THE SCIENCE OF BIOLOGY Chapter 1

Understanding Fossil Butte 50 million year old fish found at the top of Fossil Butte in Wyoming Pacific Ocean over 1000 km away How did they get there???

The Goals of Science to investigate and understand nature to explain events in nature to use those explanations to make useful predictions

The Methods of Scientists collect and organize information (data) in a careful, orderly manner look for patterns in data propose explanations that can be tested by examining the evidence

Observation Based on five senses: sight, hearing, taste, smell, touch Quantitative – numerical Ex- how many, how big, how fast Qualitative – descriptive Ex – color, texture, smell, behavior

Hypothesis Logical, testable, tentative explanation for a set of observations or a possible answer to a scientific question Arise from prior knowledge, logical inferences, or imaginative guesses

Testing hypotheses Can be done through further observation Usually done through controlled experiments A hypothesis proven to be wrong still adds to the body of scientific knowledge

Which can be answered by science? Do excessively high temps cause people to behave immorally? Do humans communicate through chemical signals called pheromones? Is walking under a ladder bad luck? Do cactus spines prevent animals from eating the cactus? ?

Scientific Method There is no universal method used by all scientists There is a logical way of thinking found in all scientific experiments Observe a problem Ask a question Create a hypothesis Design a controlled experiment Collect and analyze data Share results

Spontaneous Generation In the past, people thought life could just appear from non living matter Ex – maggots just appear on meat

Redi’s Experiment 1668 – proposed hypothesis that the maggots came from flies Tested hypothesis by placing meat in jars and covering some of the jars Everything was controlled (kept the same) except the variable (covering jars)

Redi’s Experiment Uncovered jarsCovered jars Several days pass Maggots appearNo maggots appear

Types of Variables Independent: the variable being manipulated Redi controlled the covering of the jars Dependent: the variable that changes in response to the independent variable The presence of maggots in Redi’s experiment

Spallanzani’s Experiment Tested Redi’s results Boiled to kill microorganisms What are the independent and dependent variables?? Gravy is boiled. Flask is open. Gravy is teeming with microorganisms. Gravy is boiled. Flask is sealed. Gravy is free of microorganisms.

Pasteur's Experiment Provided final proof that spontaneous generation did not occur

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment Go to Section: Pasteur's Experiment

What was Pasteur’s hypothesis? Microorganisms would not just appear Independent variable? Curved neck of flask Dependent variable? Presence of microorganisms

A Theory in Science A very well supported hypothesis When a hypothesis has been verified many times by different scientists, it becomes a theory Redi’s, Spallanzani’s, and Pasteur’s experiments led to the theory of biogenesis (life comes from life) Theories explain phenomena in nature

Characteristics of Life Made of one or more cells Reproduction – sexual or asexual Contain RNA and/or DNA – universal genetic code Growth (getting bigger) and development (changing, ex: puberty)

Characteristics of Life Need energy – metabolism is the sum of all chemical reactions in body Respond to their environment Maintain homeostasis – stable internal environment Evolve (change) over time

Put in order from smallest to largest: OrganismEcosystemTissue/Organ CommunityDNAPopulation CellsBiosphereOrgan System