Practice Start Test

Molecular Basis of Inheritance

NEET Biology · 262 questions · Page 5 of 27 · Click an option or "Show Solution" to reveal answer

Q41
In Escherichia coli, lac operon is induced by
A lactose
B promoter gene
C beta-galactosidase
D I-gene
Correct Answer
Option A
Solution

(a) Lactose acts as the inducer and is the substrate for beta-galactosidase.

Q42
The lac operon is an example of
A arabinose operon
B inducible operon
C repressible operon
D overlapping genes
Correct Answer
Option B
Solution

(b) Lac operon is an inducible operon that is induced by lactose.

Q43
An environmental agent, which triggers transcription from an operon, is a
A regulator
B inducer
C depressor
D controlling element
Correct Answer
Option B
Solution

(b) An inducer is the environmental agent that triggers transcription from an operon.

Q44
Which of the following statements is correct?
A Adenine pairs with thymine through one H-bond
B Adenine pairs with thymine through three H-bonds
C Adenine does not pair with thymine
D Adenine pairs with thymine through two H-bonds
Correct Answer
Option D
Solution

(d) A=T through 2 hydrogen bonds; G≡C through 3 hydrogen bonds.

Q45
Which of the following statements is correct?
A Adenine pairs with thymine through one HH-bond
B Adenine pairs with thymine through three HH-bonds
C Adenine does not pair with thymine
D Adenine pairs with thymine through two HH-bonds
Correct Answer
Option D
Solution

(d) Based on the observation of Erwin Chargaff that for a double stranded DNA, the ratios between Adenine and Thymine and Guanine and Cytosine are constant and equals one.

Adenine pairs with thymine through two H-bonds.

Q46
The length of DNA molecule greatly exceeds the dimensions of the nucleus in eukaryotic cells. How is this DNA accommodated?
A super-coiling in nucleosomes
B DNase digestion
C through elimination of repititive DNA
D deletion of non-essential genes.
Correct Answer
Option A
Solution

(a) The nucleosome model explains the packaging of histone proteins and DNA in the chromatin material which forms the chromosome.

Q47
Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the category mentioned against it?
A Thymine, Uracil - Pyrimidines
B Uracil, Cytosine - Pyrimidines
C Guanine, Adenine - Purines
D Adenine, Thymine - Purines
Correct Answer
Option D
Solution

(d) Purine is an organic nitrogenous base that gives rise to a group of biologically important derivatives, notably adenine and guanine.

Thymine is a pyrimidine, not a purine.

Q48
T.O. Diener discovered a free infectious RNA
A free infectious DNA
B infectious protein
C bacteriophage
D free infectious RNA
Correct Answer
Option D
Solution

(d) Theodor O.

Diener discovered the Potato Spindle Tuber Viroid, the first viroid ever identified, in 1971.

PSTVd is a small, circular RNA molecule.

Q49
Which one of the following does not follow the central dogma of molecular biology?
A Pea
B Mucor
C Chlamydomonas
D HIV
Correct Answer
Option D
Solution

(d) HIV viruses does not follow central dogma.

Central dogma is a one way flow of information from DNA to mRNA and then to protein.

Q50
If the distance between two consecutive base pairs is 0.34nm0.34 nm and the total number of base pairs of a DNA double helix in a typical mammalian cell is 6.6×109bp6.6 \times 10^9 bp, then the length of the DNA is approximately
A 2.5 meters
B 2.2 meters
C 2.7 meters
D 2.0 meters
Correct Answer
Option B
Solution

(b) Length of DNA = 0.34×10−9m×6.6×109bp=2.2m0.34 \times 10^{-9} m \times 6.6 \times 10^9 bp = 2.2 m

Ready for a full NEET mock test? Timed · full syllabus · instant results
Take a Mock Test →