Ch 3. Matter and Energy in the Ecosystem

Living vs Nonliving Living Nonliving Environment Biotic factors- all the living organisms that inhabit an environment. Examples: plants, animals, bacteria. Nonliving Environment Abiotic factors- the nonliving parts of an organism’s environment. Examples include air currents, temperature, moisture, light, and soil.

Roles of Living Things All organisms need energy to live. In ecosystem, energy moves in ONE direction: Sun Organisms Energy from sun enters ecosystem via PHOTOSYNTHESIS! Organisms gather food by: Producing, Consuming, Decomposing

Life Without Light Some autotrophs can produce food in the absence of light. Rely on energy found in inorganic compounds. This process is called chemosynthesis.

Producers Producers: organisms that make their own food using the sun’s energy. Produce sugar using carbon dioxide, sunlight and water (in a process called Photosynthesis). Examples: plants, algae, some bacteria.

Consumers Consumers: organisms that cannot make their own food. Must eat other organisms. Examples: fungi, many protists and bacteria, animals. 4 ways consumers gather food: 1.Herbivores 2. Carnivores 3. Omnivores 4.Scavengers

Herbivores: only eat plants; called primary consumers. Examples: many insects and birds, grazing animals (cows, buffalo, antelope).

Carvivores: eat herbivores or other carnivores (eat animals); called secondary or tertiary consumers. Examples: lions, snakes, hawks, spiders.

Omnivores: eat plants and animals; could be primary, secondary or tertiary consumers. Examples: humans, bears, chimpanzees.

Scavengers: feed on the bodies of dead plants or dead animals; secondary, tertiary or higher consumer. Return nutrients to the environment. Examples: vultures, hyenas, many insects.

Decomposers Decomposers: bacteria and fungi that consume the bodies of dead plants and animals or other organic waste. Recycle nutrients back into environment.

In your notes: Make a list of 10 organisms (living things) you saw on your way to school today. Label each one as a producer, consumer, or decomposer.

Trophic Levels Trophic Level: a layer in the structure of feeding relationships in an ecosystem. Levels get smaller and smaller. Producers, primary consumers, secondary consumers, tertiary consumers, etc. Producers Autrotrophs: make their own food. Puts energy into the ecosystem. The largest level because they contain the most energy (100%) Consumers Heterotrophs: cannot make own food, must obtain nourishment by eating other organisms.

Check for Understanding: List the different groups of organisms in an ecosystem, and explain how each type gathers food. How do autotrophs and heterotrophs differ? In most ecosystems, the first trophic level contains more organisms than the second trophic level. Can you suggest a reason that explains this pattern?

Ecosystem Structure

Producers and consumers depend on each other. Changes in population of one organism affect all other organisms in the ecosystem. Food Chain: a series of organisms that transfer food between the trophic levels of an ecosystem. Producersherbivorescarnivoresdecomposers

Food Web: a network of food chains representing feeding relationships among organisms in an ecosystem. More complex and more realistic. Show interdependence of organisms.

Check for Understanding: What are food chains and food webs and how are they related? Make a food web of your own (must include at least 8 organisms).

Energy in the Ecosystem Energy from sun enters ecosystem via photosynthesis. Energy then passed from producers to consumers. No food = no survival. Amount of energy available limits the structure of the food web.

Energy and Food Producers absorb only 1% of sunlight that reaches earth to make 170 billion tons of food per year! Energy used to make cells. Biomass: total amount of organic matter present in a trophic level. The amount of energy available to the next level.

Much of energy in each level is lost before it can reach following level (power the animal, in the form of heat, to make shells, fibers, bones, etc) Only 10% energy transfer. Limits the length of food chains.

Ecological Pyramids Ecological Pyramid: diagram that shows amount of energy in different trophic levels in ecosystem. Can show energy, biomass, number of organisms in each level. Producers are on the bottom (largest level). Tertiary consumer are on the top (smallest level). Growth of producers limited by lack of elements (carbon, hydrogen, nitrogen, oxygen) – not by energy from the sun.

Check for Understanding: How much of the energy that appears in one trophic level will appear in the next? What is an ecological pyramid? Where is energy lost between trophic levels? Where does this energy ultimately go?

Ch 3 Section 4 Biogeochemical Cycles

What Sustains Life of Earth? Solar energy, the cycling of matter, and gravity sustain the earth’s life.

What are the 2 secrets of survival? Two Secrets of Survival: Energy Flow and Matter Recycle. Matter is recycled, Energy is NOT recycled (it is used by the organism and lost as heat).

Biogeochemical Cycles Most important elements: oxygen, carbon, hydrogen, nitrogen. Elements must be in form cells can use. Three important cycles: 1. Water Cycle 2. Carbon Cycle 3. Nitrogen Cycle

Water Cycle

Movement of water between ocean, the atmosphere, and the land. Parts of the water cycle: Evaporation (Transpiration) Condensation Precipitation Runoff

Evaporation: movement of water into the atmosphere as it changes from liquid to gas. Transpiration: evaporation of water from leaves of plants.

Condensation: change of water from gas to water (liquid) as it cools; leads to formation of clouds.

Precipitation: the product of condensation falling to the earth in the form of rain, snow, sleet, hail, etc.

Runoff: water flowing downhill and eventually returning to the ocean.

Effects of Human Activities on Water Cycle We alter the water cycle by: Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Polluting surface and underground water. Contributing to climate change.

Carbon Cycle

Photosynthesis and Respiration are the most important parts. Movement of carbon from the atmosphere, into the food chain, into the environment and back into the atmosphere. Photosynthesis and Respiration are the most important parts. Photosynthesis uses carbon dioxide and sunlight to make sugars. Respiration breaks down the sugars to remake carbon dioxide and energy. Ocean and rocks are another good source of carbon.

Effects of Humans on Carbon Cycle We alter the carbon cycle by adding excess CO2 to the atmosphere through: Burning fossil fuels. Clearing vegetation faster than it is replaced.

Nitrogen Cycle

Organisms need nitrogen to make amino acids. Movement of nitrogen from the atmosphere, into the food chain and back into the atmosphere. Steps: Nitrogen-fixing bacteria use nitrogen to make ammonia. Ammonia gets consumed by more bacteria to make nitrogen compounds plants can use. Animals get the nitrogen we need from proteins in the plants we eat. Decomposers return nitrogen to the soil in the form of ammonia.

Effects of Humans on Nitrogen Cycle We alter the nitrogen cycle by: Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. Contaminating ground water from nitrate ions in inorganic fertilizers. Releasing nitrogen into the troposphere through deforestation.

Check for Understanding: What are the four most common elements in the human body? How do transpiration and evaporation differ? Humans are releasing large amounts of carbon dioxide into the air by burning fossil fuels like coal and oil. What effect might this carbon have on the carbon cycle?