NEW
Font size
WorksheetsMolecular Biology (19/1/2026)
Total questions: 10
Worksheet time: 7mins
Which feature best explains why DNA is more chemically stable than RNA?
A. DNA has purine bases only
B. DNA contains thymine instead of uracil
C. DNA has deoxyribose lacking an –OH at the 2' carbon
D. DNA is double-stranded
A molecule made of adenine + ribose + phosphate would be classified as:
A. A nucleoside
B. A nucleotide
C. A purine
D. A pyrimidine
If a nitrogenous base has a single six-membered ring, it must be:
A. Adenine
B. Guanine
C. A purine
D. A pyrimidine
Glycosidic bonds link nucleotides to form DNA or RNA.
True
False
Don't Know
Which pairing rule ensures accurate DNA replication?
A. Purine–purine pairing
B. Pyrimidine–pyrimidine pairing
C. Complementary base pairing (A–T, C–G)
D. Random base pairing
Which of the following correctly represents a nucleoside?
A. Nitrogenous base + phosphate
B. Nitrogenous base + ribose
C. Ribose + phosphate
D. Deoxyribose + phosphate
What structural feature defines a polynucleotide?
A. Multiple sugars bonded to each other
B. A chain of nucleotides linked by phosphodiester bonds
C. A single nitrogenous base repeated many times
D. Two antiparallel strands
Why must one DNA strand run 5' → 3' and the other 3' → 5'?
To allow proper hydrogen bonding between bases
To reduce repulsion between phosphates
To make replication faster
To increase base stacking forces
The negative charge in DNA comes from its phosphate groups.
True
False
A DNA molecule rich in guanine and cytosine would be expected to:
A. Be less stable due to fewer hydrogen bonds
B. Be more stable due to stronger base stacking and extra hydrogen bonds
C. Replicate slower
D. Be more flexible
