1. intro to bio 2011

Introduction: TheScientific Study Of Life Biology 1

Scientific Method 2

Beginnings• Aristotle (384 BCE-322 BCE or BC)• ancient Greek philosopher 3

Aristotle• Aristotle, more than any other thinker, determined the orientation and the content of Western intellectual history. He was the author of a philosophical and scientific system that through the centuries became the support and vehicle for both medieval Christian and Islamic scholastic thought: until the end of the 17 th century, Western culture was Aristotelian. And, even after the intellectual revolutions of centuries to follow, Aristotelian concepts and ideas remained embedded in Western thinking. 4

• In other words, Aristotle was so famous that his work influenced thinking in the Western world from his time to the present.• This was fine when he was right. But he was so influential that his mistakes were never noticed. 5

• Aristotle and his contemporaries believed that all problems could be solved by thinking about them.• Sometimes this worked, other times it did not.• For example, Aristotle thought that heavy objects would fall faster than lighter ones. 6

• Now that does seem reasonable at first. And this is how “science” was done in ancient times.• But what did Aristotle not do?• He never tested his ideas!• The world would have to wait almost 2000 years for that to happen. 7

Galileo Galilei•1564-1642 AD or CE•Lived in what is today Italy•Is considered to be thefirst true scientist.•Why????•Because he actually didthe experiment. 8

• Aristotle said that heavy objects fall faster than lighter ones.• So Galileo asked, “How much faster?”• So he sent students up to the top of a building and had them drop a heavy ball and a lighter one off at the same time. He had other students waiting below to measure the difference in time between the two hitting the ground. 9

• Today of course we know what happened. Much to everyone’s surprise both balls hit the ground at about the same time!• This shows that it is much preferred to test your ideas rather than merely think about them.• One test is worth a thousand expert opinions. Bill Nye 10

Key Idea• When conducting an experiment, change one factor and keep everything else exactly the same.• The one thing you change is called the variable.• All the things you keep the same are called controls. 11

Galileo’s Experiment• What was the variable in Galileo’s experiment?• The weight of the balls.• What were some controls?• Dropped from same height.• Dropped at same time.• Balls had same shape/size. 12

Scientific Method Steps• Make an observation• State the problem.• Make a hypothesis.• Conduct the experiment.• Record/analyze data.• Make a conclusion.• Report findings to others so they can repeat the experiment. 13

How is biological research done? The Scientific Method Based on Hypothetic-deductive methodStep to scientific method1. Making observations about the natural world2. Asking a question about what you have observed3. Construct hypotheses that may answer your question 14

4. Test the hypothesis by conductingexperiments or making extensive observationsin natureOrganize and collect the data. (charts, graphs,and tables) a. quantitative data- numeric values from counting or measuring b. qualitative data- descriptive characteristicsYour experiment will have one independentvariable and one dependent variable 15

Testing your Hypothesis: Experiment• A procedure to test the hypothesis. 16

ExperimentVariable – factor in the experiment that is being tested 17

ExperimentA good or “valid” experiment will only have ONE variable! 18

Controls and Variables 19

What is the Purpose of a Control?• Controls are NOT being tested• Controls are used for COMPARISON• The factor that is changed is known as the independent variable .• The factor that is measured or observed is called the dependent variable . 20

Independent variable is the variable that is varied ormanipulated by the researcher, and the dependent variableis the response that is measured.For example: the independent variable how much vitamin C you take can influence life expectancy (dependent variable).• The experiment Group One get high doses of vitamin C Group Two goes without vitamin CThe scientists will investigate if there is any statisticallysignificant difference in the life span of the people who tookthe high dose and those who took no dose. 21

5. Draw a conclusion each hypothesis based on the results of the experiments/ observations. Once done you analyze your results and state a conclusion6. If you did not answer you original question you… Formulate new questions based on what you have learned7. Repeat, repeat, repeat... 22

ReviewVariable: the Data: the Controls: theone thing you information you parts of thechange in an get when you experiment thatexperiment. test the stay the same. variable.Manipulated Responding Controllingvariable: you variable: variableschange this responds to theyourself. change you made.Independent Dependant Controllingvariable: on its variable: variablesown. depends on the change you made. 23

Introduction• Biology is the scientific study of lifeIn Latin:• ‘Bios’ = life• ‘Logos’ = study of 24

THECHARACTERISTICS OF LIFEHow we’re different from rocks. 25

What makes something alive?• Biologists sometimes say that living things are “organic”. Before we go further, let’s define this word.• The word “organic” sometimes means. . . – Raised/grown without pesticides or chemical alterations – Containing Carbon In biology, it primarily means that something is living, or was once living! 26

Scientists have found living things share commoncharacteristics, no matter what the species. . . 27

1) Cells: All living things are made of cells• Unicellular = made of one cell• Multicellular = made of 2 or more cells 28

2) Organization:• This organization contributes to their function. For instance: A stomach is made of. . atoms -> molecules -> cells -> tissues -> organ (stomach)• All of the things that come together to form a stomach contribute their own functions to the stomach’s function• Organs (like the stomach) are organized into organ systems (like the digestive system).• Organ systems work together to form an organism (like you!).• So…the whole story is this:atoms -> molecules -> cells -> tissues -> organs (stomach) -> organ systems -> organism I’m an organ! 30

3) Metabolism: All living things use energy • Together, all of the chemical reactions that happen in a living organisms make up its METABOLISM. METABOLISM • People take chemical energy (food) and change it to heat and mechanical energy • Plants take light energy (sun), and change it to chemical energy (sugars) 31

4) Homeostasis: Living thingsexpend energy to maintain a stable internal environment.• Some examples: – Goosebumps – Sweating – Thirst Sensation 32

5) Growth and DevelopmentAll living things undergo stages of growth anddevelopment, which are determined by their owngenetic codes (DNA). 33

6) Reproduction: All living things reproduce • Asexual : Reproduction by splitting or budding (1) • Sexual : Reproduction involving a male and female species(2) 34

To be considered alive, a thing must possess ALL ofthese 6 characteristics, not just some. . . . 35

For instance, a For instance. . . computer. . . .HAS: organization, uses energy, maintains homeostasis but. . .DOESN’T HAVE: cells, growth or development, or reproduction 36

Eight General Life FunctionsThe processes used to maintain life. 37

1. Respiration• the process of releasing stored chemical energy stored in nutrients, that can be converted to a form that can be used directly by the living things. 38

2. Reproduction• is the process by which living things create a new organisms.• Two Types: • Asexual reproduction: single individual produces an offspring that is identical to the parent. • Sexual reproduction: reproduction involving two parents producing and off spring that is not identical to either parent. 39

• 3. Regulation A response to changes within and around the organism.• 4. Synthesis is the process in which simple substances are combined to make complex substance needed by the organism. The substance can then become part of the body. The incorporation of these substances by an organism is called assimilation.* Metabolism: is the process that builds up and breaks down complex substances (all chemical reaction occurring within the cells of an organism are called its metabolism. 40

5. Growth the process by which livingorganisms increase cell numbers and cellsize. With increasing cell number comescell specialization.6. Excretion the removal of the waste products produced by the organism.7. Transport the exchange of materials form the surrounding environment. In small organisms this exchange occurs directly with the environment. In large organism it occurs within a system (example: circulatory) 41

• 8. Nutrition the taking in of material from the external environment and turns it into substances that can be used by the organism for growth and repair.• Two types: •Organisms that produce their own complex substances. •Organisms that take complex substances from the environment. Mnemonic deviceRunning, Resting and Recreation Seldom Gave Energy To Nancy 42

Hierarchical organization of Life Atom molecule cell tissueOrganism organ system organPopulation community Ecosystem 43

Hierarchical organization of Life 44

Classification 46

Classifying lifeKINGS PLAY CHESS ON FAT GREEN STOOLS 47

The Study of MicrobialStructure: Microscopy and Specimen Preparation 48

Scale1mm = 1,000um 49

Discovery of MicroorganismsAntony van Leeuwenhoek (1632-1723)first person toobserve anddescribemicro-organismsaccurately 50

Types of Microscopes• Light (compound)• Electron Microscope• Scanning Electron Microscope 51

I. Light Microscope• compound microscopes image formed by action of 2 lenses Magnification: the ability to make an object look larger then actual size. On a light microscope this can be up to 100X – 100 times larger Resolution the measure of clarity of an image. • The ability to separate two points that are close together. 52

Ocular lens (Eyepiece) Body Tube Nosepiece Arm Objectives Stage Stage Clips Coarse Adjustment Diaphragm Fine Adjustment Light Base Always carry a microscope with one handholding the arm and one hand under the base. 53

What’s my power?To calculate the power of magnification, multiply the power ofthe ocular lens by the power of the objective. What are the powers of magnification for each of the objectives we have on our microscopes? 55

Lenses• focus light rays at a specific place called the focal point• distance between center of lens and focal point is the focal length – short focal length ⇒more magnification 56

focal point 57

Comparing Powers of Magnification We can see better details with higher the powers of magnification, but we cannot see as much of the image.Which of these imageswould be viewed at a higher power of magnification? 58

Let’s give it a try ...1 – Turn on the microscope and then rotate the nosepiece toclick the red-banded objective into place.2 – Place a slide on the stage and secure it using the stageclips. Use the coarse adjustment knob (large knob) to get itthe image into view and then use the fine adjustment knob(small knob) to make it clearer.3 – Once you have the image in view, rotate the nosepiece toview it under different powers. Be careful with the largest objective! Sometimes there is not enough room and you will not be able to use it! 59

4 – When you are done, turn off the microscope and put up the slides you used. 60

Preparation and Staining of Specimens •increases visibility of specimen •making the internal and external structures of cell more visible by increasing contrast with background that have two common features *We will use a wet mount technique to stain our specimens 62

Example: of a Stainingtechniques• Gram stain divides microorganisms into groups based on their staining properties 63

primary stain mordant decolorization counterstainpositivenegative 64

How to make a wet-mount slide …1 – Get a clean slide and coverslip from your teacher.2 – Place ONE drop of water in the middle of the slide.Don’t use too much or the water will run off the edge andmake a mess!3 – Place the edge of the cover slip on one side of the waterdrop. 65

4 - Slowly lower the cover slip on top of the drop . Cover Lower slowly Slip 5 – Place the slide on the stage and view it first with the red-banded objective. Once you see the image, you can rotate the nosepiece to view the slide with the different objectives. You do not need to use the stage clips when viewing wet-mount slides! 66

II. Electron Microscopy• beams of electrons are used to produce images• wavelength of electron beam is much shorter than light, resulting in much higher resolution 67

a. An image is formed by passing a beam of electrons (-) over the surface or through a specimen.b. Can be magnified over 200,000Xc. Cannot view living specimens. • Operates in a vacuum • Specimen are dehydrated and/ or coated in metal. 68

Electron Microscope 69

Fly head 70

Surface of a fruit fly eye 71

III. Scanning Electron Microscope • uses electrons reflected from the surface of a specimen to create image • produces a 3-dimensional image of specimen’s surface features 72

Fly head 73

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1. intro to bio 2011

by Bob Smullen on Aug 22, 2012

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