Transcript 1.2 Nutrient Cycles and Energy Flow

1.2 Nutrient Cycles and
Energy Flow (Part 1)
pp. 22 - 29
Learning Goals

By the end of this lesson, you should:
◦ Know the steps of the following cycles: water,
nitrogen, carbon.
◦ Know the equations for photosynthesis and
cellular respiration, and where these
processes take place (plants / animals)
◦ Understand why each cycle is important to a
healthy ecosystem
Nutrient Cycles
Nutrient – Substances that an organism
uses to build and repair cells in the body.
 In a cycle there is no beginning or end.
 Nutrients cycle back and forth between
the biotic and abiotic parts of ecosystems.
 Water, carbon and nitrogen are nutrients
that all have reservoirs.

◦ A reservoir is a place where matter
accumulates / is stored
The Water Cycle
The sun warms the surface water, and the
water evaporates into the atmosphere.
 The water vapour cools and condenses to
form clouds.
 Water falling from the clouds to the
ground is called precipitation
 Water that runs from the ground into
streams or rivers is called run-off.

The Water Cycle
Some water seeps through the soil and
into ground water. Large underground
lakes are known as aquifers.
 Plants absorb some of the water in the
ground and release it through their leaves
in a process known as transpiration
 The water vapour rises and the cycle
continues.

Condensation
Evaporation
Precipitation
Transpiration
Respiration
Surface Run-Off
Percolation
• Filtering of H2O
downward through soil
The Nitrogen Cycle
All organisms need nitrogen to make
proteins
 78 % of the atmosphere is nitrogen but it
cannot be directly used by organisms.
 Organisms get nitrogen from substances
that contain nitrogen.

The Nitrogen Cycle
The act of converting nitrogen gas (N2) to
ammonia is called Nitrogen fixation
 Nitrogen fixing bacteria perform this
critical step

◦ Without the bacteria the cycle would stop
◦ Lightning only fixates 1% of the world’s
nitrogen

Most plants cannot use the ammonia
created
The Nitrogen Cycle
Nitrifying bacteria convert the ammonia
into nitrates
 Nitrates are absorbed and used by the plants
 Animals eat plants to obtain nitrogen.
 The animals then produce ammonia which is
removed as waste.
 Nitrifying bacteria then convert the
ammonia to nitrates.
 Denitrifying bacteria in the soil convert
nitrates back into nitrogen gas.

12. Nitrogen Fixation
by Lightning
1.
2.
3.
4.
5.
Nitrogen gas (N2) in Atmosphere
Nitrogen-fixing Bacteria
Fertilizers (already nitrates)
Soil Nitrates Accumulate
Uptake of Nitrates by plant roots
6. Nitrates move along food chain
7. Dead Organisms
8 -10 Nitrifying Bacteria
11. Denitrifying Bacteria
12. Fixation by Lightning
The Carbon Cycle (2 parts)
1. Photosynthesis
2. Cellular respiration
 All living things contain carbon
 Plants obtain carbon from the atmosphere
◦ Forests are carbon reservoirs as well as
coal and oil deposits
 Oceans are also reservoirs for carbon
dioxide
1. Photosynthesis
The process that plants use to capture energy
from sunlight
 Plants use chlorophyll to combine carbon
dioxide from the air (CO2) and water (H2O) to
produce a sugar called glucose (C6H12O6) and
oxygen gas (O2)

Summary
 Carbon dioxide gas + water + sunlight 
glucose + oxygen gas
 CO2 + H2O + sunlight  C6H12O6 + O2
Make a simple drawing of this
2. Cellular Respiration

The process both plants and animals use to
turn glucose into energy. The process is
almost the reverse of photosynthesis
Summary
 Glucose + Oxygen gas  Carbon dioxide +
Water + energy
 C6H12O6 + O2  CO2 + H2O + energy

Photosynthesis + Cellular Respiration =
Carbon Cycle
1. Carbon dioxide (CO2) gas
2. CO2 absorbed during
photosynthesis
3. Carbon moves along food chain
4. CO2 returned during cellular
respiration
5. Plants turn into fossil fuels (takes
time and extreme heat and pressure)
6. CO2 returned by burning fossil
fuels
7. CO2 returned during cellular
respiration
Learning Goals

By the end of this lesson, you should:
◦ Know the steps of the following cycles: water,
nitrogen, carbon.
◦ Know the equations for photosynthesis and
cellular respiration, and where these
processes take place (plants / animals)
◦ Understand why each cycle is important to a
healthy ecosystem
Homework
Read 22-29
 Answer the following Questions:

◦ p. 27 # 1, 3, 4
◦ p. 35 # 2, 4 – 6, 12, 14