GATE Ecology and Evolution Practice Quiz

Question 1

In Clementsian succession, which statement best describes the facilitation mechanism during primary succession on bare rock?

Accepted Answer

Early colonists modify the substrate in ways that make establishment of later species more likely.

Question 2

A field abandoned after cultivation is first occupied by fast-growing annual herbs. After several years, perennial grasses dominate mainly because they pre-empt light and soil resources, slowing recruitment of other species. Which succession mechanism is most consistent with this pattern?

Accepted Answer

Inhibition

Question 3

A nurse shrub in an arid habitat increases seedling establishment of a cactus by lowering soil temperature and reducing evaporative stress beneath its canopy. However, once established, the cactus competes strongly with the shrub for water. Which interpretation is most accurate?

Accepted Answer

The interaction shifts from facilitation during establishment to competition later.

Question 4

In a rocky intertidal community recovering after disturbance, early barnacle settlers occupy most available space and prevent mussel recruitment until wave action creates gaps. Which prediction follows from the inhibition model?

Accepted Answer

Mussel recruitment should increase primarily after mortality or removal of early occupants creates open space.

Question 5

A newly formed sand dune is first colonized by grasses that trap wind-blown sand and reduce surface movement, allowing shrubs to establish later. This is an example of which process driving succession?

Accepted Answer

Autogenic change caused by colonists modifying the habitat

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