Section15

Ecosystems

Biology I Factoids

Factoid 256

• Section 15

• An ecosystem is made up of communities and their environments.

Factoid 257

• Producers (autotrophs) make their own food.

Factoid 258

• Consumers (heterotrophs) get their energy by eating autotrophs (producers) or by eating other heterotrophs (consumers).

Factoid 259

• Primary consumers eat producers. Energy is transferred from the producers to the primary consumers. Primary consumers are herbivores.

Factoid 260

• Secondary consumers eat primary consumers. Energy is transferred when one organism eats another.

Factoid 261

• Decomposers break down dead organisms into detritus (organic matter).

Factoid 262

• A food chain is a series of feeding relationships starting with a producer.

Factoid 263

• A food web is a series of overlapping food chains.

Factoid 264

• The trophic level is a feeding level. Every step of a food chain is a trophic level.

Factoid 265

• An energy pyramid shows the energy that is transferred between trophic levels.

Factoid 266

• Only about 10% of the energy at each level is transferred to the next higher level. The rest is used by the organism itself and some is lost as heat.

Factoid 267

• Since only 10% of energy is transferred from one level to another, a food chain usually only has 4 or 5 trophic levels.

Factoid 268

• Biomass is the mass of dry organic materials in an organism.

Factoid 269

• A biomass pyramid indicates the amount of organic material at a given trophic level. Typically producers have the largest biomass.

Factoid 270

• A pyramid of numbers shows the approximate number of individual organisms at each level that an ecosystem can support.

Factoid 271

• The biosphere is all living things on the planet. The biosphere is divided into biomes.

Factoid 272

• Since matter can not be created or destroyed according to the Law of Conservation of Mass, it must be recycled in the environment.

Factoid 273

• The Water Cycle

Factoid 274

• Transpiration is the evaporation of water through the plant.

Factoid 275

• The Carbon-Oxygen Cycle

Factoid 276

• The Nitrogen Cycle

Factoid 277

• Nitrogen fixation is accomplished by bacteria and lightning.

• Denitrification is accomplished by bacteria.

Factoid 278

• The Phosphorus Cycle