Chapter 5 - Section 1 Energy Flow In Ecosystems

Ecosystem = interacting system that involves both organisms and their nonliving environment includes…. BIOTIC and ABIOTIC factors

One of the most important ABIOTIC factors – is ENERGY!!!! Organisms cannot survive without a constant supply of energy !!! The source of energy for most organisms is the SUN!!! – either directly or indirectly

How does energy enter most ecosystems? from the SUN “solar”/radiant/light energy must be converted into food/fuel (chemical energy) How does this conversion occur? during PHOTOSYNTHESIS By whom? plants, algae and some bacteria

Photosynthesis… process of making food/fuel (chemical energy) the food/fuel made during photosynthesis is some type of organic compound – usually carbohydrates like sugar Why make carbohydrates ?

Chemical Equation for Photosynthesis 6 H 2 O + 6 CO 2 + light energy C 6 H 12 O O 2 What are the reactants? What are the products?

Until recently it was believed that ALL life was dependent on the sun…. UNTIL…. hydrothermal vent communities were discovered deep in the ocean where there is no sunlight

Hydrothermal Vents…. complete darkness poison gas heavy metals extreme acidity enormous pressure

Hydrothermal Vents…. spew super-hot, mineral-rich water into the cold and dark ocean depths underwater geysers hot water escapes from vents (cracks) in the ocean floor – sometimes as hot as 400°C (750°F) water does not boil because it is under so much pressure

HYDROTHERMAL VENT

Discovered in 1977… chemosynthetic bacteria…. live deep in the ocean where there is no light – photosynthesis is not possible use hydrogen sulfide gas (poisonous to most organisms) to make their food utilize a process called chemosynthesis to make their food serve as the basis of the food chain in these ecosystems!!! serve as the food source for other organisms – tube worms, clams, shrimp, crabs,…. BACTERIA

“vent communities” are …. – completely isolated from each other – unique – often the only place a species can be found

Producer also known as an autotroph = “self- feeder” organism that makes its own food (fuel) plants, algae and some bacteria vvv

In order for living things to meet their energy needs…. 2 processes are essential: Photosynthesis - making the food/fuel Cellular Respiration - burning the food/fuel

ONLY some organisms can perform photosynthesis, ALL organisms must break down their food/fuel to “get the energy from it” ALL organisms can (and must) perform cellular respiration

Cellular Respiration…. breaking down food/fuel to yield/produce/release USEABLE ENERGY What is respiration? What is cellular respiration? How are these related? C 6 H 12 O O 2 6 CO H 2 O + energy (ATP) Reactants? Products?

What are some activities that require energy? digestion, walking, breathing, sleeping, excretion, growth,… excess energy may be stored as fat (for use later)

Consumer also known as a heterotroph = “other-feeders organism that gets its food (fuel) by eating other organisms animals, fungi, protozoa and some bacteria

Who Eats What - to meet their energy needs some organisms must consume (eat) others categories of heterotrophs/consumers: Herbivores “to eat herbs” - eat producers Carnivores - “to eat flesh” - eat other consumers Omnivores – “to eat all” – eat both producers and consumers Detritivores – “to eat detritus” – eat dead and decaying organic material from plants and animals – invertebrate scavengers – earthworms, beetles, grubs, snails and slugs, termites, …. – detritus = the garbage of a ecosystem” the “

Detritivore versus Decompser Detritivores (invertebrate scavengers) Decomposers or Saprotrophs “to eat detritus” (the garbage of an ecosystem) “rotten -feeders” EAT dead and decaying organic material BREAK DOWN dead and decaying organic material earthworms, beetles, grubs, snails and slugs, termites, …. bacteria and fungi ingest/consume/eat whole food CANNOT ingest/consume/eat whole food EXTRACELLULAR DIGESTION and ABSORPTION of nutrients Important in process of recycling and returning nutrients to the environment to make them available for reuse

What is a scavenger?

What are these? herbivore, carnivore, omnivore, detritivore, decomposer, scavenger

When and how does energy transfer in an ecosystem occur? any time one organism eats another How can we trace the transfer of energy in an ecosystem? by studying food chains, food webs and trophic levels

THE SUN to producers to consumers energy flows in ONE DIRECTION in an ecosystem – from the sun to producers to consumers Energy Flow through an Ecosystem

Food Chain the transfer of energy from one organism to another within an ecosystem

Food Web interrelated food chains within an ecosystem

Trophic Level a level of feeding (position) in a sequence of energy transfers each step in a food chain or food web is called a trophic level

How many trophic levels are seen in the diagram?

PYRAMID of ENERGY shows the relative amount of energy available at each trophic level each time energy is transferred from one organism to another less energy is available at the next trophic level only about 10 % of the energy available at each level is transferred to the next trophic level about 90% of the energy at each level is “lost” as heat or is used up in life processes (growth, breathing, movement,…) each level in an energy pyramid represents a trophic level

PYRAMID of BIOMASS… shows the amount of biomass (dry weight in grams ) of organisms at each trophic level

PYRAMID of NUMBERS shows the numbers (quantity of) organisms at each trophic level

In what 2 ways does the energy lost at each trophic level affect an ecosystem? 1.fewer organisms are found at the higher trophic levels 2. the number of tropic levels is limited…. ecosystems seldom have more than 3 or 4 trophic levels

Energy in Ecosystems – Let’s Review Energy Is not recycled Energy must be constantly supplied The ultimate source of energy for most living things is the sun – either directly or indirectly Energy flows in ONE DIRECTION in an ecosystem – from the sun to producers to consumers Law of Conservation of Energy - during any biological, physical, or chemical process, energy cannot be created or destroyed Law of Entropy - with every transfer (or change in form) of energy there is a” loss” of useful energy