1. An amino acid with four nitrogen atoms is:

• (A) histidine
• (B) arginine
• (C) leucine
• (D) lysine

2. An example for a basic buffer is:

• (A) phosphate
• (B) histidine
• (C) citrate
• (D) tris

3. One of the following parameters determines the efficiency of enzyme catalysis:

• (A) low Km
• (B) high Kcat
• (C) high Km/Kcat
• (D) low Km/Kcat

4. The condition required for complete denaturation of protein containing disulphide bridges is:

• (A) SDS and mercaptoethanol
• (B) trichloroacetic acid
• (C) SDS with alkali
• (D) SDS with trichloroacetic acid  

5. Z-DNA form is found in:

• (A) any DNA molecule under high salt concentration
• (B) AT rich repetitive sequences under high salt concentration
• (C) palindromic sequences under high salt concentration
• (D) methylated CG repeats under high salt concentration