a)  Bacteria and virus both are living but virus is smaller in size

 b)  unlike bacteria, virus is non-living and requires a host to be active

Ans. (b)

Viruses are not consider to be alive because they cannot reproduce themselves or carry out metabolic functions on their own. However, once entered into a host cell they are able to carry out essential functions.

Q.2  The main building block of a protein is

 a)  Amino acid

 b)  Nucleotides

Ans. (a)

Amino acid are the building block of protein containing amine and carboxylic functional group with a side chain specific to each amino acid. Not all (on α-amino acid) takes part in protein formation. Proteins have important role in building body tissues.

Q.3  The main building block of a nucleic acid is

 a)  Amino acid

 b)  Nucleotide

Ans. (b)

Nucleotides are the building blocks of nucleic acid polymers D.N.A and R.N.A, both of which are essential biomolecules within all life forms on earth. Nucleotides are composed of 3 sub-units molecules: a nitrogenous base, a five – carbon sugar (ribose or deoxyribose), and atleast one phosphate group.

Q.4  The central dogma of molecular biology, how information flows

 a)  D.N.A –> R.N.A –> Protein

 b)  Protein –> R.N.A –> D.N.A

Ans. (a)

Central dogma of molecular biology provides the basic framework for how genetic information flows from a D.N.A sequence to a protein product inside cells. This process of genetic information flowing from D.N.A  to R.N.A to protein is called gene expression.

Q.5  R.N.A  has

a) single standard molecule with Thymine base pair

b) single standard molecule with Uracil base pair

Ans. (b)

Uracil (Pyrimidine) is the demethylated form of thymine. Pyrimidine is an aromatic heterocyclic organic compound, it has the Nitrogen atom at position 1 and 3 in the ring.