1. Biogeochemical Cycles
Mrs. Stewart
Honors Biology

2. CLE Describe the events which occur during the major biogeochemical cycles. You will know you have mastered this standard when: You can predict how changes in a biogeochemical cycle can affect an ecosystem

3. Objectives:
Analyze the flow of nutrients in each biogeochemical cycle.
Evaluate the impact that humans have on the biogeochemical cycles.

4. Why do we recycle?
Think – Pair - Share

5. What sustains life on Earth?
Solar energy
The cycling of matter, energy & nutrients
Gravity

6. Two Secrets of Survival: Energy Flow and Matter Recycle
An ecosystem survives by a combination of energy flow and matter recycling.

7. MATTER CYCLING IN ECOSYSTEMS
Nutrient Cycles: Global Recycling
Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms.
Nutrients - the elements and compounds that organisms need to live, grow, and reproduce.

8. Macromolecule Review What element does every organic organism contain?
What are the 5 major elements that create all the macromolecules?
Carbon
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorous

9. Think – Pair – Share
What would happen to these elements if they were only capable of being used once?
Think about every time an organism is created and/or destroyed
They would begin disappearing (dwindling in supply)
– like fossil fuels

10. Biogeochemical Cycles
These are just illustrations or representations to show how substances move through air, water, soil, rock and living organisms.

11. Decomposition Decomposers:
ultimately responsible for recycling of chemical nutrients
releasing the nutrients in detritus
This makes nutrients available again to the autotrophs in the ecosystem

12. Recycling What nutrients get recycled? Carbon Dioxide Oxygen Water
Nitrogen
Phosphorous

13. Water Cycle

14. Movement of Water Three important processes:
Evaporation – adds water as vapor to atmosphere (heat)
Bodies of water, soil, animal bodies, etc.
Transpiration – water evaporates from the leaves of plants
Precipitation – water released from the atmosphere (temperature, air pressure)
Rain, snow, sleet, hail or fog

15. Water Cycle

16. Think-pair-share What human activities effect the water cycle?
What do we do as humans that could have positive or negative effects on this cycle
2 minutes

17. Effects of Human Activities on Water Cycle
We alter the water cycle by:
Withdrawing large amounts of freshwater.
Clearing vegetation and eroding soils.
Polluting surface and underground water.
Contributing to climate change.
How do these changes affect the surrounding ecosystems?

18. Objectives:
Analyze the flow of nutrients in each biogeochemical cycle.
Evaluate the impact that humans have on the biogeochemical cycles.

19. Carbon Cycle

20. Photosynthesis vs Cellular Respiration
Photosynthesis absorbs CO2 from the atmosphere/biosphere and releases O2
Cellular respiration absorbs O2 from the atmosphere/biosphere and releases CO2

21. Carbon is found in 5 major places:
Living and dead organisms
Carbon Dioxide (CO2) in atmosphere
Organic matter in the soil
Fossil fuels and rock deposits
Oceans – dissolved CO2 and shells

22. Do these plants contain Carbon?
What happens to the carbon now?

23. Where is the carbon?

24. Think-pair-share What human activities effect the Carbon-Oxygen cycle?
What do we do as humans that could have positive or negative effects on this cycle
2 minutes

25. Effects of Human Activities on Carbon Cycle
We alter the carbon cycle by adding excess CO2 to the atmosphere through:
Burning fossil fuels.
Clearing vegetation faster than it is replaced.

26. How do those changes affect the surrounding ecosystems?

27. Objectives:
Analyze the flow of nutrients in each biogeochemical cycle.
Evaluate the impact that humans have on the biogeochemical cycles.

28. Nitrogen Cycle

30. Nitrogen Uses: Proteins Nucleic Acids Enzymes, skin, muscles, etc. DNA
RNA

31. Forms of Nitrogen
Nitrogen is found in many forms in the atmosphere / ecosystem
N2 = nitrogen gas (79% of atmosphere)
N2O = nitrous oxide
NH3 = ammonia
NH4 = ammonium
NO3 = nitrate
NO2 = nitrite

32. Nitrogen Fixation
Converting N2 gas to nitrate (only usable form of nitrogen for most plants)
2 types:
Natural = lightning, fires and bacteria
Human = fossil fuel combustion, fertilizer manufacturing

33. Nitrogen-fixing bacteria
bacteria that transform Nitrogen gas into a usable form (Nitrate)
Live in the soil
May live in the swellings on the roots of some plants (ex. Beans, peas, clover)
These plants provide sugars for the bacteria, and the bacteria provide usable nitrogen.

34. Recycling Nitrogen Where is Nitrogen found?
Dead organisms (as proteins & nucleic acids)
Urine & dung
Decomposers: break down and release Nitrogen as NH3 (ammonia)

35. Nitrogen Processes
Ammonification – converting NH3 (ammonia) to NH4 (ammonium)
Nitrification – converting NH4 (ammonium) into NO2 (nitrite) or NO3 (nitrates)
Denitrification – anaerobic bacteria break down NO3 (nitrates) and release N2 (nitrogen gas) into the atmosphere

36. Nitrogen Sources: Plants = Nitrates from the soil
Use to form proteins
Animals = eating plants/organisms and digesting the proteins and nucleic acids
Humans = have doubled the amount of fixed N2 in the atmosphere in the last 100 years.
HOW?

37. Too much of a good thing?
Too much nitrogen in aquatic ecosystems results in:
Eutrophication = excess nutrients stimulate plant growth (algal blooms); when these plants die, decomposers use up the available oxygen during decomposition.

38. Eutrophication

39. Nitrogen Cycle

40. Think-pair-share What human activities effect the Nitrogen cycle?
What do we do as humans that could have positive or negative effects on this cycle
2 minutes

41. Effects of Human Activities on the Nitrogen Cycle
We alter the nitrogen cycle by:
Adding gases that contribute to acid rain.
Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone.
Contaminating ground water from nitrate ions in inorganic fertilizers.
Releasing nitrogen into the troposphere through deforestation.

42. Effects of Human Activities on the Nitrogen Cycle
Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined.

43. How does this affect the surrounding ecosystems?
Acid rain
creation of ground level ozone
groundwater contamination
eutrophication.

44. Exploring the Nitrogen Cycle Activity

45. Objectives:
Analyze the flow of nutrients in each biogeochemical cycle.
Evaluate the impact that humans have on the biogeochemical cycles.

46. Phosphorus Cycle

47. Overview
Movement of phosphorus from the environment, to organisms, and back to the environment
Slow process
Normally does not occur in atmosphere because phosphorus rarely occurs as a gas

48. Where do organisms get phosphorus?
Phosphorus Uses:
Essential material for animals
Form bones, teeth, molecules (DNA/RNA)
Where do organisms get phosphorus?
Plants = absorb from soil and water
Animals = eating plants & other organisms

49. Cycle
Rocks erode, and small amounts of phosphorus dissolve as phosphate PO4 3-, in soil and water
Excreted in wastes from organisms
Released by decomposers from dead organisms
Plants absorb from soil and water, through roots
Animals eat plants/other organisms
Some in fertilizers and applied to fields/crops
Washes off into streams, groundwater and soil

50. Phosphorus Cycle

51. Think-pair-share What human activities effect the Phosphorus cycle?
What do we do as humans that could have positive or negative effects on this cycle
3 minutes

52. Effects of Human Activities on the Phosphorous Cycle
We remove large amounts of phosphate from the earth to make fertilizer.
We reduce phosphorous in tropical soils by clearing forests.
We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

53. What determines population size?

54. Environment vs Habitat
Many species can survive in more than one environment.
But each species has its “home” or habitat.
Fish may be able to live in fish tanks, but would rather live in the wild

55. What do organisms need to survive?
Basic requirements for survival include:
Food
Water
Shelter

56. Competition
An important aspect of the struggle for survival involves competition for limited resources
Food
Water
Shelter
Sunlight

57. Limiting Factors
Limiting factors are factors that affect the population size of a species in a specific environment.
They can be abiotic or biotic.

58. Predator – Prey relationship
Predators are a biotic limiting factor.
They control population size by feeding on prey.
There is a delicate balance that needs to be maintained.

59. Carrying Capacity
When all the limiting factors are considered together we can determine the maximum number of organisms that can survive in an area.

60. How do we determine the Carrying Capacity of a Species?
All limiting factors must be taken into consideration.
It is very difficult to determine the actual carrying capacity.

61. The Lesson of the Kaibab Deer
Purpose:
to graph data on the Kaibab deer population of Arizona from 1905~1939
to analyze the methods responsible for the changes in the deer population
to propose a management plan for the Kaibab deer population

62. How Many Bears??

63. Kaibab Forest: North Rim of the Grand Canyon

64. Key Idea THINK-PAIR-SHARE
All organisms have the ability to produce populations of unlimited size
But their environment keeps their numbers in check.
THINK-PAIR-SHARE
How?
List examples of limiting factors.
3 minutes