Pathology and Genetics MCQ Quiz in தமிழ் - Objective Question with Answer for Pathology and Genetics - இலவச PDF ஐப் பதிவிறக்கவும்

• The specific gravity of urine is a measure of the concentration of solutes in the urine. It indicates how well the kidneys are concentrating the urine.
• A normal specific gravity range of urine is between 1.015 to 1.025. This range shows that the kidneys are functioning properly and are able to concentrate urine adequately.
• Values within this range suggest a balanced intake and excretion of fluids, and a proper functioning of the kidneys in maintaining homeostasis.

• Rationale: This range is higher than the normal specific gravity of urine. Values in this range may indicate dehydration, where the urine is more concentrated due to lack of fluids in the body. It can also suggest the presence of substances like glucose or protein in the urine, which can occur in conditions such as diabetes or kidney disease.

• Rationale: This range is not applicable to the specific gravity of urine. Specific gravity values typically range from 1.000 to 1.040. Values like 2.0 to 3.0 are not physiologically relevant and indicate an incorrect understanding of the concept.

• Rationale: This range is lower than the normal specific gravity of urine. Values in this range may indicate excessive fluid intake, resulting in very dilute urine. It can also suggest an inability of the kidneys to concentrate urine, which can occur in conditions like diabetes insipidus or chronic kidney disease.

• The normal specific gravity range of urine, 1.015 to 1.025, reflects a healthy kidney function and proper fluid balance in the body. Deviations from this range can indicate various health issues, such as dehydration, overhydration, or underlying kidney conditions.

• A positive nitrite test coupled with a negative leukocyte esterase test suggests that the bacteria responsible for the presence of nitrites have been in the urine for some time. This is typically seen in specimens that are older than 2 hours.
• Nitrites are produced by the reduction of nitrates by certain types of bacteria, which requires time. Thus, an older specimen is more likely to show a positive nitrite test if bacteria are present.
• Leukocyte esterase is an enzyme found in white blood cells (leukocytes), and its presence in urine indicates an immune response to infection. However, if the specimen is old, leukocytes may have lysed or degraded, leading to a negative leukocyte esterase test.

• Rationale: A dilute random specimen may result in lower concentrations of both nitrites and leukocyte esterase, potentially leading to false negatives for both tests. However, this does not specifically explain a positive nitrite test and a negative leukocyte esterase test.

• Rationale: While lysed leukocytes could lead to a negative leukocyte esterase test, it does not explain the positive nitrite test. Lysing of leukocytes can happen in older samples, but the key point is the age of the specimen, which is captured better by the correct answer.

• Rationale: Vaginal yeast infections do not typically produce nitrites in urine because yeast (fungi) do not reduce nitrates to nitrites. Additionally, yeast infections would not cause a positive leukocyte esterase test in urine.

• Among the given options, a specimen older than 2 hours is the most plausible explanation for a positive nitrite test and a negative leukocyte esterase test. This is because nitrite-producing bacteria have had enough time to convert nitrates to nitrites, and leukocytes may have lysed or degraded, leading to a negative leukocyte esterase test.

• The principle of the reagent strip test for detecting protein in urine is based on the "protein error of indicators." This principle relies on the ability of protein to alter the color of certain pH indicators without actually changing the pH of the solution.
• In the reagent strip test, the presence of protein in the urine causes a color change on the test strip. This color change is due to the protein affecting the indicator dye, which is specifically designed to react to protein presence rather than pH changes.
• The test strip contains a pH indicator that is highly sensitive to protein. When protein is present, it binds to the indicator, causing a color shift that is proportional to the amount of protein in the urine.

• Rationale: The use of an enzyme is not involved in the principle of the reagent strip test for detecting protein in urine. Enzymes are typically used for other types of biochemical reactions, such as glucose oxidase in glucose testing strips.

• Rationale: Copper reduction is a principle used in tests such as the Benedict's test for reducing sugars, not for detecting protein in urine. This method involves the reduction of copper ions in the presence of reducing sugars.

• Rationale: The toluidine reaction is not used in the reagent strip test for detecting protein in urine. Toluidine blue is a dye used in various staining techniques, especially in histology, but it is not relevant to protein detection in urine.

• Among the given options, "protein error of indicators" is the correct principle on which the reagent strip test for detecting protein in urine is based. This method exploits the ability of protein to cause a measurable color change in specific pH indicators, allowing for the detection and estimation of protein levels in urine samples.

The question requires matching specific staining techniques with their respective targets. Staining techniques are critical in histology, hematology, and cytology to enhance visualization of cells and tissues under a microscope. Different stains have unique affinities for particular cellular components, enabling targeted examination. Below is the rationale for the correct matches:

• 1. MGG stain (May-Grünwald-Giemsa stain) - a. Cytoplasmic details in cytology: The MGG stain is primarily used in cytology for its ability to highlight cytoplasmic details. It is particularly useful in identifying cell morphology, making it valuable in diagnosing blood disorders and cytological studies.
• 2. Leishman stain - b. Blood smear: Leishman stain is a Romanowsky-type stain used for staining blood smears. It is highly effective in differentiating between various types of blood cells and detecting abnormalities such as malaria parasites.
• 3. Papanicolaou stain - c. Cervical cytology: Commonly known as Pap stain, this technique is widely used in cervical cytology, especially for Pap smears. It helps in detecting abnormal cells, including precancerous or cancerous changes in the cervix.
• 4. PAS stain (Periodic Acid-Schiff stain) - d. Mucin/carbohydrates: PAS stain is used to detect polysaccharides such as glycogen and mucin in tissues. It is particularly useful in identifying fungal infections and mucin-producing tumors.

• This option incorrectly matches the stains to their targets. For example, MGG stain is not used for detecting mucin/carbohydrates (1-d). Similarly, Leishman stain is used for blood smears, not cytoplasmic details (2-a). The mismatches indicate a lack of understanding of the specific applications of these stains.

• This option also misattributes the stains to incorrect targets. For instance, MGG stain is not used for blood smears (1-b), and Leishman stain is not appropriate for cervical cytology (2-c). Such mismatches disregard the established uses of these staining techniques in diagnostic pathology.

• This option again provides incorrect pairings. For example, MGG stain is not used for cervical cytology (1-c), and PAS stain is not used for blood smears (4-b). These errors highlight a misunderstanding of the fundamental principles of staining techniques and their specific applications.

• The correct matches align the staining techniques with their respective targets as follows: MGG stain for cytoplasmic details, Leishman stain for blood smears, Papanicolaou stain for cervical cytology, and PAS stain for mucin/carbohydrates. Understanding these pairings is essential for accurate diagnostic and histological applications.

• Decalcifying agents are chemical substances used in histopathology to remove calcium from tissues, enabling proper sectioning and microscopic examination. Each decalcifying agent has specific properties that make it suitable for certain applications, depending on the speed of decalcification and the preservation of tissue morphology and staining quality.
• The correct answer matches each decalcifying agent in Column A with its property described in Column B:

• Nitric acid is a strong inorganic acid that acts very rapidly to decalcify tissues. However, its aggressive nature can damage tissue morphology and interfere with subsequent staining, making it less suitable for delicate specimens.

• EDTA (Ethylenediaminetetraacetic acid) is a chelating agent that binds calcium ions. It decalcifies tissues very slowly but is gentle on tissue morphology, preserving cell structures and staining quality. This makes EDTA ideal for specimens requiring detailed histological examination.

• Formic acid is a weaker acid compared to nitric acid and acts at a moderate rate. It is widely used for biopsy specimens as it provides a good balance between decalcification speed and preservation of tissue morphology.

• Hydrochloric acid is a strong acid like nitric acid and decalcifies tissues very rapidly. However, it can adversely affect staining quality and tissue morphology, making it less suitable for delicate histological studies.

• This option incorrectly associates nitric acid with "a. Very rapid, poor staining" instead of "d. Rapid, damages morphology." Similarly, EDTA is incorrectly matched with "c. Moderate, good for biopsy" instead of "b. Slow, excellent morphology." The mismatches continue for formic acid and hydrochloric acid.

• This option mismatches all the agents with incorrect properties. For example, nitric acid is paired with "c. Moderate, good for biopsy," which is not accurate as nitric acid acts rapidly and damages morphology. Similarly, EDTA is incorrectly matched with "d. Rapid, damages morphology," which contradicts its slow and gentle action.

• This option incorrectly pairs nitric acid with "b. Slow, excellent morphology," which is not accurate given its rapid action and damaging effects. The other agents are similarly mismatched, making this option incorrect.

• The correct matching of decalcifying agents with their properties is essential for selecting the appropriate agent in histopathological procedures. Among the given options, 1) 1-d, 2-b, 3-c, 4-a accurately pairs each agent with its respective characteristics, ensuring optimal results in tissue processing and microscopic examination.

• The question involves matching laboratory equipment to their primary use. Laboratory equipment is designed for specific purposes in diagnostic, clinical, and research settings, and understanding their functions ensures proper utilization in various processes.

• Rationale: A cryostat is a precision instrument used to cut thin sections of biological tissues at very low temperatures. It operates in a frozen environment and is primarily used for rapid preparation of tissue samples for histological studies.
• Additional Information: Cryostats are commonly used in procedures like immunohistochemistry and intraoperative histology to evaluate tissue sections quickly.

• Rationale: A microtome is an instrument used to cut extremely thin slices of tissue embedded in paraffin wax. The sections are prepared for microscopic examination, typically in pathology labs.
• Additional Information: Microtomes provide high precision in cutting uniform sections, which is crucial for detailed cellular and structural analysis.

• Rationale: A water bath is used in histology labs to float paraffin ribbons (thin sections of tissue embedded in paraffin) for easier transfer onto slides. This ensures smooth and intact placement of tissue sections.
• Additional Information: Water baths are temperature-controlled and maintain optimal heat settings to prevent damage to the tissue sections.

• Rationale: A hot air oven is used for sterilization of laboratory equipment and glassware. It uses dry heat to kill microorganisms, ensuring the lab tools are free from contamination.
• Additional Information: The hot air oven operates at temperatures ranging from 160°C to 180°C, and sterilization is achieved by oxidation of microbial cells.

• Incorrect Match: Cryostat is incorrectly matched with sterilization (a). The cryostat is used for freezing sections, not sterilizing equipment.
• Incorrect Match: Microtome is incorrectly matched with freezing sections (d). Microtomes are designed for cutting paraffin sections, not frozen sections.
• Incorrect Match: Water bath is incorrectly matched with cutting paraffin sections (b). Water baths are used for floating ribbons of paraffin sections, not cutting them.
• Incorrect Match: Hot air oven is incorrectly matched with floating ribbons (c). Hot air ovens sterilize equipment, not assist in handling tissue sections.

• Incorrect Match: Cryostat is incorrectly matched with floating ribbons (c). Cryostats are used for freezing sections, not floating paraffin ribbons.
• Incorrect Match: Microtome is incorrectly matched with sterilization (a). Microtomes are used for cutting paraffin sections, not sterilizing tools.
• Incorrect Match: Water bath is incorrectly matched with freezing sections (d). Water baths are used for floating ribbons, not freezing tissue samples.
• Incorrect Match: Hot air oven is incorrectly matched with cutting paraffin sections (b). Hot air ovens sterilize equipment, not cut tissue sections.

• Incorrect Match: Cryostat is incorrectly matched with cutting paraffin sections (b). Cryostats are used for freezing tissue sections, not cutting paraffin sections.
• Incorrect Match: Microtome is incorrectly matched with floating ribbons (c). Microtomes cut paraffin sections, not float ribbons.
• Incorrect Match: Water bath is incorrectly matched with sterilization (a). Water baths are used for floating ribbons, not sterilizing equipment.
• Incorrect Match: Hot air oven is incorrectly matched with freezing sections (d). Hot air ovens sterilize equipment, not freeze tissue samples.

• Matching the correct equipment with their primary use is crucial for laboratory operations. Option 1 correctly associates Cryostat with freezing sections, Microtome with cutting paraffin sections, Water bath with floating ribbons, and Hot air oven with sterilization, ensuring accurate utilization of these tools in histological and sterilization processes.

• The question asks to match specific stains with their respective applications in histology and pathology. Each stain has a unique function based on its chemical properties and the cellular components it targets.

• Hematoxylin and Eosin is the most commonly used stain for routine tissue morphology.
• Hematoxylin stains the nuclei of cells blue or purple, while eosin stains the cytoplasm and extracellular matrix pink.
• It is widely used in histopathology to examine the general structure of tissues and detect abnormalities such as tumors, inflammation, or necrosis.

• PAS stain is specifically used to detect carbohydrates, including glycogen, mucopolysaccharides, and glycoproteins.
• It reacts with the aldehyde groups formed by the oxidation of carbohydrates, resulting in a magenta color.
• This stain is particularly useful in identifying basement membranes, fungal organisms, and glycogen storage diseases.

• Sudan III is a lipid-soluble dye used to stain lipids in tissues.
• It selectively stains fat droplets red or orange, making it useful in the study of fat metabolism and lipid storage diseases.
• It is often employed in frozen tissue sections since processing with alcohol can remove lipids from tissues in paraffin-embedded sections.

• The Ziehl-Neelsen stain is a special staining technique used to identify acid-fast bacilli, such as Mycobacterium tuberculosis.
• It involves the use of carbol fuchsin (a red dye) that penetrates the waxy cell walls of acid-fast organisms, which retain the dye even after treatment with acid-alcohol.
• This method is critical in diagnosing tuberculosis and other mycobacterial infections.

• Incorrect because H&E does not detect carbohydrates (1-a is wrong). PAS detects carbohydrates, not lipids (2-b is wrong). Sudan III detects lipids, not acid-fast bacilli (3-c is wrong). Ziehl-Neelsen does not analyze routine tissue morphology (4-d is wrong).

• Incorrect because H&E does not detect lipids (1-b is wrong). PAS does not detect acid-fast bacilli (2-c is wrong). Sudan III does not target carbohydrates (3-a is wrong). Ziehl-Neelsen does not analyze routine tissue morphology (4-d is wrong).

• Incorrect because H&E does not detect acid-fast bacilli (1-c is wrong). PAS does not analyze routine tissue morphology (2-d is wrong). Sudan III does detect lipids, but Ziehl-Neelsen does not detect carbohydrates (4-a is wrong).

• Matching stains with their correct applications is critical for understanding their diagnostic uses. H&E is for routine tissue morphology, PAS for carbohydrates, Sudan III for lipids, and Ziehl-Neelsen for acid-fast bacilli. These stains are indispensable tools in histology and pathology.

• Fixatives are chemical solutions used to preserve biological tissues or specimens for microscopic examination by preventing decay and maintaining structural integrity.
• Each fixative has a specific composition that determines its application and effectiveness in preserving cellular and tissue structures.
• The correct match between fixatives (Column A) and their compositions (Column B) is as follows:
  • Formalin: Composed of formaldehyde (40%). Formalin is widely used as a tissue fixative due to its ability to crosslink proteins and stabilize tissue structures.
  • Bouin's Fluid: Contains picric acid, formaldehyde, and acetic acid. This fixative is preferred for preserving delicate structures like nuclei and is often used in histology.
  • Carnoy's Fluid: Composed of alcohol, chloroform, and acetic acid. It is ideal for rapid fixation and is commonly used for preserving nucleic acids and chromosomes.
  • Zenker's Fluid: Contains mercuric chloride and potassium dichromate. It is used for preserving cytoplasmic structures and is considered excellent for staining purposes.

• Incorrect because it mismatches the compositions of fixatives. For example, Formalin does not consist of Bouin's composition (picric acid, formaldehyde, acetic acid), and Zenker's Fluid does not include alcohol or chloroform.

• Incorrect because the compositions are entirely mismatched. Formalin is not composed of alcohol, and Bouin's Fluid does not contain mercuric chloride and potassium dichromate. Additionally, Carnoy's Fluid does not contain formaldehyde.

• Incorrect because it swaps the compositions among the fixatives. For example, Formalin does not contain mercuric chloride, and Zenker's Fluid does not consist of formaldehyde.

• The correct matches between fixatives and their compositions are critical for understanding their applications in tissue preservation and histological studies. Option 1 provides the accurate correspondence, ensuring proper identification and usage of these fixatives in laboratory settings.

• Eosin is not a nuclear stain. It is primarily used as a cytoplasmic stain in histology and pathology. Eosin stains the cytoplasm and other extracellular matrix components in shades of pink and red, and it is often used in combination with hematoxylin in the Hematoxylin and Eosin (H&E) staining technique.
• Nuclear stains are dyes specifically designed to bind to nucleic acids in the nucleus, highlighting nuclear structures. Since eosin does not specifically bind to nucleic acids or nuclear components, it does not function as a nuclear stain.

• Rationale: Hematoxylin is a well-known nuclear stain. It binds to acidic components, such as DNA and RNA, in the nucleus, staining them a deep blue or purple color. Hematoxylin is commonly used in combination with eosin in H&E staining to provide contrast between the nucleus and cytoplasm.

• Rationale: The Feulgen reaction is a specific staining technique for DNA in the nucleus. It relies on the hydrolysis of DNA with acid to produce aldehyde groups, which then react with Schiff's reagent to produce a magenta color. This makes Feulgen a highly specific nuclear stain.

• Rationale: Toluidine blue is a basic dye that binds to acidic components of the cell. It stains the nucleus blue due to its affinity for nucleic acids, making it an effective nuclear stain. It is also used for staining mast cells and cartilage.

• Among the given options, eosin is the only dye that is not a nuclear stain. While hematoxylin, Feulgen, and toluidine blue specifically target the nucleus, eosin is a cytoplasmic stain and does not bind to nuclear components. This distinction makes eosin the correct answer.

• A Barr body, also known as a sex chromatin body, is a condensed, inactive X chromosome found in the nuclei of female mammalian cells. This phenomenon is part of the dosage compensation mechanism to equalize gene expression between males (XY) and females (XX).
• The Barr body appears as a dark-staining appendage or structure attached to the periphery of the nucleus when observed under a microscope with specific staining techniques, such as Giemsa or Papanicolaou stains.
• This inactive X chromosome is tightly packed into heterochromatin, making it transcriptionally inactive and thus visible as a distinct, dark-staining nuclear feature.

• Rationale: This description does not match the appearance of a Barr body, as it is not located in the cytoplasm but rather in the nucleus. Blue cytoplasmic dots could be indicative of cellular structures like ribosomes or specific cytoplasmic inclusions, but they do not represent a Barr body.

• Rationale: Vacuoles are clear or pinkish, membrane-bound structures found within the cytoplasm of cells, often associated with storage or transport functions. Barr bodies are nuclear structures and do not resemble vacuoles in appearance, location, or function.

• Rationale: A clear round circle might describe a nuclear or cytoplasmic inclusion, such as a nucleolus or lipid droplet, but it does not describe the dense, dark-staining appearance of a Barr body. The Barr body is not clear but darkly stained, making it easily distinguishable.

• The Barr body was first discovered by Murray Barr and Ewart Bertram in 1949 and is used as a cytological marker of sex in mammals.
• The formation of the Barr body is a result of X chromosome inactivation, a process that occurs early in embryonic development in females to ensure dosage compensation for X-linked genes between males and females.
• The presence of a Barr body can be used in certain medical and forensic investigations, such as determining genetic sex or diagnosing conditions like Turner syndrome (where no Barr body is present) or Klinefelter syndrome (where an extra Barr body may be present).
• It is important to note that Barr bodies are only found in females with at least two X chromosomes. Males (XY) do not typically exhibit Barr bodies.

• The Barr body appears as a dark-staining nuclear appendage, distinguishing it from other cellular features. This unique appearance is due to the dense packing of the inactivated X chromosome into heterochromatin.