GCSE OCR BIOLOGY MATERIAL CYCLING IN ECOSYSTEMS COMPLETE REVISION SUMMARY

MATERIAL CYCLING IN ECOSYSTEMS

• The cycling of materials on Earth

• The carbon cycle

• The water cycle

• Effects of temperature, water and oxygen on the rate of decomposition

• Marking compost

• Science calculations – calculating rates

WATER CYCLE

CARBON CYCLE

DECOMPOSITION

1. a) Oxygen
2. b) Warm Conditions
3. c) Moist Conditions

DECOMPOSERS

BIODIVERSITY

• It is required to make the ecological balance as one species is dependent on the other.
• It is required for medicine like medicinal plants.
• It is required for agriculture and poultry.
• It is required to maintain ecotourism.
• Species are dependent on one another. So if one species is affected it can affect the entire population.

• Deforestation : Rapid population growth causing clearing of forests and making industries and home causing climate change and global warming_
• Population Growth – Leading to deforestation, monoculture
• Agriculture – Increasing food demand is causing monoculture causing reduction in gene pool.
• Industrialization – Due to increasing population size

AIR POLLUTION

ACID RAIN

Formation

1. a) Makes soil acidic
2. b) Damage trees and aquatic life
3. c) Corrossion of building
4. d) Errodes building and rocks

1. a) Decrease in use of fossil fuels.
2. b) Treat the waste to remove nitrogen and sulphur before evolving.
3. c) Use alternative source of energy.

MATERIAL CYCLING IN ECOSYSTEMS

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SMOG

• Mixture of nitrogen dioxide and sulphur dioxide particulates in the lower atmosphere.
• Depletes ozones layer, cause dimming effect.
• Lowers the Earth’s temperature
• If inhaled causes damage to lungs, respiratory problems and cardiovascular diseases.

WATER POLLUTION

• Fertilizers washed away
• Increases the nutrient content of water causing algal bloom

ALGAL BLOOM

• Forms green layer, block sunlight
• Death of plants, decreasing oxygen in water. Death of other species.
• Decomposers increasing further decreasing oxygen.

BIOMAGNIFICATION

LAND POLLUTION

• Solid Waste
• Plastic, metals and other man made chemicals fills the landfill sites
• Chemicals -Toxic Chemicals come from industries and agricultures sites.
• Agriculture Waste – Spray of insecticides, pesticides and weedicide contributes to land pollution.

DEFORESTATION

Causes

• Rapid industrialization, population growth and urbanization
• Clearing of forests form making home and industries. Increase in agriculture to grow food and fuel crops.

Effects

1. a) Increase in carbon dioxide levels causing global warming and climate change.
2. b) Loss of biodiversity by causing habitat destruction
3. c) Causing extinction of species.

PEAT BOG DESTRUCTION

• It is a plant material that is not decayed due to acidic conditions.
• Forms peatlands and peat bogs and are massive storehouse of carbon and host many organisms.

1. a) Unique carbon store
2. b) Habitat for many microorganism, plants and animals that can survive in acidic conditions.
3. c) Used as fuel

• Causes loss of biodiversity.
• Takes millions of years to form.

GREENHOUSE EFFECT

GLOBAL WARMING

Rise in mean temperature of the earth. It is due to the excess amount of green house gases present in the atmosphere

• Climate Change
• Habitat Loss
• Floods
• Change in Migration of Birds
• Change in distribution of plants and animals
• Change in seasonal pattern
• Loss of Biodiversity causing extinction of species.

MAINTAINING BIODIVERSITY

In situ Conservation

• It is the protection of endangered species in their own natural habitat like making national parks, wildlife sanctuary and making biosphere reserves.
• Breeding programmes are also carried in these areas to increase the population of endangered species.

Ex Situ Conservation

• Preserving the biodiversity outside their natural habitat like
• Zoos, botanical garden, tissue culture, seed banks and gene bank.

Preventing Deforestation and Combustion

• Preventing deforestation and planting more trees can reduce the carbon emissions and can prevent global warming and climate change
• Recycling and using alternative sources of energy
• Recycling and using alternative sources of energy can reduce the dependency on fossil fuels causing reducing the carbon emissions preventing global warming, climate change and its effects.

FOOD SECURITY

1. a) Population Growth
2. b) Inclination toward unhealthy and easy to cook foods
3. c) Spread of Disease
4. d) Pest and Insect attack to the crop.
5. e) Climate Change
6. f) Acid Rain and Pollution
7. g) Water Pollution
8. h) Increase in cost of agricultural supplies
9. i) Food versus Fuel Issue

EFFICIENT FOOD PRODUCTION

• Increasing more plant based products
• When plant based products are used they have the highest biomass and maximum energy as they are at the initial level of food chain.
• Plant based product reduces the dependency on animal products.
• Reducing the level of food chain
• At each trophic level, there is energy loss.
• So if the food chain levels are reduced maximum energy and biomass can be obtained.

Intensive Farming

1. a) Restricting Movement – By restricting movement energy loss in movement is prevented.
2. b) Rearing them at constant temperature – Energy loss in maintaining body temperature is prevented.
3. c) Giving them easy to digest food – It reduced energy loss in digestion.
4. d) Giving them protein rich diet – It helps to grow more biomass

SUSTAINABLE FOOD PRODUCTION

1. a) Use of genetic engineering to increase the yield of the crops and making more disease resistant and high yield variety.
2. b) Use of microorganisms for food production

KEY TERMS

1. a) Communities – It is an assemblage of populations of different species of plants, animals, bacteria and fungi which live in a particular area and interact with one another through competition, predation, mutualism, etc.
2. b) Ecosystem – It is a segment of nature consisting of a biological community and its physical environment both interacting and exchanging materials as well as energy. e.g – pond ecosystem
3. c) Interdependence – refers to a situation in which both species require the action of the other to function.
4. d) Stable Communities – A stable communities are those is in which the size of populations of all species remains comparatively constant over time.
5. e) Abiotic Factor – Non-living substances and factors of an ecosystem. E.g temperature, light, wind.
6. f) Biotic Factor – Constitute all the living members of an ecosystem. E.g Producers, Consumers, Decomposers.
7. g) Predator – It captures, kill and on another organisms called prey. Ex -tiger
8. h) Prey – an animal hunted or seized to eat, especially from a carnivorous animal
9. i) Pathogen – a bacterium, virus or other micro-organism that can cause disease.
10. j) Parasite – it feeds on another organism called host. The parasite spends a part or whole of its life on or in the body of the host.
11. k) Competition – it is a rivalry between two or more organisms for obtaining the same resources.
12. l) Abundance – The number of organisms in a population, combining intensity and prevalence.
13. m) Distribution – spatial relationship between individuals in a population.
14. n) Quadrat – A quadrant is a sampling unit used for the quantitative study of the plant community. Can be rectangular or circular. Used to measure the coverage and abundance of plants or animals
15. o) Sample Size – The sample to be take for observation.
16. p) Mean – It is the statistical value calculate by adding all the values divided by total number of values.
17. q) Range: It is the highest value take away the lowest value.
18. s) Median – It is the middle value of the data.
19. t) Mode – The value that has the greatest frequency.
20. u) Transect – A transect is a long rectangular sample. It is used to study variation in vegetation.
21. v) Adaptation – Changes in the form or behavior of an organism during its life as a response to environmental stimuli.
22. w) Biomass – mass of the individuals per unit area
23. x) Producers – They are Photosynthetic or autotrophic plants which are able to synthesize organic food from inorganic raw materials with the help of solar radiations.
24. a) Precipitation – Precipitation includes rain, snow, and hail.
25. b) Condensation – gas changing to a liquid.
26. c) Evaporation – liquid’s surface changing to a gas.
27. d) Transpiration – water vapor being released from plants and soil.
28. g) Combustion – It occurs when any organic material is reacted (burned) in the presence of oxygen to give off the products of carbon dioxide and water and Energy
29. h) Decomposition – It is the process of breaking down of a substance/waste biomass into its constituent parts by decomposers(bacteria, fungi)
30. j) Biodiversity – It refers to all aspects of variety in the living world.
31. k) Acid Rain – It is rainfall and other forms of precipitation with a pH of less than 5.
32. l) Smog – Smog is opaque or dark fog having condensed water vapours, dust, smoke and gases.
33. m) Eutrophication – It is excessive growth of algae, plants and animals in water bodies due to the nutrient enrichment particularly with nitrogen and phosphorous.
34. n) Biomagnification – It is increase in the concentration of a persistent chemical with the rise in trophic level. Eg organochlorine like DDT
35. o) Global Warming – Rise in mean temperature of the earth. It is due to the excess amount of green house gases present in the atmosphere
36. p) Greenhouse Effect – It is warming effect found in green house by allowing solar radiations to pass in but preventing long wave heat radiations to pass out due to glass panes, water vapours and carbon dioxide.
37. q) Trophic Level – Trophic level is a step or division of food chain which is characterized by the method of obtaining its food.
38. r) Pyramids of Biomass – graphic representation of biomass present sequence-wise per unit area of different trophic levels with producers at the base and top carnivore kept at the tip.
39. s) Pyramids of Number – graphic representation of number of individuals per unit area of various trophic levels step-wise with producers at the base and top carnivore kept at the tip.
40. t) Food Security – Growing sufficient healthy food to feed the population and accessibility of the population to grow or buy the healthy food. All people have access to sufficient, safe and nutritious food that meets their dietary preferences and dietary needs for an active and healthy life.
41. u) Fermenter – An organism that causes fermentation.
42. v) Biotechnology – living organisms are used to produce useful products and chemicals or to perform an industrial task. It is mainly used in agriculture, food science and medicine.

Disclaimer:

Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well

Adaption Interdependence And  Competition

• • Adaptation, Interdependence and Competition 1 MS
  • Adaptation, Interdependence and Competition 1 QP
  • Adaptation, Interdependence and Competition 2 MS
  • Adaptation, Interdependence and Competition 2 QP
  • Adaptation, Interdependence and Competition 3 MS
  • Adaptation, Interdependence and Competition 3 QP

Organising An Ecosystem

• • Organisation of an Ecosystem 1 MS
  • Organisation of an Ecosystem 1 QP
  • Organisation of an Ecosystem 2 MS
  • Organisation of an Ecosystem 2 QP
  • Organisation of an Ecosystem 3 MS
  • Organisation of an Ecosystem 3 QP

  Biodiversity and the Ecosystem

• Biodiversity & Effect of Humans on Ecosystems 1 MS
• Biodiversity & Effect of Humans on Ecosystems 1 QP
• Biodiversity & Effect of Humans on Ecosystems 2 MS
• Biodiversity & Effect of Humans on Ecosystems 2 QP
• Biodiversity & Effect of Humans on Ecosystems 3 MS
• Biodiversity & Effect of Humans on Ecosystems 3 QP
• Food Production 1 MS
• Food Production 1 QP
• Food Production 2 MS
• Food Production 2 QP
• Food Production 3 MS
• Food Production 3 QP
•  
• Trophic Levels in an Ecosystem 1 MS
• Trophic Levels in an Ecosystem 1 QP
• Trophic Levels in an Ecosystem 2 MS
• Trophic Levels in an Ecosystem 2 QP
• Trophic Levels in an Ecosystem 3 MS
• Trophic Levels in an Ecosystem 3 Q