NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT text states, 'For the current I at an instant in a circuit, the rate of work done is $\frac{dW}{dt} = I\epsilon$.'

The NCERT text states: 'Origin of replication (ori) : This is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA.'

The NCERT text mentions: 'The ligation of alien DNA is carried out at a restriction site present in one of the two antibiotic resistance genes. For example, you can ligate a foreign DNA at the BamH I site of tetracycline resistance gene in the vector pBR322. The recombinant plasmids will lose tetracycline resistance due to insertion of foreign DNA but can still be selected out from non-recombinant ones by plating the transformants on ampicillin containing medium.'

The NCERT text states: 'In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning.'

The NCERT text explains: 'The presence of a chromogenic substrate gives blue coloured colonies if the plasmid in the bacteria does not have an insert. Presence of insert results into insertional inactivation of the $\beta$-galactosidase gene and the colonies do not produce any colour, these are identified as recombinant colonies.'

The NCERT text mentions: 'For example, Agrobacterium tumifaciens, a pathogen of several dicot plants is able to deliver a piece of DNA known as ‘T-DNA’ to transform normal plant cells into a tumor...'

The NCERT text states: 'Selectable marker : In addition to ‘ori’, the vector requires a selectable marker, which helps in identifying and eliminating non-transformants and selectively permitting the growth of the transformants.'

According to the NCERT text: 'Normally, the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc., are considered useful selectable markers for E. coli.'

The NCERT text states: 'Bacteriophages because of their high number per cell, have very high copy numbers of their genome within the bacterial cells.'

While not explicitly stated in the provided excerpt about the modification of Ti plasmid, the text does mention that Agrobacterium delivers T-DNA to induce tumors. A 'better understanding... has generated knowledge to transform these tools of pathogens into useful vectors for delivering genes of interest to humans,' implying that the tumor-inducing capacity would be disarmed for safe use as a vector.