Chapter 1: Exploring Life

Biology – The Study of Life The Earth is 4.6 billion years old. Life began more than 3.5 billion years ago. First organisms (living things) were single celled. They were the only life on Earth for millions of years. Organisms changed over time (evolved)

Cell Structure and Function Cell is the basic unit of life All organisms are made of and develop from cells Some cells are composed of only a single cell: unicellular Most organisms are composed of many cells: multicellular Cells are small Cells are highly organized

In multicellular organisms, cells and groups of cells (tissues) are organized by their function Cells  tissues Tissues  organs Organs  systems

Reproduction and Inheritance All organisms produce new organisms like themselves Organisms transmit hereditary information to their offspring (reproduction)

DNA It is the chemical responsible for inheritance The passing on of traits from parents to their offspring. DNA contains instructions for traits (genes)

Matter, Energy and Organization Living things are highly organized Requires a constant supply of energy to maintain their orderly state Almost all energy comes from the sun (directly or indirectly) Process called photosynthesis

Ecosystem The community of living things in an area, along with the nonliving features of the environment. Plants and other photosynthetic organisms are an ecosystems’ producers. Consumers are animals or organisms that eat (consume) the food made by organisms.

Evolve Evolve Ability to adapt to their environment through the process of evolution Favorable characteristics are selected for and passed on to offspring

Natural Selection Process by which individuals with inherited characteristics well-suited to the environment leave more offspring than do other individuals. It works by natural environment “selecting” certain inherited traits. Natural Selection causes Evolution. The term evolution means “a process of change.”

Natural selection cannot sense what a species “needs.”

Natural Selection

Your Task Give an example of Natural Selection.