Transcript grade10Chapter8x - Westmount High School

Chapter 8
The Biosphere
The Biosphere
The Biosphere is the layer of the Earth
containing organisms and their habitats.
Associated with the biosphere are the
biogeochemical cycles of essential elements
for life.
BIOGEOCHEMICAL
CYCLES
Biogeochemical Cycle

A set of processes by which an element
passes from one environment to the next
and eventually returns to its original
environment.
◦ Carbon Cycle
◦ Nitrogen Cycle
◦ Phosphorous Cycle
The Carbon Cycle

Carbon is often described as the
building block of life, since it is the
basic element of proteins, lipids and
carbohydrates, and thus all living things.

Carbon is constantly being exchanged and
recycled through different parts of the
Earth.
Stages of the Carbon Cycle
Photosynthesis: plants and
phytoplankton take in carbon dioxide
(CO2) from the atmosphere and use it to
make sugars.
 Respiration: when living organisms CO
2
breath they release carbon dioxide back
into the atmosphere.

CO2
Stages of the Carbon Cycle

Decomposition: organisms called
‘decomposers’ break down dead
organisms and animal waste, releasing
CO2 or methane in the process.
CO2, methane
Stages of the Carbon Cycle
 Ocean
Sediment:
Carbon dioxide from the atmosphere
dissolves in oceans to form bicarbonate. This is
used by marine organisms to create their
shells and skeletons, which sink to the ocean
floor when they die, and accumulate in the
sediment, eventually forming carbonate rock.
CO2
Stages of the Carbon Cycle

Fossil fuels:
When dead plant and
animal matter are buried
under sediment, they are
converted into oil, coal or
natural gas after millions of
years.
The burning of these fossil
fuels by humans releases
carbon dioxide into the
atmosphere.
Stages of the Carbon Cycle

CO2
Volcanic eruptions and forest fires: Also
release carbon into atmosphere.
CO
2
1
1
2 Decomposers
4
3
4
Carbon into the
atmosphere (CO2)
Carbon out of the
atmosphere
Carbon into the
ground
Respiration
• animals
• plants (at night)
• decomposers (also
methane)
photosynthesis
Sedimentary rock
formation
Forms from sediments
of marine organisms
volcanoes
Carbon dioxide
dissolves in water
 Is incorporated into
shells and skeletons of
marine organisms.
Fossil fuel formation
Forms from organic
matter in bogs and
marshes
Burning something
• Forrest fires
• Fossil fuels
Carbon passed around
from organism to
organism in food chains
1
1
2 Decomposers
4
3
4
The Nitrogen Cycle

The nitrogen cycle is the biogeochemical
cycle that describes all the exchanges of
nitrogen on earth.
The Nitrogen Cycle

The vast majority of nitrogen is found in
the atmosphere, as N2, which cannot be
directly used by plants or animals.
The Nitrogen Cycle

Nitrogen is used by living organisms to
produce a number of complex organic
molecules like amino acids, proteins
and DNA.
Nitrogen is
normally the
most limiting
nutrient for
plant growth.
Stages of the Nitrogen Cycle

Nitrogen fixation:
N2
ammonium
Bacteria in soil (or associated with plant roots) convert
N2 into ammonia, which reacts with water to
ammonium.
Stages of the Nitrogen Cycle

Nitrification: bacteria convert ammonium
into nitrites, then into nitrates.
Stages of the Nitrogen Cycle

Nitrogen absorption
(Assimilation): plants
absorb nitrates or
ammonium from soil
or water and use it to
create proteins.
Animals can then get
their nitrogen by eating
the plants.
Stages of the Nitrogen Cycle

Decomposition of waste:
decomposers break down dead organisms
and animal waste, producing ammonia
which dissolves to form ammonium.
ammonium
Stages of the Nitrogen Cycle

Denitrification: certain bacteria can
convert nitrates into atmospheric nitrogen.
N2
Stages of the Nitrogen Cycle
Nitrogen recycling
(Decomposers)
Nitrogen
absorption
Nitrogen fixation
Denitrification
N2
N2
Nitrification
Nitrogen into
ground
Nitrogen
converted
Nitrogen
Nitrogen out of
passed between ground
organisms
Nitrogen
fixation
(bacteria in soil
and on plant
roots)
Nitrification
Bacteria convert
Ammonium to
Nitrate
Nitrogen
absorption by
plants
Animals eat
plants or animals
Decomposers
Break down plant
and animals waste
Denitrification
Bacteria convert
nitrates in
nitrogen
5
1
4
3
1
2
The Phosphorous Cycle - EST

Phosphorous (like nitrogen) is a
component of DNA and is therefore an
essential element or all life.
Bone consists predominantly of a
mineral containing phosphate.
Stages of the Phosphorous Cycle

Weathering of rock: water dissolves
phosphorous in the form of phosphate. 
Phosphate is transported by water.
Stages of the Phosphorous Cycle

Absorption by living organisms.
◦ Plants absorb phosphates,
◦ animals eat plants or other animals.
Stages of the Phosphorous Cycle

Decomposition of waste
◦ Return of Phosphorous to the soil through
animal waste
◦ decomposers
Phosphate
Phosphate
Stages of the Phosphorous Cycle

Proliferation of plankton and
sedimentation
◦ Phosphate in water promotes the growth of
plankton  eaten by animals
◦ Phosphate minerals precipitate 
sedimentary rock
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2
3
4
TERRESTRIAL BIOMES
Biome: a distinct ecological community
of plants and animals living together in a
particular climate.
Factors contributing to climate
Latitude
Altitude
Climate- Temperature
The main factors which influence
temperature are:
1. Latitude: as you move away from the
equator, sunlight is less intense  lower
temperature.
2. Altitude: with increases in elevation at a
given latitude, the temperature decreases.
Climate- Temperature

Temperature plays a vital role because
most organisms are adapted to live within
a very narrow temperature range.
Increasing or decreasing the temperature
by even a few degrees can cause some
species to die.
Factors affecting Terrestrial Biomes
Latitude
 Altitude
 Solar energy
 Temperature
 Precipitation
 Soil type
 Winds
 Proximity to bodies of water

Hadley Cells and climate zones
•Hot moist air rises at
the Equator (1) air
cools and water
condenses, it rains (2)
•Dry air moves
towards 30°, sinks
and warms up (3).
Latitude determines how much it
rains
•Dry hot air
moves back
towards Equator,
collecting all water
from the land
underneath (4)
 Desert
Also where Ferrel and Polar Cell meet warm moist air rises:
 water condenses  rain.
Influence of Altitude on precipitation
Andes (mountain chain)
West wind
zone
Desert in wind
shadow
Climate- Precipitation

Plays a vital role because all living organisms
require water
Climate- Precipitation

Precipitation tends to be generally higher where
air is rising & cooling, releasing moisture:
◦ near the equator, most significantlyproduces tropical rainforests or tropical
seasonal forests
◦ at 60o N & S latitude, to lesser extentproduces temperate deciduous forests,
temperate rainforests, coniferous forests.
Climate- Precipitation

Precipitation tends to be generally lower:
◦ near 30 o N & S latitude- dry, descending
air masses produce deserts (all great world
deserts lie near 30 o N or S latitude)
◦ in interiors of large continents- due to
great distance from sea (ultimate source of
most moisture)
Terrestrial Biomes: Can you name
these?
Desert
Desert
Boreal Forest
Arctic Tundra
Tropical Rainforest
Tropical Forests




Lie on either side of the equator
(warm temperatures)
High precipitation
Contain over half of the world’s
terrestrial biodiversity
Soil rather infertile due to leaching
(excessive rain), and very fast
decomposition of organic matter.
Seasonal tropical rain forest
Mainly in Africa
 Dry season of varying length

Temperate Forests
Contain mix of deciduous and coniferous
trees
 Nutrient rich soils make an excellent
habitat for plant growth and animals

• Warm and cold season
• Precipitation evenly
throughout year
Boreal Forest/Taiga
Composed mostly of coniferous trees,
which do not lose leaves/needles
 Acidic, nutrient poor soils
 Long, cold winters; short, cool summers

Taiga: trees become shorter and
more scarce
Grasslands/Shrublands
Dry, without enough rainfall to support
tree growth, but enough for grasses and
shrubs
 There are three different types:

◦ Temperate grasslands –hot summers, cold
winters  great plains north america
◦ Savannas- hot year-round; rain in summer, dry
winter
◦ Derived grasslands- farmer’s grain or grass
fields
Arctic Tundra
Surrounds the North Pole, with long, cold
winters and short summers.
 Characterized by slow plant growth and
extensive permafrost
 Grasses, bushes, moss and lichens
 Some fauna:
ex. caribou, arctic fox

Deserts
Defined as areas with less than 25cm of
annual precipitation
 Very high or very low temperatures (ex.
Antarctica)
 Rare plant life and very few animals, which
have adapted to desert life

Alpine
Biomes that are found on mountain ranges
 As altitude increases, temperature decreases,
which changes vegetation:

◦
◦
◦
◦
◦
Submontane zone (below 1300m): deciduous trees
Montane zone (1300-1800m): deciduous/coniferous trees
Subalpine zone (1800-2400m): some conifers
Alpine zone (above 2400m): few bushes and grasses
Nival zone (above 3000m): below freezing point, only some
lichen can grow here
AQUATIC BIOMES
Freshwater Biomes
Lakes
 Bodies of water surrounded by land
 slow current, deep water
 Flora/Fauna consists of microorganisms,
plants, plankton, fish, amphibians, reptiles
and birds.
Freshwater Biomes
Rivers
 Drainage channels for surface water
 Aquatic plants must be adapted to the
current and highly oxygenated water.
 Often lined by mosses and grasses.
Freshwater Biomes
Wetlands
 Areas permanently or temporarily covered
with water (fresh or salt)
o
o
o
Marshes: land covered with stagnant water, no
trees
Swamps: land covered with water but with trees
or shrubs
Peat Bogs: poorly drained soil covered with
moss ( like wet carpet)
Absorb large amounts
of water, filter water.
http://educationalminimovies.com/index.php/science/739/704-bill-nye-on-wetlands-part-1
marsh
swamp
Peat bog
Marine Biomes
Estuaries
 The broadening at the mouth of a river
that empties into the sea
 Fresh water mixes with salt water 
typical species: oysters, sponges
 Large amounts of sediment are deposited
sun
Marine Biomes
Oceans and Seas
 Have a wide variety of living conditions,
depending on depth:
◦ At the surface – phytoplankton act as direct or
indirect food for fish, jellyfish, crustaceans, mammals,
birds.
◦ Ocean floor – home of the benthos, the mollusks,
crustaceans and bottom feeding fish which eat dead
organisms on the ocean floor
>200m below surface –
not enough light for
photosynthesis (no plants),
but can still find species of
fish, eels, squid and octopus
o
Marine Biomes
Coral Reefs
 Are made of organisms called corals,
which have a hard calcium carbonate
based shell
 The habitat supports huge amounts of
biodiversity, offering food and shelter to
numerous aquatic organisms
Coral
Zooxanthellae
Zooxanthellae:
Microscopic algae inside
the cells of the coral
animal
Symbiosis: Zooxanthellae provide carbohydrates and
oxygen for coral through photosynthesis
Coral provides nutrients and habitat for zooxanthellae
Coral Reefs

Threatened by global warming, pollution,
overfishing
• Change in water
temperature may
cause expulsion of
zooxanthellea
• Sedimentation on
top of corals
prevents
photosynthesis
Factors affecting Aquatic Biomes
Salinity
Temperature
Water depth
Direction and strength of
current
 Turbidity (water clarity)
 Solar energy
 Nutrient availability
 Presence of oxygen and
carbon dioxide

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