Chapter 2: Interactions in Ecosystems pg. 32
2.1 Types of Interactions p. 34Symbiosis:
- is a biological relationship in which two species live closely together over time.
- Helps each species survive by providing food, shelter and protection.
- 3 types of relationships exist:a. Parasitism
b. Mutualism
c. Commensalism
a. Parasitism
• One partner is called the “host” and the other a “parasite”.
• Host is usually bigger and is harmed
• Host does not usually die but their lifespan may be shortened.
• Parasite obtains food and shelter from host and benefits.
• Parasites can be internal or external.
Internal Parasites
• Live inside bodies of hosts
• May stay a long time.• Ex. Tapeworms,
roundworms
External Parasites
• Live on the surface of hosts
• May stay a short time to feed and reproduce
b. Mutualism
• Both partners benefit
• Ex. Lichens, bees and flowers, termites
lichens
• Grow on solid surfaces like rocks and trees
• Consist of an algae and a fungus living together
Lichens
• Algae makes sugar just like plants which is food for both
• Fungus anchors both organisms to a surface and absorbs water needed by both
Insects and flowers
• Insects carry pollen away and help reproduction
• Flower provides food (nectar) to the insects
mutualism
• Bacteria living inside humans
• Birds living on zebras and rhinos
• Algae living on backs of spider crabs
• Microorganisms living in the gut of termites
• Sea anemones and hermit crabs
c. Commensalism
• One partner benefits and the other does not gain or lose anything.
Ex. Barnacles on the back of a whale
Ex. Birds follow army ants
Birds riding on water buffalo
Food and Populations pg. 37
• Symbiosis helps an organism survive because it provides: ______________
• Predators – are organisms that hunt and kill their food– Are carnivores or meat eaters– Ex. ______________________________
Cont’d…
• Prey
- are organisms that are hunted and killed for prey.
- ex._____________________________
Predator-Prey Relationships
• often show changes in the size of each population that repeats in a cycle.
• size of predator population is affected by the number of prey that are available
• size of predator population is affected by the number of prey hunting them
Lynx- Hare Populations
2.2 Roles of Organisms in Ecosystems (Niche) Producer
• Organisms that make their own food through a process called photosynthesis.
• Ex. Plants, algae, some bacteria
Consumer• Organisms that get
their food by eating other organisms
a. Herbivores
b. Carnivores
c. Omnivores
d. Scavengers
e. Decomposers
Photosynthesis – Producers/Autotrophs
Bacteria – algae that live ina pond
Plants – over 300 000 species on Earth
Diatoms – plankton live in the ocean
Types of Consumers
a. Herbivores
- eat only plants
ex.
b. carnivores
• Hunt and eat other animals
• Ex.
c. omnivores
• Eat both plants and animals
d. scavengers
• Eat remains of dead plants and animals
• Ex. Seagulls, crows, blackbears, raven, hawk, eagle
e. decomposers
• Do not ingest food
• Release digestive juices to the environment which break down remains of dead organisms and waste
• Absorb the digested from back in
• Ex. Bacteria, fungus, insects
Decomposers and Food pg. 43• Food can be protected from decomposers
by:1. Keeping microorganisms out of it. (bacteria,
fungus, )
a. Vacuum packed products
b. Caning
c. Sealed plastic bags and containers
d. Freezing
e. Freeze Drying
f. Salting and pickling
Micro-organisms
• Need a source of food
• Need water
• Have a range of tolerance for temperature and ph
a. Vacuum Packed Products
b. Canning
c. Containers and bags
d. Freezing food
e. Freeze Drying
f. Salting food
Pickling food
2. Killing or slowing growth of microorganisms already on it.
a. Washing hands, utensils and countertops before handling food
b. Washing food
c. Cooking food well
d. Radiation
Microbes Make Food –Fermentation (to bubble)
• Is a process carried out by microorganisms where they break down sugar and produce different kinds of waste products:1. Lactic acid – stops growth of harmful
bacteria, used to make dill pickles, sauerkraut,
pickled cabbage, some sausages, cheese
2. Alcohol – used to make beer, wine
Cont’d
3. Carbon dioxide – used to make bread rise
Fermentation in beer
Fermentation in cheese
Fermentation in bread.
Food Webs
Energy Pyramid
2.4: Cycles of Matter in EcosystemsNutrients:
- Are substances contained in food that are needed in small amounts by all living organisms
- Are taken in from the environment by producers
- Are transferred to consumers through a food chain/web
- Are reused when living organisms die and are broken down by decomposers.
Cont’d…
Ex. Minerals come from the soil
Ex. Water
Ex. Carbon comes from carbohydrates and carbon dioxide,
Ex. nitrogen comes from protein
Nutrient Cycles
• Are processes that move nutrients back and forth between the biotic and abiotic parts of the ecosystem.
• Ex. Carbon – Oxygen Cycle
• Ex. Nitrogen Cycle
• Ex. Phosphorous Cycle