Q1. High Altitude Acclimatization
Source: CSIR NET, Nov 2020, Session II
In high altitude, a number of compensatory mechanisms operate over a period of time to increase altitude tolerance in humans which is called acclimatization. The following statements propose these compensatory changes:
A. initial increase of ventilation is relatively small in high altitude but the ventilation steadily increases over the next few day
B. red blood cell 2,3-DPG increases
C. the blood pH becomes more alkaline
D. the oxygen dissociation curve is shifted to the left
E. the pH of cerebrospinal fluid is further increased
Choose the option with both incorrect statements.
1. A and B
2. B and C
3. C and D
4. D and E
Correct Answer: Option 4 (D and E)
Understanding the Core Concept
At high altitude:
- Decreased atmospheric pressure
- Decreased Partial pressure of oxygen
- Systemic hypoxia
Immediate (Minutes–Hours)
- Peripheral chemoreceptor activation
- Increased ventilation
- Decreased CO₂ → Respiratory alkalosis
Intermediate (Days)
- Renal bicarbonate excretion
- Gradual correction of blood and CSF pH
Hematologic Adaptation
- Increased 2,3-DPG in RBCs
- Rightward shift of the oxygen dissociation curve
Statement Analysis
A. Initial increase of ventilation is relatively small…
The ventilatory response to hypoxia is immediate and significant. While ventilation continues to increase over days, describing the initial response as “relatively small” is misleading.
This statement is not definitively incorrect, but it is not entirely accurate either.
B. RBC 2,3-DPG increases
Correct.
Increased 2,3-DPG reduces hemoglobin’s oxygen affinity, facilitating oxygen unloading in peripheral tissues.
C. Blood pH becomes more alkaline
Correct.
Hyperventilation lowers CO₂ levels, producing respiratory alkalosis.
D. Oxygen dissociation curve shifts to the left
Incorrect.
Although alkalosis transiently favors a left shift, the sustained rise in 2,3-DPG results in a rightward shift – the physiologically adaptive direction at high altitude.
A left shift would impair oxygen unloading.
E. CSF pH is further increased
Incorrect.
While CSF pH initially rises due to reduced CO₂, renal and choroid plexus-mediated bicarbonate adjustments restore it toward normal, permitting sustained hyperventilation.
It does not remain further increased.
Final Answer: Option 4 (D and E)
Exam Insights
High-scoring candidates recognize sequence and compensation: not isolated facts.
Q2. Vitamin and Active form correlation
Source: ICMR JRF, 2020
Coenzyme A is a derivative of-
- Thiamine
- Riboflavin
- Panthothenate
- Niacin
Correct Answer: C. Pantothenate
Understanding the core concept
Vitamin–coenzyme relationships.
A fundamental biochemistry association that must be recalled instantly.
| Vitamin | Active Form |
| B1 (Thiamine) | TPP |
| B2 (Riboflavin) | FAD, FMN |
| B3 (Niacin) | NAD+, NADP+ |
| B5 (Pantothenic acid) | Coenzyme A |
Option Evaluation
- Thiamine —TPP—-Decarboxylation reactions
- Riboflavin —FAD / FMN —-Redox reactions
- Niacin —NAD⁺ / NADP⁺ —- Oxidation–reduction reactions
- Pantothenate —- Structural component of Coenzyme A
Coenzyme A contains:
- Pantothenic acid
- β-mercaptoethylamine
- ADP moiety
Therefore, the correct answer is C. Pantothenate
Exam Insights
This is a precision recall question.
See you next with with 2 other questions.