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

Multiple Choice

Which organism do the owl and the weasel compete for in the food web?

• Hawk
• Spider
• Grasshopper
• Shrew

Multiple Choice

What might happen if you remove a primary consumer from the ecosystem?

• There would be more food for secondary consumers.
• The number of primary consumers would increase.
• The number of plants would increase.
• The number of secondary consumers would increase.

Multiple Choice

Which of the following would be the most likely effect, if there were a sudden increase in the cricket population?

• There would be a decrease in the small bird population.
• There would be a decrease in the grass/flowers population.
• There would be a decrease in the mice population.
• There would be an increase in the grass/flowers population.

Multiple Choice

How many primary consumers are there in this food web?

• 1
• 2
• 3
• 4

Multiple Choice

What percentage of energy is passed on to each tropic level?

• 10%
• 50%
• 90%
• 100%

Multiple Choice

How do producers obtain energy?

• They conduct photosynthesis.
• They consume plants.
• They consume primary consumers.
• They consume secondary consumers.

Multiple Choice

Use the diagram to answer the question.
The Mayfly is a food source for which 3 organisms?

• Frog, Dragon Fly and snake
• Frog, trout and dragon fly
• Frog, salamander and trout
• Frog and phytoplankton

Multiple Choice

Bacteria and fungi typically serve what role in an ecosystem?

• herbivore
• carnivore
• omnivore
• decomposer

Multiple Choice

The shrew provides energy for the _______.

• cricket
• grasshopper
• frog
• snake

Multiple Choice

Identify the correct food chain that demonstrates the energy flow of this food web

• Plant > Caterpillar > Bluebird > Eagle
• Plant < Rabbit < Eagle
• Plant >Lizard > Snail >Eagle
• Eagle >Lizard>Caterpillar>Plant

Multiple Choice

If the grasshopper were to be removed completely from the food web, what organism would be most effected?

• The squirrel
• The shrew
• The deer
• The rabbit

Multiple Choice

In this food chain, what will happen if the frogs become extinct?

• The snakes will increase.
• The grasshoppers will decrease.
• The eagles will remain the same.
• The grasshoppers will increase.

Multiple Choice

Where does the energy start in this food chain?

• Plant
• Sun
• Deer
• Wolf

Multiple Choice

Which of the following is not a secondary consumer?

• hawk
• lizard
• mouse
• snake

Multiple Choice

What does a Primary Consumer eat?

• Tertiary Consumers
• Secondary Consumers
• Producers

Multiple Choice

Which level will contain plants?

• A
• B
• C
• D

Multiple Choice

Which level has the most energy available?

• producer
• primary consumer
• secondary consumer
• tertiary consumer

Multiple Choice

The rabbit in this food web would be considered a:

• Decomposer
• Producer
• Secondary Consumer
• Primary Consumer

Multiple Choice

The mouse in this food web would be considered a:

• Primary Consumer
• Producer
• Tertiary Consumer
• Secondary Consumer

Multiple Choice

Which of the following would be the most likely effect, if there were a sudden increase in the cricket population?

• There would be a decrease in the small bird population.
• There would be a decrease in the grass/flowers population.
• There would be a decrease in the mice population.
• There would be an increase in the grass/flowers population.

Multiple Choice

I eat both plants and animals for energy...what am I?

• Scavenger
• Omnivore
• Carnivore
• Producer

Multiple Choice

What organisms are considered secondary consumers in this food web?

• rabbits, mice and grasshoppers

• grains, grasses and carrots

• foxes, owls, and birds

• birds only

Multiple Choice

Which organisms are primary consumers in this food web?

• tree, shrub, mountain lion

• mountain lion and deer

• squirrel, grasshopper, rabbit, deer

• shrew, snake and rabbit

Multiple Choice

Where is the least amount of energy available in an energy pyramid?

• The very bottom level

• Secondary consumer level

• The very top level

• Primary consumer level

Multiple Choice

Organisms that create their own energy from sunlight or chemicals

• Herbivore
• Omnivore
• Autotroph
• Heterotroph 

Multiple Choice

In the energy pyramid here, how much of the energy in each level gets lost as heat or used by the organism for survival?

• 80%
• 90%
• 10%
• 20%