Transcript 303 and 302 Midterm review

Midterm Review
303 & 302
A Scientific Method
Observation
Communicate
Explanation
Analyze
Test
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
1st Trophic 2nd trophic 3rd Trophic 4th Trophic
Level
Level
level
level
A Forest Food Chain
GRASS  MOUSE SNAKE  HAWK

Producer
1st
2nd
3rd
Consumer Consumer Consumer
1st Trophic 2nd trophic 3rd Trophic 4th Trophic
Level
Level
level
level
A Forest Food Chain
GRASS  MOUSE SNAKE  HAWK

Producer
1st
2nd
3rd
Consumer Consumer Consumer
Herbivore Carnivore Carnivore
1st Trophic 2nd trophic 3rd Trophic 4th Trophic
Level
Level
level
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:
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 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
http://www.npr.org/news/specials/climate/video/
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?
Easily dissolve in fat, stored
Carried by wind and water, remains in soil
DDT
Persistence and
Biomagnification
dichlor-diphenyl-trichloro-ethane
Chlorinated hydrocarbon insecticide
Banned in 1972, but still
found in 96% of samples
Used extensively in WWII
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
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%?

http://www.makingthemodernworld.org.uk/stories/the_age_of_am
bivalence/02.ST.06/?scene=2

http://www.mcgrawhill.ca/school/applets/bcscience7/bioaccumulat
ion/
IPM = Integrated Pest Managment
Biological Pesticides
And
Changing Farming Practices
Pathogens - bacteria, protozoa, fungus
Chemicals from plants
Release predatory organisms
http://www.youtube.com/watch?v=vMGLWyNcAs
Prevent Breeding / Birth Control
SCHUYLKILL WATERSHED
WISSAHICKON 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 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?