41. The primary role of oxygen in aerobic cellular respiration is to:

(A) directly produce ATP.

(B) oxidize glucose during glycolysis.

(C) act as an enzyme in the citric acid cycle.

(D) serve as the final electron acceptor in the electron transport chain.

(E) create a proton gradient across the mitochondrial membrane.

37. In photosynthesis, the splitting of water molecules (photolysis) directly contributes to the production of: (A) glucose and carbon dioxide. (B) ATP and NADPH for the Calvin cycle. (C) electrons, protons (H+), and oxygen gas. (D) pigments within the thylakoid membrane.. (E) ATP only, without NADPH.

38. The Calvin cycle (light-independent reactions) in photosynthesis primarily involves: (A) capturing light energy independently from water splitting. (B) producing ATP and NADPH from light energy. (C) converting carbon dioxide into sugars using ATP and NADPH. (D) releasing oxygen as a byproduct. (E) occurring exclusively during the night.

39. Which statement accurately describes key conceptual aspects of cellular respiration? (A) Glycolysis is a universal process that occurs with or without oxygen, serving as glucose's initial breakdown. (B) Pyruvate oxidation and citric acid cycle fully oxidize all oxygen atoms from glucose. (C) Oxidative phosphorylation uses ATP and FADH2 energy to produce NADH via single-step redox reactions. (D) The electron transport chain creates a sugar gradient for ATP synthesis. (E) Most aerobic ATP is produced exclusively in glycolysis.

40. Most of the ATP generated during aerobic cellular respiration is produced during: (A) glycolysis. (B) pyruvate oxidation. (C) the citric acid cycle. (D) oxidative phosphorylation. (E) fermentation.

42. Which statement accurately describes a key event or outcome of meiosis? (A) Meiosis produces four genetically identical daughter cells. (B) In meiosis I, sister chromatids separate. (C) Crossing over occurs during prophase II. (D) Meiosis involves two successive cell divisions, resulting in four genetically unique haploid cells. (E) Meiosis's primary purpose is to repair damaged somatic cells.

43. Which statement accurately describes a fundamental concept in Mendelian genetics? (A) Mendel used cross-pollinating peas, which made true-breeding lines easy to establish. (B) Dominant alleles have a higher inheritance frequency. (C) The Law of Segregation states that during gamete formation, alleles for a character separate and end up in different gametes. (D) Repeated self-pollination was not necessary to obtain true-breeding lines. (E) Mendel concluded independent sorting, though his chosen genes were always linked.

44. In a plant species exhibiting incomplete dominance for flower color, a cross between a red-flowered plant (RR) and a white-flowered plant (WW) would produce offspring (RW) with what phenotype? (A) Only red flowers. (B) Only white flowers. (C) Flowers with both red and white patches. (D) Pink flowers (a blend of red and white). (E) Flowers of a completely new color unrelated to parental colors.

45. During gene expression, which molecule carries the genetic code from the nucleus to the ribosomes in the cytoplasm for protein synthesis? (A) Ribosomal RNA (rRNA) (B) Transfer RNA (tRNA) (C) DNA polymerase (D) Amino acids (E) Messenger RNA (mRNA)

46. Which condition violates the assumptions of the Hardy-Weinberg principle? (A) Random mating occurs. (B) No gene flow into or out of the population.. (C) The population size is very large. (D) Natural selection favors certain genotypes. (E) No new mutations occur.

47. If a population is in Hardy-Weinberg equilibrium for a gene, its allele frequencies will: (A) remain constant across generations unless an evolutionary force acts. (B) be perfectly balanced by genetic drift and gene flow. (C) change due to active mate choice based on genotype. (D) significantly deviate from predicted genotypic frequencies. (E) always be significantly altered by new mutations in the short term.