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Semester 2 Final Review Part 2 Carbohydrates, Photosynthesis & Respiration and Ecology.

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Presentation on theme: "Semester 2 Final Review Part 2 Carbohydrates, Photosynthesis & Respiration and Ecology."— Presentation transcript:

1 Semester 2 Final Review Part 2 Carbohydrates, Photosynthesis & Respiration and Ecology

2 CYCLES WaterCarbonNitrogen

3 Energy transfer through an ecosystem is ONE WAY – Most energy is lost as heat Nutrients such as nitrogen, water and carbon are able to cycle through an ecosystem and be reused. NUTRIENT CYCLES

4 Evaporation: Liquid water rising converting to water vapor and rising to the atmosphere. Condensation: The changing of water from a vapor to a liquid Precipitation: Any form of water falling from the sky such as rain, sleet, snow, and hail Transpiration: Release of water through the leaves of plants into the atmosphere


6 Plants acquire CO 2 thru stomata in their leaves and incorporate it in to organic molecules of their own biomass  photosynthesis Link between Atmosphere and Terrestrial:

7  Carbon is cycled quickly because of high demand from plants  Some of this organic material becomes a carbon source for consumers

8 All organisms return CO 2 to the atmosphere thru respiration Decomposition recycles carbon to the soil and back to atmosphere Fires oxidize organic material to CO 2 (burning) Link to animation Link between Atmosphere and Terrestrial:

9 Carbon is also stored on land: Carbon is accumulated in wood and other durable organic material Organic detritus, under intense pressure, changes into coal and petroleum in rock.

10 Nitrogen gas (N 2 ) makes up 79% of our atmosphere Nitrogen is needed by plants and animals to make proteins and DNA –It ranks fourth behind oxygen, carbon, and hydrogen as the most common chemical element in living tissues. Most organisms CAN NOT obtain nitrogen through the atmosphere! The Nitrogen Cycle


12 Since animals cannot get nitrogen directly from the atmosphere they must eat it through plants. Certain plants can pull atmospheric nitrogen into their roots and make NO 3 –Legumes, Red Alder trees Rhizomes

13 The Nitrogen Cycle Animals then eat the plants that contain NO 3 and incorporate it into their body –DNA –Proteins

14 Cycles Vocabulary EvaporationFossil Fuels CondensationNitrate PrecipitationNitrogen Fixing TranspirationDenitrification Stomata Carbon Source Carbon Sink Decomposition Combustion

15 Climate Change

16 Greenhouse Effect Light energy from the sun (solar radiation) is either reflected or absorbed by the Earth. When it is absorbed it is converted into heat energy (infrared radiation). That heat energy either escapes the Earth through the atmosphere, or gets absorbed by greenhouse gases and reflected back down. This is how heat is trapped within the troposphere and how the Earth stays warm.

17 Greenhouse Effect Greenhouse gasses include: Water (H 2 O) Methane (CH 4 ) Carbon Dioxide (CO 2 ) Nitrous Oxide (N 2 O) The first 3 are very natural, and in fact necessary to keep the Earth warm.

18 Global Warming The greenhouse effect is natural and necessary for most life here on Earth. Without the greenhouses gases in our atmosphere the Earth’s average temperature would be -16 0 C ! This happened to Mars which lost its atmosphere. If a planet has extremely high concentrations of greenhouse gases in its atmosphere however it can have a runaway greenhouse effect. This is the case with Venus, whose high concentrations of carbon dioxide give it an average surface temperature of 425 0 C!!!

19 Effects of Climate Change High global temperatures (Heat Waves) Increased drought, extreme weather. Raising sea levels caused by melting ice. Acidification of the ocean.

20 Positive Feedback We call this a positive feedback loop where: A produces more of B, which then in turn produces more of A. Melting sea ice creates a lower albedo, which then in turn causes more ice to melt.

21 Negative Feedback Of course there is also negative feedback as well. You are probably most familiar with this in homeostasis. With negative feedback: A produces B, which then stops or lowers the production of A

22 Negative Feedback With climate change there are many more examples of positive rather than negative feedback. Here is one example of negative feedback in the climate: Global warming is expected to intensify rates of land degradation and desertification, which in turn results in more windblown dust. Dust acts to cool the surface (by raising albedo), thus lowering the temperature of the Earth.

23 Positive vs. Negative Feedback. Positive feedback tends to promote instability in systems (think spiraling out of control). Negative feedback tends to promote stability in systems (think again about homeostasis).

24 Climate Change Vocabulary Positive Feedback Negative Feedback Greenhouse Effect Greenhouse Gases Climate Change

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