24. Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be  ________.
(A) 14
(B) 16
(C) 28
(D) 56

20. A laboratory might use dideoxyribonucleotides to  ________.(A) separate DNA fragments (B) produce cDNA from mRNA (C) sequence a DNA fragment (D) visualize DNA expression

21. When gene duplication occurs to its ultimate extent by doubling all genes in a genome, what has occurred? (A) pseudogene creation (B) creation of a gene cluster (C) creation of a polyploid (D) creation of a diploid

22. A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies； but after several years, the farmer sees more and more pigweed. Which of these explanations best explains what happened? (A) The herbicide company lost its triazine formula and started selling poor-quality triazine. (B) Natural selection caused the pigweed to mutate, creating a new triazine-resistant species. (C) Triazine-resistant pigweed has less-efficient photosynthesis metabolism. (D) Triazine-resistant weeds were more likely to survive and reproduce.

23. Mutation is the only evolutionary mechanism that  ________.(A) does little to change allele frequencies (B) is more important in eukaryotes than in prokaryotes (C) happens in all populations (D) has no effect on genetic variation

25. If one organ is an exaptation of another organ, then these two organs  ________.(A) are homologous (B) are undergoing convergent evolution (C) are found in the same species (D) have the same function

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

27. If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, the regenerated bacterium will probably also ________.(A) lack antibiotic-resistant genes (B) lack a cell wall (C) lack a chromosome (D) lack water in its cytoplasm

28. Dinoflagellates  ________.(A) possess two flagella (B) are all autotrophic (C) lack mitochondria (D) include species that cause malaria

29. Most moss gametophytes do not have a cuticle and are 1-2 cells thick. What does this imply about moss gametophytes and their structure? (A) They use stomata for gas exchange regulation. (B) They can easily lose water to, and absorb water from, the atmosphere. (C) Photosynthesis occurs throughout the entire gametophyte surface. (D) They have branching veins in their leaves.

30. In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at is a protostome and not a deuterostome? (A) There is evidence of cephalization. (B) The animal is triploblastic. (C) The animal is clearly bilaterally symmetrical. (D) You see a mouth, but not an anus.