NEET-PG 2015 Practice Questions

Q: What is the molecular mass of Immunoglobulin G (IgG) in kilodaltons (kDa)?

150. **\*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.

Q: Which of the following acids is MOST commonly used as a reagent in medical laboratory analytical procedures?

Sulphuric acid is used in various laboratory processes.. ***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

Q: What is the scientific name of the plant commonly known as Thorn apple?

Datura stramonium. ***Datura stramonium*** - This is the correct **scientific name** for the plant commonly known as **Thorn apple** or Jimsonweed. - *Datura stramonium* is known for its **anticholinergic** properties due to alkaloids like atropine, scopolamine, and hyoscyamine. *Nux vomica* - This plant is scientifically known as *Strychnos nux-vomica* and is a source of **strychnine** and brucine. - It is known for its **CNS stimulant** and convulsant effects, and is not referred to as Thorn apple. *Papaver somniferum* - This is the **opium poppy**, famous for producing **opium**, from which morphine, codeine, and heroin are derived. - Its common name is not Thorn apple, and its effects are primarily **analgesic** and sedative. *Cannabis sativa* - This plant is commonly known as **marijuana** or hemp, and it produces cannabinoids such as THC and CBD. - It is recognized for its **psychoactive** and medicinal properties, and is not related to Thorn apple.

Q: In the context of pharmacology, what is the term 'Mickey Finn' commonly associated with?

Chloral hydrate. ***Chloral hydrate*** - A "Mickey Finn" is a slang term for a drink **laced with a psychoactive drug or incapacitating agent** given to an unsuspecting person. - Historically, **chloral hydrate** was a common substance used for this purpose due to its rapid sedative-hypnotic effects. *Chloroform* - While chloroform is a potent anesthetic and sedative, it is primarily used as an **inhalant** and is not typically administered orally in drinks. - Ingesting chloroform in large quantities can be **fatal due to severe hepatotoxicity and neurotoxicity**. *Methyl alcohol* - **Methyl alcohol (methanol)** is highly toxic and causes severe metabolic acidosis, blindness, and death, even in small amounts. - It does not induce the quick, incapacitating sedative effects associated with a "Mickey Finn" but rather a **delayed, severe poisoning syndrome**. *Ethylene glycol* - **Ethylene glycol** is an antifreeze agent that is also highly toxic, causing kidney failure and metabolic derangements. - Similar to methanol, its effects are **delayed and severe**, not the immediate incapacitating sedation implied by the term "Mickey Finn."

Q: The Marsch test is used to detect poisoning with which of the following substances?

Arsenic poisoning. ***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**.

Q: IgM appears in fetus at what gestational age -

20 weeks. ***20 weeks*** - The fetal immune system begins to develop around **20 weeks of gestation**, at which point the fetus starts producing its own **IgM antibodies**. - **IgM** is the first antibody isotype produced by the developing fetal **B lymphocytes** and is important for early immune responses. *10 weeks* - While some components of the immune system may start to differentiate earlier, **IgM production** at a functional level is not yet established at **10 weeks of gestation**. - At this early stage, the fetal immune system is still primarily in its **developmental phase**, with major organogenesis occurring. *30 weeks* - By **30 weeks**, the fetus has already been producing IgM for several weeks, and the immune system is more mature, capable of a more robust **antibody response**. - While **IgG** levels are significantly increasing due to maternal transfer at this stage, **IgM production** began earlier. *at birth* - At birth, a neonate has circulating **IgM antibodies**, which are indicative of prior fetal immune activation and are measurable in umbilical cord blood. - However, the initial production of **fetal IgM** occurs much earlier in gestation, not at the time of birth.

Q: Which human IgG subclass has the highest serum concentration?

IgG1. ***IgG1*** - **IgG1** constitutes approximately **60-70%** of the total IgG in human serum, making it the most abundant subclass. - Its high concentration reflects its crucial role in **neutralizing toxins**, agglutinating viruses, and opsonizing bacteria for phagocytosis. *IgG2* - **IgG2** makes up about **20-30%** of total IgG and is primarily important in protecting against **polysaccharide-encapsulated bacteria**. - While significant, its serum concentration is notably lower than that of IgG1. *IgG3* - **IgG3** is the least abundant IgG subclass, accounting for only **5-8%** of total IgG, and is characterized by a shorter half-life. - Despite its low concentration, it is highly efficient in activating the **complement system** due to its flexible hinge region. *IgG4* - **IgG4** comprises approximately **3-6%** of total IgG and is unique for its ability to undergo **Fab arm exchange**, leading to bispecific antibodies. - It does not activate complement and is often associated with allergy and protection against parasitic infections, but its concentration is significantly less than IgG1.

Q: Which of the following is an opioid derived from morphine?

Heroin. ***Heroin*** - Heroin (**diacetylmorphine**) is synthesized from **morphine** through a simple acetylation process. - Morphine, an **opiate**, is naturally derived from the opium poppy. *Cocaine* - **Cocaine** is a powerful stimulant and local anesthetic derived from the **coca plant**. - It is a **naturally occurring alkaloid** but is not structurally or functionally related to opioids. *Dhatura* - **Dhatura** (Datura stramonium) contains **tropane alkaloids** like scopolamine and atropine, which have anticholinergic effects. - It is not an opioid and does not interact with opioid receptors. *Cannabis* - **Cannabis** (marijuana) contains **cannabinoids**, primarily THC, which act on cannabinoid receptors in the brain. - It is distinctly different from opioids in its chemical structure, mechanism of action, and effects.

Q: Which of the following substances is commonly known as an arrow poison used by indigenous South American tribes?

Curare. ***Curare*** - **Curare** is the traditional name for South American arrow poisons derived from plants, primarily *Chondrodendron tomentosum* and *Strychnos* species - It acts as a **competitive non-depolarizing neuromuscular blocking agent**, blocking nicotinic receptors at the neuromuscular junction - Causes **skeletal muscle paralysis** by competing with acetylcholine, leading to respiratory failure in prey - **Clinical relevance:** Tubocurarine (d-tubocurarine), derived from curare, was historically used as a muscle relaxant in surgery; modern derivatives include atracurium, vecuronium, and rocuronium *Opium* - **Opium** is derived from *Papaver somniferum* (opium poppy) and contains alkaloids like morphine and codeine - Acts on **opioid receptors** in the CNS to produce analgesia and sedation - Not used as an arrow poison by South American tribes; its effects are analgesic rather than paralytic *Cannabis* - **Cannabis** (*Cannabis sativa*) contains psychoactive compounds like THC (tetrahydrocannabinol) - Acts on **cannabinoid receptors** producing psychoactive and analgesic effects - Not used as an arrow poison; lacks the rapid paralytic action needed for hunting *Cyanide* - **Cyanide** inhibits cytochrome c oxidase, blocking cellular respiration and causing rapid cell death - While highly toxic, it is **not the traditional arrow poison** of South American indigenous tribes - Traditional arrow poisons like curare cause neuromuscular paralysis rather than cellular asphyxiation

Q: From which part of the Papaver somniferum plant does the latex, commonly referred to as 'milk', exude?

Unripe capsule of the plant. ***Unripe capsule of the plant*** - The **latex** (or 'milk') containing **opioid alkaloids** like morphine and codeine is primarily harvested by incising the **unripe seed capsules** of the *Papaver somniferum* plant. - This milky sap is then collected and dried to produce **crude opium**. *Leaf of the plant* - The leaves of *Papaver somniferum* do not contain significant amounts of the latex and are not the primary source of **opium alkaloids**. - While some **alkaloids** might be present in trace amounts, they are not extracted commercially from the leaves. *Root of the plant* - The roots of the poppy plant are not known to exude latex or to be a significant source of medically relevant **opioid alkaloids**. - Their primary function is absorption of water and nutrients, and anchoring the plant. *Seeds of the plant* - While the dried seeds are used for culinary purposes (poppy seeds), they contain very low levels of **opioid alkaloids** compared to the latex. - The latex is produced within the **capsule** before the seeds fully mature.

Question 1

What is the molecular mass of Immunoglobulin G (IgG) in kilodaltons (kDa)?

Accepted Answer

150

Answer

400

Answer

1000

Answer

1500

Question 2

Which of the following acids is MOST commonly used as a reagent in medical laboratory analytical procedures?

Accepted Answer

Sulphuric acid is used in various laboratory processes.

Answer

Nitric acid is used in chemical analysis.

Answer

Carbolic acid is used as a disinfectant.

Answer

Oxalic acid is used in various laboratory applications.

Question 3

What is the scientific name of the plant commonly known as Thorn apple?

Accepted Answer

Datura stramonium

Answer

Nux vomica

Answer

Papaver somniferum

Answer

Cannabis sativa

Question 4

In the context of pharmacology, what is the term 'Mickey Finn' commonly associated with?

Accepted Answer

Chloral hydrate

Answer

Chloroform

Answer

Methyl alcohol

Answer

Ethylene glycol

Question 5

The Marsch test is used to detect poisoning with which of the following substances?

Accepted Answer

Arsenic poisoning

Answer

Lead poisoning

Answer

Mercury poisoning

Answer

Nickel poisoning

Question 6

IgM appears in fetus at what gestational age -

Accepted Answer

20 weeks

Answer

10 weeks

Answer

30 weeks

Answer

at birth

Question 7

Which human IgG subclass has the highest serum concentration?

Accepted Answer

IgG1

Answer

IgG2

Answer

IgG3

Answer

IgG4

Question 8

Which of the following is an opioid derived from morphine?

Accepted Answer

Heroin

Answer

Cocaine

Answer

Dhatura

Answer

Cannabis

Question 9

Which of the following substances is commonly known as an arrow poison used by indigenous South American tribes?

Accepted Answer

Curare

Answer

Opium

Answer

Cannabis

Answer

Cyanide

Question 10

From which part of the Papaver somniferum plant does the latex, commonly referred to as 'milk', exude?

Accepted Answer

Unripe capsule of the plant

Answer

Leaf of the plant

Answer

Root of the plant

Answer

Seeds of the plant

NEET-PG 2015

Biochemistry

Forensic Medicine

Microbiology

Pharmacology