<span><span>a. </span>Reproducing</span>
f. obtaining
energy
d.
maintaining structure
Why do these
three illustrate the great challenge for every species.
<span><span>
1. </span>Reproduction, is as vital for an entire race to survive. It prolongs
their generation onwards and offspring to the next centuries to pass by.</span>
<span><span>
2. </span>Obtaining energy. In both humans and animals, even plants is a
challenge because these creatures need to work in order to obtain these need
resource from food –preys.</span>
<span><span>
3. </span><span>Maintaining structure. For the living organisms to still exist they
need to keep themselves intact. Combating diseases and having nutrition. This is
a by-product of having energy. </span></span>
Answer:
If there would be no biosphere on earth the atmosphere would be quite different. There would be no oxygen to support because oxygen is liberated by plants in photosynthesis so no plants means no oxygen. The earth would be a planet without life just like Venus and Mars. Therefore, no organism would be surviving in the world.
There would be no negligible green house effect and global warming since it is all created due to activities of men.The earth's atmosphere would be much cleaner and with lesser amount of CO2 and O2 but no organism would be there to use them.
Hope it help!
