Determine the correctness or otherwise of the following Assertion (a) and the Reason (r):
Assertion: IgM is found in serum as a pentameric protein consisting of five IgM monomers.
Reason: The pentameric form of IgM is due to cross-linking of IgM monomers via peptide bond.
Options:
(A) both (a) and (r) are true and (r) is the correct reason for (a)
(B) both (a) and (r) are true but (r) is not the correct reason for (a)
(C) (a) is true but (r) is false
(D) (a) is false but (r) is true

Match the products in Group I with their respective organisms in Group II:
Group I
P. Glycerol
Q. Glutamic acid
R. Curdlan
S. Amphotericin B
Group II
1. Corynebacterium glutamicum
2. Alcaligenes faecalis
3. Dunaliella salina
4. Streptomyces nodosus
Options:
(A) P-2, Q-1, R-3, S-4
(B) P-4, Q-2, R-1, S-3
(C) P-3, Q-1, R-2, S-4
(D) P-2, Q-1, R-4, S-3

Match the items in Group I with Group II:
Group I
P. Circular dichroism
Q. X-ray crystallography
R. Freeze-drying
S. Ultracentrifugation
Group II
1. Concentration
2. Sedimentation coefficient
3. Secondary structure determination
4. Tertiary structure determination
Options:
(A) P-4, Q-1, R-2, S-3
(B) P-1, Q-4, R-3, S-2
(C) P-2, Q-3, R-4, S-1
(D) P-3, Q-4, R-1, S-2

Match the microbial growth characteristics in Group I with the corresponding features in Group II:
Group I
P. Growth associated product formation
Q. Non growth associated product formation
R. Product inhibition
S. Substrate inhibition
Group II
1. Specific growth rate decreases with increasing product concentration
2. Specific product formation rate is constant
3. Specific product formation rate is proportional to specific growth rate
4. Specific growth rate decreases with increasing substrate concentration
Options:
(A) P-1, Q-2, R-4, S-3
(B) P-3, Q-2, R-1, S-4
(C) P-2, Q-1, R-3, S-4
(D) P-2, Q-3, R-4, S-1

Match the viruses in Group I with their host cell receptors in Group II:
Group I
P. Hepatitis A virus
Q. Human immunodeficiency virus
R. Rabies virus
Group II
1. Heparan sulphate
2. Acetylcholine receptor
3. CD4 protein
4. Alpha-2 macroglobulin
Options:
(A) P-1, Q-3, R-2, S-4
(B) P-3, Q-4, R-1, S-2
(C) P-4, Q-3, R-2, S-1
(D) P-2, Q-3, R-1, S-4

25. The protein in eukaryotes which is subjected to degradation undergoes:
(A) phosphorylation
(B) carboxylation
(C) ubiquitylation
(D) methylation

24. The polymorphic domains for Class II MHC proteins are:
(A) α and β2 domains only
(B) β and α2 domains only
(C) α1 and β1 domains only
(D) α2 and β2 domains only

23. Diphtheria toxin, tetracycline and streptomycin inhibit:
(A) DNA repair
(B) DNA replication
(C) transcription
(D) translation

22. The most widely used program for multiple sequence alignment is:
(A) BLAST
(B) FASTA
(C) CLUSTAL
(D) Chime

21. In the ABO blood group system, antigenic determinants are:
(A) nucleic acid
(B) carbohydrate
(C) lipid
(D) protein