Question 1

Which of the following best describes the antiparallel nature of DNA strands?

Accepted Answer

One strand runs from 5' to 3', and the other runs from 3' to 5'.

Question 2

If a segment of DNA has the sequence 5'-ATCGTAC-3', what is the sequence of the complementary strand?

Accepted Answer

3'-TAGCATG-5'

Question 3

Which type of bond holds the two DNA strands together between the nitrogenous bases?

Accepted Answer

Hydrogen bonds

Question 4

During DNA replication, which bonds are formed to connect nucleotides in the newly synthesized strand?

Accepted Answer

Phosphodiester bonds in the sugar-phosphate backbone

Question 5

A double-stranded DNA molecule contains 30% adenine. What percentage of guanine does it contain?

Accepted Answer

20%

Question 6

Which statement about the genetic code is TRUE?

Accepted Answer

The code is redundant, meaning multiple codons can specify the same amino acid.

Question 7

What is the correct order of information flow according to the central dogma of molecular biology?

Accepted Answer

DNA → RNA → Protein

Question 8

Which of the following is a pyrimidine base found in DNA?

Accepted Answer

Thymine

Question 9

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

Accepted Answer

Translation will stop prematurely due to a stop codon.

Question 10

Which feature of the genetic code allows for silent mutations?

Accepted Answer

Redundancy: multiple codons can code for the same amino acid.

Question 11

Which process uses a DNA template to synthesize RNA?

Accepted Answer

Transcription

Question 12

If a DNA template strand reads 3'-TACGGA-5', what is the mRNA sequence produced during transcription?

Accepted Answer

5'-AUGCCU-3'

Question 13

Which of the following best explains why DNA is more stable than RNA?

Accepted Answer

DNA contains deoxyribose and lacks the 2' hydroxyl group present in RNA.

Question 14

Which of the following is TRUE about the tertiary structure of DNA?

Accepted Answer

It involves DNA being packaged with histone proteins into chromosomes.

Question 15

A DNA molecule is replicated in a semi-conservative manner. What does this mean?

Accepted Answer

Each new DNA molecule contains one old strand and one new strand.

Question 16

Which of the following is added to the 3' end of a growing DNA strand during replication?

Accepted Answer

A new nucleotide

Question 17

If a DNA molecule has 270 bases and the first codon is the start codon, how many amino acids will be in the resulting protein?

Accepted Answer

$$\frac{270}{3} = 90$$

Question 18

Which of the following is a purine base found in DNA?

Accepted Answer

Adenine

Question 19

Which process directly links genotype to phenotype in a cell?

Accepted Answer

Protein synthesis (translation)

Question 20

Which of the following statements about base pairing in DNA is correct?

Accepted Answer

Guanine pairs with cytosine.

Structure of DNA & Information Flow: Genes to Proteins

Study Guide - Practice Questions