17. Which option correctly represents the most likely sequence of the evolution of plants, from earliest to most recent?
(A) bryophytes, seedless vascular plants, gymnosperms, angiosperms
(B) seedless vascular plants, bryophytes, angiosperms, gymnosperms
(C) bryophytes, seedless vascular plants, angiosperms, gymnosperms
(D) bryophytes, gymnosperms, seedless vascular plants, angiosperms
(E) bryophytes, angiosperms, seedless vascular plants, gymnosperms

13. The largest group of prokaryotes is the ________, which obtain both energy and carbon from ________. (A) autotrophs； inorganic molecules (B) chemoautotrophs； decaying organic material (C) chemoheterotrophs； organic molecules (D) photoautotrophs； light (E) chemoautotrophs； organic material

14. Evidence for similarities between Archaea and Eukarya includes the (A) absence of introns from genes in both groups. (B) fact that both contain circular DNA without histones. (C) presence of peptidoglycan in the cell walls of both groups. (D) fact that both have several kinds of relatively complex RNA polymerases. (E) absence of cell wall in both groups.

15. ________ are toxic proteins secreted by pathogenic bacteria, and ________ are toxic components of the outer membrane of gram-negative bacteria. (A) Endotoxins； parasites (B) Endotoxins； botulinum toxins (C) Exotoxins； enterotoxins (D) Exotoxins； endotoxins (E) Endotoxins； enterotoxins

16. Plasmodium, the organism that causes malaria, is a(n) (A) amoeba. (B) stramenopile. (C) ciliate. (D) alveolate. (E) excavate.

18. Which structure is found in angiosperms but not gymnosperms? (A) root (B) spores (C) seeds (D) ovule (E) fruit

19. Most familiar types of fungi including mushrooms, puffballs, and shelf fungi are examples of (A) chytrids. (B) ascomycetes. (C) zygomycetes. (D) basidiomycetes. (E) streptomyces.

20. The function of the sphincter between the stomach and small intestine is to (A) retain chyme in the stomach until pepsin digestion is complete. (B) periodically release chyme into the small intestine in squirts. (C) release bile into the duodenum when chyme is present. (D) release pancreatic secretions into the duodenum when chyme is present. (E) pancreatic secretions transiently into the duodenum when chyme is present.

21. Which hormone is produced by adipose cells and helps to control appetite? (A) insulin (B) bile (C) gastrin (D) leptin (E) interferon

22. Which statement regarding breathing and circulation in insects is false? (A) Insects lose very little water by using a tracheal system to breathe. (B) The tracheal system of insects consists of a series of branching air tubes that extend from the surface to deep inside the body. (C) Terrestrial animals such as insects spend much more energy than aquatic animals to ventilate their respiratory surfaces. (D) The circulatory system of insects is not involved in transporting gases. (E) Insects spend little water by using a tracheal system to breathe.

23. What part of the human brain contains control centers that establish a breathing rhythm? (A) midbrain (B) cerebellum (C) pituitary (D) thalamus (E) medulla oblongata