Agrobacterium tumefaciens is a gram-negative rod-shaped bacterium. It infects plants usually through an open wound. Once it enters its plant host, it injects a section of its DNA called the T-DNA which is derived from its Ti (tumor inducing) plasmid into its host. The T-DNA is then integrated into the plant’s genome, and has two effects on the plant host. The T-DNA first directs the plant cells to make auxins and cytokinins, which causes the cells to become irregularly shaped and form a visible tumour called a gall. The T-DNA then directs the plant cell to start making opines (usually nopaline or agropine) which A. tumefaciens use as an energy source.

Correct Option: B

Agrobacterium tumefaciens is a gram-negative rod-shaped bacterium. It infects plants usually through an open wound. Once it enters its plant host, it injects a section of its DNA called the T-DNA which is derived from its Ti (tumor inducing) plasmid into its host. The T-DNA is then integrated into the plant’s genome, and has two effects on the plant host. The T-DNA first directs the plant cells to make auxins and cytokinins, which causes the cells to become irregularly shaped and form a visible tumour called a gall. The T-DNA then directs the plant cell to start making opines (usually nopaline or agropine) which A. tumefaciens use as an energy source.

Natural genetic transformation is believed to be the essential mechanism for the attainment of genetic plasticity in many species of bacteria. During bacterial evolution, the ability of Bacteria and Archaea to adapt to new environments most often results from the acquisition of new genes through horizontal transfer rather than by the alteration of gene functions through numerous point mutations. Horizontal gene transfer is defined to be the movement of genetic material between bacteria other than by descent in which information travels through the generations as the cell divides. It is most often thought of as a sexual process that requires a mechanism for the mobilization of chromosomal DNA among bacterial cells. However, because they are unable to reproduce sexually, bacterial species have acquired several mechanisms by which to exchange genetic materials. It can happen through transformation, conjugation and transduction. In bacteria, it mainly occurs by transformation and conjugation.

Correct Option: B

Natural genetic transformation is believed to be the essential mechanism for the attainment of genetic plasticity in many species of bacteria. During bacterial evolution, the ability of Bacteria and Archaea to adapt to new environments most often results from the acquisition of new genes through horizontal transfer rather than by the alteration of gene functions through numerous point mutations. Horizontal gene transfer is defined to be the movement of genetic material between bacteria other than by descent in which information travels through the generations as the cell divides. It is most often thought of as a sexual process that requires a mechanism for the mobilization of chromosomal DNA among bacterial cells. However, because they are unable to reproduce sexually, bacterial species have acquired several mechanisms by which to exchange genetic materials. It can happen through transformation, conjugation and transduction. In bacteria, it mainly occurs by transformation and conjugation.

​Several types of DNA library resources were sponsored by the DOE before and during the Human Genome Program (HGP).  These included both prokaryotic and eukaryotic vector systems, and clone libraries representing single chromosomes.  Bacterial Artificial Chromosomes (BACs) became the most broadly used resource for several reasons.  The large size was a good match for capabilities of high throughput sequencing centres. A bacterial artificial chromosome (BAC) is an engineered DNA molecule used to clone DNA sequences in bacterial cells (for example, E. coli). BACs are often used in connection with DNA sequencing. Segments of an organism’s DNA, ranging from 100,000 to about 300,000 base pairs, can be inserted into BACs. The BACs, with their inserted DNA, are then taken up by bacterial cells. As the bacterial cells grow and divide, they amplify the BAC DNA, which can then be isolated and used in sequencing DNA.

Correct Option: A

​Several types of DNA library resources were sponsored by the DOE before and during the Human Genome Program (HGP).  These included both prokaryotic and eukaryotic vector systems, and clone libraries representing single chromosomes.  Bacterial Artificial Chromosomes (BACs) became the most broadly used resource for several reasons.  The large size was a good match for capabilities of high throughput sequencing centres. A bacterial artificial chromosome (BAC) is an engineered DNA molecule used to clone DNA sequences in bacterial cells (for example, E. coli). BACs are often used in connection with DNA sequencing. Segments of an organism’s DNA, ranging from 100,000 to about 300,000 base pairs, can be inserted into BACs. The BACs, with their inserted DNA, are then taken up by bacterial cells. As the bacterial cells grow and divide, they amplify the BAC DNA, which can then be isolated and used in sequencing DNA.

The length of the unique stretch of DNA sequence that can be found only once in 3 billion base pair long genome is a 16 bases long DNA sequence from which 16s rRNA is transcribed.

Correct Option: C

The length of the unique stretch of DNA sequence that can be found only once in 3 billion base pair long genome is a 16 bases long DNA sequence from which 16s rRNA is transcribed.

There are several species of mustard. Black mustard (Brassica nigra) produces small seeds that become black at maturity. They have an extremely rich and pungent flavor, stronger than yellow mustard. White mustard (Sinapis alba) produces large yellow-colored seeds with a bitter taste that is not as pungent as other varieties. Indian mustard or mustard greens (Brassica juncea) is a green vegetable whose very tasty leaves are used in the same way as spinach. The chemicals that are responsible for pungency are stored in inactive conjugate form in compartments within the seeds and are protected from enzymes. But when seeds are crushed, the pungent chemicals come in contact with the enzymes and are converted into active chemicals which give the pungent smell.

Correct Option: B

There are several species of mustard. Black mustard (Brassica nigra) produces small seeds that become black at maturity. They have an extremely rich and pungent flavor, stronger than yellow mustard. White mustard (Sinapis alba) produces large yellow-colored seeds with a bitter taste that is not as pungent as other varieties. Indian mustard or mustard greens (Brassica juncea) is a green vegetable whose very tasty leaves are used in the same way as spinach. The chemicals that are responsible for pungency are stored in inactive conjugate form in compartments within the seeds and are protected from enzymes. But when seeds are crushed, the pungent chemicals come in contact with the enzymes and are converted into active chemicals which give the pungent smell.