34. What is the effect of a nonsense mutation in a gene?
(A) It introduces a premature stop codon into the mRNA.
(B) It changes an amino acid in the encoded protein.
(C) It has no effect on the amino acid sequence of the encoded protein.
(D) It alters the reading frame of the mRNA.
(E) It prevents introns from being excised.

30. Which of the following pairs of sugars are epimers of each other? (A) D-sorbose and D-fructose (B) D-sorbose and D-xylulose (C) D-arabinose and D-ribose (D) D-fructose and L-fructose (E) D-ribose and D-ribulose

31. Which description of fungi is correct? (A) Ascomycota: Multinucleate hyphae lack septa (B) Glomeromycota: Form arbuscular mycorrhizae (C) Ascomycota: In sexual reproduction, four ascospores are formed inside a sac called an ascus (D) Basidiomycota: In sexual reproduction, eight basidiospores are borne on a club-shaped basidia (E) Zygomycota: the heterokaryotic (dikaryotic) stage can be found in the life cycle

32. Developmentally, which type of human tooth is most similar to ivory(象牙)? (A) incisor (B) canine (C) premolar (D) molar (E) third molar (wisdom tooth)

33. How many photons are required to generate one O2 molecule during photosynthesis light reaction? (A) 2 (B)4(C)8(D) 12 (E) 16

35 Within a cell, the amount of protein made using a given mRNA molecule depends partly on (A) the rate at which the mRNA is degraded. (B) the number of introns present in the mRNA. (C) the types of ribosomes present in the cytoplasm. (D) the degree of histone acetylation (E) the degree of DNA methylation. 

36. Phylogenetic trees constructed from evidence from molecular systematics are based on similarities in________. (A) phenotypes (B) morphology (C) mutations to homologous genes (D) the pattern of embryological development (E) biochemical pathways

37. Imprinting has a great impact on normal mammalian development, fetal growth, metabolism and adult behavior. The current molecular explanation for imprinting in mammals involves differential of various DNA regions. (A) Mutations (B) Phosphorylation (C) Dephosphorylation (D) Methylation (E) Transcription

38. CRISPR-Cas9 is adapted from a naturally occurring genome editing system that bacteria use as an immune defense. Which of the following characteristics makes the CRISPR-Cas9 system an efficient way to generate knockout cell lines? (A) It precisely cuts DNA. (B) It removes random DNA bases. (C) It forms a complex with proteins. (D) It applies to both in prokaryotes and eukaryotes. (E) Its function is regulated by complementary guide RNAs.

39 Which of the following would you expect to be a problem for someone with nonfunctional chloride channeling? (A) inadequate secretion of mucus (B) buildup of excessive secretions in organs such as lungs (C) buildup of excessive secretions in glands such as the pancreas (D) sweat that includes no NaCl (E) mental retardation due to low salt levels in brain tissue

40. Plants often use changes in day length (photoperiod) to trigger events such as dormancy and flowering. It is logical that plants have evolved this mechanism because photoperiod changes (A) are more predictable than air temperature changes. (B) alter the amount of energy available to the plant. (C) are modified by soil temperature changes. (D) can reset the biological clock. (E) are correlated with moisture availability.