25. Which of the following is a role of specific transcription factors?
(A) Unwind the DNA helix
(B) Form pre-initiation complexes
(C) Bind to response elements
(D) Recruit DNA polymerase

21. When a predator approaches the bird's nest, the bird's parents pretend to get hurt, make noise to draw attention to the predator and expose themselves to increase predation risk to protect their offspring. Such altruistic behavior is best explained by the phenomenon of (A) selfish genes (B) group selection (C) individual selection (D) kin selection MNO

22. What are some potential consequences of eutrophication? (A) increased fish population (B) loss of oxygen in water bodies (C) reduction in nutrient levels (D) improvement in water clarity

23. A virus consisting of a single strand of RNA, which is reverse transcribed into complementary DNA, is referred to as a______ .(A) protease (B) retrovirus (C) bacteriophage (D) non-enveloped virus

24. What is NOT one of the key characteristics of animals that make them become efficient consumers? (A) heterotrophs (B) flagellated gametes (C) nerve and muscle cells (D) digestive system

26. How can cells with the same genes come into being unambiguously dissimilar cell types with specialized functions? By selective (A) Post-translational modification (B) Transcription (C) DNA replication (D) Translation

27. All of the following groups, when added to histones, can result in an enhanced transcription EXCEPT (A) Phosphate (B) Acetyl (C) Phenyl (D) Methyl

28. What does the binding of a probe to the membrane in a Northern blot indicate (A) The desired DNA sequence is present in the sample (B) The desired RNA sequence is present in the sample (C) The desired protein is present in the sample (D) The desired amino acid scquence is present in the sample

29. What governs the sequence by which tRNAs convey amino acids to mRNA (A) The attractivencss between an mRNA codon and an anino acid on tRNA (B) The attractiveness between an mRNA codon and a tRNA anticodon (C) The attractiveness between an mRNA anticodon and a tRNA codon (D) The attractiveness between an mRNA anticodon and an amino acid on tRNA

30. Producing 100,000 different proteins from 20,000 genes delineates (A) Alternative splicing (B) DNA repair (C) Post-translation modification (D) Elongation

31. What is the molecular event by which the operator of an operon regulates the expression of its structural gene(s)? (A) The operator codes for the repressor, which binds to the structural genes (B) The operator codcs for the repressor, which binds to the RNA polymerase (C) The operator is bound by the repressor, thereby inhibiting RNA polymerase (D) The operator is bound by the regulator gene, thereby inhibiting RNA polymerase