CHAPTER 1 The Science of Life

What is Biology?? The study of life Biologists study questions about how living things work, how they interact with the environment , and how they change over time. http://www.youtube.com/watch?v=juxLuo- sH6M

Characteristics of Life How do we distinguish between the living and non living? Biologists have established that living things share 7 characteristics of life. Organization & cells- All living organisms have some degree of organization. A cell is the smallest unit that can perform life’s processes. Some organisms are made up of one cell (bacteria) and some are made up of multiple cells (humans)

2. Response to stimuli- A stimulus is a physical or chemical change in the internal or external environment. Organisms must be able to respond and react to changes in their environment to stay alive. 3. Homeostasis- the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. 4. Metabolism- sum of all the chemical reactions that take in and transform energy and materials from the environment.

5. Growth & development- Growth of living things results from the division and enlargement of cells. Development is the process by which an organism becomes a mature adult. 6. Reproduction- Reproduction is essential for the continuation of species. 7. Change through time- The ability of populations of organisms to change over time is important for survival in a changing world.

Steps in the Scientific Method Observation Problem Statement Hypothesis Variables Experiment Data Collection Analysis Conclusion Retest

Overview

In order to verify the results, experiments must be retested. Retest (Repeatable) In order to verify the results, experiments must be retested.

Repetition vs. Replication Repetition is when the scientist performing the initial experiment conducts the experiment 3 or more times. Replication is when the initial scientist gives their experiment to another scientist. This scientist will then follow the initial scientists procedures. To either validate or invalidate their findings.

Scientific Theory vs Law Scientific Theory: possible explanation for repeatedly observed patterns in nature supported by observations & results from many investigations. Not just guesses or opinions, must be supported by observations & results from many investigations. Because it is a theory, if new data is found a theory can be revised. May have many well-supported hypotheses Ex 1: Theory of Evolution Ex 2: Big Bang Theory Scientific Law: a rule that states a pattern in nature that will occur. Must be observed repeatedly to become a law. A law, is not like a theory in that it does not attempt to explain why something happens. Usually contains one well-supported hypothesis that states that something will happen. Ex 1: The Law of Conservation of Energy Ex 2: The Earth is oblong shaped Ex 3: The sun rises in the East every morning.

Honesty vs. Bias To ensure an experiment is done ethically scientists and consumers need to ensure they use critical thinking instead of being bias (intentional or unintentional prejudice toward a specific outcome). Ways to prevent bias: Sampling – study small amounts Blind study – not knowing which item is being tested Repetition – performing the experiment at least 3 times.

Light Microscopes Compound light microscope: microscope that shines light through a specimen and has two lenses to magnify an image. Parts of a light microscope: Eyes piece (ocular lens) : Magnifies the image Objective lens: enlarges the image of the specimen Stage: platform that supports a slide holding the specimen. Light source: light bulb that provides light for viewing the image.

Compound light microscope: http://www.youtube.com/watch?v=RKA8_mif6-E

Light Microscope Labeling Game

Electron Microscopes Scanning electron microscope: passes a beam of electrons over the specimen’s surface. SEM provide three dimensional images of the specimens surface. Transmission electron microscope- transmits a beam of electrons through very tiny sliced specimen.

Dissecting Microscope Allows specimens to be seen in 3D. Used for dissections.

SI Base Units Quantity Measured Unit (Symbol) Length Meter (m) Mass Kilogram (kg) Time Second (s) Electric Current Ampere (A) Temperature Kelvin (K) Substance Amount Mole (mol) Light Intensity Candela (cd) Volume Liters (l)

Metric Prefixes Prefix Symbol Factor Number Factor Word Mega- M Metric Units The metric system has prefix modifiers that are multiples of 10. Prefix Symbol Factor Number Factor Word Mega- M 1,000,000 Million Kilo- k 1000 Thousand Hecto- h 100 Hundred Deca- da or D 10 Ten Unit m, l, or g 1 One Deci- d .1 Tenth Centi- c .01 Hundredth Milli- m .001 thousandth Micro- µ .000001 millionth

Lab Safety