Question 1
Source: CSIR-NET Nov 2020, Session II
Following is the list of cellular responses of root hair to bacterial Nod factor and timing of their induction:
| Response | Timing |
|---|---|
| P. Membrane potential depolarization | i. Within 1 minute |
| Q. Ca²⁺ spiking in and around root hair nucleus | ii. Within 10 minutes |
| R. Root hair growth perturbation (pauses, curling) | iii. Over a period of hours |
Which is the correct match?
a. P-(i), Q-(ii), R-(iii)
b. P-(ii), Q-(i), R-(iii)
c. P-(iii), Q-(i), R-(ii)
d. P-(i), Q-(iii), R-(ii)
Statement Analysis
P. Membrane Potential Depolarization — Within 1 minute
- This is one of the earliest responses after Nod factor perception
- Happens almost immediately at the plasma membrane
Hence, P = (i)
Q. Ca²⁺ Spiking — Within 10 minutes
- Calcium oscillations occur near the nucleus
- Crucial for signal transduction and gene activation
Hence, Q = (ii)
R. Root Hair Curling — Hours
- Morphological changes take time
- Includes growth pauses, deformation, and curling
Hence, R = (iii)
Correct answer: a. P-(i), Q-(ii), R-(iii)
Exam Insight
This question tests sequence-based understanding
Electrical changes — Signaling events — Morphological changes
If you remember this flow, you can solve similar questions even if you forget exact timings.
Question 2
Source: CSIR-NET Nov 2020, Session I
Which of the following is a plant secondary metabolite?
a. Kaurenoic acid
b. Abietic acid
c. Proline
d. Pyruvate
Statement Analysis
Abietic Acid
- A diterpenoid resin acid found in conifers and is involved in plant defense.
Why NOT the Others?
- Kaurenoic acid = Intermediate in gibberellin biosynthesis (primary metabolism link)
- Proline = Amino acid (primary metabolite)
- Pyruvate = Central metabolic intermediate (glycolysis)
Correct answer: b. Abietic acid
Exam Insight
- Primary metabolites — Growth, energy, survival
- Secondary metabolites — Defense, signaling, adaptation