Biology : Molecular Basis of Inheritance

If the total amount of adenine and thymine in a double stranded DNA is 55%, the amount of guanine in this DNA will be

• 45%

• 27.5%

• 25%

• 22.5%

• 22.5%

Structure of a polynucleotide chain of DNA is given below. Identify the locations (numbered 1 to 5) that show errors in the structure

• 1 and 3

• 1 and 4

• 3 and 5

• 2 and 4

• 2 and 4

The 'terminator/stop codons UGA, UAG and UAA

• Initiate translation

• Do not code for any; amino acids

• Code for only one amino acid

• Code for more than one amino acid

• Code for more than one amino acid

The variable number of tandem repeats' used as a probe in DNA fingerprinting is

• Expressed sequence tag

• Satellite DNA

• Bacterial artificial chromosome

• Restriction enzyme

• Restriction enzyme

Assertion (a) In Eukaryotes, replication and transcription occur in the nucleus but translation occurs in the cytoplasm

Reasoning (R): mRNA is transferred from the nucleus to the cytoplasm where  ribosomes and amino acids are available for protein synthesis

• A is true but R is false

• A is false but R is true

• Both A and R are false

• Both A and R are true but R is not the correct explanation for A

• Both A and R are true but R is not the correct explanation for A

Consider the statements regarding lac operon and choose the correct option

(i) lactose is the substrate for the enzyme beta-galactosidase and regulates switching on and off of the operon

(ii) lac operon consists of three regulatory genes

(iii) lac operon consists of one structural gene

(iv) regulation of lac operon by repressor is referred to as positive regulation.

• (i) and (ii) only are correct

• (iii) and (iv) only are correct

• (i) only is correct

• (iv) only is correct

• (iv) only is correct

If the four bases of DNA have to code for twenty amino acids, the code should constitute a combination of bases. This was proposed by

• Rosalind

• Har Gobind Khorana

• George Gamow

• Marshall Nirenberg

• Marshall Nirenberg

In Eukaryotes, the removal of RNA polymerase III from the nucleoplasm will affect the transcription of

• mRNA

• hnRNA

• tRNA

• 5.8S rRNA

• 5.8S rRNA

Which one of the following does not follow the central dogma in molecular biology?

• HIV

• E.coli

• Mucor

• Chlamydomonas

• Chlamydomonas

The scientists(s) who performed experiments with heavy isotopes of nitrogen to prove that DNA replicates semiconservatively is/are

• Fredrick Griffith

• Watson and Crick

• Taylor

• Meselson and Stahl

• Meselson and Stahl