Q.(a) Mention the name of man-made cereal. How it is formed ? OR

(a) Triticale is a wheat x rye hybrid with doubled chromosomes; (b) dominant epistasis is illustrated by fruit colour in summer squash.

(a) Man-made cereal -- Triticale

Triticale is the classic example of a man-made (artificial) cereal, created by plant breeders rather than occurring naturally. It was produced by hybridising wheat (Triticum species), which contributes high grain yield and good grain/baking quality, with rye (Secale cereale), which contributes hardiness, disease resistance, and tolerance to poor soil and adverse climatic conditions.

When wheat and rye are crossed, the resulting F1 hybrid is typically sterile, because the chromosome sets contributed by the two different genera (wheat and rye) are too dissimilar to pair properly during meiosis. To overcome this sterility, the hybrid's chromosome number is doubled using the chemical colchicine, which inhibits spindle formation during cell division. This produces a fertile amphidiploid (allopolyploid) -- Triticale -- which now carries complete, pairable chromosome sets from both wheat and rye, restoring normal meiosis and fertility, while combining the desirable characteristics of both parents.

(b) Dominant epistasis

Epistasis is a gene interaction in which the alleles of one gene locus mask or modify the phenotypic expression of alleles at a different, independently assorting gene locus. In dominant epistasis, it is a dominant allele of the masking (epistatic) gene that hides the effect of the other gene.

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