Re: How is it possible to keep the food web going?

Hi Kate-
You've asked two very good questions;  I'll deal with them one at a 
time.


How is it possible to keep the food web going?
     All food webs are ultimately powered by the sun.   Plants absorb 
light energy from the sun and turn it into chemical energy, in the form of 
sugars in the process of photosynthesis.  The sugars are made up of carbon, 
hydrogen, and oxygen,  which the plant gets from carbon dioxide (which it 
gets from the air),  and water (which it gets from the air and soil.)  
Plants are eaten by herbivores and used to make more herbivores,  and the 
herbivores may be eaten by carnivores.  All plants, herbivores and 
carnivores respire,  which is essentially the opposite of photosynthesis-  
where sugar and oxygen are turned into energy,  carbon dioxide and water,  
which is just what the plants need for photosynthesis!  So,  as long as the 
sun keeps shining,  plants will continue to make sugars,  and food webs 
will continue to exist.  No worries there!


What are some ways to prevent living creatures and plants dying or 
being harmed due to the UV-B Rays that filter through the Ozone Layer?
     Plants and animals have lots of neat ways to deal with UV 
radiation.  Some plants and animals produce pigments,  which protect them 
from UV.  These pigments protect the animal,  by reacting with the incoming 
UV radiation,  effectively turning it from light energy into heat energy.  
Unfortunately,  with the recent reduction in the amount of atmospheric 
ozone,  there is more UV making its way through the atmosphere to the 
planet.  While some plants and animals may be able to cope with the higher 
levels of UV,  a lot will not.  In order to prevent plants an animals being 
harmed by UV,  we must prevent the UV from reaching those plants and 
animals in the first place,   that is to prevent the UV from ever reaching 
the surface of the earth. The ozone layer does a pretty good job of that,  
if there's enough of it.   Right now there are a lot of people in a lot of 
independent and government agencies trying to figure out how we can stop 
losing the ozone we've got now-  this has lead to a number of laws aimed at 
stopping the production of chemicals that destroy ozone,  such as the CFCs 
(ChloroFluoroCarbons) which used to be found in refrigerators and aerosol 
spray cans.

Hope that helps,
MAD Scientist Rob Campbell