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Chapter 2

Chapter 2. Living things. Section 1: What is life (Part 1, pages 34-37). Organism = LIVING THING Examples: yourself, a pet, insects, plants ALL LIVING THINGS SHARE THESE CHARACTERISTICS: Cellular organizations Contain similar chemicals Use energy Respond to their surroundings

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Chapter 2

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  1. Chapter 2 Living things

  2. Section 1: What is life (Part 1, pages 34-37) • Organism = LIVING THING • Examples: yourself, a pet, insects, plants • ALL LIVING THINGS SHARE THESE CHARACTERISTICS: • Cellular organizations • Contain similar chemicals • Use energy • Respond to their surroundings • Grow and develop • Reproduce

  3. Cellular Organization • All organisms are made of small building blocks called cells • A cell is the basic unit of structure and function • Cells are so small you need a microscope to see them • Unicellular: single-celled organisms (Bacteria) • Multicellular: composed of many cells that are specialized to do certain tasks • Example: in our body, muscle and nerve cells (work together to keep us alive!)

  4. The Chemicals of life • Cells are composed of chemicals • SUCH AS… • Water (most abundant) • Carbohydrates (energy) • Proteins and lipids/fats (building materials) • Nucleic acid : genetic materials, chemical instructions that direct the cell’s activities

  5. Energy Use • Cells of organisms use energy to do what living things must do • Example: Repairing injured parts • An organisms cells are ALWAYS hard at work

  6. Response to surroundings • Plants and all other organisms react to changes in their environment • STIMULUS: a change in an organism’s surroundings that causes an organism to react • Example: temperature, light, sound…. • RESPONSE: an action or change in behavior • Example: A plant stem growing toward the sun. Stimulus?? Response??

  7. Growth and development • Living things GROW (getting larger) and DEVELOP • Development: the process of change that occurs during an organisms life to produce more complex organisms

  8. Reproduction • Organisms have the ability to reproduce, or produce offspring that are similar to the parents • Example: Robins lay eggs… that develop into young robins… that closely resemble their parents!

  9. Life Comes from life • Living things arise from living things through reproduction • ….But, four hundred years ago people believed that life could appear from nonliving things… CRAZY!?!?! • They called this… SPONTANEOUS GENERATION ***the mistake idea that living things can arise from nonliving sources http://www.youtube.com/watch?v=WNByRghR6sw

  10. Redi’s Experiment • Francesco Redi – Italian doctor (1600’s) • He designed a CONTROLLED EXPERIMENT to show flies do not arise from decaying meat • Who remembers what a controlled experiment is??? • A scientist carries out 2 tests that are identical in every respect except for one factor

  11. Redi’s Experiment • Left jar = UNCOVERED • Right jar = COVERED • Manipulated Variable? • Whether or not the jar Was covered

  12. Pasteur’s experiment • Louis Pasteur--- French chemist (mid-1800s) • Some people still did not believe Redi… so Pasteur came up with a new experiment • His experiment… demonstrated that new bacteria appeared in broth only when they were produced by existing bacteria • Both experiments convinced people that LIVING THINGS DO NOT ARISE FROM NONLIVING MATERIAL

  13. Pasteur’s experiment

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