Midterm Exam 2 - Introduction to Biology | BIS 001B, Exams of Biology

Download Midterm Exam 2 - Introduction to Biology | BIS 001B and more Exams Biology in PDF only on Docsity! 1 BIS 1B Midterm 2. Kimsey and Ward Winter 1998 1. Which of the following is a true statement? a. gastrulation is believed to have been absent in the most recent common ancestor of the Cnidaria and the Bilateria b. the Deuterostomes are a monophyletic group that includes Mollusca, Annelida and Arthropoda c. the Cnidaria are a sister group of the Platyhelminthes d. the Cnidaria are more closely related to the Porifera than to the Chordata e. bilateral symmetry and cephalization are synapomorphies of the Bilateria 2. Triploblastic development is seen in which of the following animals? a. corals b. sea slugs c. sea anemones d. jellyfish e. sponges 3. The complete body plan of all molluscs may be reduced to these basic components a. trochophore and veliger b. mantle and visceral mass c. visceral mass and head-foot d. visceral mass and mantle e. mantle and head-foot 4. The digestive system of the phylum Platyhelminthes a. is a complete gut, with separate mouth and anus b. derives from the mesoderm c. has been lost in one subgroup, the tapeworms d. involves a simple gastrovascular cavity e. is more complex than that of the annelid worms 5. The life cycles of Obelia (a hydrozoan) and Aurelia (a jellyfish) differ in that a. in Obelia the medusa stage has been lost b. in Aurelia the polyps are colonial c. in the jellyfish the medusa is the sexual stage d. in the jellyfish the medusa is the more conspicuous stage e. Obelia only reproduces asexually 6. Structures and processes found in sponges include a. nerve nets b. intracellular digestion 2 c. feeding tentacles d. mesodermal tissue e. none of the above 7. Which of the following is/are characteristic of arthropods? a. growth by ecdysis b. well developed coelom c. closed circulatory system d. protonephridia e. both (a) and (c) are correct 8. Torsion in molluscs a. is a developmental process found in gastropods and Nautilus cephalopods b. is found in all molluscs with coiling of the shell c. is a process by which chromatophores are regulated in cephalopods d. may be lost in adult sea slugs e. both (a) and (b) are correct 9. The “costs of sexual reproduction” include a. more rapid accumulation of deleterious alleles in sexual populations b. lower offspring fitness in variable environments c. a higher mutation rate in sexual progeny d. slow recombination rates compared to asexual populations e. none of the above 10. Traits indicating that Annelida and Mollusca are sister groups include a. presence of a true coelom b. development of three germ layers in the embryo c. a well developed nervous system d. presence of a trochophore larva e. all of the above 11. Compared to animals living in marine environments, those living in freshwater environments a. experience a hypotonic environment b. require osmoregulatory mechanisms to conserve water c. face the problem that salts tend to enter the body through osmosis d. all of the above e. none of the above 12. Passive diffusion of gases across the body wall a. is the primary mode of respiration in Arthropoda b. requires the maintenance of a relatively high surface area/volume ratio 5 18. Describe an example from either the Cnidaria or the Platyhelminthes of a complex life cycle in which there is a regular alternation of sexual and asexual reproduction. (You may find it useful to draw a diagram.) Explain clearly which are the sexual and asexual forms. Given what we discussed in class about the individual (short-term) benefits of sexual reproduction, which stages of the life cycle do you think would experience the most unpredictable and variable environmental conditions? (12 points) 6 19. Either What features do colonial cnidarians and social insect colonies have in common? In what ways do they differ? Can you suggest some advantages of coloniality that apply in both cases? (10 points) Or Sketch the structure of an asconoid sponge, and indicate the direction of water flow. Explain how feeding occurs. (10 points) 20. Extra Credit Question (3 points) Crustaceans are generally dioecious but, in an exception to this, most barnacles are monoecious. What aspect of the biology of barnacles might explain this difference?