As scientists have developed more productive crop varieties, farmers have switched from growing many traditional varieties to new high-yield varieties. For example, in Peru, there are about 500 native varieties of potatoes that Indians once grew. This has been reduced to about 20 genetically improved potato varieties worldwide.

Besides the number of varieties of potatoes being reduced, what else is reduced by this practice?

A. the potato gene pool
B. human dietary choices
C. types of soil nutrients
D. food chains that include potatoes

Even though the ostrich is a flightless bird, ostriches still possess wings that stretch approximately two meters across when fully extended. scientists speculate that when dinosaurs became extinct, some of the birds that lived during that time became land dwellers since they were able to consume the food that the dinosaurs once ate. over time, these species grew larger and heavier. eventually, the ostrich species became too big to fly. the wings found on ostriches are known as a. analogous structures. b. homologous structures. c. vestigial structures. d. symmetrical structures.