Unit 2 Biology Honors 9
Basics of Ecology
Ecology is the study of organisms on Earth and how they interact with the environment around them.
Energy flows through organisms (energy pyramid,) meanwhile matter cycles through the Earth (processes.)
Autotrophs
Living things that capture energy from non living sources (food) and convert it to energy are called autotrophs.
Because Autotrophs can store energy, when they are eaten by consumers that energy flows into the consumers.
When using energy from the sun, autotrophs use photosynthesis (Shown as CO2 + H2O + Sunlight → Carbs + O2.)
Without light in the bottom of the ocean, a process called chemosynthesis is used this turns CO2, O2, and chemical energy in the form of hydrogen sulfide into carbohydrates and sulfur compounds so energy is produced without the sun.
Consumers
There are three types of consumers: Herbivores eat only plants, Carnivores eat only meat and Omnivores eat both.
Scavengers, such as vultures, are animals that consume the carcasses (meat) of other animals that are already dead.
Detritivores, such as worms, feed on waste materials and break them down but not making it “disappear” forever.
Decomposers, such as bacteria, chemically break down organic matter, called detritus, and recycle them into soil.
Both Detritivores and Decomposers are Decomposers but only Bacterium/Fungi can chemically break down waste.
Consumers are also called heterotrophs because they don't have the abiltiy to make their own food like autotrophs.
Energy Flow in Ecosystems
A food chain is one series of organisms where energy is transfered from one organism to another organism.
A food web is a network of multiple food chains through which energy moves through one whole ecosystem.
A pyramid of energy shows all energy in an ecosystem, 90% of energy is lost is heat in each step of the pyramid.
All energy in the food chain is either directly or indirectly sourced from the sun (energy can't be created or destroyed.)
The pyramid of biomass shows that because there is less energy to support consumers at the top of the food chain, it would make sense that there is also a 90% reduction in biomass as we move up the pyramid. Always more producers.
The pyramid of numbers, like the pyramid of biomass, shows the relative number of organisms at each pyramid stage.
Cycles of Matter
Because there is a finite amound of matter on earth, things like water, carbon, and oxygen have to recycle.
Matter can be cycled through biological processes, geological processes, physical processes, and human activities.
Water Cycle
The water cycle begins with precipitation, where water falls from clouds to the ground here on Earth.
After precipitation, it can either go underground (percolation) or go into large bodies of water (runoff.)
Once stored, water evaporates with heat back into the clouds or goes through a process called transpiration.
Transpiration is when water from plants evaporates off of the leaves, where it is being stored inside trees.
Carbon Cycle
Plants absorb carbon dioxide (CO₂) from the atmosphere during photosynthesis, converting it into sugars.
Animals consume plants these plants, transferring carbon to their bodies and into the ground when they die.
Plants and animals release CO₂ back into the atmosphere through a process known as cellular respiration.
Over millions of years, some dead organisms carbon can become a thinh called fossil fuels (coal, oil, natural gas).
The frequent burning of fossil fuels by humans releases stored carbon as CO₂ back into our atmosphere.
Oceans absorb CO₂ from the atmosphere and store it in water or marine organisms or marine sedements.
Carbon is cycled through rocks through weathering, volcanic activity, and sedimentation and into the atmosphere.
Nitrogen Cycle
The conversion of atmospheric nitrogen into ammonia in soil through bacteria is called nitrogen fixation.
The conversion of ammonia into nitrites and thhen into other nitrates by bacteria is called nitrification.
The absorption if nitrates by plants from the soil, used to make protiens and compounds is assimilation.
Conversion of organic nitrogen from dead animals/plants into ammonia by fungi is called ammonification.
The conversion of nitrates back into atmospheric nitrogen by denitrifying bacteria is called denitrification.
Algae Blooms/Eutrophication
Eutrophication is a process that occurs in water when there are too many nutrients, commonly algae.
This can occur when artificial fertilizers made of nitrates and phosphate runs off into bodies of water.
The algae blooms cause a block in sunlight, killing the marine plants that require it underneath.
In the unstable environment fish can die without food or become unhealthy when algae dies and sinks.
Types of Populations
An R strategy species, like rabbits, have a young maturity age, more offspring, and low survivability.
An K strategy species, like elephants, have a late maturity age, less offspring, and high survivability.
Abiotic Factors are things that are non living and never have lived (for example, rocks, sunlight, etc.)
Biotic Factors are things that are living or were once alive (for example, fossils, animals, grass, etc.)
Global Systems
The Hydrosphere controls all water on earth (hydro) and works with other stystems for the water cycle.
The Atmosphere controls all weather on earth (atmo) and any and all gases within earth's atmosphere.
The Biosphere controls all biotic factors on earth (bio), such as animals, plants, bacteria, cells, etc.
The Geosphere controls any rocks and things associated with solid portions of the Earth like the crust.
Weather refers to wind, clouds, fog, precipitation, and temperature: it varies daily unlike climate.
Climate refers to the average weather in an area/biome, for example Brasil has a warm climate.
Levels of Organization
The levels or organization refer to a six level pyramid of populations on Earth from indiviudal to global.
Species is the lowest level of the pyramid, it refers to single individuals (for example: A labrador named Bob.)
Population is next on the pyramid, it refers to a group of individuals in an area (for example: Dogs in Rio)
Community is next on the pyramid, it refers to a Biotic factors in one place (for example: Living things in Rio)
An ecosystem is next, it refers to combined biotic and abiotic fatcors in an area (for example: Tijuca Park)
Biomes are second to last, they describe a large ecological area on Earth's surgace (for example: Tropical Forest)
Finally, the biosphere desrcribes regions of earth that support life and the living things in them (for example: Earth)
Population Ecology
Population is groups of organisms of the same species living in the same enviornment at the same time.
Population ecology is the study of how populations change overtime with the enviornment around them.
Population size is the number of individuals in the population of a certain species within a environment.
Population density is how many individuals are how many individuals are in only one particular area.
Population growth is how the size of the population can change overtime (exponential or logistical.)
Population Graphs
Exponential growth describes a constant growth when a quantity grows at a rate directly proportional to its size.
Logistical growth often describes a population, it is not constant and is blocked by things like the carrying capacity.
Exponential growth looks like a j curve while logistical growth is more of an s shape that varies from up to down.
Carrying capacity is the largest population size that a niche can grow while being able to be supported well.
Factors preventing a population size from growing can either be density dependant or density independant.
Density dependent factors affect larger populations such as disease, competition for resources, and predation.
Density independant factors affect all populations, regardless of size such as natural disasters and human actions.
Population Distribution
Unlike population density, population distribution describes how individuals occupy the space they live in.
Random distribution has no real pattern and their advantages and disadvantages vary through types.
Uniform distribution is evenly spaced and reduces competition and protects against most predators.
Clumped distribution is a clustered group that is good for warmth, mating, and fighting off predators.
Clumped has many disadvantages too: quick spread of disease, interspecies competition, etc.
Ecosystem Interactions
A habitat is an area where an organisms lives, it can vary from a single tree or up to a whole forest.
Microhabitats are habitats within habitats, such as bugs on tree bark or termites that live inside wood.
Microbiomes are tiny biomes within a habitat, such as bacteria in termite guts or fungi inside of soil.
Range of Tolerance
The range of tolerance descrives a range of conditons (temp, ph, O2 levesl) that an organism can survive in.
The Optimal Zone is where the species is most comfortable and thrive, most of the individuals live in this zone.
The Zone of Physiological Stress is where an organism can survive but not in ideal conditions: less individuals.
Outside the Zones of Tolerance, are the Zones of Intolerance are where species always die because needs aren't fit.
Species Interactions
A niche is an organism's role or position in an environment (food, shelter, etc.) and their interactions with each other.
Resource partitioning is when organisms break up their resources evenly between each other without any competition.
Competition explains how organisms with overlapping niches compete over resources such as food, water, and shelter.
Interspecific competition is competition that occurs between organisms of two different species (ex: a hyena and a lion.)
Intraspecific competition is competition that occurs between organisms of the same species (ex: two seals over shelter.)
The competitive exclusion principle states that if two organisms occupy the same niche, one will outcompete the other.
Predation is the act of one organism (the predator) pursuing and feeding on another organism (known as the prey.)
Herbivory is a similar process, where one organism eats only plants: both predation and herbivory have similar graphs.
Relationships
A keystone species, like a sea otter with kelp, is a species that is vital in stabilizing/diversifying an ecosystem.
A relationship where two or more organisms live together is a symbotic relationship also known as symbiosis.
Mutualism is when two or more organisms benefit from each other (for example, flowers and pollunating bees.)
Commensalism is when one organism benefits and the other is unharmed (for example, clown fish and anemones.)
Parasitism is when one organism benefits off another organism, which is being harmed (for example, dogs and ticks.)
Ecologic Succession
Is a change in an ecosystem when one community replaces another as a result of changing biotic or abiotic factors.
Primary succession is the establishment of a community on exposed rock that has been previously uninhabited.
Pioneer species, such as lichen (colony of fungi and algae), are usually the first species to colonize the exposed rock.
Lichen release enzymes that break down rock and when they die they provide rich organic matter that forms topsoil.
Small plants and shrubs then are introduced, then small trees, and eventually hardwood forests are established.
Secondary succession is after things like fires that still leave soil intact and only takes around a century to heal.
In succession it goes pioneer species, intermediate species, and the final ecosystem is known as a climax community.