1-1 what is science? - organized way of using evidence to learn about the natural world
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CHAPTER 1 THE SCIENCE OF BIOLOGY
1-1 What is Science?- organized way of using evidence to learn about the natural world
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Why do we study science?
1. investigate and understand nature2. explain events that occur in nature3. to make predictions based on those explanations
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How do we gain evidence to support our predictions?
1. Observation- use one or more of our senses
2. Collect data- information gathered from observation
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Observations can be of 2 types:
1. quantitative - involves numbers Ex. measurement or counting objects2. qualitative - characteristics not easily measured Ex. color or texture
**data (evidence) must be interpreted (analyzed) involves the formation of an inference
Inference - a logical interpretation based on prior knowledge or experience
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Explanation of evidence
Form a hypothesis - a possible explanation for what was observed - can be tested through a controlled experiment
Scientific Inquiry - a collection of data to obtain a better understandingof nature - scientists make recommendations based on theirfindings
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1-2 How scientists work to test their hypothesis1668 Francesco Redi's experiment on spontaneous generation1. State the problem: How do living things come to be?2. Form a hypothesis: Maggots arise from rotting meat (spontaneous generation)
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3. Set up a controlled experiment: a. variables - factors that can change; time, temp, etc. - one variable is changed at a time (manipulative value or independent variable) b. control - the unchanged variable c. responding variable - what is observed and changes in response to the manipulative variable (dependent variable)
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4 Observation - flies left on uncovered meat; later maggots appeared5. Hypothesis - flies produce the maggots6. Prediction - keeping flies away from meat will prevent the appearance of maggots7. Conclusion - maggots formed only when flies came in contact with meat; therefore, no spontaneous generation
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Redi's test was repeated by:1. John Needham (l700 's) - Needham experiment lent support to spontaneous generation
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2. Lazarro Spallanzani3. Louis Pasteur (1800)
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Development of a theoryNumerous investigations support a particular
hypothesis, therefore, a theory is a well-tested explanation that comes from many observations
Theories allow for accurate predictions about new situations
Theories may be revised or replaced by new evidence
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1-3 Characteristics of living things1. Made up of cells - smallest unit of life - they can: grow respond reproduce - complex and highly organized
unicellular - one cell; amoeba, paramecium
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amoeba
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multicellular - many cells; plants and animals
- cells come in a variety of sizes and shapes, each specialized to perform a special function
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2. Reproduce - production of new organisms - two kinds: a. asexual - single parent Ex. fission and budding b. sexual - two cells (sex) from different parents fuse
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Hydra – asexual reproduction (budding)
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3. Uniform genetic code - offspring resemble parents - flies make flies - dogs make dogs, etc. - DNA (deoxyribonucleic acid) contains the genetic codes that determines inherited traits
4. Grow and develop - distinctive life cycle and pattern of growth with changes that occur during life span
- cells grow in size and specialize (differentiate)
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5. Obtain and use materials and energy - occurs through metabolic processes that build (synthesis or anabolism) and break down (catabolism); together these are metabolism
6. Respond to the environment - changes in light and temperature cause organisms to respond in their own way
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7. Maintain an internal balance (homeostasis) - always threatened by environmental changes - lack of homeostasis leads to illness and possibly death.
8. Change over time (evolution) - change not apparent for thousands to millions of years - maintains survival of an organism in a world that is always changing
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Branches of Biology
Biology is organized into branches or divisions: Zoology - study of animals Botany - study of plants Ethology - study of animal behavior Paleontology - study of life from long ago
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- Life is studied at different levels of organization- Levels differ in size and complexity
Moleculescellsgroups of cells (tissues) organism population communityecosystembiosphere
See Fig. 1-21 pg 21
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1-4 Tools and Procedures used in Biology A. Common Measurement System - metric: decimal system of measurement; each unit is a multiple of 10 Ex. 1.5, 1.51, 1.512
B. Analyzing Biological Data - to find out whether certain information has changed or stayed the same - recorded in a table from which a graph is made - today, computers are used to make sense of the data
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C. Microscopes - produce magnified images of structures that cannot be seen with the naked eye - used to test cell responses under controlledconditions - show cell to cell interactions - used to select specific cells for study
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Two types: 1. light microscope - magnifies images by focusing visible light rays - magnifies 1000 times - light passes through the specimen and then through 2 lenses - chemical stains (dyes) used to show specific structures
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Compound light microscope
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2. electron microscope - magnifies images by focusing beams of electrons on specimen - objects usually smaller than 0.2 micrometers - magnifies images 1000 times smaller than thoseseen under the light microscope
Two types: a. transmission electron microscope (TEM) - beam of electrons passes through the specimen - good for studying cell interiors
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Cell organelles
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b. scanning electron microscope (SEM) - pencil-like beam runs back and forth across thesurface; good 3 dimensional image of surface
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Insect head
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Disadvantage of EM - specimens are dead and preserved; they are killedby the process
3. Phase Contrast Microscope - enhances contrast of living, unstained cellsa. Differential interference contrast
b. Phase contrast
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D. Laboratory Techniques
1. Cell cultures - groups of cells that develop from a single cell - used to test cell responses under controlled conditions - show cell to cell interactions - used to select specific cells for study
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Cell culture
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2. Cell fractionation - separates out different cell parts for study - cells put in blenderbroken cell parts added toliquid and placed in tube centrifugecell partsseparate out according to density
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E. Working Safely in Biology - Review lab safety