Download Interactions in Ecosystems

NAME: _____________________________________ DATE: ____________ BLOCK: ___
WHAT IS ECOLOGY?
• Interactions and Independence
– Ecology – study of __________________________ among and between organisms and
their _______________________________
•
Levels of Organization (small to large)
– Species – group of organisms that can breed and produce fertile offspring
– Populations – groups of the ___________________ that live in the same area
– Communities – groups of _____________________________ (therefore different
species) that live in the same area
– Ecosystem – collection of all of the organisms that live in a particular place, together
with their _______________________________________
– Biome – a group of ecosystems that have the same climate and similar dominant
communities
• Examples:
– Biosphere – part of Earth in which life exists including land, water, and air.
Climate
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Places on the earth that have different climates typically have different living organisms.
Three major climate zones due to latitude and angle of heating (earth’s tilted axis):
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Pass It Along
• Energy flows in one direction through an ecosystem, from the sun or inorganic compounds
to producers (organisms that can make their own food) through various levels to consumers
(organisms that rely on other organisms for food). Your body gets the energy and materials
it needs for growth and repair from the foods you eat.
Energy Flow
• __________________________ is the main source of energy for life on Earth.
• Less than one percent of the sun’s energy that reaches the surface is used by living things
• Autotrophs (producers) – organisms that use either light energy or inorganic chemicals
_____________________________________________________________________
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– Photosynthesis – process in which organisms use __________ to make their own
__________________________
• Examples: plants, algae, some bacteria and some protists
– Chemosynthesis - process in which organisms use inorganic ___________________ to
__________________________
• Examples: bacteria which live in volcanoes, hot springs, and deep-sea vents
• Heterotrophs (consumers) – organisms that must eat and cannot make their own
food
– Herbivores – eat only plants
• Examples
– Carnivores – eat only animals
• Examples
– Omnivores – eat both plants and animals
• Examples
– Decomposers – break down organic material
• Examples
• Feeding Relationships
– Food Chain – series of steps in which organisms transfer energy by eating or being
eaten
– Food web – links all of the food chains in an ecosystem
– Trophic Level – each ____________________in a food chain or food web
• What eats what?
This is the order:
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–
• Arrows point the direction the energy or food flows (from food to “eater”).
• Ecological Pyramid – a diagram that shows the relative amounts of energy or matter
contained within each trophic level of a food chain or web
– Energy Pyramid - shows the ____________________________________ available at
each trophic level.
• Ten Percent Rule - only about 10% of energy available within one trophic level is
transferred to next level
• Why this inefficiency?
List 3 reasons.
– Biomass Pyramid – shows the total ______________________________ within each
trophic level
– Pyramid of Numbers – shows the relative number of organisms at each trophic level
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Terms to know…
• Biotic – biological (___________________) factors that affect an ecosystem
• Abiotic – nonliving (__________________) factors that affect an ecosystem
• Niche – full range of physical and biological conditions in which an organism lives and the
way the organisms uses those conditions
Interactions in Ecosystems
• Organisms not only live together in ecological communities, but they also constantly interact
with one another. These interactions, which include predation and competition, help shape
the ecosystem in which they live.
Community Interactions
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Competition—an interaction in which organisms of the same or different species attempt
to use a resource in the same place and at the same time.
Predation—an interaction in which one organism captures and feeds on
another animal
• Symbiosis – a relationship in which _________________________________
• Three types of symbiosis:
– mutualism =
•Examples:
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commensalism =
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parasitism =
•Examples:
•Examples:
CYCLES OF MATTER
• Unlike the one-way flow of energy, matter is recycled within and among ecosystems
• Biogeochemical cycles pass molecules around again and again
• The Cycles
– Water Cycle
– Carbon Cycle
– Nitrogen Cycle
– Phosphorus Cycle
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We will focus on the nitrogen cycle.
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The Nitrogen Cycle
– All living things need nitrogen as a nutrient.
– Nitrogen gas makes up 78% of our atmosphere and yet animals and plants cannot use
nitrogen gas as a nutrient. So what’s an animal or plant to do?
– How do animals get nitrogen? They eat protein!
– How do plants get nitrogen? From ________________ that are in the soil or in the roots
of some plants.
– Plants can only use nitrogen when it is in the form of ____________________________.
– Decomposers break down organic material (e.g. dead plants and animals) in the soil.
Nitrogen comes from _____________________________________________________.
– Some bacteria live in the __________________ and help to convert nitrogen into usable
forms for plants. Plants absorb this useable nitrogen from the soil into their roots.
– Nitrogen Fixation –
– Some bacteria actually live inside of the ____________________ of certain plants (like
_________________________) and can fix nitrogen in the roots.
– This is like the bacteria that live in our guts and help us to digest food.
– Legumes include peas, beans, peanuts, soybeans, alfalfa, and clover.
– So how is this a cycle? Denitrification – some bacteria can convert nitrites
back into nitrogen gas which is released into the atmosphere
– Why do farmers sometimes plant legumes and then plow them into the ground instead of
harvesting the crop?
• Nutrient Limiting
– Primary Productivity – the rate at which
– Primary productivity depends on the availability of nutrients (water, light etc.)
– What biomes in the world have the highest primary productivity?
– Limiting Nutrient – when a single nutrient ____________________________________
(limits the photosynthesis) of an entire ecosystem
– What happens if an area like a lake suddenly receives a lot of a limiting nutrient?
– When fertilizers enter lakes, streams, rivers, and oceans from runoff they can supply the
aquatic ecosystem with an abundance of a limiting nutrient.
– This excess supply of a limiting nutrient can produce an ________________. The algae
grow quickly because it suddenly has an excess of nutrients. The algal bloom can
smother and kill other forms of life.
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• Ecological Succession – a ___________________________________ in a community
over time in response to natural and human disturbances
– As changes occur, older inhabitants die out and new organisms move in.
– Primary Succession
• Occurs where there is _____________________
– After a volcanic eruption
– Bare rock exposed by glaciers moving
• Pioneer Species –
• Lichens (made up of a fungus and an alga) can grow on bare rock.
–Lichens release chemicals that dissolve and break down rock thus making soil.
• Once there is soil, other organisms come in like mosses and small plants and
animals soon follow. Why do animals come after plants?
– Secondary Succession
• Occurs when life is removed ____________________________________________
• Plowing, fire, deforestation, drought, etc. can all spark secondary succession
• Occurs faster than primary succession. Why?
– Aquatic Succession
• Succession can also occur in aquatic ecosystems
• For example, when a large whale dies, the carcass attracts scavengers and
decomposers (sharks, crabs, and hagfishes). Smaller fishes come later after most
of the tissue has been eaten. The decomposition of the whale makes the area
high in nutrients for marine worms and other sediment dwellers. Lastly, bacteria
decompose the bones, which attracts chemosynthetic bacteria, mussels, crabs,
and clams.
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