Conditions for Life on Earth Flashcards
Finish the sentence: Most chemical reactions in living organisms….
Involve reactants that are dissolved in water
Water is most dense at what temperature?
4°c
What zone is earth in?
The Goldilocks zone
What ways did the presence of liquid water allow life to develop?
-solvent water: ‘general physiological solvent’ most chem reactions in living organisms take place here
-transport within organisms: water is the solvent in blood and sap- transports dissolved gasses, amino acids, mineral nutrients, waste products
-Temp control: evaporation of water absorbs heat
-Anomalous expansion on freezing: water cooler than 4°c floats- stopping the convection current that would cool the whole body
-Aquatic habits
-Absorption Of UV radiation:protected living organisms before the ozone layer developed
What are the 2 atmospheric gases and what are they for?
Carbon dioxide: photosynthesis & the synthesis of carbohydrates, proteins, & lipids
Nitrogen: protein synthesis
What is albedo
Measures the reflectivity of a surface
How has the presence of life brought about environmental change?
Oxygen production: first produced by bacteria then algae and then plants
Carbon sequestration: photoautotrophs absorb carbon dioxide- prevents temp rises
Ozone layer: produced by chem reactions involving oxygen and ultraviolet light in stratosphere
Biogeochemical cycles: linked by living organisms- prevents build up of waste
Transpiration: plants return water to atmosphere which increased rainfall in other areas
What are the limitations of early methods into the research of past conditions on Earth?
Lack Of sophisticated equipment
Lack Of data collection in many areas
Lack Of ancient historical data
How have methods of collecting research on the past conditions on Earth improved?
Collection Of long term data
Electronic monitoring equipment
Improved carriers for monitoring equipment: helium balloons, satellites
What are abiotic factors?
Non-living organisms that can influence where a living organism can live
how did earth’s mass it suitable for life
great enough to prevent most gases from escaping
atmospheric pressure high enough to prevent all liquid water from boiling
how did earth’s distance from the sun make it suitable for life
suitable temp.
light
allows liquid water to be present
time taken for earth to rotate produced day/night cycle fast enough to minimise excessive heating or cooling
how did earth’s axis of rotation make it suitable for life
produces seasonal variations in conditions
how does earth’s speed of rotation make it suitable for life
temp. of earth’s surface rises when exposed to sunlight and falls when not
24-hour rotation prevents temp. extremes
how does earth’s magnetic field make it suitable for life
molten layers beneath crust produce magnetic field
deflects solar wind and prevents biologically damaging radiation from reaching earth’s surface
how does earth’s temp. range make it suitable for life
0-35 degrees C
warm enough for liquid water but not hot enough to denature proteins
how do earth’s atmospheric gases make it suitable for life
CO2 for photosynthesis
nitrogen for protein synthesis
how does solar insolation make earth suitable for life
sunlight provides energy for photosynthesis
heat produced by absorption of sunlight provides energy that drives water cycle and warms earth’s surface and oceans
amount of sunlight absorbed by earth’s surface depends upon albedo
composition of atmosphere controls amount of infrared energy absorbed and converted to heat
formation of the solar system
4.57B years ago
formed from giant rotating cloud of gas and dust
sun formed at centre and planets formed around sun in process of accreation
formation of the moon
4.53B years ago
formed as a result of collision between Earth and a Mars-sized body called Theia
impact caused portion of combined mantle of Earth and Theia to be expelled into space, forming the moon
late heavy bombardment
4.1-3.8B years ago
violent period of near-constant collisions between Earth and large asteroids/comets
formation of crust and oceans
4B years ago
cooling of Earth allowed crust to form and condensation of water from atmosphere formed oceans
oldest geological evidence of life
3.5B years ago
stromatolites formed through sheets of microbes capturing sedimentary particles
successive layers of microbes and sediment result in a striated pattern of growth
proliferation of cyanobacteria
3-2.5B years ago
evolution of photosynthesis allowed cyanobacteria to convert light to chemical energy
formation of O2 by photosynthesis transformed atmosphere and allowed growth of biodiversity
evolution of eukaryotes
2B years ago
eukaryotes have a nucleus and membrane-bound organelles
organelles and nuclei may have evolved as a result of an ancient symbiotic relationship between different bacteria
evolution of multicellular organisms
1.2B years ago
multicellularity evolved several times
evolved as a result of symbiotic relationship between cells of same/different species, eventually leading to interdependency
cambrian explosion
600-500M years ago
sharp increase in diversity and amount of complex animals
cause unknown but possibly rise in atmospheric O2 and other enviro. changes may have played a role
appearance of modern humans
200,000 years ago
homo sapiens evolved from homo erectus
dinosaurs
230-65M years ago
populated Earth for 150M year
extinction caused by large asteroid impact or rise in volcanic activity
How did Isolation contribute to life on earth?
a suitable temp range was controlled by incoming isolation and its behaviour in the atmosphere. this was controlled by the surface albedo
