Homework Check: I asked you to review P. 185 – 189 in Tiger Book

1. Homework Check: I asked you to review P. 185 – 189 in Tiger Book You have 2 minutes to answer the following questions, you may use your notes. • Give an example of a saprotroph • State the type of wavelength that is reflected from the Earth’s surface (hint: it has less energy than the light coming directly from the sun).

2. Give an example of a saprotroph (decomposer) [1] • Fungus • Bacteria • (some saprophytic plants) • (some saprotrophic animals)

3. Reminder – what do saprotrophs actually do? They break down non-living organic matter into its simple constituents, which can then be absorbed through the cell wall for growth and repair Proteins are broken down into amino acids Lipids into fatty acids + glycerol Starches into disaccharides

4. State the type of wavelength that is reflected from the Earth’s surface (hint: it has less energy than the light coming directly from the sun). [1]

5. Heads Up • You will have a Quiz on Sections 5.1 (5.1.1. – 5.1.14) and on 5.2.4 (The precautionary principle) NEXT MONDAY [September 17th) • You will have MCT, short answer questions and a timed writing prompt on the precautionary principle • Quiz will last 20 minutes • You will be allowed to use any notes have have made while studying

6. Section 5.2: The Carbon Cycle and the Greenhouse effect (1/4) Monday • homework check • Nutrient cycling • The Carbon cycle • The Greenhouse Effect • TOK: The Gaia hypothesis Tuesday • The enhanced greenhouse effect and global warming • TOK: The precautionary principle • Analyse changes in atmospheric carbon dioxide using historical records PLEASE BRING YOUR LAPTOPS TO CLASS TOMORROW

7. Energy FLOWS but nutrients are RECYCLED • In any ecosystem, producers (autotrophs) provide organic compounds which are consumed through various trophic levels. • This continuous flow of energy through an ecosystem is subject to many ‘nutrient cycles’

8. Every essential element (nutrient) has its own cycle ‘Nutrient cycles’ describe how nutrients move from the physical environment into living organisms and are then recycled back into the physical environment

9. Some starter questions… • Which elements are essential for life? • Why do you think that life in our biosphere is carbon-based?.... • What would you classify as a nutrient?

10. Elements essential for life • ‘The Big Six’: Carbon, hydrogen, nitrogen, phosphorus, Sulphur • Most living organisms consist of 36 or so elements (many as ‘trace elements’ • Why carbon-based?

11. What is a nutrient? ‘Any substance assimilated by an organism, required for growth, repair and normal metabolism’ • MACRONUTRIENTS • MICRONUTRIENTS

12. Three nutrient cycles which are critical to life are the carbon cycle, the nitrogen cycle and the water cycle You only need to know about the carbon cycle

13. 5.2.1 The Carbon Cycle 5.2.1 The Carbon Cycle • Which substances contain carbon? • How do organic substances differ from inorganic substances?

14. BBC: September 9, 2012: http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/ 04/climate_change/html/carbon.stm

15. Getting to know the carbon cycle http://news.bbc.co.uk/1/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm http://www.youtube.com/watch?v=RGIllMbG22Y

16. The Carbon cycle http://bcs.whfreeman.com/thelifewire/content/chp58/5802002.html

17. 5.2 The Greenhouse Effect

18. The ‘Goldilocks Principle’: What regulates temperature on Earth? • Why is Earth “just right?”

19. The Goldilocks principle applied to ecology

20. 5.2.3 ‘Explain the relationship between rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect’

21. 5.2.3 Natural Greenhouse Effect What are greenhouse gases? Carbon dioxide Methane Oxides of nitrogen Water vapour

22. How does the enhanced greenhouse effect work? http://news.bbc.co.uk/1/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm http://www.youtube.com/watch?v=RGIllMbG22Y • http://www.youtube.com/watch?v=ab6jV4VBWZE&feature=related

23. Theory of Knowledge Link: The Gaia Hypothesis

24. Gaia in simple terms Biological systems tend to regulate the state of the earth’s environment in their favour

25. The Gaia Hypothesis • Gaia is analogous to the thermostat in your home, or the thermostat in your brain. • You set the thermostat in your home to 65 °F (18.3°C) in order to keep a comfortable living environment. When the temperature falls below this, the furnace is switched on. When the temperature in the house reaches the target, the furnace is switched off. Something more complicated, but with similar effect, goes on in our bodies. Everyone of us is a comfy 98.6 °F (37°C) now, and almost always. If our body temperature deviates very far from a narrow range, we die. The human body has a number of self-regulatory, or homeostatic, mechanisms. • The conditions for life as we know it to exist also require a relatively narrow range of circumstances. How does life modify the physical and chemical conditions of the environment? Do these metaphors enhance our understanding of connections between organisms?

26. ToK Connection: The Gaia Hypothesis What difference might it make to scientific work if nature were to be regarded as a machine with many interconnected parts? "The Gaia hypothesis says that the temperature, oxidation state, acidity, and certain aspects of the rocks and waters are kept constant, and that this homeostasis is maintained by active feedback processes operated automatically and unconsciously by the biota.” - James Lovelock, The Ages of Gaia

27. Bring a computer & a charger to class tomorrow! And read page 188.

28. Tuesday • Global warming • TOK: The precautionary principle • Analysis of historical records of atmospheric carbon dioxide levels

29. Section 5.2: Is global warming real? ….where Biology meets politics head on… http://www.youtube.com/watch?v=iH5oZLSHDZs

30. 5.2.5 ‘Evaluate the precautionary principle as a justification for strong action in response to the threats posed by the enhanced greenhouse effect.’

31. The Precautionary Principle 5.2.4 The precautionary principle holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change, must prove that it will not do harm before preceding. ‘Better safe than sorry’………

32. ToK Connection! • What are examples of the application of the precautionary principle outside of science?

33. All forms of the precautionary principle contain a version of this statement: • When the health of humans and the environment is at stake, it may not be necessary to wait for scientific certainty to take protective action. • ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation’ Rio 1992 • ‘BETTER SAFE THAN SORRY’

34. How does the precautionary principle change global environmental policy without bringing the global economy to a halt? Preventive policies encourage the exploration of better, safer, and often ultimately cheaper alternatives-and the development of cleaner products and technologies. As public awareness grows of hazards and of safer alternatives, these practices represent not only good ethics but also smart business. The markets of the 21st Century will increasingly demand safe products and sustainable technologies.

35. So….What do we do about this?5.2.4 • Do we act now? Do we need/have irrefutable evidence that global temperatures are increasing? • Should we act now? • Do we have to act now?

36. 5.2.2: Analyse the changes in the concentration of atmospheric carbon dioxide using historical records. http://seattlecentral.edu/qelp/sets/016/016.html