SNC1D Ecology
After looking and making comments about the 20 images in class, write a few sentences to summarize your thoughts.
Ecology is the study of the
Non-living (abiotic) components in the environment…
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Living organisms (biotic)…
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Biotic characteristics of an ecosystem are symbiosis, predation, and competition.
• Symbiosis is the
• Predation occurs when
The organism that is consumed is called the prey. The organism that is consuming is the predator.
• Competition occurs when

Sustainable Ecosystem
 An ecosystem that is capable of
Biotic parts of an Ecosystem
 Producers o Green plants are able to convert the sun’s energy into chemical energy for other organisms to use. o Green plants are called
 Consumers o Consumers are organisms that o There are several different kinds of consumers:
 Herbivores:
Example:
 Carnivores:
Example:
 Omnivores:
Example:
 Decomposers:
Example:
 Decomposers break down dead plants and animals. o They also break down the waste (poop) of other organisms.
 Scavengers:

Ex. crabs, earth worms, insects that eat decaying wood
 Saprotrophs :

Organisms and Energy
• Organisms are consumers of energy.
• Energy is what makes the activities of all organisms possible.
• The original source of energy, and the fuel for ecosystems,
• Radiant energy from the sun is captured through photosynthesis by green plants, algae and some bacteria. It is stored as chemical energy in carbohydrate molecules
Food Chain
• The energy passes through the ecosystem
• These interactions form
• In a food chain, energy flows from a producer to a primary
. consumer to a secondary consumer.
• A food chain always starts
Food Wed
 A single food chain illustrate only
 happens in an ecosystem.
Most organisms have
Each organism is involved in many food chains.
 Food chains
Trophic Levels
• Each level of a food chain is of what
.

• Because green plants convert radiant energy into chemical energy for ecosystems, they are called
• Animals that eat plants are called
• Animals that feed on the plant-eaters are called
• To maintain an ecosystem, there must be continual input of energy from the sun.
Pyramid of Energy
 As you go up a food chain, the amount of energy in
• Most food chains only have four or five levels
• There are usually more organisms at the lower level of a food chain, and less organisms at the top of the food chain.

The Earth’s Four Spheres
• Earth can be divided into four spheres:
• Lithosphere (litho is Greek for “stone”)
–
• Hydrosphere (hydro is Greek for “water”)
–
• Atmosphere (atmo is Greek for “air”)
–
• Biosphere (bio is Greek for “life”)
–
• The four spheres are always interacting. If something happens to one of the spheres, it can affect the other spheres.

Predators and Prey
• Predators are animals that
• Prey are animals that
• Predators need prey because:
– they use them for food
– predators need to work hard to get prey, so only
• Prey need predators because:
– predators keep
– predators help
Roles in an Ecosystem
• An organisms is
• A species is a
• Population is
• A community is
•
Habitat and Niche
Your habitat is the
• The niche of an organism is

Introduced Species and Native Species
• A native species is a
• An introduced species is a
• Introduced species can arrive naturally (animals move, seeds carried by wind) or by humans.
• Introduced species usually in an ecosystem.
• They
Natural Selection
for a niche with the native species.
• You have certain traits and they allow you to survive better than others in your population.
Evolution
• Evolution is a change in the genetic make up of a species over time.
Adaptation
• An adaptation is a change that gives you an edge on surviving.
– Webbed toes to swim faster
– A wooly coat to stay warmer
– Longer claws with which to fight better
– Larger eyes to see more

Limits on Population
• A population is a group of organisms of the same species (or type) living in the same place at the same time.
How population changes
• Many environmental factors affect population growth but only four processes can change the size of a population. o Births – o Deaths – o Immigration – o Emigration –
Limiting Factors
• Limiting factors are things that
• Resources such as
Carrying Capacity
• All ecosystems have a limited amount of resources such as food, water, and shelter.
• Each ecosystem has a carrying capacity, which is the

Abiotic
Factors that cause a population to Increase
• Favorable light
• Favorable temperature
• Favorable chemical environment
Factors that cause a population to decrease
• Too much or too little light
• Too cold or too hot
• Unfavorable chemical environment
Biotic • Sufficient food
• Low number or low effectiveness of predators
• Few or weak parasites
• Ability to compete for resources
• Insufficient food
• High number or highly effective predators
• Many strong effective parasites
• Inability to compete for resources
Factors that change population
Density-Independent Factors
(affect population because of population size)
• Flood
• Fire
• Spraying with pesticides
• Change in climate or temperature
• Destruction of habitat
• Drought
Density Dependent Factors
(affect members regardless of population size)
• Food shortage
• Competition for mates and breeding areas
• Disease caused by parasite
• Introduction of an exotic species
• Increased predation
• Competition for water and other resources is high

Competition
• Everyday animals compete for all the limiting factors –food, water, a place to live, etc.
• Each species has a negative effect on the other similar species in the ecosystem.
• There is even competition within the species. Each species harms its own members everyday through competition.
Indirect Competition
• We may cut a tree in the winter and the effects won’t be noticed until spring when birds that nested there last spring return. Now there are fewer places to nest.

Nutrient Cycles
• Producers get their nutrients from soil, water and air.
• Herbivores (plant eaters)
• Carnivores (meat eaters)
• Decomposers get their
• Organisms are made up of the following elements:
Carbon, Oxygen, Hydrogen and Nitrogen
• The nutrient elements are the elements that organisms use to support their body systems and activity. These elements are obtained from the soil, air or other organisms they consume.
• The nutrient cycles describe

Carbon
• Carbon is the basic element that makes up living things.
• It can be found in several places:
–
–
–
–
• Photosynthesis
– Plants use light energy, along with water and carbon dioxide to produce chemical energy (glucose) and oxygen.
– 6 CO
2
+ 6 H
2
C
O + light energy
6
H
12
O
6
+ O
2

• Once carbon is in the producers,
• Both plants and animals respire and respiration

 Cellular Respiration o This process returns carbon to the environment by releasing carbon from the sugar as carbon dioxide. It also releases water and a lot of energy. o C
6
H
12
O
6
+ O
2
 6 CO
2
+ 6 H
2
O + light energy
 Photosynthesis and cellular respiration are complementary processes that repeatedly cycle carbon. (they are opposites!)
 CO
2
is returned to the atmosphere from body wastes and dead decaying organisms. Decomposers break down animal and plant waste and this too returns the carbon dioxide to the soil and atmosphere.
Disrupting the Carbon Cycle
• If the carbon cycle is not balanced, there is too much carbon dioxide in the atmosphere.
• Carbon dioxide is a greenhouse gas – it traps heat near the
Earth, similar to the glass of a greenhouse.

The Nitrogen Cycle
 After Carbon, Hydrogen and Oxygen, Nitrogen the most abundant element in living things. It is essential for building proteins and the synthesis of DNA.
• 80% of the atmosphere contains nitrogen gas (N
2
) that cannot be directly absorbed by living things.
• Animlas obtain nitrogen .
• Nitrogen Fixation: Atmospheric nitrogen (N
2
) can be converted into nitrates (NO
3
) which is a useable form of nitrogen.
• Lightning: The energy from lightning causes nitrogen gas to react with oxygen, producing nitrates.
• Nitrogen-fixing bacteria can be found in the soil, water or in roots.
• Ex. N
2
+ H
2
 NH
4
+ or N
2
+ O
2
 NO
Human Activities and the Nitrogen Cycle
3
-
• Natural sources of nitrogen: bacteria, lightning
• Human sources of nitrogen: legume crops, artificial fertilizer
• Effects of nitrogen:
-Increase in nitrogen, better crops
-Saturation of nitrogen:
• Degredation of roots
• Slow growth
• Yellowing, falling leaves
• High soil acidity
• Acid rain
• Increase in algea blooms in aquatique plants
• Lowers biodiversity