Which of the following is a positive acute phase protein that enhances the acute phase response?
Location of gene on chromosome is identified by
Tyrosine kinase receptor is associated with proto-oncogene -
Which of the following is not a part of extracellular matrix (ECM)?
What is the classification of Carcinoembryonic Antigen (CEA)?
Level of which of the following is not elevated in heart disease
Which of the following acids is MOST commonly used as a reagent in medical laboratory analytical procedures?
Shadow casting is used in -
Which nutrient is lost maximally in polished rice?
What is the molecular mass of Immunoglobulin G (IgG) in kilodaltons (kDa)?
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 91: Which of the following is a positive acute phase protein that enhances the acute phase response?
- A. Fibrinogen (Correct Answer)
- B. Transferrin
- C. Albumin
- D. Prealbumin
Explanation: ***Fibrinogen*** - **Fibrinogen** is a key **positive acute phase protein** whose concentration increases significantly during inflammation - Its elevation contributes to the acute phase response by promoting **blood clotting** and influencing **erythrocyte sedimentation rate (ESR)** - Along with C-reactive protein (CRP), haptoglobin, and serum amyloid A, fibrinogen is among the major positive acute phase reactants *Transferrin* - **Transferrin** is a **negative acute phase protein**, meaning its concentration decreases during inflammation - This reduction is part of the body's iron-sequestration strategy to limit iron availability for invading pathogens - The decrease in transferrin helps restrict bacterial growth by reducing available iron *Albumin* - **Albumin** is a prominent **negative acute phase protein**, with its concentration decreasing during acute inflammation due to redistribution and reduced synthesis - It plays a vital role in maintaining **oncotic pressure** and transporting various substances - Its decline reflects the severity of inflammation and is used as a marker of the acute phase response *Prealbumin* - **Prealbumin** (also known as transthyretin) is a **negative acute phase protein** and a sensitive marker of nutritional status - Its rapid decline during inflammation makes it a useful indicator, as its synthesis is quickly reduced - It has a short half-life (2-3 days), making it more sensitive to acute changes than albumin
Question 92: Location of gene on chromosome is identified by
- A. Karyotyping
- B. Genetic mapping (Correct Answer)
- C. Microarray
- D. Genomic imprinting
Explanation: ***Genetic mapping*** - **Genetic mapping** (also called chromosome mapping) uses various techniques to determine the **physical location (locus)** of genes on a chromosome. - Techniques include **linkage analysis**, **FISH (Fluorescence In Situ Hybridization)**, chromosomal banding, and analysis of **inheritance patterns** of traits and genetic markers. - This identifies both the **relative positions** between genes and their **absolute chromosomal addresses**. *Karyotyping* - **Karyotyping** is a technique that visualizes the entire set of chromosomes in an organism. - While it can identify **large chromosomal abnormalities** like aneuploidy or major deletions/insertions, it does not pinpoint the exact location of a specific gene. *Microarray* - **Microarray** technology is used to study the expression levels of thousands of genes simultaneously or to detect specific genetic variations. - It does not directly map the physical location of a gene on a chromosome. *Genomic imprinting* - **Genomic imprinting** is an epigenetic phenomenon where certain genes are expressed in a **parent-of-origin-specific manner**. - It describes a mechanism of gene regulation rather than a method for identifying the location of a gene on a chromosome.
Question 93: Tyrosine kinase receptor is associated with proto-oncogene -
- A. RAS (RAt Sarcoma)
- B. RET (REarranged during Transfection) (Correct Answer)
- C. RB (Retinoblastoma gene)
- D. MYC (Myelocytomatosis oncogene)
Explanation: ***RET*** - RET is a **tyrosine kinase receptor** that plays a crucial role in cell signaling and development [1][2]. - It is associated with several **neoplasms**, including medullary thyroid carcinoma and multiple endocrine neoplasia type 2 [1]. *RB* - RB (Retinoblastoma protein) is a **tumor suppressor gene**, not a proto-oncogene or receptor. - Its role is largely in regulating the **cell cycle**, particularly in preventing excessive cell growth. *RAS* - RAS is a family of **GTPase proteins** involved in transmitting signals within cells, but it is not a receptor itself [1]. - It is classified as an **oncogene**, but does not function as a tyrosine kinase receptor [2]. *MYC* - MYC is a **transcription factor** involved in cell cycle progression and growth, not a tyrosine kinase receptor [2]. - It is considered an **oncogene** that promotes cellular proliferation, but it doesn't have tyrosine kinase activity [3][4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1097-1098. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 291-292. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 28-29. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 293-294.
Question 94: Which of the following is not a part of extracellular matrix (ECM)?
- A. Lectins (Correct Answer)
- B. Fibronectin
- C. Laminin
- D. Proteoglycans
Explanation: ***Lectins*** - **Lectins** are carbohydrate-binding proteins involved in various cellular processes but are typically found **on cell surfaces** or within cells, not as a major structural component of the ECM. - While they can interact with ECM components, they are not considered a direct structural element of the extracellular matrix itself. *Fibronectin* - **Fibronectin** is a critical **glycoprotein** in the ECM, playing a vital role in cell adhesion, growth, migration, and differentiation. - It links cells to collagen fibers and other ECM components, forming an essential scaffold. *Laminin* - **Laminin** is a major **glycoprotein** component of the **basal lamina**, a specialized layer of the ECM found beneath epithelial cells. - It helps in cell attachment, differentiation, and migration. *Proteoglycans* - **Proteoglycans** are macromolecules consisting of a **core protein** covalently linked to one or more **glycosaminoglycan (GAG) chains**. - They are abundant in the ECM, where they contribute to its structural integrity, hydration, and can regulate the diffusion of molecules.
Question 95: What is the classification of Carcinoembryonic Antigen (CEA)?
- A. Glycoprotein (Correct Answer)
- B. Lipoprotein
- C. Phosphoprotein
- D. Nucleoprotein
Explanation: ***Glycoprotein*** - Carcinoembryonic Antigen (CEA) is classified as a **glycoprotein** due to its structure, which consists of both **carbohydrate** and **protein** components. - This glycosylation is crucial for its function as a cell adhesion molecule and its recognition in diagnostic assays. *Lipoprotein* - **Lipoproteins** are complexes of lipids and proteins that function primarily in **lipid transport** in the blood. - CEA's primary role and structure are not related to lipid transport or being predominantly lipid-based. *Phosphoprotein* - A **phosphoprotein** is a protein that has been **covalently modified by the addition of a phosphate group**, a process crucial for cell signaling. - While proteins can be phosphorylated, the defining characteristic and major classification of CEA is its extensive glycosylation rather than phosphorylation state. *Nucleoprotein* - **Nucleoproteins** are proteins that are **structurally associated with nucleic acids** (DNA or RNA), such as histones or ribosomal proteins. - CEA does not have a structural or functional association with nucleic acids.
Question 96: Level of which of the following is not elevated in heart disease
- A. SGOT
- B. ALP
- C. LDH
- D. 5-nucleotidase (Correct Answer)
Explanation: ***5-nucleotidase*** - While other enzymes like LDH, SGOT, and ALP can be elevated in various conditions including heart disease (especially in the context of tissue damage), 5-nucleotidase is **not typically elevated in heart disease**. - Its elevation is more commonly associated with **biliary obstruction** or certain liver pathologies. *LDH* - **Lactate dehydrogenase (LDH)** is a marker of **cellular damage** and can be elevated in myocardial infarction, though it is less specific than troponins. - LDH levels rise later than CK-MB and remain elevated longer, indicating persistent tissue injury. *SGOT* - **Serum glutamic oxaloacetic transaminase (SGOT)**, also known as **aspartate aminotransferase (AST)**, is elevated in acute **myocardial infarction** due to cardiac muscle damage. - While it's a marker for cardiac injury, it's not specific as it's also highly concentrated in the liver. *ALP* - **Alkaline phosphatase (ALP)** can be mildly elevated in heart failure due to **hepatic congestion** caused by reduced cardiac output. - While its primary diagnostic significance is in bone and liver disease, its elevation in advanced heart disease is usually a secondary consequence.
Question 97: 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
Question 98: Shadow casting is used in -
- A. Light microscopy
- B. Electron microscopy (Correct Answer)
- C. Fluorescence microscopy
- D. Phase contrast microscopy
Explanation: ***Electron microscopy*** - **Shadow casting** is a technique used in **electron microscopy** to enhance contrast and reveal the three-dimensional topography of small structures and molecules by depositing a thin film of heavy metal at an angle. - This process creates areas with more metal (which appears darker) and areas shielded from the metal deposition (appearing lighter, like a shadow), thereby outlining the specimen. *Light microscopy* - **Light microscopy** uses visible light to illuminate specimens and a system of lenses to magnify images, and it does not typically employ shadow casting techniques for contrast enhancement. - While various techniques like staining are used for contrast, the principle of creating shadows by metal deposition is not applicable to light interactions with the sample. *Fluorescence microscopy* - **Fluorescence microscopy** utilizes the property of some substances to emit light of a longer wavelength when excited by light of a shorter wavelength (fluorescence), and it relies on fluorochromes for visualization, not shadow casting. - This technique creates contrast based on specific labels or autofluorescence, highlighting particular structures without direct shadowing. *Phase contrast microscopy* - **Phase contrast microscopy** converts phase shifts in light passing through a transparent specimen into changes in amplitude (brightness), which are then visible as differences in image contrast, and it does not involve metal deposition or shadow casting. - This method is particularly useful for observing live, unstained biological samples by detecting optical path differences.
Question 99: Which nutrient is lost maximally in polished rice?
- A. Proteins
- B. Thiamine (Correct Answer)
- C. Ascorbic acid
- D. Calcitriol
Explanation: ***Thiamine*** - **Polishing rice** removes the outer layers (bran and germ), which are rich in **thiamine (vitamin B1)**. - Significant loss of thiamine can lead to **beriberi**, characterized by neurological and cardiovascular symptoms. *Proteins* - While some protein is lost during milling, the primary nutritional loss in polished rice is not protein. - The germ and aleurone layer contain some protein, but the main carbohydrate-rich endosperm remains. *Ascorbic acid* - **Ascorbic acid (Vitamin C)** is not a significant nutrient in rice, so its loss during polishing is negligible. - Rice is not a primary dietary source of vitamin C. *Calcitriol* - **Calcitriol** is the active form of **vitamin D**, and rice does not naturally contain vitamin D. - Therefore, it cannot be lost during the polishing process.
Question 100: What is the molecular mass of Immunoglobulin G (IgG) in kilodaltons (kDa)?
- A. 150 (Correct Answer)
- B. 400
- C. 1000
- D. 1500
Explanation: **\*Correct Option: 150 kDa\*** - **Immunoglobulin G (IgG)** is the most abundant antibody in human serum and has a characteristic molecular mass of approximately **150 kDa**. - This mass is attributed to its structure, comprising two identical **heavy chains** (~50 kDa each) and two identical **light chains** (~25 kDa each). - IgG represents about **75-80% of total serum immunoglobulins** and is the main antibody involved in secondary immune responses. *Incorrect Option: 400 kDa* - A molecular mass of **400 kDa** is significantly higher than that of a monomeric IgG molecule. - This mass is closer to **IgM pentamers** (~900 kDa) or large protein complexes, but still does not match any standard immunoglobulin structure. *Incorrect Option: 1000 kDa* - A molecular mass of **1000 kDa (1 MDa)** is far too large for a single IgG molecule. - This weight typically corresponds to very large macromolecular structures or aggregates, such as **ribosomes** or large enzyme complexes. *Incorrect Option: 1500 kDa* - A molecular mass of **1500 kDa (1.5 MDa)** is extremely large for an individual antibody. - Such a mass would be characteristic of very large protein assemblies, viral capsids, or cellular components, not a soluble antibody.