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Edexcel IGCSE - Human Biology - Chapter 14 - Human influences on the environment

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Chandima Walpita Gamage

This document discusses ecosystems and human influences on the environment. It defines ecosystems and their key components like producers, consumers, and decomposers. It explains photosynthesis and how plants convert glucose for storage, transport, and growth. Food chains and webs show feeding relationships between trophic levels in an ecosystem. Ecological pyramids represent these relationships. The document also covers human waste treatment like sewage systems and pit latrines. It discusses pollution issues like eutrophication from excess nutrients and air pollution from carbon emissions. Reforestation helps address problems caused by deforestation.

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chandimakumara007@gmail.com Edexcel IGCSE Human Biology Chapter 14 Human Influences on the environment
Ecosystems • A distinct, self supporting system of organisms interacting with each other and with their physical environment • Can be small, such as wood or large like a tropical rainforest. • Components of an ecosystem, – Producers – green plants, that photosynthesis to produce food. – Consumers – animals who eat plants or other animals. – Decomposers – bacteria and fungi, who recycle nutrients. – Physical environmental – non biological components (water, soil and air)
Plants and Photosynthesis • This is the reversed equation for the aerobic respiration (see chapter 1)
Conversion of Glucose in plants • Starch – as a storage in plant leaves, roots and other organs. • Sucrose – for transportation. • Cellulose – as a component of the cell wall. • Lipids – as a storage in fruits and seeds (peanuts, sunflower seeds and olives) • Proteins and DNA – with the help of mineral irons from soil (nitrates and phosphates) • Chlorophyll – with the help of magnesium ions in the soil.
Feeding relationships • Food chain – simplest way of showing feeding relationship within an ecosystem – the arrow (→) means “is eaten by” • Primary consumer – organisms that eats the producer • Secondary consumer – organisms that feed on the primary consumer • Trophic levels – the different stages in a food chain • Tertiary consumer – organisms that feed on the secondary consumers • Quaternary consumer – organisms that feed on the tertiary consumers • Top carnivore – the carnivore at the end of a food chain • Food web – linking several chains together
Edexcel IGCSE - Human Biology - Chapter 14 - Human influences on the environment
Ecological pyramids • Ecological pyramids are diagrams that represent relative amounts of organisms at each trophic level. 1. Pyramids of numbers – represent the number of organisms in a trophic level 2. Pyramids of biomass – show the total mass of organisms in a trophic level (1) (2)
Why are diagrams of feeding relationships pyramid shaped? • Some part of the producer re not digested or absorbed. • Some of the absorbed materials are excreted. • Much of the material is respired to release energy and loss by water and CO2.
The flow of energy through ecosystem • Photosynthesis fixes sunlight energy as chemical energy ( Ex: Glucose) • Respiration releases from organic compounds • Almost all biological processes use energy released in respiration – Contraction – Growth – Reproduction – Excretion – Active transport • If the energy released in respiration is used to produce new cells, then the energy remains fixed in molecules in that organism. • If the energy released in respiration is used for other processes then it will eventually escape as heat from the organism. • Energy flow diagrams – shows the main ways in which energy is transferred in an ecosystem
Decomposers • Decomposers (bacteria and fungi) break down complex organic materials into simpler substances • Main decomposers are; – Bacteria – Fungi • Respiration of decomposers produce H2O and CO2 which can be used by the plants for photosynthesis • Proteins are broken down to ammonia and then to nitrates which are essential minerals for the plants • Humans use this natural decomposing process in treatment of sewage
Sewage treatment • Sewage is wet waste from houses, factories and farms. • If sewage is discharged untreated it can lead to many problems; – As aerobic bacteria uses high amount of oxygen, the depletion of water kills many of the organisms – Untreated sewage contains pathogenic bacteria which are health hazards • As a result of that only anaerobic bacteria will only survive • As the water flows down it mixes up with oxygen in the atmosphere and it increases the O2 level in the water • This allows the clean water species to survive • Aim of sewage treatment is to remove solid and suspended organic matter and pathogens and to discharge cleaner effluent to the water ways
Edexcel IGCSE - Human Biology - Chapter 14 - Human influences on the environment
Two methods of sewage treatment
Sewage treatment contd.. • Fungi and bacteria start the conversion of proteins in to ammonia and then to nitrates • Then, protozoa and larger invertebrate animals such as worms act on the organic matter • At the end effluent has less organic matter and less pathogens, but it leads to eutrophication • The waste sludge in tanks are used in other forms – The anaerobic digestion produces biogas that can be used as a fuel in electricity generators – After anaerobic digestion the dry solid leftovers used as fertilizer or used for land filling
Pit Latrines • A composting toilet is a simple way of dealing with human waste • The pit contain a hole in the ground over a sunken pit • In the pit, faeces and urine are broken down by microorganisms • An improved version is called ventilated improved pit latrine (VIP) • VIP has a covered pit and vent pipe • Vent pipe – take away odours – has a suction effect that draws clean air through the latrine – The fly screen prevent flies leaving the pit (as flies can carry pathogens outside) • Sand or sawdust may be added to the pit after use to prevent smells and discourage flies • Larger pit latrines does not need emptying and smaller ones need new pit dug
Pit Latrines
Eutrophication • A situation where a larger amounts of inorganic material (nitrates and phosphates) enter a body of water • Pollution by these minerals can have very harmful effects on an aquatic ecosystem • There are two main sources of excess minerals – From untreated or treated sewage – From artificial nitrate or phosphate fertilizers • Leaching – Fertilizer highly concentrated with nitrogen and phosphate washed out by the rain and added to streams and rivers
Process of eutrophication Death of Fish and other animals Bacteria use up oxygen Decomposition of death algae Death of algae Rapid growth of algae (Algae bloom) Increase minerals in rivers or lakes Leaching Low oxygen levels inside the lake Decrease photosynthesis of the plants Algae growth inhibits light coming inside the lake Death of Fish and other animals
Process of water purification Treated water is pumped to homes Chlorination to kill microorganisms Sending the water through a filter bed of microorganisms for oxidization Sludge is used as fertilizer or land fillings Water is pumped to settling tanks for suspension. Screening for solid objects, weeds and debris. Water is taken from a source.
Process of water purification
Pollution • Pollution takes place when humans release substances into the environment that have harmful effects and they are not easily removed by the biological processes. • Pollution is measured by the amount of pollutant.
Air pollution • Carbon dioxide – The reason rise is due to; • increase burning fossil fuels (coal, oil, natural, petrol and diesel) • Cutting down large areas of tropical rainforest (extensive deforestation) – Consequences of increased levels of CO2; • Causes global warming (enhanced greenhouse effect)
Greenhouse effect • Greenhouse gases, – CO2 – Water vapour – Methane (CH4) – Nitrous oxide (N2O) – CFCs • Describe how greenhouse gases increase temperature?
Greenhouse effect • The rise of Earth’s temperature; – Melt polar ice caps that would increase sea levels – Changing major ocean currents that result in warm water beam redirected into previous cooler areas – long term climate change – Change in the nature of ecosystems; • Species are enable to adapt to their habitat and they may extinct – Changes in agricultural practices • High temperatures might allow some pests to complete their life cycles more quickly
Air pollution contd…. • Carbon monoxide (CO) – Forms when substances containing carbon are burned with limited oxygen – Dangerous pollutant as it is colorless, ordourless and tasteless – Can cause death by aspiration – Hemoglobin has a strong affinity towards CO than the O2 – So if a person inhales CO he may lose consciousness and will cause death • Sulphur dioxide – Formed when fossils fuels are burned – Cause acid rains that would destroy plants and marine life • Nitrogen oxides – Formed when fossils fuels are burned – Cause acid rains that would destroy plants and marine life
Air pollution contd…. • Methane – Produced when micro organisms ferment larger organic molecules to release energy – Significant organic origins of microorganisms • Decomposition of waste in land fill sites by microorganisms • Fermentation by microorganisms in rumen of cattle and other ruminants • Fermentation by bacteria in rice paddy fields – Causes Global warming
Acid Rain • Normal pH of rain = 5.5 • Acid rain has a lower pH than 5.5
Consequences of deforestation • ‘Slash and burn’ adding CO2 to the environment which leads to global warming and climate change • Less trees to do photosynthesis – Less Co2 is absorbed – Less O2 is produced • Destruction of habitats and bio diversity • Reduced soil quality – No trees and plants to return minerals back to soil – No roots to hold soil together – Rain washes the minerals out ( leaching) • Leaching may cause – Eutrophication – rising water levels and floods • Produce climate change by upsetting earth’s water cycle (as a result of reduced transpiration) • Many undiscovered drugs and crop plants are lost
Reforestation
Edexcel IGCSE - Human Biology - Chapter 14 - Human influences on the environment

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Edexcel IGCSE - Human Biology - Chapter 14 - Human influences on the environment

  • 2. Ecosystems • A distinct, self supporting system of organisms interacting with each other and with their physical environment • Can be small, such as wood or large like a tropical rainforest. • Components of an ecosystem, – Producers – green plants, that photosynthesis to produce food. – Consumers – animals who eat plants or other animals. – Decomposers – bacteria and fungi, who recycle nutrients. – Physical environmental – non biological components (water, soil and air)
  • 3. Plants and Photosynthesis • This is the reversed equation for the aerobic respiration (see chapter 1)
  • 4. Conversion of Glucose in plants • Starch – as a storage in plant leaves, roots and other organs. • Sucrose – for transportation. • Cellulose – as a component of the cell wall. • Lipids – as a storage in fruits and seeds (peanuts, sunflower seeds and olives) • Proteins and DNA – with the help of mineral irons from soil (nitrates and phosphates) • Chlorophyll – with the help of magnesium ions in the soil.
  • 5. Feeding relationships • Food chain – simplest way of showing feeding relationship within an ecosystem – the arrow (→) means “is eaten by” • Primary consumer – organisms that eats the producer • Secondary consumer – organisms that feed on the primary consumer • Trophic levels – the different stages in a food chain • Tertiary consumer – organisms that feed on the secondary consumers • Quaternary consumer – organisms that feed on the tertiary consumers • Top carnivore – the carnivore at the end of a food chain • Food web – linking several chains together
  • 7. Ecological pyramids • Ecological pyramids are diagrams that represent relative amounts of organisms at each trophic level. 1. Pyramids of numbers – represent the number of organisms in a trophic level 2. Pyramids of biomass – show the total mass of organisms in a trophic level (1) (2)
  • 8. Why are diagrams of feeding relationships pyramid shaped? • Some part of the producer re not digested or absorbed. • Some of the absorbed materials are excreted. • Much of the material is respired to release energy and loss by water and CO2.
  • 9. The flow of energy through ecosystem • Photosynthesis fixes sunlight energy as chemical energy ( Ex: Glucose) • Respiration releases from organic compounds • Almost all biological processes use energy released in respiration – Contraction – Growth – Reproduction – Excretion – Active transport • If the energy released in respiration is used to produce new cells, then the energy remains fixed in molecules in that organism. • If the energy released in respiration is used for other processes then it will eventually escape as heat from the organism. • Energy flow diagrams – shows the main ways in which energy is transferred in an ecosystem
  • 10. Decomposers • Decomposers (bacteria and fungi) break down complex organic materials into simpler substances • Main decomposers are; – Bacteria – Fungi • Respiration of decomposers produce H2O and CO2 which can be used by the plants for photosynthesis • Proteins are broken down to ammonia and then to nitrates which are essential minerals for the plants • Humans use this natural decomposing process in treatment of sewage
  • 11. Sewage treatment • Sewage is wet waste from houses, factories and farms. • If sewage is discharged untreated it can lead to many problems; – As aerobic bacteria uses high amount of oxygen, the depletion of water kills many of the organisms – Untreated sewage contains pathogenic bacteria which are health hazards • As a result of that only anaerobic bacteria will only survive • As the water flows down it mixes up with oxygen in the atmosphere and it increases the O2 level in the water • This allows the clean water species to survive • Aim of sewage treatment is to remove solid and suspended organic matter and pathogens and to discharge cleaner effluent to the water ways
  • 13. Two methods of sewage treatment
  • 14. Sewage treatment contd.. • Fungi and bacteria start the conversion of proteins in to ammonia and then to nitrates • Then, protozoa and larger invertebrate animals such as worms act on the organic matter • At the end effluent has less organic matter and less pathogens, but it leads to eutrophication • The waste sludge in tanks are used in other forms – The anaerobic digestion produces biogas that can be used as a fuel in electricity generators – After anaerobic digestion the dry solid leftovers used as fertilizer or used for land filling
  • 15. Pit Latrines • A composting toilet is a simple way of dealing with human waste • The pit contain a hole in the ground over a sunken pit • In the pit, faeces and urine are broken down by microorganisms • An improved version is called ventilated improved pit latrine (VIP) • VIP has a covered pit and vent pipe • Vent pipe – take away odours – has a suction effect that draws clean air through the latrine – The fly screen prevent flies leaving the pit (as flies can carry pathogens outside) • Sand or sawdust may be added to the pit after use to prevent smells and discourage flies • Larger pit latrines does not need emptying and smaller ones need new pit dug
  • 17. Eutrophication • A situation where a larger amounts of inorganic material (nitrates and phosphates) enter a body of water • Pollution by these minerals can have very harmful effects on an aquatic ecosystem • There are two main sources of excess minerals – From untreated or treated sewage – From artificial nitrate or phosphate fertilizers • Leaching – Fertilizer highly concentrated with nitrogen and phosphate washed out by the rain and added to streams and rivers
  • 18. Process of eutrophication Death of Fish and other animals Bacteria use up oxygen Decomposition of death algae Death of algae Rapid growth of algae (Algae bloom) Increase minerals in rivers or lakes Leaching Low oxygen levels inside the lake Decrease photosynthesis of the plants Algae growth inhibits light coming inside the lake Death of Fish and other animals
  • 19. Process of water purification Treated water is pumped to homes Chlorination to kill microorganisms Sending the water through a filter bed of microorganisms for oxidization Sludge is used as fertilizer or land fillings Water is pumped to settling tanks for suspension. Screening for solid objects, weeds and debris. Water is taken from a source.
  • 20. Process of water purification
  • 21. Pollution • Pollution takes place when humans release substances into the environment that have harmful effects and they are not easily removed by the biological processes. • Pollution is measured by the amount of pollutant.
  • 22. Air pollution • Carbon dioxide – The reason rise is due to; • increase burning fossil fuels (coal, oil, natural, petrol and diesel) • Cutting down large areas of tropical rainforest (extensive deforestation) – Consequences of increased levels of CO2; • Causes global warming (enhanced greenhouse effect)
  • 23. Greenhouse effect • Greenhouse gases, – CO2 – Water vapour – Methane (CH4) – Nitrous oxide (N2O) – CFCs • Describe how greenhouse gases increase temperature?
  • 24. Greenhouse effect • The rise of Earth’s temperature; – Melt polar ice caps that would increase sea levels – Changing major ocean currents that result in warm water beam redirected into previous cooler areas – long term climate change – Change in the nature of ecosystems; • Species are enable to adapt to their habitat and they may extinct – Changes in agricultural practices • High temperatures might allow some pests to complete their life cycles more quickly
  • 25. Air pollution contd…. • Carbon monoxide (CO) – Forms when substances containing carbon are burned with limited oxygen – Dangerous pollutant as it is colorless, ordourless and tasteless – Can cause death by aspiration – Hemoglobin has a strong affinity towards CO than the O2 – So if a person inhales CO he may lose consciousness and will cause death • Sulphur dioxide – Formed when fossils fuels are burned – Cause acid rains that would destroy plants and marine life • Nitrogen oxides – Formed when fossils fuels are burned – Cause acid rains that would destroy plants and marine life
  • 26. Air pollution contd…. • Methane – Produced when micro organisms ferment larger organic molecules to release energy – Significant organic origins of microorganisms • Decomposition of waste in land fill sites by microorganisms • Fermentation by microorganisms in rumen of cattle and other ruminants • Fermentation by bacteria in rice paddy fields – Causes Global warming
  • 27. Acid Rain • Normal pH of rain = 5.5 • Acid rain has a lower pH than 5.5
  • 28. Consequences of deforestation • ‘Slash and burn’ adding CO2 to the environment which leads to global warming and climate change • Less trees to do photosynthesis – Less Co2 is absorbed – Less O2 is produced • Destruction of habitats and bio diversity • Reduced soil quality – No trees and plants to return minerals back to soil – No roots to hold soil together – Rain washes the minerals out ( leaching) • Leaching may cause – Eutrophication – rising water levels and floods • Produce climate change by upsetting earth’s water cycle (as a result of reduced transpiration) • Many undiscovered drugs and crop plants are lost