Which one of the following structures is NOT part of the respiratory zone:

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#Question id: 37966

#Plant Biotechnology

Assertion (A): Commitment to androgenesis is achieved primarily by the abolition of pollen maturation gene expression. 

Reason (R): During induction, several hundred genes are upregulated or downregulated to facilitate the developmental switch

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#Question id: 37967

#Plant Biotechnology

Assertion (A): Responsive pollen in culture always develops directly into a globular embryo. 

Reason (R): The developmental fate (embryo vs. callus) depends on the plant species.

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#Question id: 37968

#Plant Biotechnology

Assertion (A): In cereals like rice and wheat, the choice between embryo or callus formation can be manipulated. 

Reason (R): Modifying the medium composition in these species can induce either embryos or calli.

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#Question id: 37969

#Plant Biotechnology

Statement I: Cold treatment (3–6°C) helps in retarding the aging of the anther wall, thereby allowing more microspores to switch from gametophytic to sporophytic development.

Statement II: Maize responds best to standard cold treatment temperatures of 3–6°C rather than higher temperatures like 14°C

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#Question id: 37970

#Plant Biotechnology

Statement I: Hot treatment (e.g., 30°C for 24h) in Brassica stimulates embryogenesis by causing the dissolution of microtubules and displacement of the spindle.

Statement II: This thermal shock leads to normal division of the microspore nucleus.

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#Question id: 37971

#Plant Biotechnology

Statement I: Ethrel (2-chloroethylphosphonic acid) treatment increases haploid production by inducing multinucleated pollen grains.

Statement II: Pollen grains induced by Ethrel treatment are characterized by having a high density of starch grains.