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.

QUESTIONDoes light affect the growth of plants?Independent Variable

Amount of lightDependent Variable

Plant growthControl

Plant on window ledgeConstants

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 ChainGRASS

MOUSE

SNAKE

HAWK

1st Trophic Level

2nd trophic Level

3rd Trophic

level

4th Trophic

level

A Forest Food ChainGRASS

MOUSE

SNAKE

HAWK

Producer

1st Consum

er

2nd Consum

er

3rd Consum

er

1st Trophic Level

2nd trophic Level

3rd Trophic

level

4th Trophic

level

A Forest Food ChainGRASS

MOUSE

SNAKE

HAWK

Producer

1st Consum

er

2nd Consum

er

3rd Consum

erHerbivor

eCarnivor

eCarnivor

e1st

Trophic Level

2nd trophic Level

3rd Trophic

level

4th Trophic

levelWhat’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: 2nd 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

consumerthe remaining 90% is either:

1. Energy lost as heat,2.Energy/biomass is used growth as food3. Biomass excreted as waste

Actually 5-20%

Chemical Changes

http://www.npr.org/news/specials/climate/video/Video 3 – carbon and chemical change

Energy PyramidAside 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 CycleThe air is 78% nitrogen, why can’t organisms use this?

What role do bacteria play in the nitrogen cycle?

Pros & Cons

PersistenceWhy is it good? Why is it bad?How does it happen?

Carried by wind and water, remains in soilEasily dissolve in fat, stored

DDT

http://www.youtube.com/watch?v=LQ64sV0nSVU – DDT (2:55)http://www.youtube.com/watch?v=z7Lr1pCEcNU – chlordane persistent (1:44)http://www.youtube.com/watch?v=uf6KkjBCoVU – sprayed on children (0:31)http://www.youtube.com/watch?v=6Y-6hm7zpps – Rachel Carson (0:36)http://www.owlcorner.net/OwlCornerHome/BioAccumGame_files/Silent%20Spring.mov – 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/BioaccumulationConcentration of

pesticide increases as you move up the food chain

How does this relate to the Rule of 10%?

http://www.makingthemodernworld.org.uk/stories/the_age_of_ambivalence/02.ST.06/?scene=2

http://www.mcgrawhill.ca/school/applets/bcscience7/bioaccumulation/

IPM = Integrated Pest Managment

Biological PesticidesAnd

Changing Farming Practices

Pathogens - bacteria, protozoa, fungus

Chemicals from plants

Release predatory organisms

http://www.youtube.com/watch?v=vMG-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

WATER CYCLE

Fig. 13-6, p. 319

In the Primary, Secondary, Advanced columns, sort these concepts correctly

Optional, not usually done Settles large particles

Filters large particles which go to a landfill

Removes pollutants like nitrates and phosphates

Removes bacteria with chlorine or ultraviolet light

Adds O2 to promote bacterial growth

Uses a 2nd filter Bacteria added to decompose waste

What’s Left? Where’s it Go?WATER

Into a lake or river ocean

Crops/Golf coursePossible problems?

SLUDGELagoonIncineratorCrop fertilizerPossible problems?

Combined Sewer Overflow

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