Chapter 1, Section 1 What Is Life 7th Grade Life Science Mrs. Wright

The Characteristics of Living Things Cellular Organization -basic unit of structure and function -unicellular or multicellular The Chemicals of Life -all cells are composed of chemicals -primary chemicals of life: water, carbohydrates, proteins, lipids, and nucleic acids

Energy Use -grow and repair injured parts -an organism’s cells are always hard at work Growth and Development -growth is becoming larger- -development is the process of change during an organism’s life that produces a more complex organism

Response to Surroundings -all organisms react to changes in their environment -changes that cause an organism to react is a stimulus -response is the reaction to a stimulus - nonliving things do not react to stimulus Reproduction -to produce offspring that are similar to the parents

The Needs of Living Things Energy -autotrophs *make their own food *energy source is the sun -heterotrophs *eat autotrophs or other heterotrophs *energy source is also the sun, but in an indirect way

Water -obtain chemicals, break down food, grow, move substances, and reproduce Living space -plants occupy a fixed living space -animals either share or compete Stable internal conditions -homeostasis is the process by which an organism’s internal environment is kept stable in spite of changes in the external environment

Metabolicm The building up and breaking down of chemical substances necessary for life Ingestion – taking in food Digestion – food is broken down into simpler substances Respiration – taking in oxygen and using it to produce energy Excretion – removal of waste products from the body