Chapter 5 How Ecosystems Work

Section 1 Energy Flow in Ecosystems

Energy Flows in Ecosystems Most organisms depend on the sun for energy. Producers get their energy from the sun through photosynthesis and then consumers eat those producers. Photosynthesis: 6 CO2 + 6 H2O (+ sunlight)  C6H12O6 + 6 O2 (+ energy)

An autotroph can make its own food. Producers are also called autotrophs. Consumers are also called heterotrophs. An autotroph can make its own food. Most autotrophs use photosynthesis to get their energy. Some autotrophs use chemosynthesis to get their energy like the ones that live in deep-ocean ecosystems. A heterotroph gets its energy by eating others. A heterotroph breaks down the food it eats and turns it into energy through cellular respiration.

What eats what Herbivores eat only plants. Carnivores eat other consumers. Omnivores eat both. Decomposers break down dead organisms.

Each step in a food chain is called a trophic level. FOOD CHAINS FOOD WEBS Are a linear sequence showing how energy is transferred from one organism to another Show the many feeding relationships that are possible in an ecosystem Each step in a food chain is called a trophic level.

Energy Pyramids Producers form the base of the pyramid. Energy is lost as you move up the pyramid. Only 10% of the energy goes to the primary consumers, secondary consumers, and tertiary consumers.

That is all for 5.1 Time for quiz 1.

Section 2 The Cycling of Materials

Matter cycles through an ecosystem. Carbon cycles between the atmosphere, land, water, and organisms. Carbon is the essential component of life.

Humans affect the carbon cycle By burning fossil fuels and cutting down trees. This could lead to climate change.

The Nitrogen Cycle Nitrogen is cycled between the atmosphere, bacteria, and other organisms. Bacteria plays a very important role in nitrogen fixation and denitrification.

Nitrogen cycle could not happen without bacteria! NITROGEN FIXATION DENITRIFICATION When bacteria converts nitrogen gas into ammonia or some nitrate. When bacteria converts ammonia or nitrate back into nitrogen gas. Nitrogen cycle could not happen without bacteria!

The Phosphorus Cycle Is the process of moving phosphorus from the environment to organisms then back to the environment. It happens when rocks erode or ocean sediment makes it back to land.

Human affect the phosphorus cycle Excess use of fertilizers leads to accelerated eutrophication Burning coal leads to acid precipitation

That’s all for 5.2 Time for quiz 2

Section 3 How Ecosystems Change

Ecological Succession Is the gradual process of change and replacement of some or all the species in a community. The hardwood trees show the climax community when all factors are in balance.

There are two types of succession Primary happens when there is no life or soil intact. Examples: Glacier retreats or volcano erupts. Secondary happens when there is some life or soil intact. Examples: Old-field succession that occurs after farmland is abandoned, floods and forest fires.

Pioneer Species Are the first organisms to colonize an area and begin the process of ecological succession Lichens are an example of pioneer species. They break down the rock and begin the formation of soil.

That is all for 5.3 Time for quiz 3.