AIM • KMU EXAM PRACTICE

Based on the supplied Topic 10 curriculum and assessment requirements. :contentReference[oaicite:0]{index=0}

Question:

An anticoagulated blood sample obtained during a medico-legal investigation is centrifuged. The laboratory needs the liquid component containing water, electrolytes and circulating proteins. Which portion should be examined?

Options:

Correct Answer:
Plasma

Explanation: Plasma is the fluid component of blood and contains water, electrolytes and soluble proteins that may also provide inherited forensic markers.

Question:

Microscopy of a blood specimen shows very small anucleate cytoplasmic fragments derived from larger marrow cells. Their major physiological role is hemostasis rather than carriage of blood-group antigens. Which formed element is being described?

Options:

Correct Answer:
Platelets

Explanation: Platelets are anucleate cytoplasmic fragments derived from megakaryocytes and participate principally in hemostasis.

Question:

Following a struggle, a minute paint fragment from a door frame is recovered from a suspect’s jacket. The material may help establish an association with the scene despite being present only in a very small amount. How should this material be classified?

Options:

Correct Answer:
Non-biological trace evidence

Explanation: Paint is non-biological trace evidence; its forensic value comes from possible transfer and association rather than biological origin.

Question:

A deceased man’s old medical record lists his ABO phenotype as group A. Investigators are considering inheritance patterns in a family dispute. Which genotype information can be inferred from this phenotype?

Options:

Correct Answer:
AA or AO is possible

Explanation: The A phenotype may result from AA or AO genotype because the O allele is recessive to A.

Question:

A woman with blood group AB and a man with blood group O are the documented parents of a child. Which ABO phenotype would be genetically compatible with this parental combination?

Options:

Correct Answer:
A or B

Explanation: The AB parent can transmit A or B, while the O parent contributes O; therefore the child may be AO or BO.

Question:

Red cells from a questioned sample agglutinate with anti-A reagent but show no agglutination with anti-B reagent. Which ABO phenotype is most consistent with this pattern?

Options:

Correct Answer:
Group A

Explanation: Agglutination with anti-A demonstrates A antigen on the red cells, while absence of reaction with anti-B indicates lack of B antigen.

Question:

During Rh typing, a patient’s red cells show no agglutination after exposure to anti-D reagent under appropriate testing conditions. Which interpretation is most appropriate?

Options:

Correct Answer:
D antigen is not detected

Explanation: Anti-D agglutinates red cells carrying D antigen; absence of agglutination supports an Rh-negative phenotype.

Question:

A laboratory wishes to detect a soluble inherited blood protein. The examiner explains that conventional direct red-cell agglutination is unsuitable for this marker. Which feature best explains this limitation?

Options:

Correct Answer:
The marker is not naturally carried on visible cells or particles

Explanation: Direct agglutination requires particulate or cell-bound antigen; soluble markers require precipitation methods or attachment to carrier particles.

Question:

A patient develops a severe reaction after a blood unit intended for another patient is administered. A medico-legal review is started to determine how the error occurred. Which evidence is most directly useful for reconstructing the transfusion mistake?

Options:

Correct Answer:
Patient, unit and compatibility records

Explanation: Identification, blood-group and compatibility documentation can directly demonstrate where a transfusion mismatch occurred.

Question:

An Rh-negative woman was previously exposed to Rh-positive red cells. During a later exposure to Rh-positive cells, a clinically important immune reaction becomes more likely. Which underlying event best explains the increased hazard?

Options:

Correct Answer:
Previous sensitization to the D antigen

Explanation: Initial exposure can induce anti-D sensitization, making subsequent exposure to D-positive red cells more hazardous.

Question:

Several stains are present on clothing recovered after an assault. Before portions are removed for laboratory testing, the forensic examiner photographs and records their colour, dimensions, shape and distribution. What is the main reason for completing this step first?

Options:

Correct Answer:
Laboratory sampling may alter the original physical features

Explanation: Physical features should be documented before testing because collection or laboratory examination may consume or alter the original stain.

Question:

A brown stain on a floor gives a positive oxidation-based presumptive test, but subsequent examination fails to confirm blood. Which explanation best accounts for the initial result?

Options:

Correct Answer:
A non-blood substance produced a similar oxidative reaction

Explanation: Presumptive oxidation tests are sensitive but not completely specific; other substances may generate a similar colour reaction.

Question:

After an attempt to clean a floor, faint luminescent areas are detected during forensic examination. Investigators wish to use these areas for further evidentiary testing. What is the most appropriate interpretation of the luminescence?

Options:

Correct Answer:
It helps locate possible blood requiring further examination

Explanation: Luminescence-based testing is valuable for locating occult traces, but confirmation and further characterization are still required.

Question:

A group of bloodstains on a wall has a distinctive distribution that may help investigators understand how blood reached the surface. Which conclusion represents the most appropriate forensic use of this physical information?

Options:

Correct Answer:
It provides contextual information that requires cautious interpretation

Explanation: Stain shape and distribution may assist contextual reconstruction but should not be treated as independent proof of identity or events.

Question:

An old bloodstain is characterized using several genetically determined enzyme variants. The findings narrow the possible sources, but investigators also have access to modern genetic testing. Which statement best describes the value of the enzyme results?

Options:

Correct Answer:
They provide supplementary inherited characterization

Explanation: Enzyme polymorphisms can add inherited biological information, but their discriminatory power is substantially lower than DNA profiling.

Question:

A shirt containing several dried suspected bloodstains is recovered intact from a scene. The garment can be safely transported to the laboratory without removing the stains. Which collection approach best preserves the evidence?

Options:

Correct Answer:
Submit the stained garment intact when feasible

Explanation: A movable stained object may be submitted intact when appropriate, minimizing unnecessary loss, mixing or alteration of the evidence.

Question:

A cellular smear prepared during a medico-legal examination is being sent to the laboratory. Which handling principle is most important for preserving the material already deposited on the slide?

Options:

Correct Answer:
Protect it from contamination and mechanical damage

Explanation: Smears should be handled in a way that preserves deposited cells and prevents contamination or physical disruption.

Question:

Investigators suspect that saliva was deposited on the rim of a drinking glass. The glass also has areas extensively handled by several other people. Which sampling approach best reduces unnecessary contamination?

Options:

Correct Answer:
Collect specifically from the relevant contact area using clean technique

Explanation: Targeted clean collection preserves the relationship between the specimen and the relevant site while limiting contamination from neighbouring surfaces.

Question:

A recently collected semen stain on fabric is still damp. The laboratory may later require examination of both cellular and non-cellular components. Which approach best preserves the specimen?

Options:

Correct Answer:
Allow appropriate drying and preserve it separately

Explanation: Appropriate drying and separate preservation reduce moisture-related deterioration while protecting potentially useful cellular and non-cellular components.

Question:

Three separately collected biological swabs are correctly transported to the laboratory, but two labels are accidentally exchanged before analysis. The laboratory tests themselves are technically accurate. Which part of the evidentiary interpretation is now most seriously compromised?

Options:

Correct Answer:
Reliable linkage of each result to its specimen source

Explanation: Accurate laboratory analysis has limited medico-legal value if incorrect labelling prevents the result from being reliably attributed to the original specimen.