Transcript Science 9: Unit C – Environmental Chemistry

Science 9: Unit C –
Environmental Chemistry
Topic 1: A Hair-Raising Dilemma
Nutrients Needed for Survival
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A nutrient is a chemical that our bodies need for life. Our body needs
many different chemicals to survive. Most of these chemicals are
obtained by the digestion of food. The chemicals are organized into
two groups:
Organic Compounds – Compounds containing carbon atoms.
Inorganic Compounds – Compounds which do not contain carbon.
There are four kinds of organic nutrients in the body:
Carbohydrates – Sugars. Used for energy for life processes.
Contains carbon, hydrogen and oxygen.
Lipids – Fats. Used to store unused energy for later use. Larger than
carbohydrates, but containing the same elements.
Proteins/Amino Acids – Used to help repair and grow the body’s
tissues.
Nucleic Acids – DNA and RNA. Used for genetic processes of the
body.
The body needs 25 different elements to survive and thrive. Some
elements are needed in large amounts (macrominerals), and others
in very small amounts (micronutrients or trace elements).
How Sugars are broken down into
A molecule of Glucose C H
Glucose.
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Hydrolysis – A
chemical reaction in
which one or more
water molecules is
chemically bonded to
another compound.
This is how sugars and
starches are broken
down into blood sugar
(glucose).
12O6(s)
Optimum Amounts
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Having too much or too little of any nutrient,
even a trace element can lead to harmful
effects. The optimum amount of a
substance is the amount that gives the
organism the best health.
The Canada Food Guide informs the public to
the optimum amounts of various nutrients on
a daily basis.
How Nutrients Move through organisms.
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Nutrients enter the plant through the roots by the process of
diffusion. Diffusion is the process where particles go from an
area of high to low concentration. Diffusion continues until the
concentrations in the soil and the plant are equal.
Osmosis is a special type of diffusion where water moves from
an area of high to low concentration of water. This is how a plant
‘drinks.’ Because diffusion and osmosis happen automatically the
plant uses no energy in either process.
Active Transfer – Some nutrients are required in greater
amounts than diffusion can supply so the plant spends energy
taking in these nutrients. This process also serves another
purpose by restricting nutrients from competing plants.
Substrate – Material that an organism attaches itself to, moves
through or lives off of. For example the substrate of the
Earthworm is soil.
The Food Cycle
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All living things need a constant supply of raw
materials and energy to survive and grow.
The food cycle begins with plants taking in
inorganic compounds and solar energy
and chemically changing them to organic
compounds which consumers use for
energy, growth, and repair of tissues.
Farming and Fertilizer
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Fertilizers are identified by three numbers: (eg. 5-105). The first number represents the percent of
nitrogen, the second number the percent of
phosphate, and the third number the percent of
potassium. The other 80% of fertilizer is made up of
trace elements and filler.
Until 1900s plants received all of their nitrates
(nitrogen based nutrients) from nature (soil and
manure). Then commercial fertilizers were created
and the amount of nitrogen in the environment has
increased by 140 million tons/year.
Nitrogen is needed for tissue growth and repair so
plants have grown larger and healthier as more
nitrogen has become available. Crop production has
doubled worldwide.
The Problems with Modern Farming
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A lot of water is being used on farming.
Monoculture farming has led to a decrease in
genetic variety in plants making crops more
at risk for diseases.
Pests have increased as well and because of
this, the use of chemical pesticides has also
increased.