The study of life Warm-up: What does it mean to be alive? What is the definition of life?

Which of these are considered living?

order adaptation Response to the environment regulation Energy processing reproduction Growth and development

Life is the property or quality that distinguishes living organisms from dead organisms and inanimate matter, manifested in functions such as metabolism, growth, reproduction, and response to stimuli or adaptation to the environment originating from within the organism. American Heritage Dictionary Life is a characteristic that distinguishes objects that have Signaling and self-sustaining processes from those that do not, either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate. Wikipedia Life is a distinctive characteristic of a living organism from a dead organism or a nonliving thing as specifically distinguished by the capacity to grow, metabolize, respond (to stimuli), adapt, and reproduce. Biology Online

Biologists explore life from the microscopic to the global scale

From the biosphere to organisms Figure The biosphere

From cells to molecules Cell 8 Cells 6 Organs and organ systems 7 Tissues 10 Molecules 9 Organelles 50 µm 10 µm 1 µm Atoms Figure 1.3

Eleven themes that unify biology Table 1.1

LET’S TALK ABOUT THIS CLASS

What is your definition of life?

SCIENTIFIC INQUIRY At the heart of science is inquiry Biology blends two main processes of scientific inquiry: Discovery science Hypothesis-based science

Biology blends two main processes of scientific inquiry: Discovery science – Describes natural structures and processes as accurately as possible through careful observation and analysis of data Hypothesis-based science, inquiry that asks specific questions – Usually involves the proposing and testing of hypothetical explanations, or hypotheses WHAT IS A HYPOTHESIS? A possible explanation that can be tested and falsified. It is an explanation on trial.

We all use hypotheses in solving everyday problems Observations Questions Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test does not falsify hypothesis Test prediction Test falsifies hypothesis Figure 1.25

In this case study – Mimicry in king snakes is examined – The hypothesis predicts that predators in non–coral snake areas will attack king snakes more frequently than will predators that live where coral snakes are present Scarlet king snake Key Range of scarlet king snake Range of eastern color snake Eastern coral snake North Carolina South Carolina Figure 1.27 A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations

To test this mimicry hypothesis Researchers made hundreds of artificial snakes, an experimental group resembling king snakes and a control group of plain brown snakes (a) Artificial king snake (b) Brown artificial snake that has been attacked

After a given period of time – The researchers collected data that fit a key prediction Figure 1.29 In areas where coral snakes were present, most attacks were on artificial brown snakes Key % of attacks on artificial king snakes % of attacks on brown artificial snakes Field site with artificial snakes 17% 83% North Carolina South Carolina X X X X X X X X X X X X X X In areas where coral snakes were absent, most attacks were on artificial king snakes 84% 16% Key