Energy transfer Flashcards
(25 cards)
Define ecosystem.
An ecosystem is an ecological unit consisting of living organisms (biotic components) interacting with their physical environment (abiotic components).
Compare open and closed systems.
Open system exchanges both energy and matter with its surroundings.
* Energy is sourced from sunlight (photosynthesis) or produced via chemical reactions (chemosynthesis or cell respiration)
* Matter can be transferred from outside the system (via animal migration, rainfall, dispersal by wind, etc.)
Closed system only exchanges energy with its surroundings, not matter.
* While energy will flow through the system (enter and leave), matter remains and must be recycled
Explain sunlight as the principal source of energy that sustains most ecosystems.
Photosynthesis: Plants, algae, and cyanobacteria capture sunlight using chlorophyll and other pigments.
Conversion to Chemical Energy: Light energy is transformed into chemical energy, stored in carbon compounds like glucose.
Energy Transfer: This energy moves through the ecosystem as organisms consume plants and are, in turn, consumed by others.
Outline an example of an exception of sunlight as the principal energy source in most ecosystems.
Deep Ocean Ecosystems
Hydrothermal Vents: Found on the ocean floor, these vents release hot, mineral-rich water.
Chemosynthesis: Instead of sunlight, bacteria use chemical energy from reactions like the oxidation of hydrogen sulfide to produce organic compounds.
Define food chain.
A linear sequence of organisms through which nutrients and energy pass as one organism eats another.
The first organism in a food chain is always a producer, followed by consumers (primary, secondary, tertiary, etc.).
Outline the flow of energy through a food chain.
It starts with the producers: Plants, algae, and some bacteria capture sunlight through photosynthesis, converting it into chemical energy stored in carbohydrates.
Then, the primary Consumers: Herbivores, like zebras, eat plants and absorb this energy.
The Secondary Consumers: Carnivores, like lions, eat herbivores and gain energy from their tissues.
Finally, the tertiary Consumers: Apex predators, such as eagles, consume secondary consumers.
Define a food web.
A food web is a complex network of interconnected food chains, representing all the feeding relationships within a community.
A food web is more representative of actual feeding pathways because organisms can have multiple food sources and more than one predator
This means that, unlike a food chain, organisms in a food web can occupy more than one trophic level
Outline the role of decomposers in a food web.
Breaking Down Organic Matter:Decomposers like fungi and bacteria break down dead organisms, releasing nutrients back into the ecosystem.
Energy for Decomposers:They obtain energy by breaking down carbon compounds in dead matter, but this energy is also lost as heat.
Define decomposers.
Decomposers are organisms that break down dead organic matter, releasing energy and nutrients back into the ecosystem.
Saprotrophs: Organisms like bacteria and fungi that digest organic matter externally by secreting enzymes.
Detritivores: Animals like earthworms and vultures that consume dead material and break it down internally.
Outline the supply of energy to decomposers.
Dead Parts of Organisms
* Plants and animals shed parts throughout their lives, such as leaves, bark, feathers, or exoskeletons.
* These materials are rich in carbon compounds and provide energy for decomposers.
Faeces
* Not all energy consumed by animals is absorbed; some is egested as faeces.
* This waste material still contains undigested carbon compounds, which decomposers can utilize.
Explain how decomposers extract energy stored in dead organic matter.
External Digestion: Saprotrophs secrete enzymes onto organic matter, breaking down complex molecules into simpler, soluble compounds like sugars and amino acids.
Absorption:These simpler compounds are absorbed by the decomposer and used for energy through cellular respiration.
Nutrient Release: As decomposers metabolize organic matter, they release nutrients like nitrogen and phosphorus back into the soil, making them available for plants.
Define autotrophs.
Autotrophs are organisms capable of producing their own food using simple inorganic substances.
They do this through two primary processes:
* Photosynthesis: Using light energy (these are also referred to as photoautotrophs).
* Chemosynthesis: Using energy from chemical reactions.
Define carbon fixation.
Carbon fixation is the process of converting inorganic carbon into organic compounds.
State the role of autotrophs in the ecosystem.
Primary Producers: Autotrophs form the base of food chains, supporting heterotrophs (organisms that depend on others for food).
Carbon Cycling: They convert inorganic carbon into organic forms, making it accessible to other organisms.
Oxygen Production: Photoautotrophs release oxygen during photosynthesis, sustaining aerobic life.
Outline how oxidation reactions serve as a source of energy in iron-oxidizing bacteria.
Iron-oxidising bacteria found in the soil are an example of a chemoautotroph – they use the electrons from iron (oxidation) to produce ATP.
Iron-oxidizing bacteria thrive in acidic environments, such as those created by mining activities or natural erosion.
Explain the oxidation reactions as the energy source in chemoautrotrophs.
Organisms that use chemical reactions to obtain energy, enabling them to thrive in environments without sunlight.
* Oxidation reactions release energy by transferring electrons from one molecule to another.
* Chemoautotrophs use this energy to convert carbon dioxide into organic compounds.
Define chemoautotrophs.
Chemoautotrophs are organisms that obtain energy by the oxidation of electron donors in their environments.
Define heterotrophs.
Heterotrophs as organisms that use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require.
Outline the functions of digestion, assimilation and synthesis of carbon compounds in heterotrophs.
Digestion can occur internally or externally, depending on the organism.
Assimilation: Building New Molecules Once digested, the smaller molecules (e.g., amino acids, sugars) are absorbed into cells and used to synthesize the carbon compounds the organism needs.
* Proteins: Amino acids are reassembled into proteins specific to the organism.
* Nucleic Acids: Sugars and nitrogenous bases are used to build DNA and RNA.
* Lipids: Fatty acids and glycerol are combined to form cell membranes and energy stores.
Describe the relase of energy in autotrophs and heterotrophs by oxydation of carbon compounds in cell respiration.
Organisms undertake cell respiration to release the chemical energy stored in organic compounds
Carbohydrates (glucose) serve as the primary fuel source, but other compounds (lipids, proteins) may be used
The organic compounds can either be produced by the organism itself (autotrophy) or obtained from other organisms (heterotrophy)
Cell respiration can occur anaerobically (no oxygen = low ATP yield) or aerobically (oxygen = high ATP yield)
The release of energy involves oxidation reactions (high energy electrons are used in the production of ATP)
Define trophic level.
A trophic level represents a group of organisms that share the same position in a food chain, based on how they obtain energy.
Organisms are classified into trophic levels based on how they obtain energy and carbon compounds in food chains.
Organisms at the same level share similar energy acquisition methods.
Why does energy decrease at higher trophic levels?
Energy transfer between trophic levels is inherently inefficient, with only 10% of the energy from one level passed to the next.
This phenomenon occurs due to:
Heat Loss: Energy is lost as heat during metabolic processes.
Incomplete Consumption: Some parts of organisms, like bones or bark, are not eaten.
Incomplete Digestion: Some consumed material is not fully digested and is expelled as waste.
Describe the reasons why heat created by living organisms is eventually lost from the ecosystem.
During Cellular Respiration: Energy is released as heat at every stage of cellular respiration:
* Glycolysis and the Krebs Cycle: Enzymatic reactions release energy, but not all of it is captured in ATP.
* Electron Transport Chain: Energy from electron movement is used for ATP synthesis, but some energy is lost as heat.
When ATP is Used: Energy continues to dissipate as heat when ATP is used for cellular activities like muscle contraction or active transport.
Compare heat loss in autotrophs and heterotrophs.
Autotrophs
* Plants and algae store energy from sunlight in glucose during photosynthesis.
* When this glucose is used for growth or reproduction, energy is released, with some lost as heat.
Heterotrophs
* Animals and fungi consume organic molecules for energy.
* During respiration and movement, a large portion of this energy is lost as heat.
