Lesson 4.2

• Biologie
• Middelbare school
• vwo
• Leerjaar 4

Which of the following is usually true about secondary consumers in an ecosystem?

1. They eat only plants
2. They are eaten by primary consumers
3. They are fewer in number than are primary consumers
4. They contain the greatest total biomass in the system

Which of the following best explains why there are seldom more than five trophic levels in a food chain?

1. Most carnivores function at more than one trophic level
2. Top carnivores are too few in number to hunt effectively
3. The ecosystem contains too much biomass
4. Energy is lost from each trophic level

Succession

Succession: 'The change in structure and species composition of a community over time'

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Steps in succession

1. Pioneer species come in 
2. Through their existence they change the abiotic factors (add nutrients to ground, create shade, block wind etc)
3. This makes the environment suitable for other species to come in
4. These new species can outcompete the previous species making them dissapear from the system
5. This creates a follow up of species over time, because the population keep on changing the environment

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Pioneer stage (early succession)

Climax stage (late succession)

low biodiversity

high biodiversity

fluctuating abiotic factors

stable abiotic factors

Few layers

Very layered (heights of vegetation)

Closed cycles

Open cycles

Stable biomass

Increasing biomass

Scientists found, that over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities?

1. The original species became extinct
2. Species in the older community died from old age
3. The abiotic characteristics of the habitat changed
4. Diseases that killed the older organisms disappeared

Examples of Abiotic Factors include:

1. Weather, birds, plants, and animals
2. Rocks, reptiles, shrubs, trees, and grasses
3. Weather, wind, rain, sunlight, and rocks
4. Birds, plants, animals, reptiles, shrubs, trees, and grasses

How is primary succession different from secondary succession?

1. Primary succession starts with soil
2. Secondary succession start with bare rock
3. Primary succession starts with bare rock, with lichens and moss
4. Fire is an example of primary succession

How do lichens contribute to primary succession?

1. Lichens decompose organic matter from animals and plants
2. Lichens begin to break down rock to form soil
3. Lichens are nitrogen fixing bacteria
4. Lichens convert carbohydrates into fossil fuels.

A pioneer species is...

1. a large organism
2. the first organisms to adapt to a new environment
3. The best organism
4. Abiotic organisms

What is the order of succession shown in this figure?

1. A, B, C, D
2. A, D, C, B
3. C, A, D, B
4. C, D, A, B

Deflected succession

Preventing succession from proceeding to a climax system.

Often through management of humans

Which of the following is an example of deflected succession

1. Volcanic eruption
2. Letting cattle graze in a natural park
3. Planting trees
4. Flood

What type of succession is shown going from figure A to figure B?

1. Primary succession
2. Secondary succession
3. Intermediate succession
4. Deflected succession