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. Organisms changed over time (evolved)

TEN THEMES OF LIFE Each of the following themes or ideas will be encountered and discussed as we move through the year

1. Biological systems System: complex organization formed from a combination of simpler parts Systems have properties based on the arrangement and interaction of their parts Your body, like that of any organism, is a living system. Describe all the parts and interactions of your body system when you type on a computer keyboard.

2. The Cellular Basis of Life Cell is the basic unit of life. Cells are small & highly organized. All organisms are made of and develop from cell s. Single cell organisms  unicellular Organisms composed of many cells  multicellular In multicellular organisms, cells and groups of cells (tissues) are organized by their function Cells  tissues Tissues  organs Organs  systems

3. Form and Function The form of a structure in an organism is related to the function of that structure. In other words, the shape of a structure is related to the function that the structure performs for the organism Which is a better tool: A hammer or a screwdriver? Form-fits-function

4. Reproduction and Inheritance All organisms produce new organisms like themselves. Organisms transmit hereditary information (DNA) to their offspring through a process called reproduction.

5. Interaction With the Environment Every organism interacts continuously with its environment—none are isolated Requires a constant supply of energy to maintain their orderly state. Almost all energy comes from the sun (directly or indirectly). Example: Photosynthesis Plants obtain carbon dioxide gas from atmosphere, water and nutrients from soil, and energy from sun to produce food and oxygen

6. Energy and Life All activities of life require energy Organisms obtain food and energy in different ways Producers: organisms that make their own food; plants make their own food through photosynthesis Consumers: organisms that eat the food made by producers.

7. Regulation Organisms must be able to regulate their internal conditions Homeostasis: “steady state” – maintaining of internal conditions suitable for life despite changes in the external environment Example: Sweating helps maintain internal body temperature

8. Adaptation and Evolution Adaptation: inherited trait that helps the organism to survive and reproduce in its particular environment Ex: Camouflage

8. Adaptation and Evolution Natural selection: process by which individuals with inherited characteristics well-suited to the environment are more likely to leave more offspring than do other individuals It works by natural environment “selecting” certain inherited traits that will be passed on to offspring. Natural Selection causes Evolution. Evolution: change over time

8. Adaptation and Evolution

Natural selection cannot sense what a species “needs.”

Natural Selection

9. Biology and Society Modern biology affects your life Concepts you study will help you to have informed opinions about many issues DNA research  agriculture & medicine Medical discoveries  health care Evolution studies  understanding antibiotic resistance Environmental issues (e.g. water and air pollution)  how people think about their relationship to the biosphere Stem cell research  new cures

10. Scientific Inquiry Biology as a science involves asking questions about nature and using observations or experiments to find possible answers to those questions