a1.1.1 - water: the medium for life

Question 1

how did the first cells originate?

Answer 1

the first cells originated in water

• early Earth didn’t have an ozone layer to protect it from harmful UV radiation from the sun. however, the oceans blocked these harmful UV rays, allowing the first life to evolve
  
  • as UV enters the oceans, it dissipates and
    becomes less harmful with increasing
    depth, protecting organisms below and
    allowing life to thrive.
• early cells evolved membranes to separate their insides (cytoplasm) from the ocean water. bilayers naturally form in water.

Question 2

list reasons why water is an important solvent and how it is crucial for living organisms

Answer 2

water…
- makes up the fluid (cytoplasm) in all cells where all metabolic reactions occur
- makes up the fluid inside the organelles in cells
- is found between cells of multicellular organisms (intertitial fluid)
- allows transport of substances into and out of cells
- main component of blood (plasma)
- stable medium for aquatic organisms to live
- necessary for many enzymes to function and catalyze reactions