In a long term study by the evolutionary biologists Endler and Reznick, they illustrated the effect of predation on life history traits by studying guppies with different predators: cichlids and killifish. The killifish preys mostly on immature, smaller guppies and cichlids pursue mature, larger guppies. They noticed that in river portions with only killifish, the guppies were larger than in
river portions with only cichlids. In an experiment, the researchers put the smaller guppies that had previously lived only with cichlids (which eat large guppies) in a river portion that only had killifish (which eat smaller ones).
a. What did they observe over the course of eleven years?
b. What do you predict would happen if they performed the opposite experiment and mixed guppies from killifish river portions to a river with only cichlids?
a. The guppies became larger in size and matured more slowly.
b. The guppies would likely become smaller, mature more quickly and reproduce earlier.
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Which of the following is correct concerning a spherical cell?
(A) As the diameter decreases, the surface area remains the same. (B) As the diameter decreases, the surface area increases. (C) As the diameter decreases, the surface-to-volume ratio increases. (D) As the diameter increases, the volume decreases. (E) The surface-to-volume ratio is independent of the diameter.
Cheetahs were almost extinct but conservation efforts managed to save them. Now, most cheetahs are genetically identical. What phenomenon explains this?
A. Gene flow B. Bottleneck effect C. Natural selection D. Selective mating
What is the key difference between protostomes and deuterostomes?
a. Protostomes are animals with soft exteriors and deuterostomes are animals with hard exteriors (i.e., shells). b. Protostomes represent a lineage of bilaterally symmetrical animals, whereas deuterostomes represent a lineage of radially symmetrical animals. c. The protostome gut develops from back to front and the second opening becomes the mouth. The deuterostome gut develops from front to back, so the first opening is the mouth. d. The protostome gut develops from front to back, so the first opening is the mouth. The deuterostome gut develops back to front and the second opening becomes the mouth. e. Protostomes represent animals that are prokaryotes, and deuterostomes represent all over animals.
If a person is bitten by a highly venomous snake and receives a dose of venom sufficient to kill several people, that person does not have the time to build up his immunity over the next week to neutralize the venom. However, hospitals carry "antivenin" made from injecting horses with small-to-larger dosages of snake venom, and then harvesting the antibodies from the horse plasma. This is an example of
A. passive immunity. B. receiving high levels of complement. C. receiving high levels of interferon. D. developing an inflammatory response to increase the IgG production. E. active immunity.