All living things are called organisms and are made up of cells as their basic unit of structure and function. Organisms require certain needs like food, water, oxygen, living space, and proper temperature to survive. They obtain energy primarily from the sun and rely on homeostasis to maintain constant internal conditions for life processes while heterotrophs cannot produce their own food and rely on other organisms.

1. Life Science Lessons 1-2 and 1-3

2. What are living things? Lesson 1-2 Any living thing is called an organism . The basic unit of structure and function in living things is the cell . A reaction to a change in your surroundings is a reaction . The source of energy for most living things is the Sun .

3. Everything around you is made up of matter . When two or more atoms from different elements join, they form a compound .

4. What are the needs of organisms? Lesson 1-3 All organisms require food and water for growth and energy . Many living things get the oxygen they need from the air or water.

5. Most living things need oxygen to change food into energy. Living space provides an organism with air, water, food , and shelter . The ability of an organism to keep conditions inside its body constant is called homeostasis . Living things need a proper temperature to carry on their life processes.

6. A heterotroph is an organism that cannot make its own food. An organism that can make its own food is an autothoph .