Carbon and Nitrogen Cycles Explained

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Questions and Answers

What are the 4 main stages in the carbon cycle?

Respiration, photosynthesis, decomposition, combustion

Describe respiration in the context of the carbon cycle.

Living organisms release carbon dioxide (CO2) into the atmosphere as a byproduct of breaking down organic compounds to release energy.

Describe photosynthesis in the context of the carbon cycle.

Green plants and some other organisms absorb CO2 from the atmosphere and use sunlight energy to convert it into organic compounds like sugars (glucose).

Describe decomposition in the context of the carbon cycle.

<p>Decomposers like bacteria and fungi break down dead organic material (plants and animals) using enzymes. They release CO2 into the atmosphere through their own respiration.</p> Signup and view all the answers

Describe combustion in the context of the carbon cycle.

<p>Burning fossil fuels (coal, oil, natural gas) and organic matter (like wood during deforestation) rapidly releases large amounts of stored carbon into the atmosphere as CO2.</p> Signup and view all the answers

Outline the main stages of the nitrogen cycle.

<ol> <li>Nitrogen fixation (N2 gas converted to ammonia/ammonium by bacteria or lightning).</li> <li>Nitrification (Ammonium converted to nitrites, then nitrates by bacteria).</li> <li>Assimilation (Plants absorb nitrates or ammonium to make organic molecules like amino acids).</li> <li>Ammonification (Decomposers break down dead organic matter and waste, releasing ammonium).</li> <li>Denitrification (Nitrates converted back to N2 gas by bacteria, returning it to the atmosphere).</li> </ol> Signup and view all the answers

What are the biological consequences of carbon monoxide exposure?

<p>Carbon monoxide binds much more strongly to haemoglobin in red blood cells than oxygen does. This reduces the blood's ability to transport oxygen. High levels can lead to oxygen deprivation in tissues (hypoxia), impairing respiration and energy release, potentially causing fainting, coma, or death.</p> Signup and view all the answers

What are the biological consequences of sulphur dioxide pollution?

<p>Sulphur dioxide reacts with water vapour in the atmosphere to form sulphuric acid, which falls as acid rain (pH typically below 5.5). Acid rain damages plant tissues (leaves, roots), reduces photosynthesis, harms aquatic life (e.g., kills fish, damages eggs), leaches toxic metals from soil, damages buildings, and disrupts ecosystems.</p> Signup and view all the answers

Which main greenhouse gases are increased by human activities?

<p>Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), and synthetic gases like Chlorofluorocarbons (CFCs). While water vapour is a major greenhouse gas, its concentration is primarily controlled by temperature rather than direct human emissions.</p> Signup and view all the answers

How is water vapour, relevant as a greenhouse gas, formed?

<p>Naturally through evaporation from bodies of water and transpiration from plants. It is also produced during respiration and combustion processes.</p> Signup and view all the answers

What are the main human activities leading to increased Carbon Dioxide (CO2) emissions?

<p>The combustion of fossil fuels (coal, oil, natural gas) for energy (power stations, transport, industry) and deforestation (reduces CO2 uptake by photosynthesis and releases CO2 through burning or decomposition).</p> Signup and view all the answers

What are the main human activities leading to increased Nitrous Oxide (N2O) emissions?

<p>Agricultural practices (especially the use of nitrogen fertilisers), industrial processes, and the combustion of fossil fuels and biomass.</p> Signup and view all the answers

What are the main human activities leading to increased Methane (CH4) emissions?

<p>Agriculture (livestock digestion - especially ruminants like cattle, rice cultivation), decomposition of organic waste in landfill sites, and the extraction and transport of fossil fuels (natural gas leaks).</p> Signup and view all the answers

What activities led to the emission of CFCs (Chlorofluorocarbons)?

<p>Historically used as refrigerants (in fridges and air conditioners), propellants in aerosol sprays, solvents, and blowing agents for foams.</p> Signup and view all the answers

Explain how an increase in greenhouse gases results in an enhanced greenhouse effect.

<p>The Earth absorbs solar radiation and warms up, then emits infrared radiation back towards space. Greenhouse gases in the atmosphere absorb some of this outgoing infrared radiation, trapping heat and keeping the planet warmer than it would otherwise be (natural greenhouse effect). Increasing the concentration of these gases means more heat is trapped, enhancing the effect and leading to global warming.</p> Signup and view all the answers

How does human activity lead to global warming?

<p>Human activities, primarily burning fossil fuels and deforestation, release large amounts of greenhouse gases (like CO2, CH4, N2O) into the atmosphere. These gases enhance the natural greenhouse effect, trapping more heat and causing the average global temperature to rise.</p> Signup and view all the answers

List potential consequences of global warming.

<p>Melting glaciers and polar ice caps, rising sea levels (causing coastal flooding), more frequent and intense extreme weather events (heatwaves, droughts, floods, storms), changes in precipitation patterns, ocean acidification, disruption of ecosystems and habitats, shifts in species ranges, increased risk of species extinction, impacts on agriculture and food security, spread of certain diseases.</p> Signup and view all the answers

What are the biological consequences of water pollution by sewage?

<p>Sewage introduces organic waste and excess nutrients (nitrates, phosphates) into water bodies. Decomposers (bacteria) break down the organic matter, consuming large amounts of dissolved oxygen in the process (aerobic respiration). This oxygen depletion (hypoxia) can kill fish and other aquatic organisms. The excess nutrients can also lead to eutrophication.</p> Signup and view all the answers

Explain the process of eutrophication caused by leached minerals from fertilisers.

<ol> <li>Excess nutrients (nitrates, phosphates) from agricultural fertilisers are washed (leached) from soil into rivers and lakes.</li> <li>These nutrients stimulate rapid growth of algae and phytoplankton (algal bloom).</li> <li>The dense layer of algae blocks sunlight from reaching submerged plants, causing them to die.</li> <li>Bacteria decompose the dead algae and plants, consuming large amounts of dissolved oxygen.</li> <li>The resulting low oxygen levels (hypoxia or anoxia) kill fish and other aerobic aquatic life.</li> </ol> Signup and view all the answers

What is deforestation and what are its main drivers?

<p>Deforestation is the large-scale clearing of forests, often done unsustainably. Key drivers include logging for timber and paper, clearing land for agriculture (crops like soy and palm oil, cattle ranching), mining, infrastructure development (roads, dams), and urban expansion.</p> Signup and view all the answers

What are the environmental effects of deforestation, particularly relating to climate, soil, and water?

<p>Reduced photosynthesis (less CO2 uptake), increased atmospheric CO2 (from burning/decomposition), habitat loss, soil erosion (roots no longer bind soil), altered water cycles (less transpiration leading to changes in rainfall, increased surface runoff), nutrient leaching from soil (loss of fertility), and increased risk of flooding and landslides.</p> Signup and view all the answers

What are the impacts of deforestation on biodiversity, and how can these impacts be reduced?

<p>Impacts include loss of habitats, fragmentation of remaining habitats, disruption of food chains, decline in species populations, increased extinction risk, and overall reduction in biodiversity. Reduction strategies include sustainable forest management, reforestation and afforestation programs, protected areas, laws and regulations against illegal logging, and addressing the underlying economic drivers.</p> Signup and view all the answers

Define Population in ecological terms.

<p>A group of individuals of the same species living in the same geographic area at the same time, capable of interbreeding.</p> Signup and view all the answers

Define Community in ecological terms.

<p>An assemblage of all the populations of different species living and interacting with one another in a particular area or habitat.</p> Signup and view all the answers

Define Habitat in ecological terms.

<p>The natural environment or place where an organism or a biological population normally lives or occurs.</p> Signup and view all the answers

Define Ecosystem.

<p>A biological community of interacting organisms (biotic components) and their physical environment (abiotic components), functioning together as a system.</p> Signup and view all the answers

Outline a practical method using quadrats to investigate and compare the population size of a plant species in two different areas.

<ol> <li>Define the boundaries of the two areas.</li> <li>Use a method for random sampling within each area (e.g., random number coordinates).</li> <li>Place a quadrat (e.g., 1m x 1m) at the random location in the first area.</li> <li>Count the number of individuals of the target plant species within the quadrat.</li> <li>Repeat steps 3-4 multiple times (e.g., 10 times) in the first area.</li> <li>Calculate the mean number of individuals per quadrat for the first area.</li> <li>Estimate the population size: Mean density (individuals/m²) × Total area (m²).</li> <li>Repeat steps 3-7 for the second area.</li> <li>Compare the estimated population sizes or mean densities between the two areas. Use statistical tests if appropriate.</li> </ol> Signup and view all the answers

What is Biodiversity?

<p>The variety of life within a given ecosystem, biome, or the entire Earth. It encompasses genetic diversity (within species), species diversity (number of different species), and ecosystem diversity (variety of habitats and ecological processes).</p> Signup and view all the answers

What are the main human activities that reduce biodiversity?

<p>Habitat destruction and fragmentation (e.g., deforestation, urbanization), pollution (e.g., chemical, noise, light), climate change, overexploitation (e.g., overfishing, overhunting), and the introduction of invasive species.</p> Signup and view all the answers

Describe a practical method using quadrats along a transect to investigate the distribution of organisms in relation to an environmental factor.

<ol> <li>Lay a transect line (e.g., a tape measure) across the area where the environmental factor (e.g., light intensity, soil moisture) changes.</li> <li>Place quadrats at regular intervals along the transect line (systematic sampling).</li> <li>In each quadrat, identify and count the individuals of the species being studied (or measure percentage cover).</li> <li>At each quadrat location, measure the environmental factor being investigated.</li> <li>Record the data for each quadrat (species abundance and environmental factor level).</li> <li>Plot the abundance of the species against the distance along the transect or against the level of the environmental factor to observe distribution patterns.</li> </ol> Signup and view all the answers

List key abiotic (non-living) factors that affect the population size and distribution of organisms.

<p>Temperature, light intensity, water availability, oxygen concentration, carbon dioxide concentration, soil pH, soil type and structure, mineral nutrient availability, salinity, humidity, wind.</p> Signup and view all the answers

List key biotic (living) factors that affect the population size and distribution of organisms.

<p>Competition (for resources like food, water, space, mates), predation, herbivory (grazing), disease (pathogens), parasitism, availability of food, mutualism, commensalism.</p> Signup and view all the answers

Define Trophic Level.

<p>The position an organism occupies in a food chain or food web, determined by its feeding relationships (e.g., producer, primary consumer, secondary consumer, tertiary consumer).</p> Signup and view all the answers

Why are plants generally referred to as producers in an ecosystem?

<p>Because they produce their own organic food molecules (like glucose) from inorganic materials (CO2 and water) using light energy through the process of photosynthesis.</p> Signup and view all the answers

Why are animals referred to as consumers in an ecosystem?

<p>Because they cannot produce their own food and must obtain energy and nutrients by eating (consuming) other organisms (producers or other consumers).</p> Signup and view all the answers

What are decomposers and what is their ecological role?

<p>Decomposers are primarily bacteria and fungi that break down dead organic matter (dead plants, animals, waste products) into simpler inorganic substances. Their role is crucial for nutrient cycling, returning essential elements to the soil and atmosphere for producers to reuse.</p> Signup and view all the answers

Define Predators.

<p>Animals that hunt, kill, and consume other animals (referred to as prey).</p> Signup and view all the answers

What does a food chain illustrate?

<p>A linear sequence showing the flow of energy in an ecosystem, where each organism is eaten by the next organism in the chain. It starts with a producer and shows successive trophic levels.</p> Signup and view all the answers

What does a food web illustrate?

<p>A complex network of interconnected food chains, showing the multiple feeding relationships between different species within an ecosystem.</p> Signup and view all the answers

What is represented by a pyramid of numbers?

<p>It shows the total number of individual organisms at each trophic level in an ecosystem at a specific point in time.</p> Signup and view all the answers

What is represented by a pyramid of biomass?

<p>It shows the total mass of living organic matter (biomass, often measured as dry mass) at each trophic level in an ecosystem at a specific point in time.</p> Signup and view all the answers

What is dry biomass and how is it typically measured?

<p>Dry biomass is the mass of an organism or sample after all its water content has been removed. It is measured by collecting the sample, drying it in an oven at a moderate temperature (e.g., 60-100°C) until its mass becomes constant upon repeated weighing, indicating all water has evaporated.</p> Signup and view all the answers

What does a pyramid of energy transfer (or productivity) show?

<p>It shows the rate at which energy flows or is transferred through each trophic level in an ecosystem over a given period (e.g., kJ per m² per year).</p> Signup and view all the answers

Approximately what percentage of energy is transferred from one trophic level to the next in an ecosystem?

<p>Typically around 10%.</p> Signup and view all the answers

In intensive farming, why are animals sometimes kept indoors in controlled conditions?

<p>To maximize growth rate and food conversion efficiency by reducing energy losses. Controlling temperature reduces energy spent on thermoregulation, and restricting movement reduces energy spent on muscular activity. More energy from feed can then be allocated to growth (producing meat, milk, eggs).</p> Signup and view all the answers

What primarily flows through food chains in an ecosystem?

<p>Energy.</p> Signup and view all the answers

What are recycled within ecosystems, in contrast to the flow of energy?

<p>Nutrients or substances (matter), such as carbon, nitrogen, phosphorus, and water.</p> Signup and view all the answers

Explain the main ways energy is lost between trophic levels, resulting in the ~90% loss.

<p>Energy is lost primarily as heat during metabolic processes (respiration needed for movement, growth, maintenance). Not all parts of an organism are consumed by the next trophic level (e.g., bones, fur, roots). Not all consumed biomass is digested and assimilated; some is lost as waste (faeces). Energy is also lost in excretory products (urine). Endothermic animals (mammals, birds) use considerable energy for maintaining a constant body temperature.</p> Signup and view all the answers

What are the 4 stages in the carbon cycle?

<p>Respiration, photosynthesis, decomposition, combustion</p> Signup and view all the answers

Describe respiration in the context of the carbon cycle.

<p>Living organisms release CO2 into the atmosphere through respiration.</p> Signup and view all the answers

Describe photosynthesis in the context of the carbon cycle.

<p>Green plants absorb CO2 from the atmosphere, using it to form sugars/glucose.</p> Signup and view all the answers

Describe decomposition in the context of the carbon cycle.

<p>Bacteria and fungi break down dead organic material using enzymes, releasing CO2 during their respiration.</p> Signup and view all the answers

Describe combustion in the context of the carbon cycle.

<p>Burning fossil fuels and organic matter (e.g., due to deforestation) releases CO2 into the atmosphere.</p> Signup and view all the answers

What are the key stages of the nitrogen cycle?

<ol> <li>Plants absorb nitrates. 2. Plants make amino acids using nitrates and glucose. 3. Nitrogen moves through food chains via consumption. 4. Dead organic matter forms. 5. Animal waste contains nitrogen. 6. Decomposers break down waste/dead matter into ammonium compounds. 7. Nitrifying bacteria convert ammonium to nitrites, then nitrates (nitrification). 8. Denitrifying bacteria convert nitrates back to nitrogen gas. 9. Nitrogen-fixing bacteria convert nitrogen gas into ammonium compounds.</li> </ol> Signup and view all the answers

What are the biological consequences of carbon monoxide exposure?

<p>Carbon monoxide binds strongly with haemoglobin, reducing the blood's oxygen-carrying capacity. High levels can be fatal due to insufficient oxygen delivery for respiration.</p> Signup and view all the answers

What are the biological consequences of sulphur dioxide pollution?

<p>Sulphur dioxide reacts with water vapour to form sulphuric acid, leading to acid rain (pH &lt; 5.5). Acid rain damages plants (leaves, roots), reduces photosynthesis, disrupts food chains, denatures enzymes, releases toxic metals from soil, and harms aquatic life like fish eggs.</p> Signup and view all the answers

Which greenhouse gases do human activities significantly contribute to?

<p>Water vapour, Carbon dioxide (CO2), Nitrous oxide (N2O), Methane (CH4), and Chlorofluorocarbons (CFCs).</p> Signup and view all the answers

How is water vapour formed through biological and combustion processes?

<p>Water vapour is formed from respiration (in organisms), transpiration (from plants), and combustion processes.</p> Signup and view all the answers

How is atmospheric Carbon Dioxide increased by human activity?

<p>Mainly through the combustion of fossil fuels (coal, oil, gas in engines, power stations) and deforestation, which reduces the amount of CO2 absorbed via photosynthesis.</p> Signup and view all the answers

How is Nitrous Oxide generated by human activity?

<p>Primarily from the combustion of fossil fuels, particularly in car engines, and also from agricultural soil management.</p> Signup and view all the answers

How is Methane generated by human activity?

<p>Through activities such as cattle farming (enteric fermentation), rice cultivation (anaerobic decomposition in paddy fields), and decomposition of organic waste in landfill sites.</p> Signup and view all the answers

What are common sources of CFCs (Chlorofluorocarbons)?

<p>Historically used in aerosols, refrigeration systems, and deodorants.</p> Signup and view all the answers

How does an increase in greenhouse gases result in an enhanced greenhouse effect?

<p>The sun's radiation warms the Earth. The Earth reflects some of this radiation back towards space. Greenhouse gases in the atmosphere trap a portion of this outgoing radiation, which naturally maintains a temperature suitable for life. Increased concentrations of these gases trap more heat, enhancing the effect.</p> Signup and view all the answers

How does human activity lead to global warming?

<p>Human activities increase the concentration of greenhouse gases in the atmosphere. This causes an enhanced greenhouse effect, where more heat is trapped, leading to a gradual increase in the Earth's average temperature, known as global warming.</p> Signup and view all the answers

What are potential consequences of global warming?

<p>Melting of polar ice caps, rise in sea levels leading to flooding, more extreme climate changes (e.g., altered rainfall patterns, increased frequency/intensity of hurricanes, droughts), habitat destruction, disruption of food chains, species migration, species extinction, spread of pests and diseases, and overall decreased biodiversity.</p> Signup and view all the answers

What are the biological consequences of water pollution by sewage?

<p>Raw sewage contains organic waste, nitrates, and phosphates. Bacteria decompose this waste, consuming dissolved oxygen during aerobic respiration. This oxygen depletion can kill fish and other aquatic organisms. The excess nutrients (nitrates, phosphates) can also cause eutrophication.</p> Signup and view all the answers

Explain eutrophication caused by leached minerals from fertilisers.

<p>Artificial fertilisers containing minerals like nitrates and phosphates are added to soil to enhance crop growth. These minerals can be leached (washed) from the soil into rivers and lakes. This nutrient enrichment is called eutrophication.</p> Signup and view all the answers

Describe the process and consequences of eutrophication due to fertiliser pollution.

<p>Fertiliser runoff causes mineral enrichment (eutrophication) in water bodies. Excess minerals fuel rapid growth of algae (algal bloom). Surface algae block sunlight, causing underwater plants to die from lack of photosynthesis. Bacteria decompose the dead plants, consuming large amounts of dissolved oxygen through aerobic respiration. The resulting low oxygen levels (hypoxia) kill fish and other aquatic organisms.</p> Signup and view all the answers

What is deforestation and why does it occur?

<p>Deforestation is the large-scale, often unsustainable clearing of forests. Trees are removed for fuel, timber (for building, furniture, paper), and to clear land for agriculture (crops, animal grazing), housing, and roads.</p> Signup and view all the answers

What are the environmental impacts of deforestation?

<p>Decreased photosynthesis rates (less CO2 absorption, less O2 release), increased atmospheric CO2 (from burning/decay), increased soil erosion (loss of roots and canopy cover), altered rainfall patterns (less evapotranspiration), increased surface run-off and mineral leaching leading to reduced soil fertility and potential river silting.</p> Signup and view all the answers

What are the biodiversity impacts of deforestation and how can it be reduced?

<p>Deforestation results in loss of food sources, habitat loss, decreased biodiversity (fewer species), disruption of food chains, and potential extinction of endangered species. It can be reduced through laws limiting deforestation and promoting reforestation efforts.</p> Signup and view all the answers

Define Population in ecological terms.

<p>The number of individuals of a single species living within a specific ecosystem or area.</p> Signup and view all the answers

Define Community in ecological terms.

<p>All the different populations (different species) living and interacting within a specific ecosystem or area.</p> Signup and view all the answers

Define Habitat.

<p>The specific place or natural environment where an organism or species normally lives within an ecosystem.</p> Signup and view all the answers

Define Ecosystem.

<p>All the living organisms (biotic components) interacting with each other and with their physical (abiotic) environment in a particular area.</p> Signup and view all the answers

Describe a practical method to investigate and compare the population size of an organism in two different areas using quadrats.

<ol> <li>Place a quadrat (e.g., 1m²) randomly within the first area (use random coordinates). 2. Identify and count the number of the target organism within the quadrat (use a key if needed). 3. Repeat random quadrat placements multiple times in the first area. 4. Calculate the average number of organisms per quadrat. 5. Estimate the total population size by multiplying the average density by the total area size. 6. Repeat the entire procedure (steps 1-5) in the second area, ensuring similar conditions (e.g., time of day, season). 7. Compare the estimated population sizes.</li> </ol> Signup and view all the answers

What is Biodiversity?

<p>The variety or range of different species living within an ecosystem or region.</p> Signup and view all the answers

What human activities can reduce biodiversity?

<p>Human activities such as deforestation and the combustion of fossil fuels (leading to pollution like acid rain and contributing to global warming) can significantly reduce biodiversity.</p> Signup and view all the answers

Describe a practical method to investigate the distribution of organisms and measure biodiversity along a transect using quadrats.

<ol> <li>Lay down a transect line across the area where an environmental factor (e.g., light intensity) changes. 2. Place quadrats at regular intervals along the transect line. 3. Within each quadrat, identify all the different species present. 4. Count the number of individuals of each species (or estimate percentage cover). 5. Measure the relevant abiotic factor (e.g., light intensity) at each quadrat position. 6. Repeat with parallel transects for reliability. 7. Analyze the data to see how species distribution and the number of species (biodiversity) change along the environmental gradient.</li> </ol> Signup and view all the answers

List some abiotic (non-living) factors that affect the population size and distribution of organisms.

<p>Temperature, light intensity, carbon dioxide concentration, oxygen concentration, soil pH, soil mineral content, and humidity.</p> Signup and view all the answers

List some biotic (living) factors that affect the population size and distribution of organisms.

<p>Competition (for resources like food, mates, habitat), predation, grazing (herbivory), and disease (caused by pathogens).</p> Signup and view all the answers

Define Trophic level.

<p>The position an organism occupies in a food chain, indicating its feeding level (e.g., producer, primary consumer, secondary consumer).</p> Signup and view all the answers

Why are plants called producers?

<p>Because they perform photosynthesis, converting light energy into chemical energy in the form of glucose (their own 'food').</p> Signup and view all the answers

Why are animals called consumers?

<p>Because they obtain energy by feeding on other organisms.</p> Signup and view all the answers

What are decomposers and what role do they play in energy flow?

<p>Decomposers are organisms like bacteria and fungi. They break down dead plants and animals, returning the energy contained within this dead organic matter to the ecosystem, often releasing CO2 during respiration.</p> Signup and view all the answers

What are predators?

<p>Consumers (animals) that hunt and eat other animals (called prey).</p> Signup and view all the answers

What does a food chain show?

<p>It shows the feeding relationships between organisms in an ecosystem, indicating the pathway of energy transfer. It always begins with a producer.</p> Signup and view all the answers

What does a food web show?

<p>It shows the interconnected and overlapping food chains within an ecosystem, representing more complex feeding relationships.</p> Signup and view all the answers

What is a pyramid of numbers?

<p>A diagram that represents the number of individual organisms at each trophic level in an ecosystem.</p> Signup and view all the answers

What is a Pyramid of Biomass?

<p>A diagram that represents the total mass of living organisms (biomass) at each trophic level in an ecosystem at a specific time.</p> Signup and view all the answers

What is dry biomass and how is it measured?

<p>Dry biomass is the mass of organisms after all water content has been removed. It's measured by weighing a sample, heating it in an oven to remove water, re-weighing, and repeating the heating and weighing process until the mass remains constant.</p> Signup and view all the answers

What does a Pyramid of Energy Transfer show?

<p>It shows the amount of energy transferred from one trophic level to the next higher trophic level in an ecosystem over a period of time.</p> Signup and view all the answers

Approximately how much energy is typically transferred from one trophic level to the next?

<p>Around 10%.</p> Signup and view all the answers

In agriculture, why are animals sometimes kept indoors in controlled conditions?

<p>To reduce energy loss and promote faster growth. Keeping animals indoors limits their movement and maintains warmer conditions, reducing energy spent on maintaining body temperature and physical activity.</p> Signup and view all the answers

What flows through food chains in an ecosystem?

<p>Energy flows through food chains.</p> Signup and view all the answers

What are recycled within ecosystems?

<p>Substances or matter (e.g., elements like nitrogen, carbon, water) are recycled.</p> Signup and view all the answers

Explain the main ways the approximate 90% of energy is lost between trophic levels.

<p>Energy is lost through: metabolic processes like respiration (released as heat, used for movement), parts of the organism not consumed (e.g., bones, roots), undigested material excreted as faeces (egestion), waste products excreted in urine (excretion), energy remaining in dead organisms utilized by decomposers, and energy used for thermoregulation (maintaining body temperature in mammals and birds).</p> Signup and view all the answers

What are the 4 stages in the carbon cycle?

<p>Respiration, photosynthesis, decomposition, combustion</p> Signup and view all the answers

Describe respiration in the context of the carbon cycle.

<p>Living organisms release CO2 into the atmosphere through the process of respiration.</p> Signup and view all the answers

Describe Photosynthesis in the context of the carbon cycle.

<p>Green plants absorb CO2 from the atmosphere, using it to form sugars / glucose.</p> Signup and view all the answers

Describe Decomposition in the context of the carbon cycle.

<p>Bacteria and fungi break down dead organic material using enzymes, releasing CO2 during their own respiration.</p> Signup and view all the answers

Describe Combustion in the context of the carbon cycle.

<p>Burning fossil fuels (coal, oil, natural gas) and organic matter (e.g., wood during deforestation) releases stored carbon into the atmosphere as CO2.</p> Signup and view all the answers

What are the key stages of the nitrogen cycle?

<ol> <li>Plants absorb nitrates from the soil.</li> <li>Plants react nitrates with glucose to make amino acids.</li> <li>Plants are eaten by herbivores, which may be eaten by carnivores (nitrogen transfer).</li> <li>Plants and animals die, forming dead organic matter.</li> <li>Animal waste (urine) also contains nitrogen.</li> <li>Dead matter and waste are broken down by decomposers into ammonium compounds.</li> <li>Ammonium compounds are oxidized into nitrites then nitrates by nitrifying bacteria (nitrification).</li> <li>Denitrifying bacteria convert (reduce) nitrates back into nitrogen gas in the atmosphere.</li> <li>Nitrogen-fixing bacteria (in root nodules of legumes or free in soil) convert nitrogen gas into ammonium compounds.</li> </ol> Signup and view all the answers

What are the biological consequences of carbon monoxide exposure?

<p>Carbon monoxide binds strongly with haemoglobin in red blood cells, reducing their capacity to carry oxygen. High levels can lead to death because insufficient oxygen reaches tissues for respiration, thus preventing adequate energy release.</p> Signup and view all the answers

What are the biological consequences of sulphur dioxide pollution?

<p>Sulphur dioxide reacts with water vapour in clouds, forming sulphuric acid, which falls as acid rain (pH below 5.5). Consequences of acid rain include:</p> <ul> <li>Damage to plant leaves and roots, killing trees.</li> <li>Decreased photosynthesis rates.</li> <li>Disruption of food chains (fewer producers).</li> <li>Denaturation of enzymes in organisms due to low pH, slowing reactions.</li> <li>Release of toxic substances (e.g., heavy metal ions) from soil.</li> <li>Damage to fish eggs and death of fish.</li> </ul> Signup and view all the answers

Which greenhouse gases do human activities contribute significantly to?

<p>Water vapour, Carbon dioxide (CO2), Nitrous oxide (N2O), Methane (CH4), and Chlorofluorocarbons (CFCs).</p> Signup and view all the answers

How is water vapour formed and contribute to the greenhouse effect?

<p>Water vapour enters the atmosphere through evaporation, transpiration from plants, respiration from organisms, and combustion processes.</p> Signup and view all the answers

How is Carbon Dioxide (CO2) generated by human activities?

<p>Mainly through the combustion of fossil fuels (coal, oil, natural gas) in power stations, vehicles, and industry. Deforestation also contributes by reducing the amount of CO2 absorbed by photosynthesis.</p> Signup and view all the answers

How is Nitrous Oxide (N2O) generated by human activities?

<p>Primarily from agricultural practices (fertiliser use), industrial processes, and the combustion of fossil fuels, particularly in vehicle engines.</p> Signup and view all the answers

How is Methane (CH4) generated by human activities?

<p>Sources include livestock farming (enteric fermentation in cattle), rice cultivation in paddy fields, decomposition of organic waste in landfill sites, and natural gas leaks.</p> Signup and view all the answers

What are common sources of Chlorofluorocarbons (CFCs)?

<p>Historically used in aerosols, refrigeration and air conditioning systems, and as solvents and foam-blowing agents.</p> Signup and view all the answers

How does an increase in greenhouse gases result in an enhanced greenhouse effect?

<p>The sun's radiation warms the Earth. The Earth reflects some of this radiation back towards space, mostly as infrared radiation. Greenhouse gases in the atmosphere trap some of this outgoing infrared radiation, preventing it from escaping into space. This natural trapping keeps the Earth warm enough for life. An increase in greenhouse gases enhances this trapping effect.</p> Signup and view all the answers

How does human activity lead to global warming?

<p>Human activities release increased amounts of greenhouse gases (like CO2, methane, nitrous oxide) into the atmosphere. This causes an enhanced greenhouse effect, trapping more heat and leading to a gradual increase in the Earth's average temperature, known as global warming.</p> Signup and view all the answers

What are some potential consequences of global warming?

<ul> <li>Melting of polar ice caps and glaciers.</li> <li>Rise in sea levels, leading to coastal flooding.</li> <li>More extreme climate events (e.g., changes in rainfall patterns, more intense hurricanes, droughts, heatwaves).</li> <li>Destruction and shifts of habitats.</li> <li>Disruption of food chains and ecosystems.</li> <li>Migration of species to new areas.</li> <li>Increased extinction rates.</li> <li>Spread of pests and diseases to new regions.</li> <li>Overall decrease in biodiversity.</li> </ul> Signup and view all the answers

What are the biological consequences of water pollution by sewage?

<p>Raw sewage contains organic waste, pathogens, nitrates, and phosphates (from faeces, urine, detergents). Bacteria decompose the organic waste, multiplying rapidly and consuming large amounts of dissolved oxygen through aerobic respiration, while producing CO2. This oxygen depletion (hypoxia) can kill fish and other aquatic organisms that rely on dissolved oxygen for their own respiration. The excess nutrients (nitrates, phosphates) in sewage also contribute to eutrophication.</p> Signup and view all the answers

What are the biological consequences of eutrophication caused by leached minerals from fertilisers?

<p>Farmers use artificial fertilisers (containing nitrates, phosphates) to enhance crop yield by replacing soil minerals. Rainfall can wash (leach) these excess minerals from fields into rivers and lakes, causing pollution and leading to eutrophication.</p> Signup and view all the answers

Describe the process of eutrophication caused by fertiliser pollution.

<ol> <li>Excess minerals (nitrates, phosphates) from leached fertilisers enter a water body (river, lake).</li> <li>These nutrients cause rapid growth of algae (an algal bloom).</li> <li>The dense layer of algae on the surface blocks sunlight from reaching plants below.</li> <li>Submerged plants die due to lack of light for photosynthesis.</li> <li>Bacteria decompose the dead plants, reproducing rapidly.</li> <li>These decomposing bacteria consume large amounts of dissolved oxygen during aerobic respiration.</li> <li>The decrease in dissolved oxygen kills fish and other aquatic animals that cannot respire.</li> </ol> Signup and view all the answers

What is deforestation, and why does it occur?

<p>Deforestation is the large-scale, often unsustainable, clearing of forests. Reasons include: using trees for fuel, building materials, furniture, and paper; clearing land for agriculture (growing crops, grazing animals), housing, and roads.</p> Signup and view all the answers

What are the environmental impacts of deforestation?

<ul> <li>Decreased rate of photosynthesis, leading to less CO2 absorption and less O2 release.</li> <li>Increased CO2 release from burning and decay during land clearance.</li> <li>Increased soil erosion, as tree roots no longer hold soil and the canopy doesn't intercept rain.</li> <li>Reduced evapotranspiration from trees, leading to less rainfall, altered water cycles, and drier soil.</li> <li>Increased surface water run-off and leaching of minerals, reducing soil fertility and potentially causing rivers to silt up.</li> </ul> Signup and view all the answers

What are the impacts of deforestation on biodiversity, and how can it be reduced?

<p>Results in:</p> <ul> <li>Loss of diverse food sources for wildlife.</li> <li>Destruction and fragmentation of habitats.</li> <li>Decrease in biodiversity (the variety of species).</li> <li>Disruption of complex food chains.</li> <li>Potential extinction of endangered species reliant on the forest habitat. Reduced by:</li> <li>Implementing and enforcing laws to limit or prevent deforestation.</li> <li>Promoting sustainable forestry practices.</li> <li>Reforestation and afforestation programs (replanting trees).</li> </ul> Signup and view all the answers

Define Population in ecological terms.

<p>A population is the total number of individuals of one particular species living within a defined ecosystem or area at a specific time.</p> Signup and view all the answers

Define Community in ecological terms.

<p>A community consists of all the different populations (all the different species) living and interacting within a specific ecosystem or area.</p> Signup and view all the answers

Define Habitat.

<p>The specific place or natural environment where an organism or species normally lives within an ecosystem.</p> Signup and view all the answers

Define Ecosystem.

<p>An ecosystem includes all the living organisms (biotic components) interacting with each other and with their physical (abiotic) environment in a particular area.</p> Signup and view all the answers

Describe a practical method to investigate the population size of an organism in two different areas using quadrats.

<ol> <li>Choose quadrat size (e.g., 1m²).</li> <li>In the first area, place the quadrat randomly multiple times. Random placement can be achieved using random coordinates generated from measuring tapes laid along two edges of the area.</li> <li>Use a key if necessary to identify the target organism.</li> <li>Count the number of the target organism within the quadrat each time it is placed.</li> <li>Calculate the average number of organisms per quadrat.</li> <li>Estimate the total population size by multiplying the average number per quadrat by the total area (Population size = (Total area / Quadrat area) * Mean number per quadrat).</li> <li>Repeat steps 2-6 in the second area, ensuring conditions (e.g., time of day, season) are comparable.</li> </ol> Signup and view all the answers

What is Biodiversity?

<p>Biodiversity refers to the variety or range of different species living within an ecosystem or habitat.</p> Signup and view all the answers

What human activities can reduce biodiversity?

<p>Human activities such as deforestation, habitat destruction, pollution (leading to phenomena like global warming and eutrophication), overfishing, hunting, and introduction of invasive species.</p> Signup and view all the answers

Describe a practical method to investigate the distribution of organisms and measure biodiversity using quadrats along a transect.

<ol> <li>Lay down a transect line (e.g., a tape measure) across the area of interest, often chosen to cross an environmental gradient (like from shade to full sun, or from wet to dry ground).</li> <li>Place quadrats at regular intervals along the transect line.</li> <li>Within each quadrat, identify all the different species present (using keys if needed) and count the number of individuals of each species (or estimate percentage cover for plants).</li> <li>Record the abiotic factors (e.g., light intensity, soil pH, temperature) at each quadrat position if investigating links between distribution and environment.</li> <li>Repeat the process using several parallel transect lines to ensure the data is representative and calculate mean values.</li> <li>Biodiversity can be assessed by comparing the number of different species found at different points along the transect.</li> </ol> Signup and view all the answers

List some abiotic (non-living) factors that affect the population size and distribution of organisms.

<ul> <li>Temperature (affects enzyme activity, metabolic rates)</li> <li>Light intensity (crucial for photosynthesis)</li> <li>Carbon dioxide concentration (affects photosynthesis rate)</li> <li>Oxygen concentration (affects aerobic respiration rate)</li> <li>Water availability</li> <li>Soil factors (pH, mineral content, texture, moisture - affect plant growth)</li> <li>Humidity (affects water loss, especially in plants and insects)</li> </ul> Signup and view all the answers

List some biotic (living) factors that affect the population size and distribution of organisms.

<ul> <li>Competition (for resources like food, water, mates, space, light)</li> <li>Predation (predators hunting prey)</li> <li>Grazing (herbivores eating plants)</li> <li>Disease (caused by pathogens like bacteria, viruses, fungi)</li> <li>Parasitism</li> <li>Availability of food sources</li> <li>Mutualism (beneficial interactions between species)</li> </ul> Signup and view all the answers

Define Trophic level.

<p>A trophic level represents the feeding position or stage an organism occupies in a food chain or food web.</p> Signup and view all the answers

Why are plants called producers?

<p>Because they produce their own food (glucose) through the process of photosynthesis, using light energy, water, and carbon dioxide.</p> Signup and view all the answers

Why are animals called consumers?

<p>Because they obtain energy by feeding on other organisms (producers or other consumers).</p> Signup and view all the answers

What are decomposers and what is their role in energy flow?

<p>Decomposers are organisms, mainly bacteria and fungi, that break down dead organic matter (dead plants and animals, waste products). They release the energy contained within this dead material through their own respiration.</p> Signup and view all the answers

What are predators?

<p>Predators are consumers (usually animals) that hunt, kill, and eat other animals, which are known as prey.</p> Signup and view all the answers

What does a food chain show?

<p>A food chain shows the linear sequence of feeding relationships between different organisms in an ecosystem, indicating 'what eats what'. It always begins with a producer.</p> Signup and view all the answers

What does a food web show?

<p>A food web illustrates the complex network of interconnected food chains within an ecosystem, showing the multiple feeding relationships between different species.</p> Signup and view all the answers

What is a pyramid of numbers?

<p>A pyramid of numbers is a diagram that represents the total number of individual organisms at each trophic level in an ecosystem.</p> Signup and view all the answers

What is a Pyramid of Biomass?

<p>A pyramid of biomass represents the total mass of living organisms (biomass) present at each trophic level in an ecosystem at a specific time.</p> Signup and view all the answers

What is dry biomass and how is it measured?

<p>Dry biomass is the mass of organisms after all water content has been removed. It is measured by weighing a sample of the organisms, heating them in an oven (e.g., at 80-100°C) to evaporate the water, allowing them to cool, and re-weighing. This heating and weighing process is repeated until the mass remains constant, indicating all water has been removed.</p> Signup and view all the answers

What does a Pyramid of Energy Transfer show?

<p>A pyramid of energy transfer (or pyramid of energy) represents the amount of energy available or transferred at each successive trophic level in an ecosystem over a period of time.</p> Signup and view all the answers

Approximately how much energy is transferred from one trophic level to the next?

<p>Typically, only about 10% of the energy from one trophic level is incorporated into the biomass of the next trophic level.</p> Signup and view all the answers

In intensive farming, why are animals sometimes kept indoors?

<p>Animals are often kept indoors in controlled conditions to limit their movement and maintain warmer temperatures. This reduces energy loss through physical activity and heat loss to the environment, allowing more energy from their food to be converted into growth (biomass).</p> Signup and view all the answers

What flows through food chains in an ecosystem?

<p>Energy flows through food chains.</p> Signup and view all the answers

What elements are recycled within ecosystems?

<p>Substances or nutrients (e.g., carbon, nitrogen, water, phosphorus) are recycled within ecosystems.</p> Signup and view all the answers

How is approximately 90% of the energy lost between trophic levels?

<p>Energy is lost in several ways:</p> <ul> <li>Used during respiration to provide energy for life processes like movement, growth, and maintaining body temperature (lost as heat).</li> <li>Not all parts of an organism are eaten (e.g., bones, fur, roots, bark).</li> <li>Not all ingested material is digested; some is lost as faeces (egestion).</li> <li>Energy is lost in waste products like urine (excretion).</li> <li>When organisms die without being eaten, their energy is released by decomposers through respiration.</li> <li>Mammals and birds use significant energy for thermoregulation (maintaining constant internal temperature).</li> </ul> Signup and view all the answers

Flashcards

Carbon Cycle Stages?

Respiration, photosynthesis, decomposition, combustion

Respiration

Living organisms release CO2 into the atmosphere.

Photosynthesis

Green plants absorb CO2, forming sugars/glucose.

Decomposition

Bacteria and fungi break down dead organic material, releasing CO2 during respiration.

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Combustion

Burning fossil fuels and organic matter releases CO2.

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Nitrogen Cycle stages

  1. Plants absorb nitrates. 2. Nitrates become amino acids. 3. Consumption. 4. Decomposition. 5. Waste production. 6. Ammonification. 7. Nitrification. 8. Denitrification 9. Nitrogen fixation in root nodules
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Carbon Monoxide Risks

Carbon monoxide binds to haemoglobin, reducing oxygen transport, and can cause death.

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Sulphur Dioxide harms

Sulphur dioxide forms acid rain which damages plants, disrupts food chains, and harms aquatic life.

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Greenhouse Gases

Water vapour, carbon dioxide, nitrous oxide, methane, CFCs.

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Water Vapour Formation

From respiration, transpiration, combustion.

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Carbon Dioxide Formation

Combustion of fossil fuels and deforestation.

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Nitrous Oxide Formation

From combustion of fossil fuels (car engines).

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Methane Formation

Cattle farming, rice fields, decomposition in landfill sites.

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CFCs Formation

Aerosols, fridges, deodorants.

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Greenhouse Effect

Greenhouse gases trap reflected radiation, maintaining a suitable temperature for life.

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Global Warming Cause

Increased greenhouse gases cause more heat to be trapped, leading to global warming.

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Global Warming Results

Melting ice caps, rising sea levels, extreme climate changes, habitat destruction, etc.

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Sewage Pollution Results

Sewage decomposition by bacteria uses up O2, killing fish; extra nutrients cause eutrophication.

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Eutrophication Results

Fertilisers cause algal blooms. Algae block light and plants die. Bacteria use up O2, killing fish.

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Pollution From Fertilisers

Fertilisers cause algal blooms. Algae block light and plants die. Bacteria use up O2, killing fish.

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Deforestation

Large scale, unsustainable forest clearance for fuel, land, etc.

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Deforestation Results

Decreased photosynthesis, increased CO2, soil erosion, less rainfall, mineral leaching.

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Deforestation Consequences

Loss of food types, habitats, biodiversity, disrupted food chains, extinction.

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Population

Number of one species living in an ecosystem.

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Community

All the populations (different species) living in an ecosystem.

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Habitat

The place where an organism or species lives in an ecosystem.

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Ecosystem

All the organisms living and interacting with each other in an area along with the physical (abiotic) conditions.

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Practical uses of quadrats

Use quadrats randomly in two areas, count organisms, calculate average, and estimate population size.

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Biodiversity

The variety (range) of different species in an ecosystem.

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Biodiversity Reduction

Human activity - Deforestation, combustion of fossil fuels resulting in global warming.

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Distribution & Biodiversity

Use quadrats along a transect line, identify species, count organisms, and repeat to calculate mean values.

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Abiotic factors?

Temperature, light intensity, CO2 concentration, O2 concentration, soil pH / mineral content, humidity.

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Biotic factors?

Competition for food / mate / habitat, Pathogens/Disease, Predation (caused by carnivore), grazing (caused by herbivore).

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Trophic Level

Feeding level of an organism in a food chain e.g. primary consumer

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Plants = Producers

Because they carry out photosynthesis, producing their own 'food' - glucose

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Animals = Consumers

As they feed on other organisms

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Role of decomposers

bacteria, fungi that return energy to the atmosphere in respiration

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Predators

Consumers which eat animals called prey

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What food chains show

The feeding relationships between organisms (what eats what). It begins with a producer

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What food webs show

The interacting food chains in an ecosystem

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Pyramid of Numbers

Shows number of organisms at each trophic level in an ecosystem

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Pyramid of Biomass

Shows the mass of living organisms (biomass) at each trophic level in an ecosystem

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Dry Biomass

Mass of organisms without water

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Pyramid of Energy Transfer

The amount of energy transferred between tropic levels in an ecosystem

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Energy transferred

10%

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Intensive farming

  • Less movement, Warmer conditions (less heat loss) To reduce energy loss and promote growth
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Energy In Ecosystems

Energy flows through food chains

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Substances Recycled

Substances (E.g. nitrogen, carbon)

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Energy Loss

  • used in respiration, providing energy for e.g. movement (lost as heat),- Lost in parts of the organism that are not eaten (e.g. roots/bark, bones/fur) - lost in parts not digested in faeces (egestion) - Lost in urine (excretion) - Death/decomposition
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Study Notes

Carbon Cycle Stages

  • Respiration releases CO2 into the atmosphere from living organisms.
  • Photosynthesis absorbs CO2 from the atmosphere, converting it into sugars/glucose by green plants.
  • Decomposition involves bacteria and fungi breaking down dead organic material with enzymes, releasing CO2 through respiration.
  • Combustion is the burning of fossil fuels and organic matter, which releases CO2.

Nitrogen Cycle Stages

  • Plants absorb nitrates from the soil.
  • Nitrates react with glucose to create amino acids in plants.
  • Herbivores consume plants, and carnivores may then eat herbivores.
  • Dead plants and animals become dead organic matter.
  • Animal waste (urine) contains nitrogen.
  • Decomposers break down dead matter and waste into ammonium compounds.
  • Nitrifying bacteria oxidize ammonium compounds into nitrites, then nitrates (nitrification).
  • Denitrifying bacteria reduce nitrates back into nitrogen gas, which is released into the atmosphere.
  • Nitrogen-fixing bacteria in root nodules and soil convert nitrogen gas into ammonium compounds.

Biological Consequences of Carbon Monoxide

  • Carbon monoxide binds strongly to haemoglobin, reducing oxygen transport in the body.
  • High levels of carbon monoxide can cause death due to insufficient oxygen reaching tissues for respiration.

Biological Consequences of Sulphur Dioxide

  • Sulphur dioxide reacts with water vapour in clouds, which forms sulphuric acid.
  • This results in acid rain, with a pH below 5.5.
  • Acid rain damages plant leaves and roots and can kill trees.
  • The rate of photosynthesis in plants decreases.
  • Food chains are disrupted due to fewer producers.
  • Low pH denatures enzymes, slowing down chemical reactions.
  • Toxic substances, like heavy metal ions, are released from the soil.
  • Fish eggs are damaged, and fish may die.

Greenhouse Gases

  • Human activities contribute to greenhouse gases, including water vapour, carbon dioxide, nitrous oxide, methane, and CFCs.
  • CFCs also damage the ozone layer.

Formation of Greenhouse Gases

  • Water vapour forms from respiration, transpiration, and combustion.
  • Carbon dioxide forms from the combustion of fossil fuels like coal, oil, and gas and from deforestation, which reduces CO2 absorption.
  • Nitrous oxide forms from the combustion of fossil fuels in car engines.
  • Methane forms from cattle farming, rice fields, and decomposition in landfill sites.
  • CFCs form from aerosols, fridges, and deodorants.

Enhanced Greenhouse Effect

  • Solar radiation warms the Earth.
  • The Earth reflects radiation, and greenhouse gases trap much of it.
  • This process maintains a temperature suitable for life.
  • Increased greenhouse gases due to human activity trap more heat, leading to global warming.

Potential Results of Global Warming

  • Melting of polar ice caps.
  • Rising sea levels and flooding.
  • Extreme climate changes, such as altered rainfall patterns, hurricanes, and droughts.
  • Destruction of habitats.
  • Disruption of food chains.
  • Migration of species.
  • Extinction of species.
  • Spread of pests/diseases.
  • Decreased biodiversity.

Biological Consequences of Sewage Water Pollution

  • Raw sewage contains organic waste, nitrates, and phosphates from faeces, urine, and detergents.
  • Decomposing bacteria reproduce rapidly and use up dissolved O2, producing CO2.
  • Fish die due to a lack of O2 for respiration.
  • Additional nutrients cause eutrophication, leading to the death of aquatic organisms, similar to the effects of fertilisers.

Biological Consequences of Eutrophication

  • Fertilisers contain minerals, such as nitrates and phosphates, which can be leached into rivers and lakes.
  • This mineral enrichment, called eutrophication, causes algae to grow rapidly (algal bloom).
  • Algae block light, causing plants below to die, lacking light for photosynthesis.
  • Bacteria feed on dead plants, reproduce quickly, and use up O2 during aerobic respiration.
  • Oxygen depletion kills fish because they cannot respire.

Deforestation

  • Deforestation is large-scale, unsustainable forest clearance.
  • Trees are used for fuel, building, furniture, and paper.
  • Cleared land is used for crops, grazing, housing, and roads.

Consequences of Deforestation

  • Photosynthesis rates decrease, which means less CO2 is absorbed, and less O2 is released.
  • Burning and decay during land clearance release more CO2.
  • Soil erosion increases due to a lack of roots and canopy interception.
  • Evapotranspiration decreases, leading to less rainfall and reduced water retention in the soil, disrupting the water cycle.
  • Runoff increases, causing mineral leaching and soil fertility loss, which can silt up rivers.
  • Food sources are lost.
  • Habitats are lost.
  • Biodiversity decreases.
  • Food chains are disrupted.
  • Endangered species face extinction.

Reducing Deforestation

  • Laws can limit or prevent deforestation.
  • Replanting trees can help mitigate the effects of deforestation.

Ecological Definitions

  • Population: The number of one species living in an ecosystem.
  • Community: All the populations (different species) living in an ecosystem.
  • Habitat: The place where an organism or species lives in an ecosystem.
  • Ecosystem: All the organisms living and interacting in an area, along with the physical (abiotic) conditions.

Quadrat Practical for Population Size

  • Place a 1m² quadrat randomly using coordinates.
  • Identify organisms using a key.
  • Count the number of organisms in each quadrat and calculate the average.
  • Multiply the average by the area size to estimate the population size.
  • Repeat the process in another area during the same day/season.

Biodiversity

  • Biodiversity is the variety (range) of different species in an ecosystem.
  • Human activities like deforestation and fossil fuel combustion reduce biodiversity.

Quadrat Practical for Distribution and Biodiversity

  • Organism distribution and biodiversity are affected by changes in abiotic factors.
  • Place quadrats along a transect line at regular intervals.
  • Identify different species within each quadrat and count their numbers (or measure percentage cover).
  • Use parallel transect lines to calculate mean values.

Abiotic Factors

  • Temperature affects enzyme activity, such as in photosynthesis.
  • Light intensity and CO2 concentration affect the rate of photosynthesis.
  • Oxygen concentration affects the rate of respiration.
  • Soil pH and mineral content affect plant growth rates.
  • Humidity affects plant growth and water loss.

Biotic Factors

  • Competition for food, mates, or habitat.
  • Predation (by carnivores) and grazing (by herbivores).
  • Disease (caused by pathogens like bacteria and viruses).

Trophic Levels

  • Trophic level defines an organism's feeding level in a food chain.
  • Plants are called producers because they produce their own food (glucose) through photosynthesis.
  • Animals are called consumers because they feed on other organisms.
  • Decomposers, such as bacteria and fungi, return energy from dead organisms to the atmosphere via respiration.
  • Predators are consumers that eat other animals (prey).
  • A food chain shows the feeding relationships between organisms, starting with a producer.
  • A food web shows the interacting food chains in an ecosystem.

Ecological Pyramids

  • Pyramid of Numbers shows the number of organisms at each trophic level.
  • Pyramid of Biomass shows the mass of living organisms (biomass) at each trophic level.
  • Dry biomass is the mass of organisms without water.
  • Pyramid of Energy Transfer shows the amount of energy transferred between trophic levels.

Energy Transfer

  • Approximately 10% of energy is transferred from one trophic level to the next.
  • Animals are kept indoors to reduce movement and maintain warmer conditions, which minimizes energy loss and promotes growth.
  • Energy flows through food chains in an ecosystem.
  • Substances (e.g., nitrogen, carbon) are recycled within food chains in an ecosystem.
  • 90% of energy is lost between trophic levels due to:
    • Respiration (energy for movement, lost as heat).
    • Parts of the organism not eaten (e.g., roots/bark, bones/fur).
    • Undigested parts in faeces (egestion).
    • Loss in urine (excretion).
    • Death/decomposition (energy released by decomposers).
    • Thermoregulation in mammals and birds.

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