A farm pond, usually dry during winter, has plenty of water and aquatic pond life during the summer. One summer, Sarah returns to the family farm from college. Observing the pond, she is fascinated by some six-legged organisms that can crawl about on submerged surfaces or, when disturbed, seemingly "jet" through the water. Watching further, she is able to conclude that the "mystery organisms" are ambush predators, and their prey includes everything from insects to small fish and tadpoles.
From this description, one can conclude that the organisms that have caught Sarah's attention are
A) insects.B) crustaceans.
C) aquatic spiders.
D) myriapods.
E) eurypterids.
Answer: A
Sarah noticed the presence of many empty exoskeletons attached to emergent vegetation. These exoskeletons looked exactly like those of the largest of the "mystery organisms" she had seen in the pond. They also looked similar to the bodies of the dragonflies that patrolled the surface of the pond. If Sarah had learned a lot from her college biology class, what should she have concluded about the mysterious pond organisms?
A) They are larval dragonflies, destined to undergo incomplete metamorphosis.B) They are larval dragonflies, destined to undergo complete metamorphosis.
C) They are adult dragonflies, so old that they can no longer fly, have fallen into the pond, but have not yet drowned.
D) They are adult dragonflies that must, like many amphibian species, return to water in order to mate.
Answer: A
If the pond organisms are larvae, rather than adults, Sarah should expect them to have all of the following structures, except
A) antennae.
B) an open circulatory system.
C) an exoskeleton of chitin.
D) complex eyes.
E) sex organs.
Answer: E
Sarah observed that the mystery pond organisms never come up to the pond's surface. If she catches one of these organisms and observes closely, perhaps dissecting the organism, she should find
A) gills.B) spiracles.
C) tracheae.
D) book lungs.
Answer: A
Sarah had learned that ancestral (Carboniferous era) dragonfly species were much larger than extant dragonfly species are, with wingspans of 70 cm. This struck her as odd, because she had also learned that one of the things that keeps insects small is their relatively inefficient respiratory system. Which two hypotheses might help account for the large size of ancestral dragonflies?
1.If the atmosphere during the Carboniferous era had featured a higher oxygen content than the modern atmosphere, then the tracheae might have been a sufficient means for oxygen delivery to the interior tissues.
2. If large size was a drawback, then the large dragonflies underwent extinction, which explains why all extant dragonflies are smaller.
3. If the ancestral dragonflies had possessed muscles that permitted effective ventilation of the tracheae, then the tracheae might have been a sufficient means for oxygen delivery to the interior tissues.
4. If ancestral dragonflies existed during greenhouse conditions, then they must have survived by decreasing their activity levels, such as no longer capturing prey in flight. Thus, for them, an ineffective respiratory system was sufficient.
A) 1 and 2
B) 1 and 3
C) 1 and 4
D) 2 and 3
E) 2 and 4
Answer: B
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