Biology 2 /SL Review Book Topic G.2 Ecosystems and Biomes
Name _________________________
Review Book Topic G2: Ecosystems and Biomes
Assessment Statements
G.2.1
Define gross production, net production and biomass.
G.2.2
Calculate values for gross production and net production using the equation:
gross production – respiration = net production.
G.2.3
Discuss the difficulties of classifying organisms into trophic levels.
G.2.4
Explain the small biomass and low numbers of organisms in higher trophic levels.
G.2.5
Construct a pyramid of energy, given appropriate information.
G.2.6
Distinguish between primary and secondary succession, using an example of each.
G.2.7
Outline the changes in species diversity and production during primary succession.
G.2.8
Explain the effects of living organisms on the abiotic environment, with reference to the
changes occurring during primary succession.
G.2.9
Distinguish between biome and biosphere.
G.2.10
Explain how rainfall and temperature affect the distribution of biomes.
G.2.11
Outline the characteristics of six major biomes.
Key facts
1. Energy flows through an ecosystem from the Sun to producers to consumers, however, some food
chains are supported by bacteria which can trap chemical energy.
2. Energy is lost as heat or used as maintenance as it flows through the food chain. The percentage of
heat transferred to the next trophic levels runs between 5-20%.
3. Gross production is the total amount of energy trapped in the organic matter produced by plants
per area per time in kilojoules. Net production is the gross production minus the energy lost in
respiration.
4. Biomass is the dry weight of an organism measured in grams per square meter per year.
5. Energy pyramids are block diagrams that show the energy flow (Kj m-2 yr-1) in each trophic level of an
ecosystem. Blocks are scaled in proportion to the values.
6. There are fewer numbers of organisms and smaller biomass values as trophic levels increase
because biomass is lost during respiration (as glucose is broken down into carbon dioxide and water)
at each trophic level and energy loss at each level does not allow many organisms to exist at the top
trophic level.
7. Difficulties classifying organisms into trophic levels include that some consumers eat both primary
and secondary consumers, and omnivores eat both animals and plants.
8. Primary succession occurs when plants begin growing on a previously barren or lifeless area.
Examples might include a newly created volcanic island or newly exposed beach. It begins with no
life or soil in a new area, lichen and mosses are the first plants, biomass and production are low.
9. Secondary succession occurs when plants take over following a natural or artificial upheaval of the
primary succession. It occurs much faster than primary succession because soil is already present
and there may be existing seeds and roots present (e.g., following a forest fire). Biomass and
production are higher.
10. Living organisms change the abiotic (non-living) environment in several ways. Organic matter
increases. Soil gets deeper. Soil erosion lessens. Soil structure improves. Mineral recycling increases.
11. The living part of Earth is called the biosphere. Biomes are divisions of the biosphere defined by its
vegetation and community structure. Biomes are controlled by weather patterns and topography.
Biology 2 /SL Review Book Topic G.2 Ecosystems and Biomes
Name _________________________
12. Biomes in North America that are determined by combinations of temperature, rainfall, and
elevation include tundra, coniferous forest, temperate forest, desert, and tropical rainforest
Complete the following.
1. Compare and contract gross production and net production in an ecosystem.
2. Discuss the difficulties of classifying organisms into trophic levels.
3. Distinguish between primary and secondary succession using a new volcanic island and the island
following a massive eruption of ash as examples.
4. How does soil change due to living things?
5. Compare and contrast grassland and tundra in terms of temperature, moisture, and characteristics
of vegetation.
6. Draw an energy pyramid that matches the following description. Producers 72,000 kJm-2yr-1; primary
consumers 4000 kJm-2yr-1; secondary consumers 200 kJm-2yr-1.