The Science of Life

1. The Science of Life

2. DO NOW • List as many characteristics of all living things as you can.

3. Biology-the study of life

4. Characteristics of Life:Organization • Organization-the high degree of order within an organisms internal & external parts, and in its interactions with the living world.

5. Levels of Organization • Organ system-groups of specialized parts that carry out a certain function in the organism. • Organs-structures that carry out specialized jobs within an organ system. • Tissue-group of cells that have similar abilities and that allow the organ to function.

6. Cells-must be covered by a membrane, contain all genetic information necessary for replication, and be able to carry out all cell functions. • Atoms-the simplest particle of an element that retains all the properties of a certain element.

7. Characteristics of Life: Cells • Cells-the smallest unit that can perform all of life’s processes; highly organized, tiny structures . • All living things are made of cells. • Unicellular-made up of one cell • Ex. Bacteria • Multicellular-made up of multiple cells. • Ex. You

8. Characteristics of Life: Response to Stimuli • Stimulus-a physical or chemical change caused by an event in the internal or external environment. • Ex. Pupils dilate, sweat, shiver, blink, cough, sneeze, yawn, urinate.

9. Do Now • List the levels of organization of organisms.

10. Characteristics of Life:Homeostasis • Homeostasis-the maintenance of constant internal conditions in spite of changes in the environment; maintaining a stable internal environment. • Ex. Temperature, water content, uptake of nutrients by the cell

11. Characteristics of Life:Metabolism • Metabolism-chemical reactions that take in and transform energy and materials from the environment. • The energy that drives metabolism in animals comes from food. • Ex. Photosynthesis=Autotroph/Producer • Ex. Food from another source= Heterotroph/Consumer

12. Characteristic of Life:Growth and Development • Growth and Development-results from the division and enlargement of cells. • Cell Division-formation of two new cells from an existing cell.

13. Characteristic of Life:Reproduction • Reproduction-the process by which organisms make more of their own kind • Not essential to the survival of an individual organism, but is essential to the survival of the species. • Species-a group of genetically similar organisms that can produce fertile offspring

14. Characteristic of Life:Reproduction • Heredity-the passing of traits from parents to offspring • Why children look like their parents. • Transmitted by DNA • Genetic engineers are trying to create plants that are more nutritionally balanced • Researchers making progress in treating or curing AIDS.

15. Characteristic of Life:Reproduction • Asexual reproduction-hereditary information from different organisms is not combined. • Results in offspring that are identical to their parent • Sexual Reproduction-hereditary information recombines from two organisms of the same species. • Results in offspring that are similar but NOT identical to their parent.

16. Characteristic of Life:Change • Change Through Time-individuals do not change; populations change

17. Do Now • Which characteristic of life is the most important and why?

18. Diversity of Life • Evolution-“descent with modification”-inherited characteristics within populations change over generations. • Natural Selection-organisms that have certain favorable traits are better able to survive and reproduce successfully than organisms that lack these traits. • Adaptation-traits that improve an individual’s ability to survive and reproduce.

19. Fields of Biology • Ecology- studies organisms interacting with each other and with the environment • Ecosystem-communities of living species and their physical environments.

20. Do Now • What is the scientific method and why do we use it?

21. Scientific Method • Based on 2 important principles: • Events in the natural world have natural causes. • Uniformity-the fundamental laws of nature operate the same way at all places and times. • Does not follow a rigid set of rules

22. Scientific Method Steps • Observation- perceiving a natural occurrence that causes a question. • Generally begins with an unexplained observation about nature. • Hypothesis- testable possible explanation of an observation • Must be: • Testable-there must be some way to check its validity • Falsifiable-there must be some observation or experiment that could show that it is not true.

23. Scientific Method Steps 3. Prediction-statement that forecasts what would happen in a test situation if the hypothesis were true.

24. Scientific Method Steps 4. Experiment-a planned procedure to test a hypothesis • Controlled Experiment-compares an experimental group and a control group and only has one variable • Control group- Nothing changes • Experimental group-One factor changes • Independent variable- the variable that is changed in an experiment • Dependent variable­ the variable that is measured in an experiment . • Blind Experiment-the biologist who scores the results is unaware of whether a given subject is part of the experimental or control group.

25. Scientific Method Steps 5. Collecting and Analyzing Data- • Quantitative data-measured in numbers • Qualitative data-measured by value 6. Drawing Conclusions-an experiment can only disprove, not prove a hypothesis.

26. Scientific Theory Steps 7. Constructing a Theory-a unifying explanation for a broad range of observations • Is NOT an assumption made by scientists that implies a lack of certainty • May be revised as new evidence is presented. 8. Communicating Ideas

27. Do Now • List the steps of the scientific method.