10 Science
Ecology Notes
Chapter Two
Read the introduction p. 48 - 49 about how ecosystems change and yet stay
the same - balance and equillibrium.
Organic vs. Inorganic
Organic Substances contain carbon, hydrogen and often oxygen and nitrogen
Examples include proteins, sugars and fats
Inorganic substances are those that do not contain combinations of carbon
and hydrogen atoms. Examples include water carbon dioxide and ammonia
All life building matter on Earth is recycled. It goes through cycles of
inorganic molecules to organic and back again.
Food is organic. Digestion breaks down complex organic molecules into
simpler molecules. Cells then use these simple molecules as the building
blocks of living tissue etc. When an organism dies, this tissue is then
converted (decomposed) back into inorganic molecules....nutrients.
In this way organic substances are temporarily held in the bodies of living
organisms.
Questions p. 51 # 1,4,5 & 6
Pesticides
insecticides - herbicides - fungicides - bactericides
Pro's Pests can and have devastated crops
Pests like mosquitos carry life threatening viruses malaria, west nile
Pests can be unattrractive or even revolting
Pest can have economic impact as well (see #1 & 2 above)
Early pesticides - 500 BC sulfur used to repel insects
15th century - arsenic, lead & mercury
18th century - nicotine sulfate and other chemicals
extracted from plants
Next wave of pestisides - chemically produced
1939 dichlorodiphenoltrichloroethane DDT (banned in 1971)
worldwide 2.5 million tonnes annually
used in shampoos, matresses, paints
Important variable - how fast they decompose Persistance (see p. 53)
Bioconcentration? (see figure p. 54)
Some pesticides (chlorine based)do not dissolve in water (only fat).
They therefore cannot be excreted and thus accumulate in fatty tissue.
(p. 54)
Modern Pesticides
Not Chlorine based - soluble in water - can be broken down by the
liver and excreted - low persistance
Shelf life of a pesticide - caused by organisms adapting to the
environment
Ironically by applying pesicides we inadvertantly produce species
with greater resilience to the pesticide - "super bugs" - how? (see p.
55)
Complete handout on Pests and the carbon cycle
Questions p. 58 # 2 - 9
Photosynthesis & cellular respiration p. 61 # 2,3,5,&6
6CO2 + 6H2O + light energy
C6 H12O6 + 6O2
C6H12O6 + 6O2
6H2O + 6CO2 + energy
The Carbon Cycle
Carbon is a key element for all living things. It is found in both
inorganic and organic compounds.
Inorganic reservoirs (in order of increasing "delay") of carbon are:
 carbon dioxide in our atmosphere - about .03% for 3 years
 carbon dioxide in our oceans - for about 3000 years
 carbonates in the earth's crust - for about 3000000 years
Delay refers to the amount of time the carbon "spends" in this
inorganic form before it is cycled into organic carbon through
photosynthesis.
Organic reserviors (in order of increasing "delay") of carbon are:
 bodies of living organisms
 bodies of dead organisms where decomposition occurs
 bodies of dead organisms where decomposition does not occur
due to a lack of oxygen i.e. bogs, peat, coal & oil
These reservoirs and the delays above maintain balance to sustain
ecosystems. The effect of human impact is essential to offset this
balance either by
 deforestation - which reduces the amount of photosynthesis and
thereby decreases the amount of CO2 removed from the
atmosphere
 burning fossil fuels - which increases the amount of CO2 in the
atmosphere
This is where an understanding of the greenhouse effect and its effect
on global temperatures comes in. (refer to an inconvenient truth)
Question p. 65 # 1 - 8