The lac operon is a group of genes in bacteria that are involved in the metabolism of lactose, a type of sugar.
So, the correct option is (A): Lactose
Study the given molecular structure of double-stranded polynucleotide chain of DNA and answer the questions that follow. 
(a) How many phosphodiester bonds are present in the given double-stranded polynucleotide chain? 
(b) How many base pairs are there in each helical turn of double helix structure of DNA? Also write the distance between a base pair in a helix. 
(c) In addition to H-bonds, what confers additional stability to the helical structure of DNA?
Use the given information to select the amino acid attached to the 3′ end of tRNA during the process of translation, if the coding strand of the structural gene being transcribed has the nucleotide sequence TAC. 
 
Student to attempt either option-(A) or (B): 
(A) Write the features a molecule should have to act as a genetic material. In the light of the above features, evaluate and justify the suitability of the molecule that is preferred as an ideal genetic material. 
OR 
(B) Differentiate between the following:
The output (Y) of the given logic implementation is similar to the output of an/a  …………. gate.
The process by which the instructions present in our DNA are converted into a functional product, such as a protein is called Gene Expression. It is a tightly coordinated process that allows a cell to respond to its changing environment.
In the meanwhile process, genetic codes from the DNA code are converted into a protein with the help of translation and transcription. The genetic expression shows the process of the genetic makeup of an organism as its physical traits. All over the process, the information flows from genes to proteins.
For a better understanding, let us take the example of the Keratin genes. Keratin is a protein that helps in the formation of our hairs, nails, and skin. Usually, these things grow at a continuous speed as our hairs, nails, and skin get worn down over a period of time. The production of excessive keratin could form many hairs on the skin, dry and hard skin, and thick and long nails. To avoid this, it is necessary to regulate the expression of the keratin gene.
Regulation of gene expression includes different mechanisms through which our cells manage the amount of produced protein by our genes.
