Genetics And Plant Breeding - Study Mode

[#431] Repressor protein binds to which site in Lac Operon model?
Correct Answer

(C) Operator

Explanation

Solution: Repressor protein binds to the operator site in the Lac Operon model. The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in E. coli and many other enteric bacteria. The operator site where the repressor binds is a DNA sequence with inverted repeat symmetry. The two DNA half-sites of the operator together bind to two of the subunits of the repressor.

[#432] Chromosomes are best seen in
Correct Answer

(C) Metaphase

Explanation

Solution: Chromosomes are best seen in metaphase. Chromosomes are threadlike structures made of protein and a single molecule of DNA that serve to carry the genomic information from cell to cell. Metaphase is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their condensed and coiled stage. These chromosomes, carrying genetic information, align in the equator of the cell before being separated into each of the two daughter cells, thus chromosomes are visible in this stage.

[#433] A fertilized mature ovule which possesses an embryonic plant, food reserve and protective coating in a plant species is
Correct Answer

(D) None of these

Explanation

Solution: A fertilized mature ovule that possesses an embryonic plant, food reserve and protective coating in a plant species is the seed, none of the options are given. Embryo Sac is the female gametophyte of a seed plant, consisting of a thin-walled sac within the nucellus which contains the egg nucleus and other nuclei that produce endosperm upon fertilization. An embryogenic callus is a defined and known genotype compared to seedlings, the high regeneration potential, and the stability of the regenerated plants. The embryo is an unborn offspring with a developed heart and organs under the development process.

[#434] The chromatin which permanently remains in the heterochromatic region is
Correct Answer

(A) Constitutive heterochromatin

Explanation

Solution: The chromatin which permanently remains in the heterochromatic region is Constitutive heterochromatin. Constitutive heterochromatin domains are regions of DNA found throughout the chromosomes of eukaryotes. The majority of constitutive heterochromatin is found in the pericentromeric regions of chromosomes but is also found at the telomeres and throughout the chromosomes.

[#435] For Hybrid seed production of onion which system is used?
Correct Answer

(B) CMS

Explanation

Solution: For Hybrid seed production of onion CMS system is used. Cytoplasmic male sterility (CMS), a condition under which a plant is unable to produce functional pollen, is widespread among higher plants. Hybrid-onion (Allium cepa) seed is produced using systems of cytoplasmic male sterility (CMS) and two different CMS systems have been genetically characterized. S cytoplasm was the first source of onion CMS identified in the 1920s, followed by T cytoplasm which was described in the 1960s.