21. Which class of immunoglobulin contains epsilon heavy chains?
A) IgM
B) IgA
C) IgE
D) IgG

22. What are immunoglobulins?
A) Carbohydrates
B) Nucleic acids
C) Glycoproteins
D) Lipids

23. What structural shape is the most widely recognized feature ofimmunoglobulins?
A) 'Y' or 'T'
B) Circle
C) Square
D) Line

24. What are heavy chains of immunoglobulins named based on?
A) Their molecular weights
B) Their antigenic properties
C) Their amino acid sequence
D) Their glycosylation pattern