What is the “X-dropoff” parameter in BLAST extension? A) Maximum number of gaps allowed B) Database size limit C) The score threshold below which extension stops  D) Number of mismatches tolerated

Why does COBALT perform better than ClustalW for aligning distant homologs? A) It’s faster B) It uses domain information as constraints to guide alignment C) It only works with proteins D) It requires fewer sequences

What does GEO (Gene Expression Omnibus) store? A) Protein structures B) DNA sequences C) Gene expression data from microarray and RNA-seq experiments D) Clinical variants

Which NCBI database is considered the “original DNA memory of life”? A) RefSeq B) GenBank C) SRA D) Genome

Why is the BLOSUM62 matrix called “62”? A) It contains 62 amino acids B) Sequences with ≥62% identity were clustered during matrix construction C) It was created in 1962 D) It uses 62 scoring parameters

What is the clinical significance of the EGFR T790M mutation? A) It makes cancer more aggressive B) It has no clinical relevance C) It is a benign polymorphism D) It confers resistance to first-generation EGFR inhibitors through steric blocking  

What is the typical length range for good PCR primers? A) 10-15 nucleotides B) 18-24 nucleotides C) 30-40 nucleotides D) 50+ nucleotides

Why is SRA (Sequence Read Archive) important for scientific reproducibility? A) It stores final analysis results B) It validates all experiments C) It preserves raw sequencing data, allowing independent reanalysis with new algorithms D) It only stores successful experiments

In the affine gap penalty model, why is gap extension penalty lower than gap opening penalty? A) Evolutionary evidence shows extending an existing gap is less costly than creating a new one B) It’s computationally easier C) It prevents all gaps D) It speeds up alignment

What is the primary advantage of using tBLASTn over BLASTp? A) Finding protein-coding genes in unannotated DNA sequences B) Faster computation C) Higher sensitivity for closely related proteins D) Better for DNA-DNA comparison