APES Semester One Study Guide
UNIT ONE
Ecosystem Basics
Individual - one organism
Population - group of individuals of same species
Community - all living organisms in an area
Ecosystem - all living and nonliving things in an area
Biome - large area with similar climate conditions that determine plant and animal species
(distributed based on latitude)
Organism Interactions
Symbiosis: any close and long-term interaction between two organisms of different species
Competition - organisms fighting over a resource, limits population size
Predation - one organism using another for energy source
- Herbivores eating plants
- Carnivores killing prey
- Parasitism
Mutualism - relationship that benefits both organisms
Commensalism - relationship that benefits one organism and doesn’t impact other
Trophic Cascades
Removal or addition of a predator has a ripple effect down through lower trophic levels
Primary Productivity
● Rate that solar energy is converted into organic compounds via photosynthesis over a unit
of time
● High PP=high plant growth, lots of food and shelter for animals
● Ecosystems with high PP are usually more biodiverse
Net Primary Productivity
Amount of energy leftover for consumers after plants have used some for respiration
Respiration Loss - plants use energy by doing plant things
10% Rule/ 2nd Law of Thermodynamics
- Each time energy is transferred, some is lost as heat
- Only about 10% of energy makes it up to the next trophic level
Cycles
Carbon Cycle Nitrogen Cycle Phosphorus Cycle
, - Some steps are slow - Reservoirs hold - Stored in rocks,
(sedimentation/burial) Nitrogen for a short released by
and some are quick period of time weathering
- Limiting nutrient
(fossil fuel burning) - Atmosphere is main
- Added to fertilizers,
- Atmosphere is key reservoir detergents, contributes
reservoir - Critical plant and to runoff
- Carbon sink stores animal nutrient -
carbon - ocean, DNA, amino acids for
sediments, plants, soil proteins
- Carbon sources - Nitrogen Fixation:
produces carbon - process of being
fossil fuels, converted into
deforestation biologically available
NH3 or NO3
- Bacteria Fixation -
certain bacteria in soil
or in plant root
nodules convert into
ammonia
- Synthetic FIxation -
humans combust
fossil fuels to convert
into nitrates
-
Eutrophication
Because they’re limiting nutrients, excess N and P leads to eutrophication, and fuels algae
growth. This blocks sunlight and kills plants. When algae eventually dies, bacteria that breaks
down the dead plant mass uses up all the oxygen in the water, which kills aquatic animals.
Bacteria then need more oxygen to decompose the animals, creating a positive feedback loop.
Aquatic Biomes
Salinity - salt determines which species can survive and usability for drinking
Depth - influences how much sunlight can penetrate and be used for photosynthesis
Flow - determines which organisms survive and how much O2 can dissolve
Temperature - warmer water holds less O2, and supports fewer organisms
UNIT ONE
Ecosystem Basics
Individual - one organism
Population - group of individuals of same species
Community - all living organisms in an area
Ecosystem - all living and nonliving things in an area
Biome - large area with similar climate conditions that determine plant and animal species
(distributed based on latitude)
Organism Interactions
Symbiosis: any close and long-term interaction between two organisms of different species
Competition - organisms fighting over a resource, limits population size
Predation - one organism using another for energy source
- Herbivores eating plants
- Carnivores killing prey
- Parasitism
Mutualism - relationship that benefits both organisms
Commensalism - relationship that benefits one organism and doesn’t impact other
Trophic Cascades
Removal or addition of a predator has a ripple effect down through lower trophic levels
Primary Productivity
● Rate that solar energy is converted into organic compounds via photosynthesis over a unit
of time
● High PP=high plant growth, lots of food and shelter for animals
● Ecosystems with high PP are usually more biodiverse
Net Primary Productivity
Amount of energy leftover for consumers after plants have used some for respiration
Respiration Loss - plants use energy by doing plant things
10% Rule/ 2nd Law of Thermodynamics
- Each time energy is transferred, some is lost as heat
- Only about 10% of energy makes it up to the next trophic level
Cycles
Carbon Cycle Nitrogen Cycle Phosphorus Cycle
, - Some steps are slow - Reservoirs hold - Stored in rocks,
(sedimentation/burial) Nitrogen for a short released by
and some are quick period of time weathering
- Limiting nutrient
(fossil fuel burning) - Atmosphere is main
- Added to fertilizers,
- Atmosphere is key reservoir detergents, contributes
reservoir - Critical plant and to runoff
- Carbon sink stores animal nutrient -
carbon - ocean, DNA, amino acids for
sediments, plants, soil proteins
- Carbon sources - Nitrogen Fixation:
produces carbon - process of being
fossil fuels, converted into
deforestation biologically available
NH3 or NO3
- Bacteria Fixation -
certain bacteria in soil
or in plant root
nodules convert into
ammonia
- Synthetic FIxation -
humans combust
fossil fuels to convert
into nitrates
-
Eutrophication
Because they’re limiting nutrients, excess N and P leads to eutrophication, and fuels algae
growth. This blocks sunlight and kills plants. When algae eventually dies, bacteria that breaks
down the dead plant mass uses up all the oxygen in the water, which kills aquatic animals.
Bacteria then need more oxygen to decompose the animals, creating a positive feedback loop.
Aquatic Biomes
Salinity - salt determines which species can survive and usability for drinking
Depth - influences how much sunlight can penetrate and be used for photosynthesis
Flow - determines which organisms survive and how much O2 can dissolve
Temperature - warmer water holds less O2, and supports fewer organisms
