Question 1

Which of the following statements best explains the chemical difference between the pentose sugars in DNA and RNA, as shown in the image?

Accepted Answer

Deoxyribose in DNA has one less oxygen atom on the second carbon compared to ribose in RNA.

Question 2

Which of the following best describes the flow of genetic information in a cell?

Accepted Answer

DNA \rightarrow RNA \rightarrow Proteins

Question 3

Which nitrogenous base is found in RNA but not in DNA?

Accepted Answer

Uracil

Question 4

Which type of RNA carries the genetic code from the nucleus to the ribosome for protein synthesis?

Accepted Answer

Messenger RNA (mRNA)

Question 5

If a codon on mRNA is AUG, what is its function during translation?

Accepted Answer

It codes for methionine and serves as a start signal for translation.

Question 6

How many different amino acids can be specified by the four RNA bases using a triplet code?

Accepted Answer

20

Question 7

Which of the following codons is a stop codon in the genetic code?

Accepted Answer

UAG

Question 8

A mutation changes the DNA sequence from AAA to AAG. Both codons code for the same amino acid. What is this an example of?

Accepted Answer

Redundancy in the genetic code

Question 9

Which statement best describes the 'one gene–one polypeptide' hypothesis?

Accepted Answer

Each gene codes for a single polypeptide, which may be a part of a protein.

Question 10

Which of the following is NOT a function of RNA in the cell?

Accepted Answer

Carrying genetic information from one generation to the next

Question 11

A scientist discovers a new organism whose proteins are made up of 25 different amino acids. What is the minimum number of nucleotide bases per codon required to code for all 25 amino acids?

Accepted Answer

3

Question 12

Which of the following best explains why the genetic code is described as 'universal'?

Accepted Answer

The same codons specify the same amino acids in nearly all organisms.

Question 13

Which RNA molecule is responsible for bringing amino acids to the ribosome during translation?

Accepted Answer

tRNA

Question 14

A patient has a genetic disorder caused by a mutation in a gene that codes for a non-enzyme protein. Which hypothesis does this observation contradict?

Accepted Answer

One gene–one enzyme hypothesis

Question 15

Which of the following is a correct pairing of DNA and RNA bases during transcription?

Accepted Answer

A (DNA) pairs with U (RNA)

Question 16

If a gene codes for a protein made of two different polypeptide chains, how many genes are required to produce this protein?

Accepted Answer

2

Question 17

Which of the following best describes the role of rRNA in the cell?

Accepted Answer

It forms the core structure of the ribosome and catalyzes peptide bond formation.

Question 18

A mutation changes a codon from UAU to UAA. What is the likely effect on the resulting protein?

Accepted Answer

Translation will stop prematurely, resulting in a truncated protein.

Question 19

Which of the following best describes why not all genes code for proteins?

Accepted Answer

Some genes code for functional RNA molecules that are not translated.

Question 20

Which of the following is a real-life example of the importance of the start codon in protein synthesis?

Accepted Answer

A mutation in the start codon (AUG) can prevent translation initiation, resulting in no protein being produced.

Protein Synthesis and the Genetic Code

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