Transcript The 4 Conditions for Life on Earth

Conditions for Life
The Goldilocks Zone
 Earth’s life-sustaining
conditions are possible
because of its position in
the solar system
 It is not too hot and not
too cold – if the Earth
was any closer or further
away from the Sun, the
planet could not support
life
Other Life Sustaining Conditions
 Earth’s rotation on its axis and orbit
around the Sun helps distribute heat
evenly around the planet
 Earth’s magnetic field protects the planet
from deadly radiation and particles
 Earth’s gravitational field holds the
atmosphere in place preventing oxygen,
nitrogen, and carbon dioxide from
escaping into space
Four Conditions for Life
1. Stable Temperature Range
2. The Importance of Water
3. The Importance of Gases
4. The Role of the Atmosphere
Stable Temperature Range
 A stable temperature range (-50 to about +50 degrees
Celsius) allows life to thrive – the average temperature
has been between 10-20 degrees Celsius for 3.5 billion
years
 The greenhouse effect allows for heat in the
atmosphere (carbon and water vapor) to be re-radiated
back to Earth
 Without proper water and carbon, the earth would be
-73 degrees C.
The Greenhouse Effect
 Plants play a significant
role in creating a stable
temperature through
releasing water vapor and
oxygen by the processes of
photosynthesis and
transpiration
 Dark areas of vegetation
absorb heat from the sun’s
rays and limit the albedo
effect – heat being
reflected back into space
Photosynthesis
The Importance of Water
 First water likely came from volcanic activity – water collected on the
cooling surface and as vapour in the atmosphere creating the water cycle
 Biologists believe earth first began in the oceans – blue-green algae
 Oceans cover 2/3 of the Earth – absorbs heat and distributes it around
the world and controls our weather patterns and climates
 Helps distributes nutrients to plants
and other organisms
 No living this consists of less than 50%
water
 Water is the metabolizing agent that
allows plants and animals to dissolve
minerals and nutrients to create energy
The Importance of Gases
 78% nitrogen, 21% oxygen, carbon dioxide 0.03% -
quite different than other planets in the solar system
 The plants have removed most of the carbon dioxide
that originally existed and produced lots of oxygen
 Without life on earth, carbon dioxide would increase
 The production of carbohydrates, fats, and proteins
require oxygen, carbon, and nitrogen atoms from the
atmosphere, and hydrogen from water
The Role of the Atmosphere
 Layer of gases about 80-100 kms thick –
very thin compared to size of Earth
 Helps maintain a consistent temperature
 Shields earth from collisions with cosmic
particles (meteors)
 Oxygen levels at 21 allow for life, if they
drop, animal life would not be possible, if it
exceeds 25% most plants would be
consumed by fire
 Oxygen is produced by plants and
consumed by animals and the burning of
plants and fossil fuels
The Four Spheres
1. Lithosphere – earth’s crust (soil,
rocks, and minerals)
2. Hydrosphere – earth’s water
3. Atmosphere – the gases in the air
4. Biosphere – all living things
(plants, bacteria, animals)
Biosphere
 Encompasses all living organisms including humans
 Divided into separate but interdependent units called
ecosystems – well defined habitats hosting systems of
interacting organisms
 Nutrient Cycle - Continuation of life depends on the
constant recycling of chemical ingredients called
nutrients (Example: plants and animals die and
decompose)
Biosphere – The Carbon Cycle
 The movement of carbon from the
atmosphere into plants, animals,
and the soil and then back again
 Plants take carbon dioxide from the
atmosphere to produce food through
photosynthesis and release oxygen –
animals breath oxygen and eat plants
 Dead animals and plants decay and
return carbon to cycle
 Over production of carbon dioxide
from factories and burning
rainforests causes climate change
Biosphere – Nitrogen Cycle
 Most powerful element in the
Earth’s atmosphere
 Microscopic bacteria live on
the roots of certain plants
known as legumes and
converts nitrogen to ammonia
and nitrates which the plant
absorbs and converts to
protein – food production
Biosphere – Oxygen Cycle
 Oxygen produced by the
respiration of plants – 90% of
oxygen used is replaced by
algae in oceans
 Oxygen created by
photosynthesis
Biosphere – Water Cycle
 Water must be recycled
through the atmosphere and
back to the Earth’s surface
 Most from evaporation –
some from transpiration;
water drawn by plants and
released through their leaves
 Groundwater dissolves
nutrients in the soil