Consider the following statements regarding T-cell activation:

Statement I: MHC-I molecules are found on almost all nucleated cells in the body.

Statement II: Cytotoxic T cells utilize their CD4 co-receptor to stabilize the binding to MHC-I.

TLS Online TPP Program

#Question id: 39257

#Plant Biotechnology

Q. Assertion (A): The main purpose of producing asymmetric hybrids is the introgression of specific desirable genes into another species.

Reason (R): Asymmetric hybridization allows selective elimination of chromosomes from one parent while retaining specific genes.

TLS Online TPP Program

#Question id: 39258

#Plant Biotechnology

Q. Assertion (A): Asymmetric hybrids often contain multiple genome copies of the non-irradiated parent.

Reason (R): Irradiation of one parent leads to extensive chromosome breakage and deletion.

TLS Online TPP Program

#Question id: 39259

#Plant Biotechnology

Q. Assertion (A): After repeated backcrossing of asymmetric hybrids with N. plumbaginifolia, plants with a diploid N. plumbaginifolia genome and a few A. belladonna chromosomes were recovered.

Reason (R): Backcrossing helps eliminate unwanted alien chromosomes while retaining selected genes.

TLS Online TPP Program

#Question id: 39260

#Plant Biotechnology

Q. Assertion (A): All asymmetric hybrids contained nitrate reductase gene and rDNA repeats of Atropa belladonna.

Reason (R): rDNA repeats are often preferentially retained during asymmetric hybridization.

TLS Online TPP Program

#Question id: 39261

#Plant Biotechnology

Q.Assertion (A): Hybrids obtained from irradiated carrot and non-irradiated rice protoplast fusion resembled rice plants.

Reason (R): The non-irradiated parent usually contributes more intact genomic material.

TLS Online TPP Program

#Question id: 39262

#Plant Biotechnology

Q. Assertion: The fusion of B. napus (AACC) and B. nigra (BB) results in a hybrid with the genomic constitution AABBCC. 

Reason: This specific interspecific fusion was primarily conducted to transfer resistance against Phoma lingam (black-leg disease) to rapeseed.