All of the following are required more during lactation as compared to pregnancy, except ?
What is the iron requirement for a normal menstruating adult female?
Which nut has the highest protein content among the following options?
What is the primary effect of moderate alcohol consumption on cholesterol levels?
What is the effect of moderate alcohol consumption on lipid profiles in dyslipidemia?
Cystatin C levels are used for
Which of the following statements about Maple Syrup Urine Disease (MSUD) is true?
3 beta hydroxysteroid dehydrogenase deficiency causes increased production of -
Which of the following conditions is primarily treated with Vitamin B6?
Critical temperature for liquid nitrogen is ?
NEET-PG 2013 - Biochemistry NEET-PG Practice Questions and MCQs
Question 121: All of the following are required more during lactation as compared to pregnancy, except ?
- A. Niacin
- B. Energy
- C. Iron (Correct Answer)
- D. Vitamin A
Explanation: ***Iron*** - **Iron requirements are significantly higher during pregnancy** (~27 mg/day) due to the expansion of maternal red blood cell mass, fetal development, and placental iron needs. - During lactation, iron requirement decreases to **~9-10 mg/day**, lower than in pregnancy, as **lactational amenorrhea** (absence of menstruation) reduces iron loss. - This represents the **most significant decrease** in requirement from pregnancy to lactation among the listed nutrients. *Vitamin A* - The **recommended daily allowance (RDA) for Vitamin A is higher during lactation** (~1300 μg/day) compared to pregnancy (~800 μg/day). - This increased requirement ensures **adequate transfer to breast milk** to support infant's **vision development and immune function**. *Niacin* - **Niacin requirements during lactation** (~17 mg/day) are **similar to pregnancy** (~18 mg/day). - While lactation involves increased metabolic demands, niacin requirements do not show a marked increase compared to pregnancy, unlike Vitamin A and Energy. - This option is less clearly "required more" during lactation. *Energy* - **Energy requirements are significantly higher during lactation** to fuel milk production, which is energetically demanding. - A lactating woman typically needs an **additional 500 kcal/day**, compared to ~300 kcal/day in the 2nd/3rd trimester of pregnancy.
Question 122: What is the iron requirement for a normal menstruating adult female?
- A. 30 mg/day
- B. 35 mg/day
- C. 20 mg/day
- D. 15 mg/day (Correct Answer)
Explanation: ***15 mg/day*** - The recommended daily iron intake for a normal menstruating adult female was **15 mg/day** according to guidelines at the time of this examination (NEET-2013). - This higher requirement compared to males and post-menopausal women is due to **iron loss in menstrual blood**, averaging approximately **0.5-1 mg/day** additional iron loss. - **Note:** Current guidelines recommend **18 mg/day** (US RDA) or **21 mg/day** (ICMR, India), but this question reflects the 2013 standard. *20 mg/day* - This amount is **higher than the typical recommendation** for healthy menstruating women without significant pathology. - While some women with heavier menstrual bleeding might require this, it's not the baseline requirement for normal menstruation. *30 mg/day* - This intake level is typically recommended for **pregnant women** in the second and third trimesters or individuals with **diagnosed iron deficiency anemia** requiring therapeutic supplementation. - It is significantly more than the daily requirement for a healthy menstruating female. *35 mg/day* - This is an **excessively high** daily iron intake for a healthy menstruating female. - Such high doses are usually prescribed for **severe iron deficiency anemia** or specific medical conditions under supervision. - Chronic intake at this level without medical indication could potentially lead to adverse effects.
Question 123: Which nut has the highest protein content among the following options?
- A. Walnut
- B. Coconut
- C. Groundnut (Correct Answer)
- D. Almond
Explanation: ***Groundnut*** - **Groundnuts** (peanuts) contain approximately **26 grams of protein per 100 grams**, which is the highest among the given options. - While botanically classified as legumes, groundnuts are commonly grouped with nuts in nutritional contexts. - They are also rich in **healthy fats**, **fiber**, and various **B vitamins**. *Almond* - **Almonds** contain about **21 grams of protein per 100 grams**, making them the second highest in protein content among the options. - They are excellent sources of **vitamin E**, **magnesium**, and **healthy monounsaturated fats**. *Walnut* - **Walnuts** contain approximately **15 grams of protein per 100 grams**, which is lower than both groundnuts and almonds. - They are notably rich in **omega-3 fatty acids** (alpha-linolenic acid). *Coconut* - **Coconut flesh** has relatively low protein content, around **3.3 grams per 100 grams**. - It is primarily known for its high content of **medium-chain triglycerides** and **saturated fats**.
Question 124: What is the primary effect of moderate alcohol consumption on cholesterol levels?
- A. Total cholesterol
- B. Low-Density Lipoprotein (LDL)
- C. Very Low-Density Lipoprotein (VLDL)
- D. High-Density Lipoprotein (HDL) (Correct Answer)
Explanation: ***High-Density Lipoprotein (HDL)*** - Moderate alcohol consumption is known to **increase HDL cholesterol** levels. - HDL cholesterol helps in the **reverse cholesterol transport**, removing excess cholesterol from tissues and transporting it back to the liver for excretion. *Total cholesterol* - The effect of moderate alcohol on **total cholesterol** is less consistent and may vary, as it is a sum of HDL, LDL, and 20% of VLDL. - While HDL increases, other components might remain unchanged or show minimal variation, thus not making it the primary and direct effect. *Low-Density Lipoprotein (LDL)* - Moderate alcohol consumption generally has **little to no significant effect** on **LDL cholesterol** levels. - Some studies suggest a slight decrease or no change, but it is not the primary lipid affected. *Very Low-Density Lipoprotein (VLDL)* - There is generally **no significant direct effect** of moderate alcohol consumption on **VLDL cholesterol** levels. - Excessive alcohol intake, however, can elevate triglycerides, which are the main component of VLDL particles.
Question 125: What is the effect of moderate alcohol consumption on lipid profiles in dyslipidemia?
- A. Decreased HDL levels
- B. Increased HDL levels (Correct Answer)
- C. Increased triglyceride levels
- D. Decreased LDL levels
Explanation: ***Increased HDL levels*** - Moderate alcohol consumption is known to **increase high-density lipoprotein (HDL) cholesterol levels**, which is often considered beneficial for cardiovascular health. - This effect is thought to be mediated by alcohol's influence on **hepatic lipoprotein metabolism**, leading to enhanced HDL production and reduced catabolism. *Decreased HDL levels* - This is incorrect, as multiple studies have consistently shown that **moderate alcohol consumption** tends to elevate, rather than decrease, HDL cholesterol. - Low HDL levels are associated with increased cardiovascular risk, making this effect an undesirable outcome that is not typical of moderate drinking. *Increased triglyceride levels* - While heavy or chronic alcohol consumption can lead to **increased triglyceride levels**, moderate intake typically has a neutral or only slightly elevated effect, if any, often overshadowed by the HDL increase. - Significant hypertriglyceridemia is a concern with **excessive alcohol use**, not usually with moderate consumption in healthy individuals. *Decreased LDL levels* - Moderate alcohol consumption generally has **little to no significant effect** on **low-density lipoprotein (LDL) cholesterol levels**, often referred to as "bad" cholesterol. - While HDL increases are observed, alcohol does not effectively lower LDL, which is a primary target in the management of dyslipidemia.
Question 126: Cystatin C levels are used for
- A. Detecting UTI
- B. Estimating GFR (Correct Answer)
- C. Screening for Renal Ca
- D. Estimating difference between CRF and ARF
Explanation: ***Estimating GFR*** - **Cystatin C** is a **proteinase inhibitor** produced by all nucleated cells at a constant rate, and its level in the blood is inversely related to the **glomerular filtration rate (GFR)**. - Unlike **creatinine**, Cystatin C levels are less affected by **muscle mass, diet, or inflammation**, making it a more reliable marker for early and subtle changes in GFR, especially in certain populations. *Detecting UTI* - **Urinary tract infections (UTIs)** are primarily detected through **urinalysis** (presence of **leukocytes, nitrites**, and **bacteria**) and **urine culture**. - **Cystatin C** is a serum marker for renal function and has no direct role in detecting the presence of bacterial infection in the urinary tract. *Estimating difference between CRF and ARF* - Differentiating between **chronic renal failure (CRF)** and **acute renal failure (ARF)** typically involves assessing the **chronicity of symptoms**, trend in **creatinine levels**, and **kidney size** and **echogenicity** on ultrasound. - While Cystatin C can reflect current GFR, it doesn't inherently provide discriminatory power between acute and chronic processes without serial measurements or additional clinical context. *Screening for Renal Ca* - **Renal cell carcinoma (RCC)** screening is primarily done using **imaging techniques** like **ultrasonography, CT, or MRI**, especially in individuals with risk factors or symptoms like **hematuria**. - **Cystatin C** is a marker of kidney function and does not serve as a tumor marker for renal cancer.
Question 127: Which of the following statements about Maple Syrup Urine Disease (MSUD) is true?
- A. FeCl3 turns navy blue
- B. Asymptomatic
- C. Deficiency of branched chain amino acid enzymes (Correct Answer)
- D. Hyperaminoaciduria of aromatic amino acids
Explanation: ***Deficiency of branched chain amino acid enzymes*** - MSUD is caused by a deficiency in the **branched-chain alpha-keto acid dehydrogenase complex (BCKDC)**, an enzyme responsible for metabolizing **leucine, isoleucine, and valine**. - This enzyme deficiency leads to the accumulation of these **branched-chain amino acids (BCAAs)** and their corresponding branched-chain alpha-keto acids in the body. *Asymptomatic* - MSUD is a severe metabolic disorder that is **not asymptomatic**; it typically presents with distinct neurological and metabolic symptoms shortly after birth. - Clinical manifestations can include **poor feeding, lethargy, seizures**, and a characteristic **maple syrup odor** in urine and earwax. *FeCl3 turns navy blue* - The **ferric chloride test (FeCl3 test)** in MSUD typically yields a **green-gray or dark-green color** when testing for the accumulation of alpha-keto acids (specifically alpha-ketoisocaproic acid). - A **navy blue color** with FeCl3 is more characteristic of **alkaptonuria** due to the presence of homogentisic acid. *Hyperaminoaciduria of aromatic amino acids* - MSUD is characterized by the accumulation and excretion of **branched-chain amino acids (leucine, isoleucine, valine)** and their corresponding keto acids. - **Hyperaminoaciduria of aromatic amino acids** (e.g., phenylalanine, tyrosine, tryptophan) is seen in other conditions like **phenylketonuria (PKU)**, not MSUD.
Question 128: 3 beta hydroxysteroid dehydrogenase deficiency causes increased production of -
- A. DHEA (Correct Answer)
- B. Progesterone
- C. Deoxycortisol
- D. Estradiol
Explanation: ***DHEA*** - The enzyme **3 beta-hydroxysteroid dehydrogenase (3β-HSD)** is crucial for converting **delta-5 steroids (pregnenolone, 17-OH-pregnenolone, and DHEA)** into **delta-4 steroids (progesterone, 17-OH-progesterone, and androstenedione)**. - A **deficiency** in 3β-HSD leads to the accumulation of its substrates, particularly **DHEA (dehydroepiandrosterone)** and **17-OH-pregnenolone**, due to the impaired conversion in the steroid synthesis pathway. - Among the accumulated substrates, **DHEA** has weak androgenic activity, making it clinically significant in this enzyme deficiency. *Progesterone* - **Progesterone** is a delta-4 steroid, which is synthesized from **pregnenolone** via the action of **3β-HSD**. - A deficiency in this enzyme would **decrease** the production of progesterone, not increase it, as the enzyme is required for its synthesis. *Deoxycortisol* - **Deoxycortisol (11-deoxycortisol)** is a precursor to cortisol, formed later in the adrenal steroid synthesis pathway from **17-hydroxyprogesterone**. - Its production would be **decreased** by a 3β-HSD deficiency, as the pathway is blocked upstream, reducing the formation of downstream products like cortisol and its precursors. *Estradiol* - **Estradiol** is an estrogen, synthesized from androgens (like testosterone) via the enzyme **aromatase**. - A deficiency in 3β-HSD would impair the production of androgens like androstenedione and testosterone, which are precursors for estradiol, thereby leading to a **decrease** in estradiol levels, not an increase.
Question 129: Which of the following conditions is primarily treated with Vitamin B6?
- A. Cystathionuria
- B. None of the options
- C. Xanthourenic aciduria
- D. Homocystinuria (Correct Answer)
Explanation: ***Homocystinuria*** - The most common form of **homocystinuria** is caused by **cystathionine β-synthase (CBS) deficiency**, which requires **pyridoxal phosphate (Vitamin B6)** as a cofactor. - Approximately **50% of patients** with CBS deficiency are **B6-responsive**, making **high-dose Vitamin B6 (100-500 mg/day)** a **first-line primary treatment** for these cases. - This is a **clinically significant condition** that requires treatment, manifesting with features like **ectopia lentis, marfanoid habitus, intellectual disability, and thromboembolism**. - B6 supplementation enhances residual CBS enzyme activity and reduces plasma homocysteine levels. *Cystathionuria* - Caused by **cystathionine γ-lyase deficiency**, which also uses **Vitamin B6** as a cofactor. - This is generally a **benign, asymptomatic condition** that does **NOT require treatment**. - While B6 can reduce cystathionine accumulation, it is **not a primary treatment indication** because the condition is clinically insignificant. *Xanthurenic aciduria* - Caused by **kynureninase deficiency** in the **tryptophan metabolism pathway**, which requires **pyridoxal phosphate**. - This is a **rare and usually benign condition** that does not typically require treatment. - Not a primary indication for B6 therapy. *None of the options* - Incorrect, as **Homocystinuria** (CBS deficiency) is a **primary indication** for high-dose Vitamin B6 therapy in B6-responsive patients.
Question 130: Critical temperature for liquid nitrogen is ?
- A. 36.5°C
- B. -20°C
- C. -147°C (Correct Answer)
- D. -242°C
Explanation: ***-147°C*** - The **critical temperature** is the temperature above which a gas cannot be liquefied, no matter how much pressure is applied. For **liquid nitrogen**, this value is approximately **-147°C**. - At temperatures above **-147°C**, nitrogen exists only in its gaseous phase. *36.5°C* - This temperature is close to **human body temperature** and is not relevant to the critical temperature of nitrogen. - Nitrogen would be in a gaseous state at this temperature and below its critical pressure. *-20°C* - While a low temperature, **-20°C** is still well above nitrogen's **critical temperature**. - At **-20°C**, nitrogen would be a gas unless subjected to very high pressures. *-242°C* - This temperature is below the **critical temperature** of nitrogen, but it is also below its **boiling point** of **-196°C**. - At **-242°C**, nitrogen would be a liquid, but this value is not its critical temperature.