Energy Flow Lesson

Energy Flow

Energy flow is the transfer of energy from one organism to another in an ecosystem.

Energy

• What are producers and what is another name for them?

• They are organisms that get their energy from nonliving resources, meaning they make their own food; they're also called autotrophs.

• What are consumers and what is another name for them?

• Consumers are organisms that get their energy by eating other living or once-living resources; they're also called heterotrophs.

• What do all ecosystems depend on as their original source of energy?

• The sun.

Food Chains

• What is a food chain?

• A food chain is a sequence that links species by their feeding relationships.

• Rather than describe every potential relationship, this model chain only follows the connection between one producer and a single chain of consumers within an ecosystem. 

• Which way do the arrows point?

• In the direction energy is flowing... towards the organism doing the consuming.

Multiple Choice

Which model correctly shows energy flow in a food chain?

Types of Consumers in a Food Web

• Herbivores- eat only plants

• Carnivores- eat only animals

• Omnivores- eat plants and animals

• Detritivores- eat detritus, or deadorganic matter

• Decomposers- break down organic matter into simpler compounds; important to the stability of an ecosystem because they return vital nutrients back into the environment

Review Questions

• Name the carnivores.

• Red-tailed hawk only eat chipmunks and grouse.

• Name the herbivores.

• Deer eats berries and flowers. Marmot eats grasses. Chipmunk eats seeds.

• Name the omnivores.

• Grizzly bear eats both berries and deer. Grouse eats both berries and butterflies.

Multiple Choice

• red fox

• black bear

• deer

• rabbit

Multiple Choice

Decomposers are important in the food chain because they:

• produce their own food using light from the Sun.

• stop the flow of energy from one organism to another.

• break down dead organisms and recycle nutrients into the soil.

• are microscopic and other organisms cannot consume them.

Trophic Levels

• 1. Producers: at the bottom; hold the most energy

• 2. Primary consumers; eat producers

• 3. Secondary consumers; eat primary consumers

• 4. Tertiary consumers; eat secondary consumers

• 5. Quaternary consumers; eat tertiary consumers; usually an apex predator

Multiple Choice

What trophic level do the crabs belong to?

• Producer

• Primary consumer

• Secondary consumer

• Tertiary consumer

Energy Pyramid

• - shows the energy flow between trophic levels in an ecosystem.

• - total energy used by producers far exceeds the energy used by the consumers they support.

• - unit of measurement used to describe the amount of energy at each trophic level in an energy pyramid is the kilocalorie (kcal).

• - has a very large section at the base for the producers, and sections that become progressively smaller above.

• Because energy is lost at each stage of a food chain, the longer the chain is, the more energy is lost overall.

• Between each tier, up to 90 percent of the energy is lost as heat into the atmosphere; therefore, only 10% of the energy is moved to the next level.

Biomass Pyramid

• - a diagram that compares the biomass of different trophic levels within an ecosystem

• - provides a picture of the mass of producers needed to support primary consumers, the mass of primary consumers required to support secondary consumers, and so on.

• In a pond ecosystem, a biomass pyramid shows that the total dry

  mass (given in grams per square meter, or g/m2) of algae within the pond is far greater than the dry mass of fish.

• This example illustrates yet again the important role producers play in maintaining a stable ecosystem.

Numbers Pyramid

• - shows the number of individual organisms at each trophic level in an ecosystem.

• - particularly effective in showing the vast number of pro- ducers required to support even a few top level consumers

Review Questions

• Which trophic level do the grasses represent?

• Producers. Now, which trophic level do the jackrabbits represent?

• Primary consumers. Which trophic level do the long-tailed weasels represent?

• Secondary consumers. Which trophic level do the great horned owls represent?

• Tertiary consumers. Which level has the greatest amount of energy?

• If there are 10,000 calories in the grasses, how many calories are in the jackrabbits?

• 1,000 calories.

Multiple Choice

• kelp to have less food.

• crabs to have more food.

• sea ducks to have less food.

• arctic foxes to have more food.

Multiple Choice

Multiple Choice

Which of the following would you most likely see at the bottom of an energy pyramid?

• Grass

• Mice

• Snakes

• Hawk

Multiple Choice

Which of the following would you most likely see at the top of a biomass pyramid in an ocean food chain?

• Plankton

• Small fish

• Large fish

• Great white shark

Multiple Choice

If the seeds, nuts, roots, grass, leaves, and flowers level had 1,000 kcal, how many kcal would be in the hawks and owls level?

• 1,000 kcal

• 100 kcal

• 10 kcal

• 1 kcal