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Lesson Overview Studying Life Lesson Overview 1.3 Studying Life Lesson Overview Studying Life Characteristics of Living Things Biology is the study of life. But what is life? What characteristics do all living things share? Living things are all - made up of basic units called cells - based on a universal genetic code - obtain and use materials and energy - grow and develop (change) - reproduce - respond to their environment - maintain a stable internal environment (homeostasis) - evolve. Lesson Overview Studying Life Characteristics of Living Things #1 - Living things are made up of one or more cells. unicellular = made of one cell (bacteria) multicellular = made of many cells (us!) - Cells can grow, respond to their surroundings, and reproduce. Lesson Overview Studying Life Characteristics of Living Things #2 - Based on a universal genetic code. - All organisms store the complex info they need in a genetic code written in DNA. - DNA is copied/passed from parent to offspring and is almost identical in every organism on Earth. Lesson Overview Studying Life Characteristics of Living Things #3 - Living things grow and develop. - A single fertilized egg divides again and again. - As these cells divide and differentiate = they begin to look different from one another and to perform different functions. Lesson Overview Studying Life Characteristics of Living Things #4 - Living things respond to their environment. - A stimulus is a signal to which an organism responds. - For example, some plants can produce unsavory chemicals to ward off caterpillars that feed on their leaves. Lesson Overview Studying Life Characteristics of Living Things #5 - Living things reproduce. - Most plants and animals engage in sexual reproduction, cells from two parents (sperm + egg) unite to form the first cell of a new organism. - Asexual reproduction is when one cell splits, or divides, into two new identical cells. Lesson Overview Studying Life Characteristics of Living Things #6 - Living things maintain a stable internal environment. - All living organisms maintain homeostasis. - For example, even though it’s cold outside, your internal temperature remains close to 98.6ºF. Lesson Overview Studying Life Characteristics of Living Things #7 - Living things obtain and use energy. - The sum of all chemical reactions in your body = metabolism. Lesson Overview Studying Life Characteristics of Living Things #8 - Over generations, groups of organisms evolve, or change over time.