सामान्य कृषि एवं कोशिका जीवविज्ञान

Green Fluorescent Protein (GFP), originally isolated from the jellyfish Aequorea victoria by Osamu Shimomura, is a vital scorable/reporter marker widely used in plant transformation. It contains an intrinsic tripeptide fluorophore (Ser65-Tyr66-Gly67) that absorbs blue light (excitation peak around 395 nm / 475 nm) and emits bright green fluorescence (emission peak around 509 nm) non-destructively without requiring any exogenous chemical substrate or cofactor.

In Mendelian genetics, a standard monohybrid cross begins by mating two true-breeding homozygous parental strains possessing contrasting traits (e.g., $AA \times aa$). All resulting offspring in the first filial ($F_1$) generation receive one dominant allele ($A$) and one recessive allele ($a$), rendering 100% of the $F_1$ individuals uniformly and completely heterozygous ($Aa$).

Mycoplasmas (class Mollicutes) are the smallest known self-replicating organisms. Key features include the absolute lack of a peptidoglycan cell wall and resistance to beta-lactam antibiotics. Crucially, most Mycoplasma species are not obligate intracellular parasites and can indeed be readily cultured in vitro in specialized cell-free artificial media enriched with serum/sterols, producing characteristic 'fried-egg' morphology colonies. Therefore, stating that 'they cannot be cultured in laboratory' is false.

• test cross involves mating an individual showing the dominant phenotype ($A\_$) with a homozygous recessive tester ($aa$).
• If the dominant parent is homozygous dominant ($AA$):
  $$AA \times aa \implies 100\% \text{ Aa (All dominant phenotype, 0\% recessive)}$$
• If the dominant parent is heterozygous dominant ($Aa$):
  $$Aa \times aa \implies 50\% \text{ Aa (dominant)} : 50\% \text{ aa (recessive)}$$
  Here, exactly half ($1/2$) of the progenies display the recessive trait.
• Thus, obtaining half recessive progenies confirms that the dominant parent is heterozygous dominant (Option 2).