Select the two statements out of the four (A - D) given below about lac operon.

(A) Glucose or galactose may bind with the repressor and inactivate it

(B) In the absence of lactose, the repressor binds with the operator region

(C) The z-gene codes for permease

(D) This was elucidated by Francois Jacob and Jacques Monod

The correct statements are

  • (B) and (C)

  • (A) and (C)

  • (B) and (D)

  • (A) and (B)

The one aspect which is not a salient feature of genetic code, is its being

 

  • degenerate

  • ambiguous

  • universal

  • specific

Satellite DNA is useful tool in

  • organ transplantation

  • sex determination

  • forensic science

  • genetic engineering

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

  • Pea

  • Mucor

  • Chlamydomonas

  • HIV

Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a triplet?

  • Nirenberg and Mathaei

  • Hershey and chase

  • Morgan and Sturtevant

  • Beadle and Tatum

Semi-conservative replication of DNA was first demonstrated in

  • Drosophila melanogaster

  • Escherichia coli

  • Streptococcus pneumoniae

  • Salmonella typhimurium

What is not true for genetic code?

  • A codon in mRNA is read in a non-contiguous fashion

  • It is nearly universal

  • It is degenerate

  • It is unambiguous

In the DNA molecule

  • the total amount of purine nucleotides and pyrimidine nucleotides is not always equal

  • there are two strands, which run parallel in the 5’ → 3’direction

  • the proportion of adenine in relation to thymine varies with the organism

  • there are two strands, which run antiparallel-one in 5’ → 3’ direction and other in 3’ → 5’

Which one of the following pairs of codons are correctly matched with their function or the signal for the particular amino acid?

  • GUU, GCU – Alanine

  • UAG, UGA – Stop

  • AUG, ACG – Start/methionine

  • UUA, UCA – Leucine

Haploids are more suitable for mutation studies than the diploids. This is because

  • haploids are reproductively more stable than diploids

  • mutagenes penetrate in haploids more effectively than is diploids

  • haploids are more abundant in nature than diploids

  • all mutations, whether dominant or recessive are expressed in haploids

Telomere repetitive DNA sequences control the function of eukaryotic chromosomes because they:

  • act as replicons

  • are RNA transcription initiator

  • help chromosome pairing

  • prevent chromosome loss

Molecular basis of organ differentiation depends on the modulation in transcription by:

  • RNA polymerase

  • ribosome

  • transcription factor

  • anticodon

The length of DNA molecule greatly exceeds the dimensions of the nucleus in eukaryotic cells. How is this DNA accommodated?

  • Deletion of non essential genes

  • Super-coiling in nucleosomes

  • DNAse digestion

  • Through elimination of repetitive DNA

During transcription RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure. What is it’s DNA-binding sequence?

  • TTAA

  • AATT

  • CACC

  • TATA

Differentiation of organs and tissues in a developing organism, is associated with:

  • developmental mutations

  • differential expression of genes

  • lethal mutations

  • deletion of gens

The Okazaki fragments in DNA chain growth:

  • result in transcription

  • polymerize in the 3’-to-5’ direction and forms replication fork

  • prove semi-conservative nature of DNA replication

  • polymerize in the 5’-to-3’ direction and explain 3’-to-5’ DNA replication

The two polynucleotide chains in DNA are:

  • parallel

  • discontinuous

  • antiparallel

  • semiconservative

One gene-one enzyme relationship was established for the first time in:

  • Neurospora crassa

  • Salmonella typhimurium

  • Escherichia coli

  • Diplococcus pneumoniae

A sequential expression of a set of human genes occurs when a steroid molecule binds to

the:

  • transfer RNA

  • messenger RNA

  • DNA sequence

  • ribosome

Which antibiotic inhibits interaction between t-RNA and m-RNA during bacterial protein synthesis?

  • Erythromycin

  • Penicillin

  • Streptomycin

  • Tetracycline

Amino acid sequence, in protein synthesis is decided by the sequence of

  • t-RNA

  • m-RNA

  • c-DNA

  • r-RNA

One gene-one enzyme hypothesis was postulated by:

  • R. Franklin

  • Hershey and Chase

  • A. Garrod 

  • Beadle and Tatum

One turn of the helix in a B-form DNA is approximately:

  • 20 nm

  • 0.34 nm

  • 3.4 nm

  • 2 nm

Antiparallel strands of a DNA molecule means that:

  • one strand turns anti-clockwise

  • the phosphate groups of two DNA strands, at their ends, share the same position

  • the phosphate groups at the start of two DNA strands are in opposite position (pole)

  • one strand turns clockwise

Complete genomic sequence of the following plant has been recently announced is

  • Arabidopsis thaliana

  • Tritium vulgare

  • Cucurbita pepo

  • Pisum sativum

Okazaki fragments are proportions of DNA

  • synthesized on the leading strand of DNA replication fork

  • synthesized on the lagging strand of DNA replication fork

  • produced during the digestion of DNA by restriction endonucleases

  • none of the above

Transcription in case of eukaryotes takes place in

  • nucleus

  • nucleolus

  • cytoplasm

  • ribosome

Which of the following banding group is used in staining both plant and animal chromosome?

  • C-group

  • G-group

  • R-group

  • N-group

Which of the following is nonsense codon?

  • UAG

  • UAA

  • UGA

  • all the above

Frameshift mutation occurs when

  • base is subsituted

  • base is deleted or added

  • anticodons are absent

  • none of these

0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Botany Quiz Questions and Answers