Examples 1
- Humans: We require oxygen to sustain aerobic respiration for energy production during activities like running or swimming.
- Birds: Flying birds need a continuous supply of oxygen to support their high metabolic rate during flight.
- Fish: Many fish species need oxygen dissolved in water to respire through their gills.
- Plants: During photosynthesis, plants produce oxygen as a byproduct, but they also need oxygen for cellular respiration.
Aerobic
- Grazing food chain: Energy flows from producers (plants) to primary consumers (herbivores) to secondary consumers (carnivores) in a grazing food chain.
- Detritus food chain: Energy flows from dead organic matter (detritus) to decomposers, which break it down into simpler compounds, supporting detritivores and decomposers.
- Marine food web: In ocean ecosystems, energy flows through interconnected food chains and webs, with plankton forming the base and larger predators at higher trophic levels.
- Terrestrial ecosystems: In terrestrial ecosystems, energy flows from plants to herbivores to carnivores, with energy transfer occurring at each trophic level through feeding relationships.
Energy Flow
- Forests: Trees, shrubs, and other vegetation in forests collectively represent biomass, serving as habitats for various organisms and contributing to carbon storage.
- Wetlands: Wetland areas contain significant biomass in the form of plants, such as reeds and cattails, as well as microbial communities in the sediment.
- Agricultural fields: Crops cultivated in agricultural fields, such as corn, wheat, and soybeans, constitute biomass that can be harvested for food, fuel, or other purposes.
- Ocean ecosystems: Phytoplankton and seaweed in marine ecosystems contribute to biomass, supporting the food web and providing resources for marine life.
Biomass
- Tropical rainforest: The Amazon Rainforest is an example of a complex ecosystem comprising diverse plant and animal species interacting with each other and their physical environment.
- Coral reef ecosystem: Coral reefs are highly diverse ecosystems found in shallow, warm waters, supporting a wide range of marine life and providing essential habitat and resources.
- Grassland ecosystem: Savannas and prairies are examples of grassland ecosystems characterized by grasses, herbivores, and predators adapted to open landscapes with seasonal variations.
- Desert ecosystem: Deserts are ecosystems with low precipitation and sparse vegetation, inhabited by specialized plants and animals adapted to arid conditions.
Ecosystem
- Humans: As heterotrophs, humans obtain energy by consuming organic matter in the form of plants, animals, and other food sources.
- Dogs: Dogs are heterotrophs that rely on a diet of meat, grains, and other organic materials for energy and nutrition.
- Fungi: Fungi are heterotrophic organisms that obtain nutrients by decomposing organic matter or by forming symbiotic relationships with plants.
- Parasites: Parasitic organisms like tapeworms and fleas are heterotrophs that rely on host organisms for energy and nutrients.
Heterotroph
- Anaerobic bacteria: Found in oxygen-deprived environments like deep sea vents, these bacteria can break down organic matter without oxygen.
- Fermentation: Yeast in bread dough produces carbon dioxide and alcohol through anaerobic respiration when oxygen is lacking.
- Muscle cells: During intense exercise, muscle cells can switch to anaerobic respiration to produce energy without sufficient oxygen, leading to the buildup of lactic acid.
- Wetlands: In the oxygen-poor sediments of wetlands, anaerobic bacteria break down organic matter, releasing methane gas.
Anaerobic
- Predators: The presence of predators like lions in an ecosystem can influence the behavior and distribution of prey species, affecting population dynamics.
- Plants: Vegetation in an ecosystem provides food, shelter, and habitat for various animals, influencing their survival and reproductive success.
- Decomposers: Bacteria, fungi, and other decomposers break down organic matter, recycling nutrients and contributing to soil fertility in ecosystems.
- Pollinators: Bees, butterflies, and other pollinators play a crucial role in plant reproduction by transferring pollen between flowers, facilitating fertilization and seed production.
Biotic Factors
- Dodo bird: The dodo bird went extinct in the 17th century due to habitat destruction and hunting by humans.
- Passenger pigeon: Once the most abundant bird species in North America, the passenger pigeon was driven to extinction in the early 20th century due to overhunting and habitat loss.
- Tasmanian tiger: The thylacine, or Tasmanian tiger, became extinct in the 20th century primarily due to persecution by humans and habitat fragmentation.
- Baiji dolphin: The Baiji dolphin, native to the Yangtze River in China, was declared functionally extinct in the early 21st century due to habitat degradation and pollution.
Extinction
- Bald eagle: The bald eagle (Haliaeetus leucocephalus) is a species of bird of prey native to North America and the national symbol of the United States.
- Tiger: The tiger (Panthera tigris) is a large carnivorous mammal found in various habitats across Asia and is classified into several subspecies, each adapted to different environments.
- Oak tree: Oaks (genus Quercus) are a diverse group of tree species found in forests, woodlands, and urban areas worldwide, providing habitat and resources for many other organisms.
- Blue whale: The blue whale (Balaenoptera musculus) is the largest animal on Earth and a species of marine mammal found in oceans globally, primarily feeding on krill.
Species
- Freshwater: A vital resource for life, used by humans, animals, and plants for drinking, irrigation, sanitation, and industrial purposes.
- Timber: Wood harvested from forests serves as a resource for building materials, furniture, paper products, and fuelwood.
- Petroleum: Crude oil extracted from underground reservoirs is a non-renewable resource used for producing gasoline, diesel, plastics, and other petroleum-based products.
- Agricultural land: Land used for farming and crop cultivation provides essential resources like food, fiber, and biofuels to sustain human populations.
Resource
- Deer population in a forest: The carrying capacity of a forest ecosystem determines the maximum number of deer that can be sustained without depleting resources like food and shelter.
- Fish population in a lake: The carrying capacity of a lake ecosystem dictates the maximum number of fish that can be supported by available resources such as oxygen levels and food supply.
- Human population in a city: Urban areas have a carrying capacity influenced by factors like infrastructure, housing availability, and access to resources like water and food.
- Agricultural land: The carrying capacity of agricultural land refers to the maximum sustainable yield of crops that can be produced without degrading soil fertility or depleting resources.
Carrying Capacity
- Plants: Through photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose, fulfilling their energy needs.
- Algae: Phytoplankton in oceans and lakes are autotrophs that form the base of many aquatic food chains, converting sunlight into energy.
- Cyanobacteria: These autotrophic bacteria perform photosynthesis, contributing to oxygen production and nutrient cycling in various ecosystems.
- Some bacteria: Certain bacteria in deep-sea vents use chemical energy from minerals to synthesize organic compounds, functioning as autotrophs in extreme environments.
Autotroph
- Photosynthesis: Plants absorb carbon dioxide from the atmosphere during photosynthesis, converting it into glucose and releasing oxygen.
- Respiration: Animals and plants release carbon dioxide into the atmosphere through respiration as they metabolize organic compounds for energy.
- Decomposition: Decomposers break down organic matter, releasing carbon dioxide back into the atmosphere as they respire and decompose organic materials.
- Combustion: Burning fossil fuels releases carbon dioxide into the atmosphere, contributing to the carbon cycle and influencing climate change.
Carbon Cycle
- Darwin's finches: The different species of finches on the Galápagos Islands evolved through adaptive radiation from a common ancestor, leading to speciation based on beak morphology and feeding habits.
- Cichlid fishes in African lakes: Cichlid species in African rift lakes like Lake Malawi and Lake Tanganyika underwent rapid speciation due to geographic isolation and ecological specialization.
- Hawaiian honeycreepers: The diverse species of honeycreepers in Hawaii evolved from a single ancestral species through adaptive radiation and speciation in response to varied island habitats.
- Ring species: Ring species like the Ensatina salamander exhibit a continuous gradient of variation around a geographic barrier, representing a continuum of speciation from adjacent populations.
Speciation
- Overfishing: Harvesting fish populations beyond sustainable levels can lead to overexploitation, depletion of fish stocks, and ecosystem collapse in marine environments.
- Illegal logging: Unsustainable logging practices, including illegal deforestation and clear-cutting, result in habitat destruction, loss of biodiversity, and soil erosion.
- Poaching: Illegal hunting and poaching of wildlife for their fur, tusks, horns, or other body parts threaten endangered species and disrupt ecosystems.
- Overharvesting: Unsustainable exploitation of resources like timber, minerals, and freshwater can lead to habitat degradation, loss of biodiversity, and ecosystem services.
Overexploitation
- Sunlight: Solar energy powers photosynthesis in plants, providing the basis for most ecosystems' energy flow.
- Fossil fuels: Oil, coal, and natural gas are sources of energy formed from organic matter over millions of years and are widely used for electricity generation and transportation.
- Wind energy: Wind turbines convert kinetic energy from wind into electricity, providing a renewable source of energy with minimal environmental impact.
- Food: Energy derived from the consumption of food fuels metabolic processes in organisms, enabling growth, movement, and reproduction.
Energy
- Tropical rainforests: These regions exhibit high biodiversity, hosting a wide variety of plant and animal species, including insects, birds, mammals, and amphibians.
- Coral reefs: Coral reefs are among the most diverse ecosystems on the planet, supporting a plethora of marine life, including fish, invertebrates, and algae.
- Grasslands: Grassland ecosystems, such as the African savannas, are home to diverse species of grazing mammals, predators, birds, and insects.
- Tropical oceans: The warm waters of tropical oceans harbor an abundance of biodiversity, including colorful fish, corals, sea turtles, and marine mammals.
Biodiversity
- Climate: The temperature, humidity, and precipitation in a forest determine the types of plants and animals that can thrive there.
- Soil composition: The pH levels and nutrient content of soil influence the growth of plants and the organisms that depend on them.
- Sunlight: The amount of sunlight in an aquatic ecosystem affects the depth at which photosynthesis can occur, thus impacting the distribution of aquatic plants and algae.
- Altitude: High altitude affects air pressure and temperature, influencing the types of vegetation and animals found in mountainous regions.
Abiotic factors
- Sugars: Glucose, fructose, and sucrose are examples of organic compounds commonly found in fruits, vegetables, and sweetened foods.
- Lipids: Fats, oils, and cholesterol are organic molecules important for energy storage, cell membrane structure, and hormone synthesis.
- Proteins: Proteins are organic macromolecules composed of amino acids, serving as structural components, enzymes, and signaling molecules in living organisms.
- DNA: Deoxyribonucleic acid (DNA) is an organic molecule containing genetic information, composed of nucleotides arranged in a double helix structure.
Organic
- Water: Although essential for life, water is an inorganic compound made of hydrogen and oxygen atoms.
- Salt: Sodium chloride (table salt) is an inorganic compound commonly used as a seasoning and food preservative.
- Minerals: Rocks and minerals such as quartz, feldspar, and calcite are inorganic substances found in the Earth's crust.
- Metals: Elements like iron, copper, and gold are inorganic substances with various industrial, technological, and structural applications.
Inorganic
- Burmese python in the Florida Everglades: The introduction of Burmese pythons to the Everglades has led to a decline in native wildlife populations, including small mammals and birds.
- European starlings in North America: European starlings, introduced to North America in the 19th century, compete with native bird species for nesting sites and food resources.
- Zebra mussels in the Great Lakes: Zebra mussels, originally from Eurasia, have invaded the Great Lakes, disrupting aquatic ecosystems and causing economic damage to infrastructure.
- Kudzu in the southeastern United States: Kudzu, a fast-growing vine from Asia, has become a problematic invasive species, smothering native vegetation and altering habitats.
Invasive Species
- Primary producers: Plants, algae, and photosynthetic bacteria form the base of food chains as primary producers, converting sunlight into chemical energy.
- Primary consumers: Herbivores that feed directly on primary producers occupy the second trophic level, transferring energy from plants to higher trophic levels.
- Secondary consumers: Carnivores and omnivores that feed on herbivores occupy the third trophic level, transferring energy from primary consumers to tertiary consumers.
- Tertiary consumers: Apex predators at the top of food chains, such as large carnivores, occupy the fourth trophic level and play a crucial role in regulating ecosystem dynamics.
Trophic Levels
- Human population growth: Rapid population growth in many regions leads to overpopulation, straining resources, increasing pollution, and exacerbating environmental problems.
- Pest outbreaks: Insects like locusts can experience population explosions due to favorable conditions, leading to overpopulation and damage to crops and vegetation.
- Urban sprawl: Expansion of cities and suburbs results in overpopulation in urban areas, putting pressure on infrastructure, housing, and natural resources.
- Wildlife management: In some cases, overpopulation of certain animal species can lead to ecological imbalances and conflicts with humans, requiring management interventions.
Overpopulation
- Cellular respiration: Metabolism includes processes like cellular respiration, where organic molecules are broken down to release energy for cellular activities.
- Photosynthesis: Metabolism also encompasses photosynthesis, where plants and some bacteria convert light energy into chemical energy stored in glucose molecules.
- Digestion: In animals, metabolism involves digestion, absorption, and assimilation of nutrients from food to provide energy and building blocks for growth and repair.
- Anabolism: Metabolism includes anabolic processes where small molecules are synthesized into larger molecules, such as proteins, nucleic acids, and carbohydrates.
Metabolism