14. Which physical elements
contributed to the great
amount of available energy on
the primitive earth at the time
of the origin of life?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
3.5 billion years ago water cycle was
faster today, resulting in hard
with intense electrical
discharges. was also no chemical
from the ozone layer
ultraviolet radiation. The temperatures
the atmosphere and on planet
surface were very . Electricity,
radiation and heat large
available energy sources.