 Applicable Examinations:
– RRB Paramedical Recruitment (Laboratory Assistant Grade II, CEN 05/2026)
– Central Recruitment Boards: DSSSB Lab Technician, ESIC MLT, AIIMS Laboratory Technician, CGHS
– State Medical Faculty and State Paramedical Board Technical Examinations

Test Instructions & Features:
– 30 Questions | Fully Bilingual (English +  Hindi)
– Timed CBT Mode: 30 Minutes (1 Minute per Question)
– CBT Marking Scheme: +1.00 for Correct Answer, -0.33 for Incorrect Answer (1/3rd Negative Marking)
– Step-by-Step Technical Explanations for Every MCQ