Molecular Basis of Inheritance — Page 22 | NEET Biology

Q211

A sequential expression of a set of human genes

A messenger RNA

B DNA sequence

C ribosome

D transfer RNA.

Correct Answer

Option B

Solution

(b) A sequential expression of a set of human genes is the DNA sequence.

Because gene is the functional unit of DNA sequence.

Q212

Jacob and Monod studied lactose metabolism in E.coli and proposed operon concept. Operon concept is applicable for

A all prokaryotes

B all prokaryotes and some eukaryotes

C all prokaryotes and all eukaryotes

D all prokaryotes and some protozoans

Correct Answer

Option B

Solution

(b) Operon model applies to all prokaryotes and some eukaryotes.

Q213

In E.coli during lactose metabolism repressor binds to

A regulatory gene

B operator gene

C structural gene

D promoter region

Correct Answer

Option B

Solution

(b) The repressor protein binds to the operator to block transcription.

Q214

During transcription, the DNA site at which RNA polymerase binds is called

A enhancer

B promoter

C regulator

D receptor

Correct Answer

Option B

Solution

(b) The promoter region is where RNA polymerase binds to initiate transcription.

Q215

What does "lac" refer to in what we call the lac operon?

A The number 1,00,000

B Lactose

C Lactase

D Lac insect

Correct Answer

Option B

Solution

(b) "lac" refers to lactose — the inducer of the operon.

Q216

Which one of the following makes use of RNA as a template to synthesize DNA?

A DNA polymerase

B RNA polymerase

C Reverse transcriptase

D DNA dependant RNA polymerase

Correct Answer

Option C

Solution

(c) Reverse transcriptase (RNA-dependent DNA polymerase) is found in retroviruses like HIV.

Q217

During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called?

A AAAT box

B TATA box

C GGTT box

D CAAT box

Correct Answer

Option B

Solution

(b) TATA box (~28 bp upstream) is the recognition site where RNA polymerase binds.

Q218

One gene-one enzyme hypothesis was postulated by

A Hershey and Chase

B A. Garrod

C Beadle and Tatum

D R. Franklin

Correct Answer

Option C

Solution

(c) Beadle and Tatum postulated the one gene-one enzyme hypothesis.

Q219

Gene regulation governing lactose operon of E.coli that involves the lac I gene product is :

A Negative and inducible because repressor protein prevents transcription

B Negative and repressible because repressor protein prevents transcription

C Feedback inhibition because excess of b-galactosidase can switch off transcription

D Positive and inducible because it can be induced by lactose

Correct Answer

Option A

Solution

(a) Lac operon is negatively regulated (repressor blocks transcription) and inducible.

Q220

Which of the following is required as inducer(s) for the expression of Lac operon?

A Glucose

B Galactose

C Lactose

D Lactose and galactose

Correct Answer

Option C

Solution

(c) Lactose is the inducer for the lac operon — it inactivates the repressor.