C4.2 Transfer of energy and matter Flashcards
What is an ecosystem composed of?
An ecosystem is composed of all the organisms in an area together with their abiotic environment.
What is a system? (in biology)
A system is a set of interacting or independent components.
What are the two types of systems?
- Open system
- Closed system
What is an open system?
Open system: where energy can enter or exist, but chemical resources cannot be removed or replaced.
What is a closed system?
Closed system: where energy can enter or exit, but chemical resources cannot be removed or replaced.
What is the initial source of energy in an ecosystem?
Sun light is the initial source of energy that sustains most ecosystems, as it is needed to produce glucose in photosynthesis.
What organisms use light as an energy source?
Plants, eukaryotic algae and cyanobacteria carry out photosynthesis and are referred to as producers or autotrophs.
What are heterotrophs?
Heterotrophs use the sunlight indirectly and are therefore still dependent on it.
How are organisms supplied with energy when they in a cave?
Organism must be adapted to life in a cave. Streams entering the cave bring dead organic matter which supplies a source of energy. Some caves (e.g. Movile Cave in Romania) do not receive any influx. energy is produced by archaebacteria through chemical reactions with sulphides, methane or other as substrates.
How are organisms supplied with energy when they in a deep sea?
In marine and freshwater ecosystems light must pass through water to reach producers. Transmission is not 100% and only shorter wavelengths will penetrate further in pure water which is why the sea often appears blue. The source of energy in deep sea often originates from bacteria which can use sulphides as a source of energy.
What is the flow of chemical energy through food chains?
Energy enters as light, flows as nutrients through the food chains and usually leaves as heat.
How are nutrients recycled in food chains?
Nutrients can cycle through successive food chains of consumers, decomposers and autotrophs. E.g. recycled nutrients include carbon, nitrogen and phosphorus.
What is the recycling of nutrients a good example of?
The recycling of nutrients is a good example of an interaction between biotic and abiotic factors within an environment. Nutrients are absorbed from the environment, used by living organisms and then returned to the environment. This process can be conceptualized as a cycle.
What is the purpose of a food chain?
A food chain shows the flow of energy through a sequence of organism, each of which feeds on the previous one. (arrows indicate direction of energy flow)
What are the different levels (trophic [feeding] level) of food chain?
- Primary producers
- Primary consumers
- Secondary consumers
- Tertiary consumers
- Quaternary consumers
How do producers obtain energy?
Most producers absorb sunlight using chlorophyll and other photosynthetic pigments. The light energy is converted to chemical energy, which is used to make carbohydrates, lipids and all the other carbon compounds that are required.
How do consumer obtain energy?
Consumers obtain energy from the carbon compounds in the organisms on which they feed. Primary consumers feed on producers (=herbivores); secondary consumers feed on primary consumers (=carnivores); tertiary consumers feed on secondary consumers, and so on. No consumers feed on the last organism in a food chain.
How do decomposers feature in a food chain?
Decomposers, fungi and many bacteria, obtain their energy and raw materials from the waste (e.g. faeces) and remains (e.g. dead bodies) of other organisms.
What does a food web represent?
A food web represents the complexity of trophic (feeding) relationships by showing interacting and interconnecting food chains and the many consumers there are.
How are decomposers supplied with energy?
Decomposers are supplied with energy from carbon compounds in dead organic matter such as faeces, shed exoskeletons of an insect or reptile, dead plant material such as fallen leaves.
How do some decomposers obtain their energy?
Decomposers such as saprotrophs secrete digestive enzymes into dead organic matter and digest it externally by absorbing the products of digestion such as sugars and amino acids.
How do saprotrophs break down complex insoluble carbon compounds?
Saprotrophs also break down complex insoluble carbon compounds into soluble ones, and by doing so recycling dead matter which otherwise would build up over the years. Decomposers are the waste disposers and recyclers.
What is an autotrophs?
Autotrophs= organisms that use external energy sources to synthesize organic compounds from inorganic substances (CO2, HCO3- as carbon sources). Energy in the form of sunlight is required for carbon fixation and for building macromolecules.
What is an heterotrophs?
Heterotrophs = synthesize organic compounds by taking in and digesting carbon compounds
What is an photoautotrophs?
Make organic compounds using energy derived from the sun. A small amount of solar radiation which reaches the Earth is absorbed by chloroplasts. Plants, eukaryotic algae and cyanobacteria can use the radiation from the sun to produce chemical energy (glucose, amino acids) via a process called photosynthesis.
When is chemoautotrophs?
A variety of prokaryotic bacteria make organic compounds using energy from the oxidation of chemicals, using chemical reactions. Sulphur, hydrogen sulphides, iron sulphides, hydrogen or ammonia as sources of energy can be oxidized to release energy. This energy is used to synthesize carbon compounds (glucose, amino acids).
What are consumer?
Ingest organic matter which is living or killed. Occurs internally.
What are saprotrophs?
Feeds on non-living matter by secreting enzymes and absorbing products. Occurs externally.
How do chemoautotrophs use iron sulphides as source of energy?
Iron sulphides (FeS2) as a source of energy for chemoautotrophs is found in sedimentary rocks formed in low-oxygen environments.
- during mining or erosion, rocks are exposed to air
- Iron oxidizing bacteria use Fe^2+ ions and oxidize them further to Fe^+3 ions
- The electrons from this reaction are used to drive energy production (ATP) processes in the cell membrane of these organism
How do heterotrophs synthesize their carbon compounds they require?
Heterotrophs are organisms which have to take in and digest organic compounds (carbohydrates, lipids, proteins) from other organism to assimilate and use them to produce energy or build large complex carbon compounds.
What are the two classification within heterotrophs? And how are they determined?
Depending on the type of digestion heterotrophs can be further classified as consumers and saprotrophs.
How does assimilation occurs heterotrophs?
Assimilation requires absorption of carbon compounds across a digestive membrane. This means the substances must be small to pass through - usually achieved through digestion by enzymes.
How do both autotrophs and heterotrophs release of energy?
Release of energy in both autotrophs and heterotrophs by oxidation of carbon compounds in cell respiration.
why do organisms require energy? And how it is supplied?
Living organisms need energy for a range of different cell activities: Synthesis of large molecules like DNA, RNA and proteins; active transport of molecules across membranes, and vesicular transport of molecules with cells. ATP supplies all the energy.
How can organisms be classified due to their feeding relationships?
trophic levels offer a way of classifying organisms by their feeding relationships with other organisms in the same ecosystem. Trophic level 1= producer, Trophic level 2 = Primary consumer, Trophic level 3 = Secondary consumer, Trophic level 4 = Tertiary consumer
How can energy flow between trophic levels be represented?
Energy flow can be represented using pyramids of energy. It is measured in units of energy per unit area per unit time kJ/year/m^2. When energy transformations take place, including those in living organisms, the process is never 100% efficient, commonly being 10-20%, but often variables.
Why is 100% of energy transferred to the next trophic level?
- Incomplete consumption = don’t normally consume the entire organisms (bones or hair), energy left in dead body parts passes to saprotrophs e.g. fungi or detritus feeders
- Incomplete digestion = not all parts of food ingested by organisms are digested & absorbed e.g. cellulose thus is egested in faeces
- Cell respiration = carbohydrates, proteins and other energy-containing substances are oxidised to carbon dioxide and water releasing energy and these products don’t provide the next trophic level with energy
How much energy is lost between trophic levels?
Around 90% of energy is lost between trophic levels ( leaving on average 10% of energy being passed on to the next level)
Why is heat lost to the environment in organisms?
A lot of heat is lost to environment in both autotrophs & heterotrophs due to conversion of chemical energy to heat in cell respiration. Heat resulting from cell respiration makes living things warmer. This heat passes from hotter to cooler bodies and is eventually lost to the abiotic environment. Heat energy is unusable to organisms & is lost from ecosystems.
What can chemical energy (ATP), produced through cellular respiration, be converted into?
Chemical energy (ATP) produced by an organism through cellular respiration can be converted into a number of different forms of energy:
- electrical energy during transmission of a nerve impulse
- kinetic energy during muscle contractions
- light energy when producing bioluminescence
Why is heat loss inevitable in organisms?
All of these reactions are exothermic & release thermal energy (heat) as a by-product. Living organisms cannot turn this heat into other forms of usable energy. this heat energy is released from the organism & is lost from ecosystem (unlike nutrients, which are recycled).
What is the initial source of energy in a food chain? And why is it necessary?
Sunlight = initial source of energy for almost all communities. energy flows through food chain being lost at each stage in form of heat, which is why a continuous supply of initial energy is needed. nutrients are recycled.
Why is the number of trophic level limited?
The number of trophic levels is limited by how much energy enter ecosystem. If energy is low at start of food chain, then energy will be quickly lost making chain very short. Abundant energy at start can sustain multiple trophic levels.
What is biomass?
Biomass = total mass of a group of organisms within one trophic level. It consists of cells & tissues of those organisms, including carbohydrates & other carbon compounds that they contain. It is unit mass in an area or volume.
What reduces the biomass in higher trophic levels?
Energy losses reduce the biomass of higher trophic levels.
What is happens to biomass as you go up the trophic levels?
Biomass diminishes between trophic levels because some molecules along food chain are lost ( CO2, excretion, H2O in transpiration etc…) so they cannot participate in accumulating biomass. 10000 copepods –> 10 hearing –> 1 seal –> 1 shark
What is the production in an ecosystem?
Production in ecosystems is the accumulation of carbon compounds in form of biomass. When organism grow, biomass accumulated.
What is productivity split into?
- Primary productivity
- Secondary productivity
What is primary productivity split into?
- Gross primary productivity (GPP)
- Net primary productivity
What is Gross primary productivity (GPP)?
GPP = is total biomass of carbon compounds made in plants by photosynthesis.
What is net primary productivity?
Net primary productivity = is GPP minus biomass lost due to respiration of plant & available to consumers.
What is secondary productivity?
Secondary productivity = is accumulation of carbon compounds in biomass by animals & other heterotrophs through ingestion of sugars & amino acids from food followed by being built up into macromolecules.
What are the only organisms that are considered primary producers?
Although both, autotrophs and heterotrophs produce biomass by growing & reproducing, only plants & other autotrophs are considered as primary producers because they synthesize carbon compounds from CO2 & other inorganic substances.
Why is there such a big different the net production of primary and secondary production?
Because carbon compounds are used in cellular respiration as respiratory substrates in secondary production, not all will be passed on to next trophic level & therefore result in a loss of biomass. This is why net production is always lower than gross production in an ecosystem. Secondary production declines with each successive trophic level from primary consumers onwards.
What can you deduce about the economic & environmental aspects of energy availability for consumers of meat?
Eating meat of any kind is both economically & environmentally expensive. Compared with growing plants for direct human consumption, producing meat usually required that more land be cultivated, more water by used for irrigation, more fossil fuels be burned, & more chemicals fertilizers & pesticides be applied to croplands used for growing grain.
What is the difference between primary and secondary productivity?
What is carbon sink?
It is when photosynthesis exceeds respiration, there is net uptake, The ecosystem is acting as a carbon sink. CO2 from the atmosphere or water moves into autotrophs for photosynthesis.
What is a carbon source?
If respiration exceed photosynthesis, there is net release. The ecosystem is acting as a carbon source. CO2 from plants or aquatic plants respiration
Why is carbon special?
Carbon is one of main elements found in all organic molecules including carbohydrate, protein & lipids.
Where is carbon found?
Carbon is found in pools, which is an inorganic or organic supply of carbon.
How is carbon moved between 4 pools?
Carbon is moved between these 4 pools by variety of biological, geochemical or industrial processes called fluxes.
What is a pool?
Pool = a reserve of element. It can organic or inorganic. E.g. CO2 in atmosphere is organic pool of carbon, biomass of producers in an ecosystem is an organic pool.
What is a flux?
Flux = transfer of elements from one pool to another. E.g. CO2 is absorbed by autotrophs through photosynthesis.
What are the 3 main types of carbon flux due to living organisms in ecosystems?
- Photosynthesis - absorption of CO2 from air or water & its conversion to carbon compounds
- Feeding - gaining carbon compounds from other organisms
- Respiration - release to atmosphere of CO2 produced by respiring cells
Which ones are main pools of Earth?
- Atmosphere
- Biosphere
- Hydrosphere ( Oceans, Lakes etc…)
- Sediments
Explain why fossil fuels are classified as non-renewable resources when carbon cycle indicates they are renewed (refer to pictorial carbon cycle).
It takes millions of years to form fossil fuels thus it will run out before it replenishes itself.
Diffusion is a flux that moves CO2 from atmosphere to hydrosphere & back again. Taken together these fluxes are largest in cycle. suggest why.
The surface areas of oceans, lakes & entire atmosphere is very large, thus amount CO2 that can be moved between these pool is also very large.
What happens when carbon sinks are burned?
E.g. biomass, peat, coal, oil & natural gas form big carbon sinks. When these carbon supplies burn as a fuel in complete combustion (within sufficient oxygen) carbon dioxide & water is released.
Fuel + O2 –> CO2 + H2O
How is oil & gas formed?
Oil & gas are formed over a large period of time. The source material for this originated from dead marine organism containing calcium carbonate. When buried under the sediment layer, heat & compression acts on transforming these organism in oil & gas, which are stored away in pockets of rocks or sand
How is coal formed?
- Before the dinosaurs, many giant plants died in swamps
- Over millions of years, plants were buried under water & dirt
- Heat & pressure turned dead plants into coal
what is peat?
Peat = 1st stage in coal formation, consists of incompletely decomposed organic matter. Decaying plant material, usually in wet areas, is prevented from decaying fully by acidic & anaerobic conditions.
How is coal formed from peat?
When sediments accumulate over partially decomposed peat, coal is formed by further transformation through weight & pressure.
Where does the majority of CO2 emission originate?
Although wild forest fires caused by lightening or spontaneous ignition of coal supplies sometimes can lead naturally to combustion of large fuels supplies, majority of CO2 emission from combustion originates from burning of fossil fuels by humans.
How is CO2 levels been measured over last 100 yrs?
- Ice core (CO2 conc from past yrs has been collected)
- Historical date take more effort to collect & is more variables in reliability or results produced e.g. data collected experimentally at observatory in Mauna Loa, Hawaii
How was the data collected in Mauna Loa, Hawaii, presented?
Presented on the Keeling curve, which shows that annual rhythm of CO2 conc is lower in summer months & higher in winter months (due plants growth occurs in summer thus photosynthesis rates). Also shows trend is increasing over the year.
What is the relationship between aerobic respiration and photosynthesis?
Aerobic respiration by autotrophs is dependent on atmospheric O2 produced by photosynthesis, & photosynthesis is dependent on atmospheric CO2 produced by respiration by heterotrophs.
What is carbon, hydrogen & oxygen needed in organisms?
Carbon, hydrogen & oxygen are needed to make carbohydrates, lipids & other carbon containing compounds.
What is nitrogen & phosphorus required for in organisms?
Nitrogen & phosphorus are also needed to make many of these compounds.
What other chemical elements are required by organisms?
15 other elements are needed by living organisms - some in traces only (Mg, Ca, Mn, Cu, Na, K …) e.g. haemoglobin, chlorophyll, structural materials…
How do autotrophs obtain inorganic nutrients?
Autotrophs obtain their inorganic nutrients from abiotic environment (air, soil, rock) including carbon & nitrogen.
How do autotrophs obtain chemical elements?
Heterotrophs obtain these elements from food they eat, but also from abiotic environment (Na, K, Ca …)
How does the recycling of chemical elements occur?
Recycling of chemical elements required by living organisms in ecosystems happens in form of nutrient cycles, e.g. carbon or nitrogen cycle.
What is the role of decomposers in recycling chemical elements?
Decomposers (saprotrophs & detritivores) break down body parts of dead organisms, or organic matter left over in faeces. Digestive elements of decomposers convert nutrients that were ‘locked-up’ in complex organic matter into a more usable form for themselves & for other organisms.
What is the nitrogen cycle? And how does it work?
The nitrogen cycle is an important nutrient cycle which uses bacteria in soil to trap nitrogen (N2) from air or in form of proteins, enzymes, DNA etc from dead animals & plants. Other bacteria then convert nitrogen into ammonia (NH3) & ammonium (NH^+4), & finally into useful nitrates (NO3^-2). Nitrates can by assimilated by plants & incorporated back into proteins or chlorophyll … & essentially eaten by animals which further use nitrogen.
What is nitrification and why is it so important?
When ammonium is oxidised into nitrites and then nitrates, can be used by plants or renitrify into nitrogen gas.
