25. According to the principle of maximum parsimony, when considering multiple phylogenetic hypotheses, which explanation should systematists investigate first?
(A) The most complex explanation consistent with all known facts.
(B) The explanation that incorporates the most recently discovered genetic mutations.
(C) The simplest explanation that is consistent with the facts.
(D) The explanation that best aligns with previously established taxonomic classifications.

21. If a diploid cell in the G1 phase of the cell cycle has a DNA content of 'x', what would be the DNA content of the same cell at metaphase of meiosis I?(A) 0.25x (B) 0.5x (C) x (D) 2x

22. The relatively short interval of time (535–525 million years ago) during which large forms of many present-day animal phyla first appear in the fossil record is known as what?(A) The Permian extinction (B) The Cambrian explosion(C) The Mesozoic era (D) The colonization of land

23. How might an error during meiosis lead to polyploidy in plants?(A) Failure of homologous chromosomes to separate during meiosis I, leading to diploid gametes.(B) Random assortment of chromosomes during metaphase I, resulting in gametes with extra chromosomes.(C) Crossing over between non-sister chromatids, creating recombinant chromosomes.(D) Nondisjunction in mitosis during gamete formation in the diploid organism.

24. A population has an allele 'a' with a frequency of 0.45. If the population is in Hardy-Weinberg equilibrium, what is the expected frequency of the homozygous dominant genotype (AA)?(A) 0.2025 (B) 0.3025 (C) 0.4950 (D) 0.5500

26. Two organisms, with genotypes BbDD and BBDd, are mated. Assuming independent assortment of the B/b and D/d genes,what is the probability of obtaining an offspring with the genotype BbDd?(A) 1/16 (B) 1/8 (C) 1/4 (D) 1/2

27. Which of the following characteristics, structures, or processes is common to both bacteria and viruses?(A) Metabolism (B) Ribosomes(C) Genetic material composed of nucleic acid (D) Cell division

28. Which type of sensory receptor detects physical deformation in the body's environment associated with pressure, touch,stretch, motion, or sound?(A) Chemoreceptor (B) Electromagnetic receptor(C) Nociceptor (D) Mechanoreceptor

29. Which of the following describes the ploidy and state of a fungal cell in the heterokaryotic stage?(A) Haploid (n), with a single nucleus.(B) Diploid (2n), formed after karyogamy.(C) Dikaryotic (n + n), containing haploid nuclei from two parents.(D) Polyploid, with multiple sets of chromosomes from a single parent.

30. Imagine you want to study a human crystallin protein. To obtain a sufficient amount of this protein, you decide to clone its gene. Assuming you know the gene sequence, which approach would allow you to produce the protein in a suitable system like bacteria?(A) Isolate lens cells, extract genomic DNA, and insert the entire gene directly into a bacterial expression vector.(B) Isolate lens cells, extract mRNA, use reverse transcriptase to make cDNA, and insert the cDNA into a bacterial expression vector.(C) Directly synthesize the protein from its known amino acid sequence using a chemical synthesizer.(D) Use PCR to amplify the gene from a brain cell and insert it into a eukaryotic yeast expression vector.

31. Which statement accurately distinguishes Ulva from Caulerpa regarding their multicellular organization?(A) Ulva is a colonial protist, while Caulerpa is a true multicellular alga with specialized tissues.(B) Ulva forms true multicellular bodies through cell division and differentiation, whereas Caulerpa achieves largesize via repeated nuclear division without cytoplasmic division, making it not truly multicellular.(C) Caulerpa exhibits alternation of generations, while Ulva only has a single-celled haploid stage.(D) Both are truly multicellular, but Ulva has a simpler organizational plan compared to Caulerpa's complex thallus.