Which chemical is synthesized by some sponges and acts as an antibiotic?
A) streptomycin
B) spongin
C) calcium carbonate
D) silica
E) cribrostatin
Answer: E
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Biology
- A student observes a wormlike organism crawling about on dead organic matter. Later, the organism sheds its outer covering. One possibility is that the organism is a larval insect (like a maggot). However, it might be a member of the phylum ________, and one way to distinguish between the two possibilities is by looking for ________.
- Nematode worms and annelid worms share which of the following features?
- How many of the following can be used to distinguish a nematode worm from an annelid worm? 1. type of body cavity 2. number of muscle layers in the body wall 3. presence of segmentation 4. number of embryonic tissue layers 5. shape of worm in cross-sectional view
- Humans most frequently acquire trichinosis by
- Which of the following is a characteristic of nematodes?
- Which of the following is found only among annelids?
- A radula is present in members of which clade(s)?
- A terrestrial mollusc without a shell belongs to which clade?
- Which mollusc clade includes members that undergo embryonic torsion?
- If a lung were to be found in a mollusc, where would it be located?
- A brachiopod can be distinguished from a bivalve by the presence of
- While sampling marine plankton in a lab, a student encounters large numbers of fertilized eggs. The student rears some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth. The embryo develops into a trochophore larva and eventually has a true coelom. These eggs probably belonged to a(n)
- The larvae of many common tapeworm species that infect humans are usually found
- What would be the most effective method of reducing the incidence of blood flukes in a human population?
- Planarians lack dedicated respiratory and circulatory systems because
- The excretory organs of annelids are
- Against which hard structure do the circular and longitudinal muscles of annelids work?
- The organ(s) of respiratory gas exchange in oligochaetes is (are)
- Which characteristic(s) is (are) shared by both cnidarians and flatworms?
- Corals are most closely related to which group?
- Which clade in the phylum Cnidaria includes "jellies" with rounded (as opposed to boxlike) medusae?
- The members of which clade in the phylum Cnidaria occur only as polyps?
- Which of the following is true of members of the phylum Cnidaria?
- How many of the following are characteristics of at least some members of the phylum Cnidaria? 1. a gastrovascular cavity 2. a polyp stage 3. a medusa stage 4. cnidocytes 5. a pseudocoelom
- Sponges are most accurately described as
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