Biochemistry
1 questionsWhich of the following is required for proper effects of Insulin?
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 871: Which of the following is required for proper effects of Insulin?
- A. Chromium (Correct Answer)
- B. Selenium
- C. Copper
- D. Iron
Explanation: ***Chromium*** - **Chromium** is an essential trace mineral that plays a crucial role in enhancing the action of **insulin** by promoting its binding to cell receptors. - It is a key component of **glucose tolerance factor (GTF)**, which helps cells absorb glucose more efficiently. *Selenium* - **Selenium** is an antioxidant and is involved in thyroid hormone metabolism and immune function, but it does not directly facilitate insulin action. - While important for overall health, it has no known direct requirement for the proper effects of insulin. *Copper* - **Copper** is involved in various enzymatic reactions, iron metabolism, and connective tissue formation, but it is not directly required for insulin's proper function. - High levels of **copper** can even negatively impact glucose metabolism in some contexts. *Iron* - **Iron** is essential for oxygen transport in hemoglobin and myoglobin, as well as for many enzymatic processes, but it does not directly enhance insulin sensitivity or action [1]. - Both **iron deficiency** and **iron overload** can indirectly affect metabolic health but do not directly influence insulin's effects in the same way chromium does [2].
Internal Medicine
2 questionsThrombocythemia is characterized by an elevated platelet count.
Which of the following is NOT a criterion for the diagnosis of Primary Hyperaldosteronism?
NEET-PG 2015 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 871: Thrombocythemia is characterized by an elevated platelet count.
- A. Low platelets
- B. Neutrophilia
- C. Monocytosis
- D. Elevated platelet count (Correct Answer)
Explanation: Elevated platelet count - Thrombocythemia is a condition specifically defined by an abnormally high number of platelets (thrombocytes) in the blood [2]. - This elevated count can lead to issues with both bleeding and clotting [2]. Low platelets - Low platelets, also known as thrombocytopenia, is the opposite of thrombocythemia [1]. - This condition is associated with an increased risk of bleeding [1]. Neutrophilia - Neutrophilia refers to an elevated count of neutrophils, a type of white blood cell, which is typically seen in bacterial infections. - It does not directly describe the platelet count. Monocytosis - Monocytosis indicates an increase in monocytes, another type of white blood cell, often seen in chronic infections or inflammatory conditions. - This term is unrelated to platelet levels.
Question 872: Which of the following is NOT a criterion for the diagnosis of Primary Hyperaldosteronism?
- A. Diastolic Hypertension without edema
- B. Low Plasma Renin Activity
- C. Hyperkalemia (Correct Answer)
- D. Hyperaldosteronism which is not suppressed by volume expansion
Explanation: Primary hyperaldosteronism is typically characterized by **hypokalemia** due to excessive aldosterone-mediated potassium excretion in the urine, not hyperkalemia [1]. Hyperkalemia would suggest other conditions, such as **adrenal insufficiency** or kidney disease, rather than primary hyperaldosteronism [2]. *Diastolic Hypertension without edema* - **Diastolic hypertension** is a common presentation of primary hyperaldosteronism due to increased **sodium and water retention**, leading to expanded extracellular volume. - The absence of significant edema is also common, as the body often develops an **"escape phenomenon"** where natriuresis occurs despite high aldosterone, preventing overt fluid overload [3]. *Low Plasma Renin Activity* - In primary hyperaldosteronism, the high aldosterone levels **suppress renin secretion** through negative feedback mechanisms. - Therefore, a **low plasma renin activity** (PRA) or plasma renin concentration (PRC) is a key diagnostic feature [4]. *Hyperaldosteronism which is not suppressed by volume expansion* - Normally, volume expansion would suppress aldosterone secretion. However, in primary hyperaldosteronism, aldosterone production is **autonomous** and remains elevated even after volume expansion. - This lack of suppression is a critical diagnostic criterion, often assessed through various **confirmatory tests** like saline infusion or oral sodium loading.
Microbiology
6 questionsWhich organism is considered the PRIMARY prototype for Ziehl-Neelsen (acid-fast) staining identification?
Viral DNA is integrated into Bacterial DNA in:
What is the primary use of the freezing method in microbiology?
Granulomatosis infantiseptica is caused by:
Salmonella and Shigella can be differentiated from other Enterobacteriaceae members by isolation on:
Which of the following statements about anthrax toxin is false?
NEET-PG 2015 - Microbiology NEET-PG Practice Questions and MCQs
Question 871: Which organism is considered the PRIMARY prototype for Ziehl-Neelsen (acid-fast) staining identification?
- A. Escherichia coli
- B. Mycobacterium tuberculosis (Correct Answer)
- C. Streptococcus pneumoniae
- D. Clostridium difficile
Explanation: ***Mycobacterium tuberculosis*** - The **Ziehl-Neelsen (ZN) stain** is the classic **acid-fast staining** technique used to identify **Mycobacterium species**, particularly **M. tuberculosis** - **Mycobacteria** possess high content of **mycolic acid** (60-90 carbon fatty acids) in their cell wall, making them resistant to decolorization by acid-alcohol - After staining with **carbol fuchsin** (heated), acid-fast bacilli retain the **red/pink color** while non-acid-fast organisms are decolorized and counterstained blue - M. tuberculosis is the **prototype organism** for acid-fast staining and remains the primary clinical application of ZN stain - **Note:** Modified ZN stain (using weaker 1% H2SO4) is used for **weakly acid-fast organisms** like Nocardia and Cryptosporidium *Streptococcus pneumoniae* - This is a **Gram-positive coccus** identified by **Gram staining**, not acid-fast staining - Appears as lancet-shaped diplococci on Gram stain - Lacks mycolic acid in cell wall and cannot retain carbol fuchsin after acid-alcohol decolorization *Escherichia coli* - This is a **Gram-negative bacillus** with thin peptidoglycan layer and outer membrane - Identified by **Gram staining** (appears pink/red) and biochemical tests - Not acid-fast and would be completely decolorized in ZN staining procedure *Clostridium difficile* - This is an **anaerobic, Gram-positive, spore-forming bacillus** - Identified by **Gram staining** and anaerobic culture - Lacks mycolic acid and acid-fast properties, making it unsuitable for ZN staining
Question 872: Viral DNA is integrated into Bacterial DNA in:
- A. Lysogenic cycle (Correct Answer)
- B. Bacterial transduction
- C. Bacterial transformation
- D. Bacterial conjugation
Explanation: ***Lysogenic cycle*** - In the **lysogenic cycle**, the **bacteriophage DNA integrates** into the host bacterial chromosome, becoming a **prophage**. - This integration allows the viral genome to be **replicated along with the host DNA** without immediately lysing the cell. *Bacterial transduction* - **Transduction** involves the transfer of **bacterial DNA** from one bacterium to another via a bacteriophage, not the integration of viral DNA into the host genome. - While phages are involved, the primary event is the accidental packaging and transfer of bacterial genes, not viral integration into the host for replication. *Bacterial transformation* - **Transformation** is the process where bacteria take up **naked DNA from their environment** and incorporate it into their own genome. - This DNA is typically from another bacterium or is artificially introduced, not viral DNA undergoing a natural integration process within the cell. *Bacterial conjugation* - **Conjugation** is the transfer of genetic material (usually a **plasmid**) between bacteria through direct cell-to-cell contact, mediated by a **pilus**. - This process involves the transfer of bacterial or plasmid DNA, not the integration of a viral genome into the host chromosome.
Question 873: What is the primary use of the freezing method in microbiology?
- A. Sterilization of heat-sensitive materials using freezing
- B. Killing bacteria at high temperatures
- C. Stimulating the growth of microorganisms
- D. Preservation of microorganisms through freezing (Correct Answer)
Explanation: ***Preservation of microorganisms through freezing*** - The **frozen phenomenon** or **cryopreservation** is primarily used to maintain the viability and genetic integrity of microbial cultures over long periods. - This involves rapidly freezing microorganisms, often with cryoprotectants like **glycerol** or **DMSO**, to minimize cell damage from ice crystal formation. *Sterilization of heat-sensitive materials using freezing* - Freezing is **not a reliable sterilization method** as it does not consistently kill all microbial life, especially bacterial spores. - While freezing inhibits microbial growth, it does not achieve the complete eradication required for **sterilization**. *Killing bacteria at high temperatures* - Killing bacteria at high temperatures is achieved through methods like **autoclaving** or **pasteurization**, not freezing. - High temperatures denature microbial proteins and damage cell structures, leading to cell death. *Stimulating the growth of microorganisms* - Freezing generally **inhibits microbial growth** and metabolism, putting microorganisms into a dormant state. - Growth stimulation typically involves providing optimal **nutrients, temperature, and atmospheric conditions** for replication.
Question 874: Granulomatosis infantiseptica is caused by:
- A. Pseudomonas
- B. Chlamydia trachomatis
- C. Group D streptococci
- D. Listeria (Correct Answer)
Explanation: ***Listeria*** - **Granulomatosis infantiseptica** is a severe manifestation of congenital **listeriosis**, caused by *Listeria monocytogenes*. - This condition is characterized by widespread **granulomas** and **microabscesses** in various organs of the infected newborn. *Pseudomonas* - *Pseudomonas aeruginosa* is a common cause of healthcare-associated infections but is not typically associated with **granulomatosis infantiseptica**. - It can cause severe infections in immunocompromised individuals, including **pneumonia**, **sepsis**, and wound infections. *Chlamydia trachomatis* - *Chlamydia trachomatis* is a common cause of **conjunctivitis** and **pneumonia** in neonates, acquired during passage through the birth canal. - It does not cause **granulomatosis infantiseptica**. *Group D streptococci* - While Group D streptococci (e.g., *Enterococcus faecalis*) can cause neonatal infections like **sepsis** and **meningitis**, they are not the causative agents of **granulomatosis infantiseptica**. - This condition is specifically linked to **Listeria**.
Question 875: Salmonella and Shigella can be differentiated from other Enterobacteriaceae members by isolation on:
- A. MacConkey agar
- B. Mannitol salt agar
- C. BCYE medium
- D. XLD agar (Correct Answer)
Explanation: ***XLD agar*** - **Xylose Lysine Deoxycholate (XLD) agar** is a selective and differential medium used to isolate and identify *Salmonella* and *Shigella* species from other Enterobacteriaceae. - It differentiates *Salmonella* and *Shigella* based on their ability to ferment **xylose**, decarboxylate **lysine**, and produce **hydrogen sulfide (H2S)**. *MacConkey agar* - **MacConkey agar** is a selective and differential medium used to isolate Gram-negative bacteria and differentiate them based on **lactose fermentation**. - While it can grow *Salmonella* and *Shigella* (which are non-lactose fermenters), it does not specifically differentiate them from other non-lactose fermenting Enterobacteriaceae. *Mannitol salt agar* - **Mannitol salt agar (MSA)** is a selective and differential medium primarily used for the isolation of **staphylococci**. - It is highly selective due to its high salt concentration and differentiates staphylococci based on their ability to ferment **mannitol**. *BCYE medium* - **Buffered Charcoal Yeast Extract (BCYE) medium** is a specialized enrichment medium used for the isolation of **Legionella species**. - It provides specific nutrients required for the growth of *Legionella* and is not suitable for differentiating *Salmonella* and *Shigella* from other Enterobacteriaceae.
Question 876: Which of the following statements about anthrax toxin is false?
- A. Increase cAMP
- B. Has three components
- C. Coded by plasmid
- D. Inhibits protein synthesis (Correct Answer)
Explanation: ***Inhibits protein synthesis*** - Anthrax toxin, specifically the **lethal factor (LF)**, is a **zinc-dependent metalloprotease** that cleaves and inactivates **mitogen-activated protein kinase kinase (MAPKKs)**, leading to cell death, not directly inhibiting protein synthesis. - The **edema factor (EF)** component of the toxin is an **adenylate cyclase** that increases **intracellular cyclic AMP (cAMP)**, which also does not directly inhibit protein synthesis. *Has three components* - Anthrax toxin is indeed composed of three distinct proteins: **protective antigen (PA)**, **edema factor (EF)**, and **lethal factor (LF)**. - PA is necessary for EF and LF to enter host cells, while EF causes edema and LF is responsible for cytotoxicity. *Increase cAMP* - The **edema factor (EF)** component of anthrax toxin is a **calmodulin-dependent adenylate cyclase**. - Once inside the cell, EF converts **ATP to cyclic AMP (cAMP)**, leading to increased intracellular cAMP levels, which disrupts water homeostasis and causes edema. *Coded by plasmid* - The genes encoding the anthrax toxin components (PA, EF, and LF) are located on a large plasmid known as **pXO1**. - This plasmid, along with another plasmid (pXO2) carrying genes for the capsule, is crucial for the full virulence of *Bacillus anthracis*.
Pathology
1 questionsThe tissue of origin of the Kaposi's sarcoma is
NEET-PG 2015 - Pathology NEET-PG Practice Questions and MCQs
Question 871: The tissue of origin of the Kaposi's sarcoma is
- A. Lymphoid
- B. Vascular (Correct Answer)
- C. Neural
- D. Muscular
Explanation: ***Vascular*** - Kaposi's sarcoma originates from the **vascular tissue**, specifically from endothelial cells lining blood vessels [2]. - The lesions are characterized by **angiogenesis**, leading to the formation of vascular tumors with dilated endothelial cell-lined vascular spaces [1]. *Muscular* - Muscular tissue is involved in **voluntary** and **involuntary movements** but is not related to the etiology of Kaposi's sarcoma. - This condition does not arise from **muscle cells** or any muscular components. *Neural* - Neural tissue consists of **neurons** and **glial cells**, which are not implicated in Kaposi's sarcoma. - Kaposi's sarcoma does not originate from any **neural structures** or pathologies. *Lymphoid* - Lymphoid tissue primarily concerns the immune system, particularly the **lymphatic system**, and does not give rise to Kaposi's sarcoma. - This malignancy does not derive from **lymphoid components** like lymphocytes or lymph nodes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 526-527. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 282-283.