Free CLEP Science and Mathematics Exam Braindumps (page: 6)

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The best current evidence that modern-day birds evolved from certain lineages of dinosaurs or other reptiles may be supplied by the fact that

  1. some dinosaurs, like birds, could fly
  2. transitional fossils such as Archaeopteryx have been discovered
  3. birds and reptiles both exhibit some parental care for their young
  4. no birds have ever been found living during the same time period as dinosaurs
  5. modern-day crocodiles are genetically similar to certain lineages of modern-day birds

Answer(s): B

Explanation:

The best evidence that modern-day birds evolved from reptile lineages is that transitional fossils are plentiful. These fossils, such as the famous Archaeopteryx, show creatures with both reptilian and bird-like characteristics (e.g. the claws and body shape of a reptile with the feathers of a bird).



Malfunctioning sodium-potassium pumps along a neuron's axon would likely result in

  1. an increased frequency of action potentials
  2. a reversal in the movement of chloride ions across the axon membrane
  3. action potentials that move from axon to dendrite
  4. a rapid decrease in the ability of the axon to conduct an action potential
  5. the use of neurotransmitters to move the action potential down the axon

Answer(s): D

Explanation:

Without working pumps, the axon could not maintain a negative potential inside compared to outside (accomplished by the pumping out of 3 Na+ ions while pumping in only 2 K+). Therefore, the axon itself would be unable to depolarize and transmit an action potential. In addition, the Na-K pump is needed to reverse the membrane potential along the axon once sodium ions have rushed inside. If this depolarization cannot be reversed, the neuron can no longer carry action potentials.



Which of the following conditions could result in a decreased production of Substance C?

  1. Addition of Substance B
  2. Boiling Enzyme 1
  3. Mixing Enzyme 1 with Enzyme 2
  4. Addition of Enzyme 2
  5. Removal of Substance D

Answer(s): B

Explanation:

Boiling most enzymes will result in their denaturation--loss of 3-D structure. When denatured, enzymes lose their ability to catalyze reactions. Additions or removals beyond Substance C (e.g. choice E) are unlikely to result in any changes to the production of C, which is "upstream" from the change. The addition or mixing of any enzymes is likely to increase Substance C's production.



Which graph shows the likely relationship between a predator species and its prey over a six year cycle?



  1. Option A
  2. Option B
  3. Option C
  4. Option D
  5. Option E

Answer(s): A

Explanation:

The graph of a predator-prey interaction is usually depicted as a series of linked fluctuations. As the prey population rises, the predator population follows with a slight lag; as the predators eat too much prey, the predator population falls with a slight lag behind the fall in the prey population. This will continue as long as the survival of the prey population is linked to the size of the predator's population and vice-versa.






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