SUNLIGHT
- most plants and some animals (ex: some jelly fish) rely on sunlight for photosynthesis to make energy and survive
TEMPERATURE
- the bodies of animals have enzymes needed for us to survive. if the temperature is too hot, these enzymes cannot work anymore, and we will die
- if it is too cold, like in the -10 degrees Celsius, some organisms are not able to adjust and the water content may freeze up (causing organism to freeze)
WATER
- for organisms like humans, we are made of mostly water, which is important for keeping us alive. if there is not enough water in the environment, we will die of thirst
O2 AND CO2
- plants need CO2 for photosynthesis to keep alive
- most other organisms need O2 to make energy and stay alive
SALINITY
- salinity can control certain important processes in an organism's body
- sometimes, if it is too salty in the environment, the water in the cells of some organisms will diffuse out, leaving the cells dry
pH
- extremely acidic or basic environments will harm organisms
- body needs optimum pH to operate properly
