Mineral Nutrition

• Statement (I) is True: Reactive oxygen species ($\text{O}_2^{\bullet-}$, $\text{H}_2\text{O}_2$, $^{\bullet}\text{OH}$) initiate self-propagating free-radical chain reactions of lipid peroxidation in polyunsaturated fatty acids, disrupting membrane fluidity and inducing cell death.
• Statement (II) is True: Plants genetically adapted to thrive under high salt concentrations ($\gt 200\text{ mM NaCl}$) are classified as halophytes, whereas non-adapted, salt-sensitive species are classified as glycophytes.
• Conclusion: Both Statement (I) and Statement (II) are true.

Correct option: (1) Both Statement (|) and Statement (II) are true.

• Statement (I) is True: Heat stress directly disrupts weak hydrogen bonds and hydrophobic interactions, leading to membrane hyperfluidity and structural denaturation of protein complexes.
• Statement (II) is False: The primary physical lesion of cold/freezing stress is membrane rigidification and phase transition from a flexible liquid-crystalline to a solid gel phase, inducing electrolyte leakage and dehydration, NOT disturbed cofactor binding.
• Conclusion: Statement (I) is true but Statement (II) is false.

Correct option: (3) Statement (I) is true but Statement (II) is false.

• Assertion (A) is True: In the angiosperm female gametophyte (embryo sac), the large diploid/dikaryotic central cell is functionally a female gamete alongside the haploid egg cell.
• Reason (R) is True & Explains (A): In double fertilization, one sperm cell fertilizes the egg cell to form the diploid zygote ($2n$), while the second sperm cell fuses with the central cell (containing two polar nuclei) to form the triploid ($3n$) primary endosperm nucleus.
• Conclusion: Both (A) and (R) are true and (R) is the correct explanation of (A).

Correct option: (1) Both (A) and (R) are true and (R) is the correct explanation of (A)

• Climacteric vs Non-Climacteric Fruits:
• Climacteric: Characterized by an autocatalytic burst of ethylene production accompanied by a sharp respiratory climacteric peak at the onset of ripening. Guava (Psidium guajava), banana, mango, and tomato are climacteric.
• Non-Climacteric: Ripen gradually without an ethylene peak or respiratory burst (e.g., citrus/lemon, cashew apple, bell pepper).

Correct option: (2) Guava