Life on Earth - It's Alive!
Look closely at the photographgraph of the big horn sheep to the left. Think about the sheep's relationship with other organisms. Are there other living things that the sheep depends on for food or protection? Does the sheep provide food for other organisms? Does it require other organisms to reproduce? Take a few minutes and list as many relationships as you can think of that this sheep might have with other organisms.
Living organisms always affect other organisms either directly or indirectly. Organisms and the organic matter they produce are called biotic factors in an environment.
Variations in the biotic factors influence the organisms that are found in an environment. Compare the environment of the big horn sheep shown to the left with the sheep shown in the first photographgraph. What obvious biotic differences exist between these two ecosystems? What abiotic differences are there between the two ecosystems? Make a list of the differences and compare your list with a friend.
Step outside and look for any animal (even an insect will do). List all of the biotic things that are in this animal's environment. List at least ten things. Next to each item in your list, describe what would happen to the animal if that item either didn't exist or changed drastically in numbers.
Abiotic factors influence biotic factors. The photograph below shows a desert ecosystem. Observe the photographgraph closely. What obvious and implied biotic and aboitic factors can you describe in this ecosystem? List as many biotic and abiotic differences as you can see or imply.