Practice Test

1.

1 point

What is the composition of the backbone of DNA?

alternating sugar and phosphate molecules

complementary base pairs

alternating sugar and base molecules

a polysaccharide

2.

1 point

A certain gene codes for a polypeptide that is 120 amino acids long. Approximately how many nucleotides long is the mRNA that codes for this polypeptide likely to be?

30

40

360

480

3.

1 point

In a DNA molecule, the amount of adenine is equal to the amount of thymine

True

False

4.

1 point

The 5' end of each Okazaki fragment begins with: ____

the same RNA primer that was used on the leading strand

a DNA primer binding to the template DNA

DNA polymerase binding to the template DNA

an RNA primer complementary to the template strand

a small DNA primer

5.

1 point

Which of the following are connected by a hydrogen bond?

the hydrogen and oxygen atoms of a single water molecule

a base pair of a DNA molecule

two amino acid molecules of a dipeptide

two glucose molecules in a disaccharide

6.

1 point

DNA replication involves the breaking of bonds between: _________

bases

sugars and bases

phosphates and bases

sugars and phosphates

7.

1 point

Where is the anticodon located?

tRNA

mRNA

DNA

ribosome

8.

1 point

DNA replication is a ________ process

progressive

conservative

dispersive

semi-conservative

9.

1 point

Okazaki fragments are necessary because: ______

polymerase can only build DNA in the 5' to 3' direction

polymerase can only build DNA in the 3' to 5' direction

polymerase can only build short pieces of DNA

there are many origins of replication

10.

1 point

Which enzyme is more active during replication of the lagging strand of DNA than it is during the replication of the leading strand?

helicase

RNA primase

DNA polymerase III

RNA polymerase

11.

1 point

Which of the following does NOT describe DNA?

organic molecule

antiparallel strands

nucleic acid

carries a positive charge

12.

1 point

Nucleotides in a SINGLE STRAND of DNA are held together by:________

ionic bonds

hydrogen bonds

covalent bonds

metallic bonds

13.

1 point

Centromeres and telomeres are considered to be structural DNA

True

False

14.

1 point

What is removed to form mature eukaryotic mRNA?

RNA primers

exons

RNA polymerases

introns

15.

1 point

What is a difference between the sense and antisense strands of DNA?

Nucleotides are linked to the sense strand by hydrogen bonding during transcription, but not the antisense strand

The sense strand has the same base sequence as tRNA, but the antisense strand does not

Nucleotides are linked to the antisense strand by hydrogen bonding during transcription, but not to the sense strand

The antisense strand has the same base sequence as mRNA, but the sense strand does not

16.

1 point

Protein-coding genes make up 95% of all our DNA

True

False

17.

1 point

Which enzyme removes the RNA primer during replication?

RNA primase

DNA polymerase I

DNA ligase

helicase

18.

1 point

A biochemist isolated and purified molecules needed for DNA replication. When some DNA was added replication occured, but the DNA molecules formed were defective. Each consisted of a normal DNA strand paired with segments of DNA a few hundred nucleotides long. Which of the following had been left out of the mixture?

DNA ligase

helicase

nucleotides

DNA polymerase 3

19.

1 point

In the structure of DNA, what bonds with cytosine?

deoxyribose

ribose

thymine

adenine

20.

1 point

What is the function of helicase?

it forms bonds between DNA nucleotides

it adds new nucleotides to the DNA helix

it forms the DNA helix

it separates DNA strands