NEET-PG 2012

1213 Questions — Page 24 of 122

Anatomy

2 questions

Q231

Nutrient artery runs ?

Q232

Bronchogenic sequestration is seen in which lobe?

NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs

Question 231: Nutrient artery runs ?

A. Away from epiphysis (Correct Answer)
B. Towards metaphysis
C. None of the options
D. Away from metaphysis

Explanation: ***Away from epiphysis*** - The **nutrient artery** runs away from the **dominant (faster-growing) epiphysis** towards the non-dominant end of the bone. - This follows the classic anatomical rule: **"To the elbow, from the knee"** - nutrient arteries point towards the elbow in upper limb bones and away from the knee in lower limb bones. - The **nutrient foramen** is directed obliquely away from the more actively growing end, established during bone development. - Examples: In the humerus, it runs towards the elbow (away from proximal epiphysis); in the femur, it runs away from the knee (away from distal epiphysis). *Towards metaphysis* - While the artery does course towards the metaphyseal region of the slower-growing end, this option is less anatomically precise. - The standard teaching emphasizes the relationship with the **dominant epiphysis** rather than the metaphysis. *Away from metaphysis* - This is **incorrect** - the nutrient artery actually runs **towards** the metaphysis of the non-dominant end. - It runs **away from** the dominant epiphysis, not away from the metaphysis. *None of the options* - This is incorrect as **"Away from epiphysis"** correctly describes the direction of the nutrient artery relative to the dominant growing end.

Question 232: Bronchogenic sequestration is seen in which lobe?

A. Left lower lobe (Correct Answer)
B. Right upper lobe
C. Left upper lobe
D. Right middle lobe

Explanation: ***Left lower lobe*** - **Bronchopulmonary sequestration**, particularly the **intralobar type**, most commonly affects the **posterior basal segment of the left lower lobe**. [1] - This congenital malformation involves a segment of lung tissue that lacks normal communication with the tracheobronchial tree and receives its blood supply from a systemic artery. [1] *Right upper lobe* - While sequestration can occur anywhere, the **right upper lobe** is a much less common location for bronchopulmonary sequestration compared to the lower lobes. - Sequestration in the upper lobes is rare and usually associated with specific anatomical variations. *Right middle lobe* - The **right middle lobe** is also an infrequent site for bronchopulmonary sequestration. - The typical presentation involves the basal segments of the lower lobes due to embryonic developmental patterns. *Left upper lobe* - **Left upper lobe** involvement in bronchopulmonary sequestration is uncommon. - The majority of cases are found in the lower lobes, especially the left lower lobe.

Biochemistry

5 questions

Q231

Which amino acid among the following has significant UV absorption at 280 nm used in protein quantification?

Q232

Which of the following processes does not occur in mitochondria?

Q233

Chemiosmotic coupling of oxidative phosphorylation is related to which of the following?

Q234

Which of the following does not play a role in protein synthesis?

Q235

Which of the following types of bonds is considered the weakest?

NEET-PG 2012 - Biochemistry NEET-PG Practice Questions and MCQs

Question 231: Which amino acid among the following has significant UV absorption at 280 nm used in protein quantification?

A. Tyrosine (Correct Answer)
B. Alanine
C. Histidine
D. Arginine

Explanation: ***Correct Option: Tyrosine*** - Tyrosine contains a **phenol functional group** (aromatic ring with hydroxyl group), giving it **significant UV absorption at 280 nm** (specifically ~274 nm) - Along with **tryptophan** and **phenylalanine**, tyrosine is one of the three aromatic amino acids used for **protein quantification via UV spectroscopy** - The aromatic side chain with conjugated double bonds enables strong UV light absorption *Incorrect Option: Alanine* - Alanine has a **methyl group** as its side chain (non-polar, aliphatic) - **Lacks aromatic rings** or conjugated systems - Does **not absorb UV light** at 280 nm *Incorrect Option: Histidine* - Histidine has an **imidazole ring** (heterocyclic aromatic) in its side chain - While technically aromatic, it has **minimal UV absorption at 280 nm** (weak absorption around 210-230 nm) - **Not used for protein quantification** at 280 nm due to insignificant absorption at this wavelength *Incorrect Option: Arginine* - Arginine contains a **guanidinium group** (highly basic, polar) - **Non-aromatic structure** without conjugated double bonds - Does **not exhibit UV absorption** at wavelengths used for protein analysis

Question 232: Which of the following processes does not occur in mitochondria?

A. Fatty acid oxidation
B. Electron transport chain
C. Glycogenolysis (Correct Answer)
D. Citric acid cycle (Kreb's cycle)

Explanation: ***Glycogenolysis*** - **Glycogenolysis** is the breakdown of **glycogen** into glucose, which primarily occurs in the **cytosol** of cells, mainly in the liver and muscles. - This process is crucial for maintaining blood glucose levels and providing energy during periods of fasting or increased demand, and it does not take place within the mitochondria. *Fatty acid oxidation* - **Fatty acid oxidation**, also known as beta-oxidation, is a mitochondrial process that breaks down fatty acids into **acetyl-CoA** for energy production. - This occurs extensively within the mitochondrial matrix, producing ATP. *Electron transport chain* - The **electron transport chain** is located in the **inner mitochondrial membrane** and is the final stage of aerobic respiration, producing the majority of ATP. - It involves a series of protein complexes that transfer electrons to oxygen, creating a proton gradient for ATP synthesis. *Citric acid cycle (Kreb's cycle)* - The **citric acid cycle**, or **Krebs cycle**, is a central metabolic pathway that occurs in the **mitochondrial matrix**. - It oxidizes acetyl-CoA, derived from carbohydrates, fats, and proteins, to produce ATP, NADH, and FADH2.

Question 233: Chemiosmotic coupling of oxidative phosphorylation is related to which of the following?

A. ATP generation by pumping of neutrons
B. Formation of ATP at substrate level
C. ATP generation by pumping of protons (Correct Answer)
D. ATP formation by transport of electrons

Explanation: ***ATP generation by pumping of protons*** - **Chemiosmotic coupling** links the electron transport chain's activity to ATP synthesis through the generation of a **proton gradient** across the inner mitochondrial membrane. - The energy released from the flow of electrons through complexes I, III, and IV is used to pump protons from the mitochondrial matrix to the intermembrane space, creating a **proton motive force** that drives ATP synthase. *Formation of ATP at substrate level* - **Substrate-level phosphorylation** involves the direct transfer of a phosphate group from a high-energy substrate to ADP to form ATP, independently of a proton gradient. - This process occurs in reactions like those in **glycolysis** and the **Krebs cycle**, not in oxidative phosphorylation via chemiosmosis. *ATP generation by pumping of neutrons* - **Neutrons** are subatomic particles with no electric charge and are not involved in biological processes like ATP generation or membrane transport. - Pumping of neutrons has no physiological relevance in cellular energy metabolism. *ATP formation by transport of electrons* - While **electron transport** is an integral part of oxidative phosphorylation, it does not directly form ATP. - The energy released during electron transport is used to create the **proton gradient** (chemiosmotic coupling), which then drives ATP synthesis, rather than ATP being formed directly by electron movement.

Question 234: Which of the following does not play a role in protein synthesis?

A. m-RNA
B. ATP
C. Intron (Correct Answer)
D. Exon

Explanation: ***Intron*** - Introns are **non-coding regions** within a gene that are transcribed into RNA but are subsequently **spliced out** before translation. - They do not carry genetic information for protein synthesis; their removal ensures the correct sequence of amino acids is produced. *Exon* - Exons are the **coding regions** of a gene that contain the genetic information for protein synthesis. - After introns are removed, exons are ligated together to form the **mature mRNA** that is translated into protein. *m-RNA* - **Messenger RNA (mRNA)** carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm. - It serves as the **template** for protein synthesis through the process of translation. *ATP* - **Adenosine triphosphate (ATP)** provides the **energy** required for various steps in protein synthesis, including mRNA transcription, amino acid activation, and ribosome movement. - It is a crucial energy currency that fuels the process of forming peptide bonds and assembling the polypeptide chain.

Question 235: Which of the following types of bonds is considered the weakest?

A. Covalent
B. Hydrogen
C. Electrostatic
D. Van der Waals (Correct Answer)

Explanation: ***Van der Waals*** - **Van der Waals forces** are very **weak, short-range attractive forces** that arise from transient fluctuations in electron distribution, creating fleeting dipoles. - They are crucial for phenomena like **protein folding** and **molecular recognition**, but are easily overcome. *Covalent* - **Covalent bonds** involve the **sharing of electron pairs** between atoms, resulting in very strong and stable connections. - They require a significant amount of energy to break, making them fundamental to the structure of most organic and biological molecules. *Hydrogen* - **Hydrogen bonds** are **intermolecular forces** that occur when a hydrogen atom covalently bonded to a highly electronegative atom (like **oxygen** or **nitrogen**) is attracted to another electronegative atom. - While weaker than covalent bonds, they are significantly stronger than Van der Waals forces and play critical roles in **DNA structure** and **water properties**. *Electrostatic* - **Electrostatic interactions** (also known as **ionic bonds** or salt bridges) occur between oppositely charged ions or polar molecules. - These forces can be quite strong, especially in a non-polar environment, and are important for **protein stability** and **enzyme-substrate binding**.

Internal Medicine

1 questions

Q231

Creola bodies are seen in:

Pathology

2 questions

Q231

In which organ are corpora amylacea typically observed in a pathological context?

Q232

Which of the following does not belong to the family of selectins?

NEET-PG 2012 - Pathology NEET-PG Practice Questions and MCQs

Question 231: In which organ are corpora amylacea typically observed in a pathological context?

A. Thymus
B. Lymph node
C. Spleen
D. Prostate (Correct Answer)

Explanation: ***Prostate*** - **Corpora amylacea**, also known as prostatic concretions, are common, benign findings in the prostate gland, especially with increasing age. - They are composed of glycoproteins and often found within the **acini and ducts of the prostate**. *Thymus* - The thymus is known for **Hassall's corpuscles**, which are epithelial reticular cells arranged concentrically, playing a role in T-cell selection. - **Corpora amylacea** are not typically found in the normal thymus. *Lymph node* - Lymph nodes are characterized by their lymphoid follicles, germinal centers, and medullary cords. - While they can have various inclusions or changes in disease states, **corpora amylacea** are not a typical pathological finding in lymph nodes. *Spleen* - The spleen is primarily involved in filtering blood and immune responses, with distinct red and white pulp regions. - **Corpora amylacea** are not associated with the normal or pathological histology of the spleen.

Question 232: Which of the following does not belong to the family of selectins?

A. P selectin
B. L selectin
C. A selectin (Correct Answer)
D. E selectin

Explanation: ***A selectin*** - ***A selectin*** is not a recognized member of the selectin family, which includes other specific types. - The known selectins are **E-selectin**, **L-selectin**, and **P-selectin**, demonstrating a distinct classification [1]. *E selectin* - E selectin is a specific type of selectin expressed on **endothelial cells** activated by cytokines [1]. - It plays a crucial role in **leukocyte adhesion** during inflammation, distinguishing it as part of the selectin family [1]. *L selectin* - L selectin is involved in the **homing** of leukocytes to lymph nodes and forms part of the selectin family [1]. - Responsible for the initial tethering and rolling of leukocytes on **venular endothelium** [1]. *P selectin* - P selectin is found on platelets and endothelial cells and is critical in the **aggregation** of platelets and leukocytes. - It is also an established member of the selectin family, involved in **inflammatory responses** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 87.