Ecology

A biotic or abiotic factor that restricts the numbers of organisms in an ecosystem is called a (an) ____.

• Tolerating factor

• limiting factor

• primary succession

• end point

One community replacing another as a result of changing abiotic and biotic factors is called ____.

• ecological succession

• temperate change

• end point

• tropical succession

Which statement is true based on this picture?

• Temperature does not affect the physiology of steelhead.

• Colder water is always better for steelhead survival.

• Steelhead cannot tolerate temperature above or below a certain limit.

• There is no upper limit for steelhead temperature tolerance.

The first organisms to appear during ecological succession are called ____.

• succession plants

• pioneer species

• end point species

• primary organisms

What is a climax community?

• stable community with little change in species numbers

• community consisting of pioneer organisms

• community left behind immediately after a forest fire

• community with no biotic factors

How do ecologists benefit from creating models?

• Biotic factors can be ignored.

• Random factors have a greater effect on results.

• Abiotic factors can be ignored.

• Variables can be more easily controlled.

Tree branches are an example of a ____.

• niche

• habitat

• biome

• mutualism

What does a decrease in salmon population due to an increase in river temperature indicate?

• an abiotic factor affecting a biotic factor

• change in population but not in abiotic factors

• an effect of predation

• an unchanging biological community

This graph shows that the growth of ____ is decreased by higher temperature.

• paramecium

• colpidium

• colpidium and paramecium

• neither organism

What significant function can parasitism have in the ecosystem?

• the formation of lichens

• benefiting the health of hosts

• population decrease of an overabundant species

• increasing habitat size