Molecular Basis of Inheritance
Test 5

Correct answer Carries: 4.

Wrong Answer Carries: -1.

In the Meselson and Stahl experiment, which isotope was used to label the original DNA strands?

Carbon-14
Sulfur-35
Nitrogen-15
Phosphorus-32
3

Nitrogen-15 was used to label the original DNA strands to demonstrate semiconservative replication.

Which of the following is NOT a characteristic of the genetic code?

It is triplet in nature
It is ambiguous
It is nearly universal
It is degenerate
2

The genetic code is unambiguous, meaning each codon specifies only one amino acid.

Which scientist(s) used radioactively labeled sulfur and phosphorus to confirm that DNA is the genetic material?

Avery, MacLeod, and McCarty
Meselson and Stahl
Hershey and Chase
Beadle and Tatum
3

Hershey and Chase used sulfur-35 to label proteins and phosphorus-32 to label DNA in bacteriophage experiments.

What is the function of the terminator sequence in transcription?

Initiates RNA polymerase binding
Signals the end of transcription
Starts the translation process
Releases the ribosome from mRNA
2

The terminator sequence signals RNA polymerase to stop transcription and release the RNA transcript.

Which of the following statements about mutations is correct?

Mutations always lead to harmful effects.
Silent mutations do not change the amino acid sequence.
Mutations cannot be inherited.
Mutations are always caused by environmental factors.
2

Silent mutations do not alter the amino acid sequence and usually have no effect on protein function.

Which of the following statements about genetic code is incorrect?

The genetic code is universal.
Each codon codes for multiple amino acids.
The genetic code is triplet in nature.
The genetic code is non-overlapping.
2

Each codon codes for only one specific amino acid, not multiple amino acids.

Which of the following is a correct statement about histones?

Histones help in DNA packaging.
Histones degrade RNA molecules.
Histones are enzymes involved in replication.
Histones prevent DNA replication.
1

Histones help package DNA into chromatin, making it more compact within the nucleus.

Which of the following is incorrect about post-transcriptional modifications in eukaryotes?

Introns are removed by splicing.
A 5' cap is added to the mRNA.
A poly-A tail is added to mRNA.
Post-transcriptional modifications occur in the cytoplasm.
4

Post-transcriptional modifications occur in the nucleus, not in the cytoplasm.

Which of the following statements about the Lac operon is correct?

It is regulated by a repressor protein
It is present only in eukaryotic cells
It codes for tRNA synthesis
It is always active regardless of lactose availability
1

The Lac operon is regulated by a repressor protein that prevents transcription in the absence of lactose.

Which enzyme is responsible for adding a poly-A tail to mRNA in eukaryotes?

DNA polymerase
RNA polymerase
Poly-A polymerase
Helicase
3

Poly-A polymerase adds a poly-A tail to mRNA to enhance its stability and regulate translation.

Performance Summary

Score:

Category Details
Total Attempts:
Total Skipped:
Total Wrong Answers:
Total Correct Answers:
Time Taken:
Average Time Taken per Question:
Accuracy:
0