Seed Health

• Amphidiploid (Allopolyploid behaving as diploid):
• An allopolyploid containing two complete sets of non-homologous diploid genomes derived from two distinct ancestral species (e.g., $2n = 2x_1 + 2x_2$).
• Because each chromosome has exactly one homologous partner from the same parental genome, meiosis exhibits strict bivalent pairing with regular disjunction, functioning genetically and cytologically as a normal diploid. (Correct answer: Option 3)

• Haploid Chromosome Numbers ($n$) in Major Field Crops:
• Hordeum vulgare (Barley): Diploid species with $2n = 2x = 14$; haploid chromosome number is $n = 7$ $\rightarrow$ (II)
• Chickpea (Cicer arietinum): Diploid pulse with $2n = 2x = 16$; haploid chromosome number is $n = 8$ $\rightarrow$ (I)
• Sunflower (Helianthus annuus): Diploid oilseed with $2n = 2x = 34$; haploid chromosome number is $n = 17$ $\rightarrow$ (IV)
• Rice (Oryza sativa): Diploid cereal with $2n = 2x = 24$; haploid chromosome number is $n = 12$ $\rightarrow$ (III)
• Systematic Match: (A)-(II), (B)-(I), (C)-(IV), (D)-(III) corresponds to Option 3.

Correct option: (3) (A) - (II), (B) - (1), (C) - (IV), (D) - (ttl)

• Reactive Oxygen Species (ROS) Scavenging System:
• Enzymatic Scavengers: Superoxide Dismutase (SOD, converts $O_2^{\bullet-}$ to $H_2O_2$), Catalase (CAT, decomposes $H_2O_2$ to $H_2O$), and Peroxidase (POX).
• Non-Enzymatic Antioxidant: Glutathione (GSH) is a non-enzymatic tripeptide thiol antioxidant that acts as a substrate in the ascorbate-glutathione cycle, not an enzyme. (Correct answer: Option 2)

• Reproductive Isolating Mechanisms (RIMs): Biological barriers (pre-zygotic and post-zygotic) that prevent individuals of different species from producing viable, fertile offspring.
• Primary Function: In evolutionary biology and plant speciation, the fundamental role of reproductive barriers is preventing interspecific gene flow, thereby maintaining taxonomic boundaries and genetic distinctiveness. (Correct answer: Option 2)