Question

Which statement best describes a keystone species

Answer 1

Answer:

Option D,  it has a strong influence on the ecosystem

Explanation:

Keystone species are an essential part of an ecosystem and their functions/mark cannot be replaced by any other organism. Once the keystone species is removed from an ecosystem, the ecosystem struggles to sustain  or it changes radically. A keystone species in majority of ecosystems/food web is a predator but this is not true in all ecosystems/or with all keystone species.  

For example – there was a trophic cascade when the Gray wolves in the greater Yellowstone ecosystem were removed.  

Answer 2

The answer is D

One way to remember this is when you are building a bridge there is one piece right in the middle that keeps the whole thing from collapsing that is called the key-stone. If a keystone species goes extinct then the rest of the ecosystem will crumble around it.