Biochemistry
1 questionsWhich of the following acids is MOST commonly used as a reagent in medical laboratory analytical procedures?
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 571: Which of the following acids is MOST commonly used as a reagent in medical laboratory analytical procedures?
- A. Nitric acid is used in chemical analysis.
- B. Carbolic acid is used as a disinfectant.
- C. Oxalic acid is used in various laboratory applications.
- D. Sulphuric acid is used in various laboratory processes. (Correct Answer)
Explanation: ***Sulphuric acid*** is the most commonly used acid in medical laboratory analytical procedures. - **Sulfuric acid (H₂SO₄)** is a strong mineral acid with the **widest range of applications** in clinical and research laboratories - Used extensively as a **catalyst and reagent** in numerous analytical procedures including **protein digestion**, **Kjeldahl nitrogen estimation**, and **enzymatic assays** - Essential in **sample preparation** for heavy metal analysis and trace element detection - Utilized in **deproteinization** procedures and various **colorimetric assays** - Its strong **dehydrating properties** make it valuable in multiple biochemical protocols *Nitric acid* - **Nitric acid (HNO₃)** is primarily used for **acid digestion** of samples in trace element analysis - Strong **oxidizing agent** but has more **specialized applications** compared to sulfuric acid - More commonly used in **environmental and toxicology testing** than routine clinical biochemistry - Its highly **corrosive and oxidizing nature** limits its use in routine procedures *Carbolic acid* - **Carbolic acid (phenol/C₆H₅OH)** is technically not a mineral acid but a weak organic acid - Historically used as an **antiseptic and disinfectant** (Lister's antiseptic) - Modern laboratory use is **limited** to specific applications like **phenol-chloroform extraction** in molecular biology - Due to **toxicity concerns**, largely replaced by safer alternatives in routine disinfection *Oxalic acid* - **Oxalic acid (C₂H₂O₄)** is an organic dicarboxylic acid with **specialized applications** - Used in **decalcification of bone samples** for histopathology - Functions as a **reducing agent** in specific analytical procedures - Not a routine reagent in general medical laboratory practice compared to sulfuric acid
Forensic Medicine
8 questionsAmong the following organs, which takes the longest to putrefy in females?
In which condition is adipocere formation most likely to occur?
The characteristic color of adipocere is:
Arsenic poisoning presents with symptoms mimicking which condition?
What test is used to detect the presence of semen in the vaginal secretions of a rape victim?
The Marsch test is used to detect poisoning with which of the following substances?
Which vein is most commonly used for blood collection during post-mortem examinations?
Which form of lead is considered the least toxic?
NEET-PG 2015 - Forensic Medicine NEET-PG Practice Questions and MCQs
Question 571: Among the following organs, which takes the longest to putrefy in females?
- A. Hair
- B. Bone
- C. Uterus (Correct Answer)
- D. Cartilage
Explanation: ***Uterus*** - The **uterus** (particularly the **pregnant/gravid uterus**) is the organ that takes the **longest to putrefy in females**. - This is due to its **thick muscular walls** and **dense fibrous tissue composition**, making it highly resistant to bacterial degradation and putrefaction. - The uterus maintains its structural integrity post-mortem significantly longer than other organs, which is a classical teaching in forensic medicine. - In males, the analogous organ is the **prostate gland**. *Hair* - **Hair is composed primarily of keratin**, a protein highly resistant to decay and can persist for very long periods. - However, hair is **not an organ** but rather an appendage/derivative of skin, and the question specifically refers to organs. - While hair resists decomposition exceptionally well, it doesn't qualify as an answer to this question. *Bone* - Although bones are very durable and can persist for centuries, they undergo decomposition through the action of **microorganisms and environmental factors**. - **Bone decomposition** involves degradation of organic components (collagen, proteins), while the mineral matrix (hydroxyapatite) remains stable longer. - Bones are slower to decompose than most soft tissues but faster than the uterus in the context of putrefaction. *Cartilage* - Cartilage is a **relatively resistant connective tissue** due to its avascular nature and dense extracellular matrix. - However, it is still susceptible to **enzymatic breakdown and bacterial action** during decomposition. - Cartilage degrades faster than the dense muscular tissue of the uterus.
Question 572: In which condition is adipocere formation most likely to occur?
- A. Dead body exposed to air
- B. Dead body buried in damp, clay soil (Correct Answer)
- C. Burial in dry hot air
- D. None of the options
Explanation: **Dead body buried in damp, clay soil** - **Adipocere formation**, also known as "grave wax," is a post-mortem change where **body fats** hydrolyze into fatty acids and ammonia, forming a waxy, soap-like substance. - This process requires specific conditions: a **moist, anaerobic environment**, and temperatures above freezing, often found in **damp, clay soil** or submerged in water. *Dead body exposed to air* - Exposure to air promotes **putrefaction** (decomposition by bacteria and enzymes) and **mummification** (drying out of tissues), rather than adipocere formation. - An **aerobic environment** does not support the chemical reactions necessary for fat hydrolysis into adipocere. *Burial in dry hot air* - High temperatures and dry air promote **desiccation** and **mummification**, leading to the preservation of tissues by drying. - The lack of moisture in a dry environment inhibits the hydrolysis of fats required for adipocere formation. *None of the options* - This option is incorrect because the conditions described in "Dead body buried in damp, clay soil" are ideal for adipocere formation.
Question 573: The characteristic color of adipocere is:
- A. Grayish white (Correct Answer)
- B. Black
- C. Brown
- D. Red
Explanation: ***Grayish white*** - Adipocere, also known as **grave wax**, is a waxy substance formed during the decomposition of a body in specific environmental conditions. - Its characteristic appearance is that of a **grayish-white, greasy, or crumbly** material, resulting from the hydrolysis and hydrogenation of body fats. *Black* - A **black discoloration** in a decomposing body is typically associated with **putrefaction** and the formation of **sulfmethemoglobin**, not adipocere formation. - This indicates a different stage and process of decomposition, usually in the presence of oxygen and bacterial activity. *Brown* - **Brown discoloration** can be seen in various stages of decomposition due to the breakdown of blood pigments, but it is not the characteristic color of **adipocere**. - Adipocere's formation involves the transformation of fat into fatty acids, giving it a distinct pale color. *Red* - **Red discoloration** is generally associated with fresh blood or **carbon monoxide poisoning (cherry-red lividity)** in a deceased body. - It is not a feature of adipocere formation, which involves chemical changes to body fat over a longer period.
Question 574: Arsenic poisoning presents with symptoms mimicking which condition?
- A. Cholera (Correct Answer)
- B. Dhatura poisoning
- C. Morphine poisoning
- D. Barbiturates poisoning
Explanation: ***Cholera*** - **Acute arsenic poisoning** often presents with severe **gastrointestinal symptoms** such as profuse watery diarrhea and vomiting, which can lead to rapid dehydration and shock, mimicking **cholera**. - Both conditions cause significant **fluid and electrolyte loss**, leading to similar clinical presentations in their acute phases. *Dhatura poisoning* - Dhatura poisoning primarily affects the **central nervous system** and presents with **anticholinergic symptoms** such as dry mouth, dilated pupils, blurred vision, delirium, and tachycardia. - This symptom profile differs significantly from the profuse gastrointestinal distress seen in acute arsenic poisoning. *Barbiturates poisoning* - Barbiturate poisoning causes **central nervous system depression**, leading to drowsiness, ataxia, reduced reflexes, and eventual respiratory depression. - These neurological symptoms are distinct from the severe gastrointestinal and dehydrative features of acute arsenic poisoning. *Morphine poisoning* - Morphine poisoning is characterized by the **opioid triad**: pinpoint pupils, respiratory depression, and depressed mental status (coma). - While it can cause some gastrointestinal symptoms like constipation, it does not typically present with the severe watery diarrhea and vomiting that mimic cholera.
Question 575: What test is used to detect the presence of semen in the vaginal secretions of a rape victim?
- A. Methylene blue staining
- B. Acid phosphatase test (Correct Answer)
- C. Benzidine test
- D. Lugol's iodine test
Explanation: ***Acid phosphatase test*** - The **acid phosphatase test** is used to detect the presence of **spermatozoa** in vaginal secretions by identifying the prostatic enzyme **acid phosphatase**, which is a component of semen. - A positive result indicates recent sexual intercourse and is crucial in **forensic investigations** of sexual assault. *Methylene blue staining* - **Methylene blue staining** is commonly used to visualize cells and bacteria in various samples, particularly for identifying **bacterial vaginosis** via clue cells. - It is not specifically used for the detection of semen or spermatozoa in sexual assault cases. *Lugol's iodine test* - **Lugol's iodine** is primarily used to detect **glycogen** in cervical cells during a Schiller test, which helps identify abnormal or cancerous cells. - It is not a standard test for detecting the presence of semen in sexual assault investigations. *Benzidine test* - The **benzidine test** was historically used as a preliminary test for the presence of **blood** by detecting hemoglobin. - However, due to its **carcinogenic properties**, it has largely been replaced by safer and more specific tests for blood detection.
Question 576: The Marsch test is used to detect poisoning with which of the following substances?
- A. Lead poisoning
- B. Mercury poisoning
- C. Nickel poisoning
- D. Arsenic poisoning (Correct Answer)
Explanation: ***Arsenic poisoning*** - The **Marsh test** is a historical but significant chemical test used to detect the presence of **arsenic**. - It involves reacting a suspected sample with zinc and sulfuric acid to produce **arsine gas (AsH₃)**, which is then heated and decomposes to form a characteristic **"arsenic mirror"** (metallic arsenic deposit) on a cold surface. - This is a highly sensitive test and was one of the first reliable methods for detecting arsenic in forensic investigations. *Lead poisoning* - **Lead poisoning** is typically diagnosed by measuring **blood lead levels** and can affect multiple organ systems. - Clinical signs include **anemia**, **neurological symptoms**, and a **"lead line"** on the gums. *Mercury poisoning* - **Mercury poisoning** is diagnosed by measuring mercury levels in **blood**, **urine**, or **hair**. - It often presents with **neurological impairments**, such as tremors and cognitive dysfunction, and renal damage. *Nickel poisoning* - **Nickel poisoning** is less common and often results from occupational exposure, typically manifesting as **dermatitis** or **respiratory issues**.
Question 577: Which vein is most commonly used for blood collection during post-mortem examinations?
- A. Femoral vein (Correct Answer)
- B. Antecubital vein
- C. Jugular vein
- D. Carotid artery
Explanation: ***Femoral vein*** - The **femoral vein** in the groin region is frequently chosen for post-mortem blood collection because it is large, superficial, and easily accessible, even in cases of significant trauma or decomposition. - Blood from the femoral vein is generally considered less prone to **post-mortem redistribution** of drugs and endogenous substances compared to central veins. *Antecubital vein* - The **antecubital vein** (in the elbow crease) is a common site for blood collection in living individuals but is less preferred post-mortem due to its smaller size and potential for damage or disfigurement during autopsy. - Its accessibility can be limited depending on the body's condition and positioning during a post-mortem examination. *Jugular vein* - While large, the **jugular vein** in the neck is generally less preferred for routine post-mortem blood collection than the femoral vein due to its proximity to the heart and great vessels. - Blood samples from the jugular vein may be more significantly affected by **post-mortem redistribution** of substances due to fluid shifts. *Carotid artery* - The **carotid artery** is an artery, not a vein, and is typically avoided for routine post-mortem blood collection unless specific arterial samples are required. - Accessing an artery can be more challenging and may provide blood that is less representative of general systemic circulation compared to venous samples for toxicology.
Question 578: Which form of lead is considered the least toxic?
- A. Lead acetate
- B. Lead oxide
- C. Lead carbonate
- D. Lead sulphide (Correct Answer)
Explanation: **Correct Option: Lead sulphide** - **Lead sulphide (galena)** has very low solubility in biological systems, meaning it is poorly absorbed by the body. - Due to its poor absorption and insolubility, it is considered the **least toxic** form of lead among the options listed. - It is essentially inert in the gastrointestinal tract and passes through without significant absorption. *Incorrect: Lead acetate* - **Lead acetate** is a highly soluble lead compound and is therefore readily absorbed by the body, making it significantly toxic. - It has been historically used in various applications (sugar of lead), increasing exposure risk and demonstrating its high bioavailability. - Soluble salts of lead are the most dangerous forms. *Incorrect: Lead oxide* - **Lead oxide** (like litharge or red lead) is moderately soluble and can be absorbed through ingestion or inhalation, contributing to lead toxicity. - It is used in paints and batteries, leading to industrial and environmental exposure risks. - Chronic exposure can lead to significant lead accumulation. *Incorrect: Lead carbonate* - **Lead carbonate** (white lead) is also a relatively soluble lead compound and is readily absorbed by the body, making it highly toxic. - It was historically used extensively in paints and cosmetics, contributing to significant lead poisoning cases. - The solubility in gastric acid makes this form particularly dangerous when ingested.
Physiology
1 questionsWhat is the average size of platelets in micrometers?
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 571: What is the average size of platelets in micrometers?
- A. 4-5 µm
- B. 3-4 µm
- C. 2-3 µm (Correct Answer)
- D. 1-2 µm
Explanation: ***2-3 µm*** - Platelets, also known as **thrombocytes**, are small, anucleated cell fragments crucial for **hemostasis**, and their average diameter generally falls within the range of 2-3 micrometers. - This **small size** allows them to easily navigate through capillaries and aggregate rapidly at sites of vascular injury. *3-4 µm* - While platelets can vary slightly in size, an average of 3-4 µm is generally considered a bit on the larger side and not the typical average diameter. - Larger platelets might be seen in certain conditions like **idiopathic thrombocytopenic purpura (ITP)**, but this is not the average normal size. *4-5 µm* - This range is significantly larger than the typical size of normal circulating platelets. - Platelets this large would be considered **macroplatelets** and could indicate specific pathological conditions or inherited platelet disorders. *1-2 µm* - This size range is generally considered smaller than the average normal platelet size. - Very small platelets might be seen in some specific conditions, but it's not the usual average for healthy individuals.