grade 7 science unit 1 - bjhbrooker · unit 1. symbiosis interactions ... other microorganisms,...
TRANSCRIPT
Interactions Within
Ecosystems
Chapter 2
Grade 7 Science
Unit 1
Symbiosis
Interactions between the biotic parts of the environment.
There are 3 types:
1. Parasitism
2. Mutualism
3. Commensalism
1. Parasitism
One organism will benefit (the
parasite) and the other is harmed
(the host).
2. Mutualism
Both organism benefit.
Lichen = algae + fungus
3. Commensalism
One organism benefits while the
other neither gains or loses.
Salty Seeds
Core Lab Activity 1-2B p. 22
1. Producers
Plants can produce their own
food from the abiotic
environment. (photosynthesis)
Water + carbon dioxide + Sunlight
Food (sugar) + oxygen
Roles of Organisms in the
Ecosystem
1. Producers
2. Consumers
3. Decomposers
4. Scavengers
2. Consumers
Animals must consume, eat
other organisms. (the biotic
environment)
Can be classified as... herbivores,
carnivores, or omnivores.
Herbivore:
Animals that eat ONLY plants
(producers).
Omnivore:
Animals that eat both plants
AND animals.
Carnivore:
Animals that eat ONLY other
animals.
3. Decomposers
Organisms that break down dead and waste materials into their basic parts.
They release chemicals that break apart dead tissues and cells and absorb the nutrients for their own use.
Examples include bacteria and
other microorganisms, fungi and
worms.
4. Scavengers
Animals that eat decaying
animals and waste materials.
Examples include vultures, dung
beetle larvae, houseflies, crows
and some gulls.
Microorganisms...
are found in a variety of habitats (air, soil, water)
play important roles in relation to human food supplies
have been studied to enhance food preservation techniques
Conditions that affect
Microorganism Growth
1. Temperature
2. Moisture
3. Light
4. Acidity
5. Salinity
Food Preservation
Creates an environment which
destroys existing decomposers
and then prevents or slows down
their growth rate.
Methods of Food Preservation
1. Pickling
2. Salting
3. Drying
4. Smoking
(the above started out of necessity )
1. Refrigerating
2. Freeze-drying
3. Radiation
4. Canning
(These are more modern and
technology based.)
Food Chains
The transfer of energy from organism to organism. Arrows show the direction of energy flow.
Green plants are the food (energy) source for all consumers and decomposers.
Producers Primary
Consumers
Secondary
Consumers
A
Sample
Food
Chain
Food Webs
Interconnecting food chains.
A
Marine
Food
Web
Energy Pyramids
Describes the gradual loss of
energy in food chains
About 10% is lost as you move
from one level to the next and
10% of the new energy is lost as
you move up and so on.
Energy in grass: 10 000 J
Energy in mice: 1000 J
Energy in weasel: 100 J
Energy in hawk: 10 J
Note: Energy pyramids are
not exact. Energy is
transferred to other types
(eg. heat) as it moves from
one level to the next. ie.
Not all of the 10% is
transferred.
Nutrient Cycles
Nutrients, such as nitrogen and carbon, are recycled in the environment.
All organisms are eventually recycled and their nutrients are returned to the soil by the action of decomposers.