Unit 1 Apes review

Miller&Spoolman  text page: 5.1, p103-108

Learning Objective:  Explain how the availability of resources influences species interactions.

Essential Knowledge

1. In a predator-prey relationship, the predator is an organism that eats another organism (the prey).

2. Symbiosis is a close and long-term interaction between two species in an ecosystem. Types of symbiosis include mutualism, commensalism, and parasitism.

3. Competition can occur within or between species in an ecosystem where there are limited resources. Resource partitioning— using the resources in different ways, places, or at different times—can reduce the negative impact of competition on survival.

Ecosystem Basics

• Individual  -one single organism/living thing (ex: one elk)

• Population – group of organisms that are the same species (ex: elk herd)

• Community – all the living organisms in a given area (ex: trees, grass, elk, beaver, bacteria, and fungi)

• Ecosystem – all the living AND non-living organisms in a given area (ex: trees, grass, elk, beaver, bacteria, fungi, rocks, soil, and water)

• Biome – large area with similar climate and determines plants/animals that live there (ex: Tropical rainforest – warm temp and lots of rainfall)

Biotic vs Abiotic -  Googled this bc video did not cover it – Biotic factors are living things within an ecosystem; such as plants, animals, and bacteria, while abiotic are non-living components; such as water, soil and atmosphere

Interactions

• Competition ( -,- ) – organisms fighting over a resource like food/shelter, limits pop size

• Predation / Parasitism ( +, -) – one organism using another for energy source (hunters, parasites, even 

                                           Herbivores)

• Mutualism (+,+ ) – relationship that benefits both organisms (coral reef)

• Commensalism (+,0) – one specifies benefits and other doesn’t impact (birds in a tree)

Predation 

• Herbivores –(plant eaters) eat plants for energy (giraffe/trees)

• True Predators - (carnivores) kill/eat prey for energy =) 

           leopards/giraffe)

• Parasites -uses a host organism for energy, often without killing 

          them (mosquitoes, tapeworms, sea lamprey)

• Parasitoids – lays eggs inside a host organism, eggs hatch and 

          larvae eat host for energy (parasitic wasps/caterpillars, bot fly)

Symbiosis

Define Symbiosis 

– Sym – together; bio- living; osis – condition. 

ANY close and long-term interaction between two organisms of different species

Define Mutualism – Organisms of diff species living together in a way that benefits both

Coral    Coral provide (animals) provide reef structure and CO2 from photosynthesis for algae

             Algae provide sugars for coral to use as energy from photosynthesis

Composite Organisms 

Lichen – algae and fungi living together

 Algae provide sugars (energy) from photosynthesis 

 Fungi provide nutrients

Legumes – Googled this bc video did not cover it - Plants with root nodules containing nitrogen-fixing bacteria; includes clover, alfalfa, peas, and soybeans

Competition

What does competition do to population size and why? Reduces pop size since there are fewer resources available and fewer organisms can survive

Resource Partitioning/sharing: Different species using the same resource in diff ways to reduce competition (usually be of adaptation and evolution)

• Temporal partitioning – species competing for same resources get it at different TIMES (ex: wolf/coyote night vs day)

• Spatial Partitioning (using diff areas of a shared resource (ex: diff length roots getting water/nutrients at diff depths bc of root lengths; ex2: warbler birds use same tree but make nest at diff areas of the tree)

• Morphological partitioning – using diff resources based on diff. evolved body features (ex: ferret and ermine with slightly diff jaw sizes and tooth so slightly diff size of preys required)

Miller&Spoolman text page: 4.1, p81; 7.1 p145-148; 7.2 p148-158; 7.3 p162

Learning Objective: Describe the global distribution and principal environmental aspects of terrestrial biomes.

Essential Knowledge

1. A biome contains characteristic communities of plants & animals that result from, & are adapted to climate.

2. Major terrestrial biomes include taiga, temperate rainforests, temperate seasonal forests, tropical rainforests, shrubland, temperate grassland, savanna, desert, and tundra.

3. The global distribution of nonmineral terrestrial natural resources, such as water and trees for lumber, varies because of some combination of climate, geography, latitude and altitude, nutrient availability, and soil.

4. The worldwide distribution of biomes is dynamic; the distribution has changed in the past and may again shift as a result of global climate changes.

Biome Characteristics

Biome – An area that shares a combination of avg. yearly temp/precipitation (climate)

Climate  - yearly/annual temp/precipitation

Organisms in a Biome  - uniquely adapted to live in that biome (ex: camels have humps store energy for fat when unable to find energy for long periods of time and cacti have thick long cuticles/coat that prevent water loss through evaporation for hard dry conditions of desert. Shrubs and grass with long roots so they can quickly bounce back from wildfires.

Latitude  -  distance from equator determines  temp/precipitation so biomes have predictable patterns

Tundra & Boreal = higher lat; 60 degrees + (colder bc sunlight reflected most and low precipitation)

Temperate biomes = mid lat (30-60 degrees) (moderate sunlight, reasonably warm, cooler during seasons, moderate rain)

                               Tropical = closer to equator (warmer bc direct sunlight 

                                     hit and higher precipitation)

Climatogram

Biomes are defined by annual temp and precipitation avg.

NutrientAvailability

Plants need soil nutrients to grow, and this is diff for each biome and so soil nutrient availability determines the producers for the biome and the other trophic levels as well.

Examples:

Tundra-  low nutrients bc permafrost (doesn’t allow dead organic matter to be broken down by decomposers so low nutrients, low water availability, and so fewer plants survive here)

Tropical Rainforest – nutrient-poor soil bc high competition from so many diff species

Boreal forest – nutrient-poor soil (bc low temp and low decomposers rate of dead organism matter)

Temperate forest – nutrient rich soil (bc lots of dead organic matter from falling leaves and warm temp/moisture for decomposers

Shifting Biomes

Climate is not stable on earth and as climate continues to warm, this shifts biomes too! Example, boreal forests are beginning to shift up north because of climate change. The permafrost layer is thawing out bc of climate change and you see the nutrient-poor soil becoming nutrient-rich and supporting tree species it couldn’t have before and it becomes too warm for trees like spruce and aspen to continue to stay in that same latitude.

Miller&Spoolman text page: 8.1 p169-170; 8.2 -p171-175; 8.4 p178-181, 

Learning Objective: Describe the global distribution and principal environmental aspects of aquatic biomes.

Essential Knowledge

1. Freshwater biomes include streams, rivers, ponds, and lakes. These freshwater biomes are a vital resource for drinking water.

2. Marine biomes include oceans, coral reefs, marshland, and estuaries. Algae in marine biomes supply a large portion of the Earth’s oxygen, and also take in carbon dioxide from the atmosphere.

3. The global distribution of nonmineral marine natural resources, such as different types of fish, varies because of some combination of salinity, depth, turbidity, nutrient availability, and temperature.

Charact. of Aquatic B

Salinity -How much salt there is in a body of water, determines which species can survive and usability for drinking (fresh water vs estuary vs ocean)

Depth – Influences how much sunlight can penetrate and reach plants below the surface for photosynthesis

Flow – Movement of water and determines which plants and organisms can survive, how much O2 can dissolve into water (Ex: Rapidly moving water such as river and streams allows better mixing of water and air, leaving more dissolved O2 in the water)

Temperature – warmer holds less dissolved O2 so it can support fewer aquatic organisms.

Freshwater: Rivers & Lakes 

Rivers vs Lakes

Rivers have high O2 due to high flow (more mixing of air wand water- also carry nutrient-rich sediments (deltas/flood plains = fertile soil)

Lakes standing bodies of fresh water (source of drinking water)

Freshwater: Wetlands

Wetland - area with soil submerged/saturated in water for at least part of the year, but shallow enough for emergent plants 

Plants living here have to be adapted to living with roots submerged in standing water (cattails, lily pads, reeds)

Freshwater wetlands examples below: 

Swamp – Ex: cyprus tree - adapted to live w/ roots submerged in water

Marsh – Ex: Reeds and cattails - adapted to live w/ roots submerged in water

Bog – Extremely acidic soil. Ex: spruce and sphagnum moss 

Benefit$ of Wetland$

Storage - Stores excess water during storms, lessening floods

Recharge -Recharges groundwater by absorbing rainfall into so

Filter -Roots of wetland plants filter pollutants from water draining through

Habitat - Highly plant growth due to lots of water & nutrients (dead organic matter) in sediments

Estuaries

Define Estuary: Areas where rivers empty into the ocean and mix of fresh & salt water (species adapt to this ex: mangrove trees)

Highly productive because: Plant growth) due to nutrients in sediments deposited in estuaries by river 

Salt Marsh – Estuary hab, along coast in temperate climates & breeding ground for many fish & shellfish species

Mangroves - trees with long, stilt roots stabilize shoreline & provide habitat for many species of fish & shellfish

Coral Reef 

-Warm shallow waters beyond the shoreline; most diverse marine (ocean) biome on earth

-Mutualistic relationship between coral (animals) & algae (plants)

-Coral take CO2 out of ocean to create calcium carbonate exoskeleton (the reef) & also provides CO2 to the algae 

-Algae live in the reef & provide sugar (energy) to the coral through photosynthesis 

Both species rely on the other:

- Coral couldn't survive without energy from algae

Algae need the home of the reef & CO2 from the coral

Intertidal Zones

-Narrow band of coastline between high & low tide

-Organisms must be adapted to survive crashing waves & direct sunlight/heat during low tide

Ex: Barnacles, sea stars, crabs that can attach themselves to rocks

-Shells & tough outer skin can prevent drying out (desiccation) during low tides

- Different organisms are adapted to live in different zones

      Examples- Spiral wrack (type of seaweed) curls up & secretes mucus to retain water during low tide

Open Ocean

Low Productivity per unit of area because just too deep for most plants to survive so algae and phytoplankton are usually only here

-LARGE biome and covers a lot of the earth so algae and phytoplankton that live here made it a carbon sink and a lot of CO2 taken out of the atmosphere and produces a lot of O2.

Photic zone – area where sunlight can reach (photosynthesis)

Aphotic zone – aka abyssal zone and area too deep for sunlight. Many have adaptation such as bioluminescence and sustain high 

                                                               pressures due to all the water above

Miller&Spoolman text pages: 3.4 p65-66

Learning Objective: Explain the steps and reservoir interactions in the carbon cycle.

Essential Knowledge

1. The carbon cycle is the movement of atoms and molecules containing carbon between sources and sinks.

2. Some of the reservoirs in which carbon compounds occur in the carbon cycle hold those compounds for long periods of time, while some hold them for relatively short periods of time.

3. Carbon cycles between photosynthesis and cellular respiration in living things.

4. Plant and animal decomposition have led to the storage of carbon over millions of years. The burning of fossil fuels quickly moves that stored carbon into atmospheric carbon, in the form of carbon dioxide.

C Cycle Overview

Molecules that contain carbon – CO2, glucose, CH,

Some steps quick (FF combustion) and some very slow (sedimentation and burial)

Carbon Sink / Reservoir –

• Atmosphere is key C reservoir, increasing levels of C in atmosphere which leads to global warming

• Carbon sink: a carbon reservoir that stores more carbon than it releases

Carbon Sources – processes that add C to atmosphere, such as Fossil fuel (oil, cool, nat gas) combustion, Animal agriculture (cow burps/farts bc of the CH4, methane release), and Deforestation releases CO2 from trees

Carbon Balance

Photosynthesis:

-plants, algae, phytoplankton 

-Removes CO2 from atmosphere and converts it to glucose 

-Glucose is the biological form of C and stores (chemical) energy in form of sugar

- CO2 sink

Respiration

-Done by plants and animals to release stored energy

-Uses O2 to break glucose down and release energy

-Releases CO2 into atmosphere

- CO2 source (adds CO2 to atmosphere)

When balanced: Both processes are very quick and when Carbon between biosphere and atmosphere is balanced then there is: NO NET C INCREASE IN ATM.

Ocean & Atmosphere

Direct Exchange  - CO, moves directly between atmosphere & the ocean by dissolving into & out of ocean water at the surface

• Speed: Happens very quickly & in equal directions, balancing levels of CO, between atmosphere & ocean

• ↑atm CO2 = ↑ oceanic CO2 = ocean acidification (C in ocean turns to carbonic acid, which decreases pH in ocean)

Ocean Sinks

• algae and phytoplankton - Take CO, out of the ocean & atm through photosynthesis

• coral and shells - Coral reef & marine org with shells also toke CO, out of the ocean to make calcium carbonate exoskeleton 

• sedimentation - when marine org die, their bodies sink to ocean floor where they’re broken down into sediments that contain C

• burial - over, long. periods of time, pressure of water compresses C-containing sediments on ocean floor into sedimentary stone (limestone, sandstone] - long-term C reservoir

Fossil Fuels

• Burial - slow, geological process that stores C in underground sinks like sedimentary rock or fossil fuels (sediments compressed by pressure from overlying rock layers or water)

• Fossil Fuels (FF) - coal, oil, and Nat. gas are formed from fossilized remains of org Malter Ex: dead ferns (coal] or marine algae & plankton (oil)

• Extraction and Combustion - digging up or mining FFs & burning them for energy (releases CO2 into atmosphere)

Miller&Spoolman  text pages: 3.4 p66-68

Learning Objective: Explain the steps and reservoir interactions in the nitrogen cycle.

Essential Knowledge

1. The nitrogen cycle is the movement of atoms and molecules containing nitrogen between sources and sinks.

2. Most of the reservoirs in which nitrogen compounds occur in the nitrogen cycle hold those compounds for relatively short periods of time.

3. Nitrogen fixation is the process in which atmospheric nitrogen is converted into a form of nitrogen (primarily ammonia) that is available for uptake by plants and that can be synthesized into plant tissue.

4. The atmosphere is the major reservoir of nitrogen. 

N Cycle Overview

*Key difference from C cycle: N reservoirs hold N for relatively short period of time compared to C cycle

Ex: plants, soil, atmosphere

Sources - Release N into atmosphere

Sinks - Take N out of the atmosphere in increasing amounts

N₂ conundrum - Atmosphere is main N reservoir (78% atmosphere). N in atm. exists mostly as N2, gas, not useable by plants or animals 

N₂

NO₃^-

NO₂^-

NH₃

NH₄⁺

N₂O

Nitrogen Fixation

Nitrogen Fixation – from N2 into  NH3 or NO3- y bacteria primarily but also by lightning

Natural Nitrogen Fixation

1. Lightning fixation

2. Nitrogen Fixing Bacteria 🡪

       A. Soil – bacteria in soil symbiotic relationship with plant root nodules convert N2 into ammonia (NH3)

       B. Legumes – rhizobacteria live in root nodules of legumes (peas, beans) and fix N for them in return for amino acids from the plant

Anthropogenic / Synthetic fixation 🡪 humans combust FF’s to convert N2 gas into Nitrate (NO3-) – nitrates are added to synthetic fertilizers like Miracle Grow and in agriculture

Other N Cycle Steps

• Assimilation  - N to NO or NH3  

  • Plants – roots take in NO3 or NH3  from soil and assimilate into plants

  • Animals – … animals eat other plants or animals and assimilate N

• Ammonification –Soil bacteria, microbes, decomposers converting to waste and dead biomass back to NH3 and returning it to soil 

• Nitrification – NH4  to No2- (nitrite)  and then NO3- (nitrate)  by soil bacteria

• Denitrification – Soil N as NO3- (nitrate) to Nitrous oxide (N2O) to N2 in atmosphere 

critical to every step*

Human Impacts on N Cycle

Climate – No2-  (nitrous oxide) = greenhouse gas which warm earth's climate 🡪 Produced by denitrification of nitrate in agricultural soils (especially when waterlogged/over watered)

Ammonia Volatilization: excess fertilizer use can lead to NH3 , gas entering atm.

problematic bc causes

- NH3  , gas in atm = acid precipitation (rain) causing environmental issues and respiratory irritation in humans and animals

-Less N stays in soul for crops to use for growth (lost profit)

Leaching and Eutrophication – synthetic fertilizer use leads to nitrates (NO3-) and leaching, or being carried out of soil by water

(more detail below)

Eutrophication 

Googled: Positive Feedback Loop and Eutrophication

Positive Feedback Loop - Eutrophication is an example of a positive feedback loop, where change in the system promotes further change in the same direction. Eutrophication the positive feedback process by which nutrient enrichment of aquatic systems ultimately results in the death of fish and macroinvertebrates due to suffocation. During this process, elevated nutrient levels in streams cause increased growth of aquatic plants.

Miller&Spoolman text pages: 3.4, p68-69

Learning Objective: Explain the steps and reservoir interactions in the phosphorus cycle.

Essential Knowledge

1. The phosphorus cycle is the movement of atoms/mlcls containing phosphorus between sources and sinks.

2. The major reservoirs of phosphorus in the phosphorus cycle are rock and sediments that contain phosphorus-bearing minerals.

3. There is no atmospheric component in the phosphorus cycle, and the limitations this imposes on the return of phosphorus from the ocean to land make phosphorus naturally scarce in aquatic and many terrestrial ecosystems. In undisturbed ecosystems, phosphorus is the limiting factor in biological systems.

Phosphorus Cycle Basics

      Sources 

Sinks/reservoirs - Rocks & sediments containing P minerals = major reservoir

The P Cycle is EXTRA slow. Why? - Takes a long time for P minerals to be weathered out of rocks & carried into soil/bodies of water. NO GAS PHASE of P (doesn't enter atmosphere)

Phosphorus Sources and Mini-Loops

Natural Source of P - weathering of rocks that contain P minerals.

• Wind & rain break down rock & phosphate (PO,) is released and dissolved into water; rainwater carries phosphate into nearby soils & bodies of water

• Weathering is so slow that P is often a limiting nutrient in aquatic & terrestrial ecosystems

Synthetic Source of P - mining phosphate minerals & adding to products like synthetic fertilizers & detergents/cleaners

Synthetic fertilizers containing phosphates are added to lawns or ag. Fields; runoff carries P into nearby bodies of water. Phosphates from detergents & cleaners enter bodies of water via wastewater from homes

Assimilation - Just like N, P is absorbed by plant roots & assimilate into tissues (food chain)

Excretion/Assimilation (loop like assimilation and ammonification in N cycle and photosynthesis/respiration in Carbon cycle

Rock & Roll

Phosphate does NOT dissolve very well in water so it: forms solid bits of phosphate that fall to the bottom as sediment (sedimentation)

Sedimentation - P sediments compressed into sed. rock over long time periods by pressure of above water

Geologic Uplift - tectonic plate collision forcing up rock layers that form mountains.

P cycle can start over again with weathering and release phosphate from rock

Eutrophication – too much N and P from runoff from N and P fertilizers and human/animal waste. N and P are limiting nutrients and extra of it leads to eutrophication (excess nutrients) which fuels algae growth. P is insoluble too. Algae bloom covers the surface of body of water, blocks sunlight and kills plants below. Algae also die off and the decomposers feeding on the algae use the O2 (decomp is aerobic process) so lower O2 levels also kills the fish. Bacteria decompose the dead fish … more aerobic respiration and depleted O2. Positive Feeback Loop created as seen in the notes above!

Miller&Spoolman text pages: 3.4 p62-65

Learning Objective: Explain the steps and reservoir interactions in the hydrologic cycle.

Essential Knowledge

1. The hydrologic cycle, which is powered by the sun, is the movement of water in its various solid, liquid, and gaseous phases between sources and sinks.

2. The oceans are the primary reservoir of water at the Earth’s surface, with ice caps and groundwater acting as much smaller reservoirs.

Water Cycle Overview

Driven by: Energy from the sun

Largest Reservoir: Ocean

Most important reservoirs:

Ice caps and groundwater are smaller reservoirs but useable for humans (Glaciers are the BIGGEST freshwater source)

Transp &Evapo-T

(driven by sun’s energy) Transpiration – process that plants use to draw groundwater from roots to their leaves … and the stomata opening (leaf openings) and allowing evaporation into atmosphere from leaf)

(driven by sun’s energy) Evapotranspiration – amount of H2) that enters atmosphere from transpiration and evaporation combined

Runoff & Infiltration

Precipitation leads to

                            Infiltration                  OR              Runoff

Infiltration: Water trickles through soil down into groundwater aquifers (if ground permeable)

Runoff:  recharges surface waters, but can carry pollutants into water sources (not permeable ground)

Loopy

Key things to know about BIOGEOCHEMICAL cycles – C-N-P-H₂O

Carbon – long/short time scales for sinks/sources

Nitrogen – Diff processes to drive from sinks/sources, In atmopshere but N be “fixed” before assimilation

Phosphorus – No atmospheric component and mainly in rocks

Water – Driven by sun’s energy and recharges our groundwater(infiltration) and surface waters (run off)

Miller&Spoolman text pages: 3.3 p61

Learning Objective: Explain how solar energy is acquired and transferred by living organisms.

Essential Knowledge

1. Primary productivity is the rate at which solar energy (sunlight) is converted into organic compounds via photosynthesis over a unit of time.

2. Gross primary productivity is the total rate of photosynthesis in a given area.

3. Net primary productivity is the rate of energy storage by photosynthesizers in a given area, after subtracting the energy lost to respiration.

4. Productivity is measured in units of energy per unit area per unit time (e.g., kcal/m²/yr).

5. Most red light is absorbed in the upper 1m of water, and blue light only penetrates deeper than 100m in the clearest water. This affects photosynthesis in aquatic ecosystems, whose photosynthesizers have adapted mechanisms to address the lack of visible light. 

PP Basics

Primary Productivity: Rate that solar energy is converted into organic compounds via photosynthesis over a unit of time

You can also think of PP as:  Rate of photosynthesis of all producers in an area over a given period of time

-Since photosynthesis leads to growth, you can also think of PP as the amount of plant growth in an area over a given period of time

HIGH PP = HIGH plant growth = LOTS of food and shelter for animals = HIGH biodiversity

Calculating PP

NPP

Net Primary Productivity 

Amount of energy (biomass) left over for consumers after plants have used some for respiration

GPP

Gross Primary Productivity

Total amount of sun energy (light) that plants capture and convert to energy (glucose) through photosynthesis

RL

Respiration Loss

Plants use up some of the energy they generate via photosynthesis by doing cellular resp

Ecological Efficiency

Ecological Efficiency is The portion of incoming solar energy that is captured by plants & converted into biomass (NPP or food available for consumers)

1% of incoming solar energy is captured and converted into GPP via photosynthesis

Of that 1% only 0.4% is converted into biomass/plant growth (NPP). 

Some ecosystems are more efficient (higher NPP) than others

Trends in Productivity

In general, higher PP/NPP leads to higher biodiversity

3 important factors that contribute to PP – water availability, higher temp, and nutrient availability

Biomes with high PP/NPP

-Swamps/marshes (terrestrial ecosystem), Coral reefs (marine ecosystem), tropical rainforest (terrestrial ecosystem), and Salt marshes (marine ecosystem)

Biomes with low PP/NPP

Tundra, Desert, and Open ocean

Miller&Spoolman  text pages: 3.3 p59-61; 3.4 p62-69

Learning Objectives: Explain how energy flows and matter cycles through trophic levels. 

Determine how the energy decreases as it flows through ecosystems.

Essential Knowledge

1. All ecosystems depend on a continuous inflow of high-quality energy in order to maintain their structure and function of transferring matter between the environment and organisms via biogeochemical cycles.

2. Biogeochemical cycles are essential for life and each cycle demonstrates the conservation of matter.

3. In terrestrial and near-surface marine communities, energy flows from the sun to producers in the lowest trophic levels and then upward to higher trophic levels.

4. The 10% rule approximates that in the transfer of energy from one trophic level to the next, only about 10% of the energy is passed on.

5. The loss of energy that occurs when energy moves from lower to higher trophic levels can be explained through the laws of thermodynamics.

Conservation of Energy

Law of Conservation of Mass        vs     First Law of Thermodynamics

Matter and energy are never created nor destroyed: they only change forms

Ex: Trees die and biogeochemical elements returned to soil/atmosphere

Ex: Sun rays/light energy hit leaves and converted to glucose (chemical energy)

1st Law of Thermodynamics – energy is never created or destroyed – can see this in Biogeochemical cycles (conservation of matter) AND food webs (conservation of energy)

2nd Law of  ThermoD

2^nd Law of Thermodynamics     

Each time energy transferred, 

some given off as heat

10% Rule – In trophic pyramids, only 10% to next level, other 90% lost as heat

Trophic Levels & 10% Biomass 

Tertiary consumers – animals that eat secondary consumers or carnivores and omnivores (aka top/apex predators)

Secondary Consumers: animals that eat primary consumers or herbivores (aka carnivores and omnivores)

Primary Consumers: animals that eat plants (herbivores)

Producers (plants) “produce” – really converts sun’s light energy into chemical energy (glucose)

10% rule applies to biomass (or mass of all living things at each trophic level) – Hence why we have more producers in an ecosystem

Calculations

1 kg

95.00 J

8 kg

100 J

10 kg

950.00 J

80kg

1,000 J

100 kg

9,500.00 J

800 kg

10,000 J

1000kg

95,000.00J

8000 kg

100,000J

Miller&Spoolman text pages: 2.1 p44-47; 3.2 p54-58; 3.3 p59; 9.1 p191

Learning Objective: Describe food chains and food webs, and their constituent members by trophic level.

Essential Knowledge

1. A food web is a model of an interlocking pattern of food chains that depicts the flow of energy and nutrients in two or more food chains.

2. Positive and negative feedback loops can each play a role in food webs. When one species is removed from or added to a specific food web, the rest of the food web can be affected.

Food Web Basics

-Shows matter and energy flow through ecosystem from organism to organism.

-When one organism preys on (eats) another, the matter (C/N/H2O/P) and energy (glucose, muscle tissue, etc.) are passed on to the predator

-Arrows in food webs indicate direction of energy flow (point to the org. taking in the energy)

Food Web vs. Chain

Food chains just show one linear path of energy and matter

Food webs have at least 2 different, interconnected food chains. Webs show that organisms can exist at different trophic levels. 

Organisms can occupy different trophic levels within the food levels.

grass 🡪  hare 🡪  owl (sec. cons.)

grass 🡪 grasshopper 🡪 robin 🡪 owl (tert. cons.)

Trophic Cascade

When describing effects, need to include increase or decrease in pop size of a given species impact the rest of the food web. 

Trophic Cascade – removal or addition of a top predator has a ripple effect down through lover trophic levels.