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YDT • İngilizce 2. ADIM • 5. DENEME

36. According to the passage, the extinction of grey
35. - 37. soruları aşağıdaki parçaya göre cevaplayınız. wolves ----.

Certain species are more significant for the maintenance A) raised public awareness about the importance of
protecting keystone species
of ecosystems than others. Such keystone species are
crucial for the species composition and the functioning B) led conservation biologists to worry that the
of the ecosystem. The fact that other species depend ecosystem had much less biodiversity
on or are strongly influenced by the keystone species C) influenced any organism adversely, from animals
becomes apparent when the keystone species is and plants to bacteria and fungi
removed. Keystone species—which can be any D) increased the elk and deer populations, and their
organism, from animals and plants to bacteria and overgrazing of plants caused insects to disappear
fungi—are usually not the most abundant species E) enabled scientists to fully understand their critical
in the ecosystem. Although present in relatively role in the food web as a keystone species
small numbers, they exert a profound influence
on the entire ecosystem because they often affect
the available amount of food, water, or some other
resource. Identifying and protecting these species are
important goals of conservation biologists because if
a keystone species disappears from an ecosystem,
other organisms may become more common or rare or
even disappear. An example of a keystone species is a
top predator such as the grey wolf. Where wolves were
hunted to extinction, populations of deer, elk, and other
herbivores exploded. As these herbivores overgrazed
the vegetation, plant species that could not tolerate
such grazing pressure disappeared. Smaller animals
such as insects disappeared from the ecosystem
because the plants they depended on for food had
become fewer. So, the disappearance of the wolf
meant that the ecosystem had much less biodiversity.

35. Which statement is true about keystone species 37. What is the passage mainly about?
according to the passage?
A) The characteristic features that identify keystone
A) They may not be the largest or most abundant species
species in an ecological community. B) The effects of a recently discovered keystone
B) Animals, such as predators, are the most significant species
examples of keystone species. C) The ways of protecting our planet’s keystone
C) Many keystone species are listed as endangered or species
threatened with extinction. D) Examples of keystone species all around the
D) The removal of the keystone species will adversely world
affect herbivores. E) The importance of keystone species in the
E) All the species present in an ecosystem have equal ecosystem
importance for biodiversity.

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