Transcript The Biosphere

The Biosphere
• Carbon Cycle
• Nitrogen Cycle
• Oxygen Cycle
• Water Cycle
The Four Spheres
Scientists divide regions on the Earth into
four spheres:
–
–
–
–
Lithosphere – Earth’s crust, soil, rocks etc.
Hydrosphere – all water on Earth
Atmosphere – all gases in the air
Biosphere – all life
• Each sphere contains many natural cycles that
contribute to our survival
Biosphere means
and was coined
The“life-zone”
Biosphere
by Dr. Vladimir Vernadsky
The biosphere encompasses all living things
It is divided into separate, but
interdependent units called ecosystems
The Biosphere cont.
• Ecosystems are well-defined habitats hosting
systems of interacting organisms.
• The continuation of life within the biosphere
depends on the constant recycling of nutrients.
• Nutrients are chemical ingredients found on
Earth, which are necessary for the continuation
of life.
The Nutrient Cycle
• Nutrients come from decaying biomaterial
(dead things) that become gases (move into
atmosphere) and solids and liquids that are
released into the soil and water for living
plants and animals to use as nutrients
• This is referred to as the nutrient cycle –
there are four nutrient cycles
The Carbon Cycle
• The Carbon cycle is a nutrient cycle
• It is the movement of carbon from the
atmosphere into plants, animals, and the
soil, and then back into the atmosphere
again
• Carbon is an essential component of life
on Earth.
The Carbon Cycle (cont’d)
• Plants take carbon dioxide from the
atmosphere and use it to produce their
own food through photosynthesis
• The plants form carbohydrates
• They also release oxygen
• Animals breathe oxygen and eat carbon –
storing plants
• The animals, in turn, breathe out carbon
dioxide
• When both plants and animals die,
decomposition releases carbon dioxide
into the air and it is used again
The Carbon Cycle (cont’d.)
The Carbon Cycle (cont’d)
• Carbon dioxide is also a greenhouse gas –
it helps to regulate Earth’s temperature
• When there is vast clear cutting and
burning of forests, massive amounts of
carbon is released into the atmosphere
and carbon dioxide-processing plants are
destroyed.
The Carbon Cycle (cont’d)
• This creates an imbalance affecting the
greenhouse effect
• Too much carbon dioxide in the air can
increase the global temperature (global
warming) – like on planet Venus where
there is too much carbon dioxide in the
air.
TheNitrogen
Nitrogen
Cycle
The
Cycle
• The nitrogen cycle is a nutrient cycle
• Nitrogen is the most plentiful element in
Earth’s atmosphere – 78%
• Nitrogen has to change to ammonia and various
compounds called nitrates before it is useful to
living things
The
Nitrogen
Cycle
Cont’d
The Nitrogen Cycle
• This is accomplished by microscopic
bacteria living on the roots of legumes
(alfalfa, peas, beans, and clover)
• An exchange takes place between plants
and the bacteria – plants take in nitrogen
compounds, the bacteria receive
carbohydrates
• The plant converts the ammonia and
nitrates into proteins
The Nitrogen
Cycle
(Cont’d)
The Nitrogen Cycle
• All life on earth depends on these bacteria
• When animals eat the plants they use the
proteins and other nitrogen compounds to
build amino acids – the building block of life
• When animals produce waste, or die,
decomposition breaks down the amino acid
proteins back into ammonia and nitrates
The Nitrogen Cycle Cont’d
• These nitrates are reabsorbed into water,
soil and plant roots or fixed again by the
bacteria
• This bacteria can release free nitrogen in
the atmosphere through denitrification –
the cycle then repeats.
The Oxygen Cycle
The Oxygen Cycle
• The Oxygen cycle is a nutrient cycle
• The majority of oxygen is produced by
the respiration (breathing) of plants
• Oxygen is a by-product of photosynthesis
90% of all oxygen is replaced through the
respiration by algae in the world’s oceans
The Oxygen
Cycle
The Oxygen
Cycle
(cont’d)
• Plants release oxygen into the air
• Some oxygen reacts with carbon in the
air to produce carbon dioxide
• Some is breathed in by animals and
breathed out as carbon dioxide
The Oxygen Cycle
• More oxygen is taken back by plant roots
reversing photosynthesis producing
carbon dioxide and water – this, in turn,
combines with soil nutrients allowing
plants to grow
The Water Cycle
The Water Cycle (cont’d)
• The water cycle is a nutrient cycle
• Water must be constantly recycled
through the atmosphere as water vapour
and back to Earth’s surface
TheWater
Water
Cycle
The
Cycle
• Water vapour is the result of evaporation
of bodies of water (oceans, lakes, etc.) and
transpiration where water is taken up by
plant roots and released to the air
through leaves
The Water Cycle
The Water Cycle (cont’d)
• In the atmosphere this water vapour
collects as clouds, condenses, and falls to
the Earth as precipitation
• It then runs into rivers, lakes, oceans,
and percolates down through soil as
ground water
• The groundwater dissolves nutrient so
plants can use them as food
The Water
The Water
CycleCycle
Cont’d
• Some groundwater filters into permeable
rocks like sandstone or limestone and can
be stored in empty layers between rocks
called aquifers
• The top layer of the stored water is called
the water table
The Water Cycle
The Water Cycle (cont’d)
• Humans extract water from the water
table and use it
• This water returns through sewage and
waste disposal where it evaporates and
the cycle begins again.
Suggested Activity
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Activity 7
Please read pages 48 – 53 of your text. Take
special note of the illustrated diagrams of each
cycle of the biosphere.
Create four concept maps each outlining one
cycle of the biosphere: water, carbon, oxygen,
and nitrogen.
In no less than a page discuss how each of these
cycles are interconnected and interdependent.