Conditions for Life Conditions for Life

The Goldilocks Zone 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 ConditionsOther Life Sustaining ConditionsEarth’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 LifeFour Conditions for Life1.1. Stable Temperature RangeStable Temperature Range

2.2. The Importance of WaterThe Importance of Water

3.3. The Importance of GasesThe Importance of Gases

4.4. The Role of the AtmosphereThe Role of the Atmosphere

Stable Temperature RangeStable Temperature RangeA 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 EffectThe Greenhouse EffectPlants 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

PhotosynthesisPhotosynthesis

The Importance of WaterThe Importance of WaterFirst 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 GasesThe Importance of Gases78% 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 AtmosphereThe Role of the AtmosphereLayer 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 SpheresThe Four Spheres1.1. Lithosphere – earth’s crust Lithosphere – earth’s crust

(soil, rocks, and minerals)(soil, rocks, and minerals)

2.2. Hydrosphere – earth’s water Hydrosphere – earth’s water

3.3. Atmosphere – the gases in the Atmosphere – the gases in the airair

4.4. Biosphere – all living things Biosphere – all living things (plants, bacteria, animals)(plants, bacteria, animals)

BiosphereBiosphereEncompasses 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 CycleBiosphere – The Carbon CycleThe 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 CycleBiosphere – Nitrogen CycleMost 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 CycleBiosphere – Oxygen CycleOxygen produced by the

respiration of plants – 90% of oxygen used is replaced by algae in oceans

Oxygen created by photosynthesis

Biosphere – Water CycleBiosphere – Water CycleWater 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