CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method

Eight Properties of Living Things 1) Life is highly ordered and complex in structure. 2) Living things regulate their internal environments (homeostasis). 3) Living things grow by adding on new parts to pre-existing structures using energy. 4) Living things use energy to maintain order and structure. 5) Living things respond actively to the environment using energy. 6) Living things reproduce by passing on hereditary information to their offspring. 7) Groups of living things (populations) evolve over several generations. 8) Individual living things are made of one or more cells.

CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method

Levels of Biological Organization Organelle Mitochondrion Ecosystem (Biome) African savanna Increasing complexity

CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method

Cellular Basis of Life Living things are composed of one of two types of cells –Prokaryotic Simple and tiny Example: bacterial cell –Eukaryotic Complex and times larger Example: cells of a western hemlock tree

CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method

How Do Biologists Classify and Catalog Life?

Three Domain System of Classifying Living Things Bacteria Eucarya Plants Animals Fungi Protists Soil bacteria Water bacteria Disease bacteria Photosynthetic bacteria “Extreme” bacteria that live in high salt, hot water, acid, or alkali (unusual “bacteria”) All living things Domain Eukarya

Classification Is Based on a Hierarchy of Groupings or Taxons Domain etc.

The Taxonomic Hierarchy

CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method

Evolution: Biology’s Unifying Theme 1.In a group of organisms of the same kind there is: –Individual variation 2.Different individuals have different levels of reproductive success 4.Groups (populations) of organisms exhibit descent with modification Population with varied inherited traits Elimination of individuals with certain traits Reproduction of survivors Modification: Increased frequency of traits that enhance survival and reproductive success – Overproduction & competition 3.Those individuals with successful traits pass on their traits to subsequent generations

CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method

Four Steps of the Scientific Method 1) Observation Measure the natural world using own senses or extensions of the senses (microscopes, detectors, etc.) Test: experiment or additional observations Observations Questions Hypotheses Prediction 2) Hypotheses Formation Form tentative, predictive, and testable statements about two variables that explain the observations 3) Experimentation Test how one hypothesis variable effects the other using multiple trials and baseline experiments (controls) 4) Conclusion Accept or reject the hypotheses based on experimental data Form conclusions

The Process of Science: Can Colors Protect a Snake? Questions: Are some snakes colored because it confers a survival advantage? Do predators avoid colored snakes because they learn that they have poisonous bites? Observations and Questions

Making tentative, predictive, and testable statements about snake coloration The Process of Science: Hypothesis Formation with Two Variables –The less brightly colored and distinctive the pattern on a snake, the less often it will be attacked by predators. –The coloration pattern of a snake has no effect on the attack frequency of predators. Independent variable: set before the experiment begins –The more brightly colored and distinctive the pattern on a snake, the less often the snake will be attacked by predators. Dependent variable: measured during the course of experimentation Null hypothesis: There is no correlation between variables

The Process of Science: Experimentation Birds allowed to attack different colored artificial snakes

The Process of Science: Experimentation Multiple trials: Experiment repeated 10 times for each snake type to reduce the chance of collecting “freak” or unrepresentative data Controlled variables to guarantee that only snake color effected bird attacks Artificial snakes were all: on the same background exposed to attack for the same amount of time exposed to attack during the same time each day made of identical materials

Process of Science: Theories What is a scientific theory, and how is it different from a hypothesis? –Theories are widely accepted hypotheses that have undergone rigorous and repetitive testing by a large number of scientist

CHAPTER 1 Biology: Exploring Life The Study of Biology What Does It Mean to be Alive? Levels of Biological Complexity The Cellular Nature of Life Categorizing Living Things Evolution as a Unifying Theme Process of Science: The Scientific Method