Mount St. Helens: A Story of Succession

If an ecosystem experiences a natural disaster, which criterion increases an organism’s chance of survival?

• there are few abiotic factors in the environment

• the organisms are large

• the population size is small

• the species exhibit inherited genetic variation

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NGSS.MS-LS4-4

Surtsey is an island located south of Iceland. The island was formed by a volcanic eruption and first appeared in 1963. The table below contains descriptions if changes in the population and diversity of species on Surtsey. Which of these lists the descriptions in the correct order of ecological succession on Surtsey?

• I, II, IV, III

• IV, III, I, II

• III, I, II, IV

• II, IV, I, III

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-4

An ecosystem reaches ________ when there are not too many of a species alive or dead.

• stand-still

• equilibrium

• limit

• maximum population density

The growth of which of the following usually occurs first in primary succession?

• lichens

• grasses

• trees

• shrubs

Which of these is a main difference between primary and secondary succession?

• Primary succession happens slowly, and secondary succession happens rapidly.

• Small plants grow first during primary succession, while large trees grow first in secondary succession.

• Primary succession occurs after a natural disaster, but secondary succession occurs before a natural disaster.

• Primary succession is the colonization of new sites, while secondary succession is colonization of previously inhabited sites.

The last stage of succession in this pond is that the pond will become-

• deeper and clearer

• filled with soil

• polluted by acid rain

• salty due to evaporation

Tags

NGSS.MS-LS2-3

NGSS.MS-LS2-4

After a volcanic eruption has covered an area with lava, which of the following is the most likely order of succession in the repopulation of the area?

• Grasses, trees, mosses, lichens

• Shrubs, grasses, trees, lichens

• Lichens, grasses, shrubs, trees

• Mosses, grasses, lichens, trees

A farmer stops cultivating a large tract of farmland and abandons it. The natural changes taking place soon afterwards, such as the growth of wild grasses and weeds, can be considered secondary succession and not primary succession because-

• A new ecosystem develops.

• There is already soil present.

• The land is not controlled by humans.

• Wild grasses and weeds make soil from rock.

Tags

NGSS.MS-LS2-4

Which is an example of an event that would occur before primary succession?

• tornado

• hurricane

• lava flow

• forest fire

Which statement describes how the ecosystem shown is likely to change after ecological succession?

• The variety of fish species

  will increase.

• The number of plants will

  increase.

• The level of the water will increase.

• The elevation of the hills will increase.

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-4