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Name: ____________________________________ Block: ____________ Date: ____________________________
Science 10: Energy Flow
Science 10: Biology! Energy Flow & Trophic Levels (Ch 2.1, 2.2, 2.4)
: a thin layer of atmosphere, land and water in which all life is found on Earth. Biotic factors (components) are .
Example:
Abiotic factors (components) are . Example:
Large regions that contain many ecosystems with similar abiotic and biotic components are called . A. Practice Questions: Textbook (2.1) p.24 #1-3 Organisms interact with ecosystem in two ways:
1. FROM ecosystems
2. TO ecosystems The transfer of energy from ecosystems to organisms and between organisms is called energy . Producers (aka ) produce energy. Plants are producers because they produce carbohydrates during . Consumers (aka ) consume energy. Consumers can also be an energy source for another consumer.
• eat plants (e.g. grasshopper) • eat consumers (e.g. wolf) • eat consumers and producers
(e.g. black bear) But where does this energy flow really start…? Food Chains and Food Webs Food chain: model showing the energy flow from and . This energy flow can also be represented by food or food . Trophic level: in the food chain.
60 MHR • Unit 1 Sustaining Earth’s Ecosystems
Food chains and food websFood chains are models that show the flow of energy from plant to animaland from animal to animal (Figure 2.6). Each step in a food chain is called atrophic level. Trophic levels in a food chain show the feeding and nicherelationships among organisms. Since plants and phytoplankton such asalgae are the producers, they are at the first trophic level and are referred toas primary producers.
Figure 2.6 A terrestrial foodchain and an aquatic foodchain show the flow ofenergy up the trophic levels.
In Figure 2.6, you can see that primary consumerssuch as grasshoppers and zooplankton (microscopicaquatic animals) are in the second trophic level. Theyobtain their energy by eating primary producers.Secondary consumers such as frogs and crabs are inthe third trophic level and obtain their energy by eatingprimary consumers. In the fourth trophic level aretertiary consumers such as hawks and sea otters thatfeed on secondary consumers to obtain energy.
When ecologists discuss the diet or behaviour oforganisms in a food chain, they often use the termsdetrivores, herbivores, and carnivores. In terrestrialecosystems, detrivores include small insects,earthworms, bacteria, and fungi (Figure 2.7). Figure 2.7 Detrivores in this forest ecosystem include
carpenter ants, pill bugs, snails, and mites. Unseen aredecomposer bacteria that vastly outnumber these detrivores.
BCS10_C02_5th 3/11/08 1:07 PM Page 60
Name: ____________________________________ Block: ____________ Date: ____________________________
Science 10: Energy Flow
Trophic Level Example Name of Type of Organism Energy Source
4th Top carnivores: hawks, sea otter _________________ Consumers (TC) Obtain energy from ___________
3rd Carnivores: frogs, crabs _________________ Consumers (SC) Obtain energy from ___________
2nd Herbivores: grasshopper, krill _________________ Consumers (PC) Obtain energy from ___________
1st Plants: grass, algae __________________ Producer (PP) Obtain energy from ___________
At the end of the chain (the tertiary consumer), where does the energy go…? digest detritus (dead animals and plants and waste) (e.g. earthworm & fungus) Decomposers: break down and , changing them into usable nutrients. This is called . What are examples of decomposers? What happened to this leaf? Where did the rest of the leaf go?
B. Practice Questions: Textbook (2.2) p.29 #2-4, 7, 11 C. Practice Questions: Textbook (2.4) p.37 #1, 2, 4, 5, 7-9, 12
Chapter 2 Energy flow and nutrient cycles support life in ecosystems. • MHR 61
Figure 2.9 Bighorn sheep (A) and western tiger swallowtail butterflies (B) are herbivores.
A B
Detrivores are consumers that obtain their energy and nutrients byeating the bodies of small dead animals, dead plant matter, and animalwastes. Detrivores feed at every trophic level (Figure 2.8) and make uptheir own important food chains. In fact, food chains based on deadplant and animal matter actually outnumber food chains based on livingplants and animals. Detrivores such as earthworms and beetles are also animportant energy source for consumers such as birds.
Herbivores, such as grasshoppers, are primary consumers that eatplants. Carnivores, such as spotted frogs, are secondary consumers thateat primary consumers. Carnivores also eat other secondary consumersand are often at the tertiary level of a food chain. Carnivores at this levelare often referred to as top carnivores, top consumers, or top predators.Figure 2.9 and Figure 2.10 on the next page show more examples ofherbivores and carnivores.
first trophic level
primary producers(plants)
secondtrophic level
primary consumers(herbivores)
third trophic level
secondary consumers(carnivores)
fourthtrophic level
tertiary consumers (top carnivores)
Figure 2.8 Detrivores feedat every trophic level.
detrivores and decomposers
energy fromthe Sun
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Name: ____________________________________ Block: ____________ Date: ____________________________
Science 10: Energy Flow
Science 10: Biology! Ecological Pyramids (Ch 2.5)
There are three types of ecological pyramids (or food pyramids). 1. Pyramid of Energy: a model that shows the of energy from one trophic level to the next. *This is the most commonly used ecological pyramid. Since % of the energy is lost between each trophic level, ecosystems support -‐many
-‐less
-‐far less
-‐very few
2. Pyramid of Numbers: a model that shows the total number of organisms in each trophic level.
3. Pyramid of Biomass Biomass: the total mass of and organisms (plants, animals, fungi and microorganisms) in a certain area. *The biomass of plants on Earth is >100 x greater than the biomass of animals.
D. Practice Questions: Textbook (2.5) p.41 #1-7, 9, 13
Name: ____________________________________ Block: ____________ Date: ____________________________
Science 10: Energy Flow