Question 1

Which of the following best explains why Garrod's study of alkaptonuria was significant in the history of genetics?

Accepted Answer

It demonstrated that inherited diseases can result from the absence of specific functional enzymes, linking genes to biochemical pathways.

Question 2

Beadle and Tatum's experiments with Neurospora led to which important genetic hypothesis?

Accepted Answer

One gene–one enzyme hypothesis

Question 3

Why is the 'one gene–one enzyme' hypothesis considered too simplistic today?

Accepted Answer

Some genes code for non-protein products, and some genes can produce multiple products through alternative splicing.

Question 4

In the classic Griffith experiment, what was the key finding when live R strain bacteria were mixed with heat-killed S strain bacteria?

Accepted Answer

The R strain bacteria were transformed by material from the S strain, acquiring the ability to cause disease.

Question 5

Avery, MacLeod, and McCarty demonstrated that DNA is the transforming material by showing that:

Accepted Answer

Destruction of DNA prevented transformation, while destruction of proteins or RNA did not.

Question 6

In the Hershey and Chase experiment, which radioactive label was found inside the bacteria, indicating the genetic material of the phage?

Accepted Answer

$$^{32}\mathrm{P}$$

Question 7

If a DNA sample contains 30% adenine, what percentage of guanine does it contain?

Accepted Answer

$$20\%$$

Question 8

During DNA replication, which enzyme is responsible for relieving the twisting tension ahead of the replication fork?

Accepted Answer

Topoisomerase

Question 9

Which of the following statements about the leading and lagging strands during DNA replication is correct?

Accepted Answer

The lagging strand is synthesized in short fragments called Okazaki fragments.

Question 10

Which of the following best describes the function of telomerase in eukaryotic cells?

Accepted Answer

It extends the ends of linear chromosomes to prevent loss of genetic material during replication.

Question 11

In eukaryotic transcription, what is the role of the TATA box?

Accepted Answer

It is a promoter element that helps position RNA polymerase for transcription initiation.

Question 12

Which of the following modifications occurs to eukaryotic pre-mRNA before it leaves the nucleus?

Accepted Answer

Addition of a 5' cap and a poly-A tail, and removal of introns by splicing.

Question 13

A mutation that changes a single base in a gene, resulting in a different amino acid in the protein, is called:

Accepted Answer

Missense mutation

Question 14

Which of the following best explains why a frameshift mutation is often more severe than a point mutation?

Accepted Answer

It alters the reading frame, potentially changing every amino acid downstream of the mutation.

Question 15

Which of the following is true about the lac operon in E. coli?

Accepted Answer

It is an inducible operon that is turned on in the presence of lactose.

Question 16

In the trp operon, what happens when tryptophan is present in high concentrations?

Accepted Answer

Tryptophan acts as a corepressor, activating the repressor to bind the operator and block transcription.

Question 17

Which of the following best describes the difference between proto-oncogenes and tumor suppressor genes?

Accepted Answer

Proto-oncogenes promote cell division, while tumor suppressor genes inhibit it.

Question 18

A patient inherits one mutated copy of a tumor suppressor gene. What is the most likely consequence?

Accepted Answer

They have an increased risk of developing cancer if the second copy is also mutated.

Question 19

Which of the following statements about translation is correct?

Accepted Answer

The ribosome moves along the mRNA in the 5' to 3' direction, synthesizing the polypeptide from the N-terminus to the C-terminus.

Question 20

Which of the following best explains the concept of 'wobble' in tRNA-mRNA pairing?

Accepted Answer

The third base of the codon can pair flexibly, allowing one tRNA to recognize multiple codons.

Molecular Genetics, Gene Expression, and Regulation: Study Notes for General Biology

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