Chapter 1 The Science of Life

Transcription

1 Chapter 1 The Science of Life

2 (Sect. 1) Biology how living things work how living things interact w/the environment how living things change over time

3 7 Characteristics of Life 1.Organization & the presence of 1 or more cells 2.Response to stimuli 3.Homeostasis 4.Metabolism 5.Growth & development 6.Reproduction 7.Change over time

4 1. Organization high degree of order w/in an organism s internal & external being & w/its interactions w/the living world Cell the smallest unit of organization that carries on the functions of life - cells are organized to perform certain jobs Unicellular- bacteria (Domain Bacteria & Archaea) Multicellular- humans (Domain Eukarya)

5 CELLS TISSUES ORGANS ORGAN SYSTEM ORGANISM

6 2. Response to Stimuli Stimuli- physical or chemical change in the internal or external environment Response- reaction to a stimulus

7 3. Metabolism- sum of all chemical reactions carried on by an organism (take in & transform energy & materials from the environment) anabolism-reactions that build up catabolism-reactions that break down -Organisms use energy to be able to perform functions such as: a) grow b) react c) move d) reproduce

8 4. Homeostasis a balance that must occur in living things (a stable level of conditions inside an organism) --body temperature, water content, ph, etc.

9 5. Growth & Development- (growth)all living things grow & increase in size Development- process by which an organism becomes a mature adult

10 6. Reproduction living things produce new individuals similar to their parents essential for the continuation of a species 2 kinds of reproduction: sexual & asexual

11 Heredity- DNA (deoxyribonucleic acid) Gene- instructions for a single trait of an organism

12 (Sect. 2) 7. Change Through Time -Throughout development genetics don t change -but over time, populations evolvechange over time

13 -Due to changes in ecosystemscommunities of living species & their physical environments -Natural selection- organisms w/more favorable traits survive & reproduce better than those w/unfavorable traits

14 (Sect. 3) The Scientific Process A.Scientists use an organized approach: scientific method - series of steps to learn how things work Operates on 2 principles: 1.Events in natural world have natural causes 2.Fundamental laws that govern nature are uniform

15 B. 6 Steps of the Scientific Method 1. Observation- noting or perceiving objects or events by using the 5 senses (causes a question to form) 2. Hypothesis- proposes an explanation/educated guess based on prior information (can be tested) 3. Prediction- If/then statement (If the hypothesis is true, then this would happen)

16 4. Experiment- test the hypothesis, usually comparing results of an unknown result to that of a known (numbered steps for the procedure) Control: a standard for comparison Constant: a factor that doesn t vary in any part of the experiment Independent Variable: manipulated on purpose Dependent Variable: the response to the independent variable

17 5. Data- collected & analyzed as tables, charts, graphs - is data reliable - does it support or reject hypothesis Quantitative data are expressed as numbers, obtained by counting or measuring. Qualitative data are descriptive and involve characteristics that can t easily be measured.

18 6. Conclusion- report to others so rejection, verification or modification of the hypothesis occurs (peer review) - inferences: conclusion made on facts & previous knowledge rather than on direct observations (not directly testable) - theory: highly tested, generally accepted principle - law: mathmatical

19 -Honors Bio 1 has a set procedure for writing lab reports -- you must WRITE THEM THIS WAY!!!!

20 I. Title - Make up your own or use the title from the lab handout be descriptive - You might want to put your name here II. Purpose - Describe the purpose of the experiment (complete sentence)

21 III. Problem - in the form of a question, describe what question the experiment or activity is trying to solve?????? IV.Hypothesis - a proposed reason or explanation for what has been observed; an educated guess. - in this class, we will use the If, then format.

22 V.Materials - List the materials needed and used in your lab VI. Procedure - Write out the steps of the experiment - BE SUPER-SPECIFIC!!!!!!!! - You will probably be able to copy the procedure directly from the lab handout

23 VII. Data -Will sometimes be in the form of a table &/or graph with titles -Be sure to use proper measurements and units VIII. Sample Calculations - Show your work (like in math class) to demonstrate how you got the data you did

24 IX. Analysis -Answer the questions that are asked in the lab handout -You must retype the questions -Type your answers in complete sentences

25 X. Conclusion -Give an overview of what was done and how -Does your data show a trend? -Was your hypothesis supported or falsified? -Explain why; if false, explain what might have gone wrong and how the experiment can be changed

26 -Also explain what your data means in terms of the Problem posed at the beginning of the lab report -Explain any errors that might or did occur

27 (Sect. 4) Seeing Small Stuff Microscopes ***Magnification = the ability to enlarge ***Resolution = the ability to see things clearly

28 1. COMPOUND LIGHT MICROSCOPE Passes a beam of light through an object and then through 2 or more lenses Sample must be very thin These lenses enlarge the image and bend the light toward your eye See also p

29 COMPOUND LIGHT MICROSCOPE (cont.) eyepiece usually has magnification (power) of 10x Low power is 4x Medium power is 10x High power is 40x Total magnification of high power is 10 x 40 = 400x

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31 PROPER USE OF A MICROSCOPE 1.Clip slide onto stage and attempt to center the specimen over the opening in the stage. 2.Go to low power and using the coarse adjustment knob bring the specimen into focus. Once in focus, center the specimen in your center of view.

32 3. Go to medium power and bring specimen into focus using the course or fine adjustment knob. Center the specimen in your field of view. 4. Go to high power and bring the specimen into focus using the fine adjustment knob only. Center the specimen in your field of view.

33 Advantages Disadvantages Living specimen if clear Size Cost Easy to use Easy to stain organism Thin and clear specimen 3-D cannot be seen clearly, must focus on each layer Low mag. (200X) As mag. increase, resolution decreases

34 2. STEREO MICROSCOPE Has an objective and eyepiece for each eye Gives a 3-D view and can view large objects which light will not pass through May magnify up to 40x

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36 3. ELECTRON MICROSCOPE Uses magnets to bend beams of electrons instead of lenses to bend light Advantages Great magnification Reveals details View cell parts, viruses, etc. Disadvantages Must use vacuum chamber Cost Size Special training

37 Two Types of Electron Microscopes TEM Transmission electron microscope e- pass through specimen and hit fluorescent photographic film Only dead specimens (200,000X) Scanning electron microscope Used to see surfaces of whole objects (3-D) SEM Can view and photograph living cells Image on TV screen (100,000 X)

38 1. Transmission electron microscope (TEM)

39 2. Scanning electron microscope (SEM)

40 MEASUREMENTS International System of Units (SI- Syste me International d Unite s): revised version of the metric system -used to clearly communicate a measurement to others, so as not to confuse units. p

41 Metric Units of Length Kilometer km 1 km = 1000m Meter m Base unit Decimeter dm 10dm = 1m Centimeter cm 100 cm = 1m Millimeter mm 1000 mm = 1m Micrometer µm µm = 1m Nanometer nm nm = 1m p. 23 tables

42 Metric Units of Volume Liter L Base unit Milliliter ml 1000 ml = 1L Cubic centimeter cm 3 1 cm 3 = 1mL microliter µl µl = 1L Volume: amount of space occupied by an object.

43 Units of Mass Kilogram (base unit) kg 1 kg = 1000 g Gram g 1g = kg Milligram mg 1000 mg = 1g microgram µg µg = 1g Mass: measurement of the amount of matter in an object

44 Mass VS Weight Mass is a measure of the quantity of matter of an object. Weight is the force that measures the pull on a given mass by gravity. * an astronaut on the moon can be weightless, due to less gravitational pull, but they can never be massless

45 Which is heavier? A ton of feathers or a ton of bricks? * they both weigh the same; a ton! Why does it seem as if the bricks would be heavier? *DENSITY!

46 The ratio of the mass of an object to its volume. Density = mass volume Always use g/ml or g/cm 3 as units of density

47 Time & Temperature * time will be measured in minutes and seconds * temp will be measured in o C (degrees Celsius) 100 o C = water boils 37 o C = human body temperature 0 o C = water freezes 20 o C - 25 o C = room temperature (R.T.)

48 In the laboratory, we need to take special precautions to avoid accidents so we don t get hurt. What are some rules we might have in the lab? *see the Honors Biology 1 safety contract!