Trophic Cascades and Keystone Species

A keystone species has...

• big impact on ecosystem, big population
• small impact on ecosystem, small population
• big impact on ecosystem, small population
• None of these

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What is a keystone species?

• A species that helps to hold an ecosystem together

• A species that lives in or around rocks

• Keys and stones have nothing to do with ecology

• A keystone isn't a living thing, it's just a stone

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The term biodiversity means:

• a wide variety of plants and animals in an ecosystem
• only a few types of plants and animals in an ecosystem
• an ecosystem composed mostly of plants
• an ecosystem composed mostly of animals

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A sea otter and a sea star are examples of...

• invasive species
• keystone species
• native species 
• symbiotic species

Based on the graph shown, what is the effect of removing a keystone species from an ecosystem?

• biodiversity goes up
• biodiversity goes down
• biodiversity stays about the same
• not enough information to tell

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NGSS.MS-LS2-4

A species that maintain biodiversity by keeping prey populations controlled are called...

• Introduced Species
• Apex Predators
• Invasive Species
• Keystone Species

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Trophic cascades refer to...

• impacts that reach beyond adjacent trophic levels.

• impacts that reach the adjacent trophic level.

• impacts that reach only one trophic level.

• impacts that reach the top trophic level

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Starfish are probably the most important predator in the shallow ecosystem because they eat basically anything that they can come across. Their feeding activities control the whole ecosystem. This is an example of the starfish ___.

• habitat
• biotic factors
• tolerance level
• niche

___ states that two species cannot exist together if they compete for the same resources. One will either die out or migrate, or they will adapt to separate resources.

• Hardy-Weinberg Principle
• Limiting Nutrient Principle
• Competitive Exclusion Principle
• Tolerance Principle

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Which ecological problem was NOT caused by elk?

• Few trees were on river banks

• Small mammals couldn't hide from predators due to less grass and shrub cover.

• Weather patterns changed and there were more severe storms.

• Rivers were muddy, making it harder for fish and amphibians to survive.

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