303 & 302 Midterm Review

A Scientific Method Observation Explanation Test AnalyzeCommunicate

The Scientific Processes Sarah was interested in studying the effects of lack of sunlight on the height of plants. She took two identical trays and filled them with the same type of soil and planted the same type of seed in each. She then decided that she would keep one tray in a room that was completely dark and the other on the window ledge. She watered each with 50 mL of water a day.

QUESTION Does light affect the growth of plants? Independent Variable Amount of light Dependent Variable Plant growth Control Plant on window ledge Constants Amount of water, type of soil, type of seed, trays

Answers continued… Hypothesis If a plant is placed in the dark, then it will not grow as tall as plant in normal sunlight. Improvements? More plants

A Forest Food Chain GRASS  MOUSE  SNAKE  HAWK 1 st Trophic Level 2 nd trophic Level 3 rd Trophic level 4 th Trophic level

A Forest Food Chain GRASS  MOUSE  SNAKE  HAWK Producer1 st Consumer 2 nd Consumer 3 rd Consumer 1 st Trophic Level 2 nd trophic Level 3 rd Trophic level 4 th Trophic level

A Forest Food Chain GRASS  MOUSE  SNAKE  HAWK Producer1 st Consumer 2 nd Consumer 3 rd Consumer HerbivoreCarnivore 1 st Trophic Level 2 nd trophic Level 3 rd Trophic level 4 th Trophic level What’s still missing?

What did the popcorn race demonstrate? Why are food chains rarely more than 4 or 5 members (trophic levels) long? Which law does this demonstrate?

The 10% Rule: 2 nd Law of Thermodynamics in action As you travel up the food chain, the amount of energy transferred to each organism declines – only 10% of the energy is passed on to the next consumer the remaining 90% is either: 1. Energy lost as heat, 2.Energy/biomass is used growth as food 3. Biomass excreted as waste Actually 5-20%

Chemical Changes Video 3 – carbon and chemical change

Energy Pyramid Aside from ethics…why might eating at a lower trophic level be a good idea?

Particle Size = Soil Texture SAND, SILT, CLAY

Soil Layers in ground

The Nitrogen Cycle The air is 78% nitrogen, why can’t organisms use this? What role do bacteria play in the nitrogen cycle?

Pros & Cons

Persistence Why is it good? Why is it bad? How does it happen? Carried by wind and water, remains in soilEasily dissolve in fat, stored

DDT – DDT (2:55) – chlordane persistent (1:44) – sprayed on children (0:31) – Rachel Carson (0:36) – spraying on people dichlor-diphenyl-trichloro-ethane Chlorinated hydrocarbon insecticide Persistence and Biomagnification Banned in 1972, but still found in 96% of samples Used extensively in WWII Thin eagle shells

Biomagnification/Bioaccumulation Concentration of pesticide increases as you move up the food chain How does this relate to the Rule of 10%? bivalence/02.ST.06/?scene=2 bivalence/02.ST.06/?scene=2 ion/ ion/

IPM = Integrated Pest Managment Biological Pesticides And Changing Farming Practices

Pathogens - bacteria, protozoa, fungus

Chemicals from plants

Release predatory organisms LWyNcAs

Prevent Breeding / Birth Control

Plant companion crops

WISSAHICKON WATERSHED SCHUYLKILL WATERSHED DELAWARE WATERSHED

How would you define a point source and a nonpoint source?

What do you see?

ANIMATION

Gulf of Mexico Dead Zone

How are wetlands a proactive solution?

Earth = the natural filter

WATER CYCLE

Fig. 13-6, p. 319

In the Primary, Secondary, Advanced columns, sort these concepts correctly Optional, not usually doneSettles large particles Filters large particles which go to a landfill Removes pollutants like nitrates and phosphates Removes bacteria with chlorine or ultraviolet light Adds O 2 to promote bacterial growth Uses a 2 nd filterBacteria added to decompose waste

What’s Left? Where’s it Go? WATER Into a lake or river  ocean Crops/Golf course Possible problems? SLUDGE Lagoon Incinerator Crop fertilizer Possible problems?

Combined Sewer Overflow Wastewater tx plants will always be in the basin of a watershed…why?