Chapter 1 Exploring Life Power Point Lectures for

Chapter 1 Exploring Life Power. Point Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Overview: Biology’s Most Exciting Era • Biology is the scientific study of life • Biologists are moving closer to understanding: – How a single cell develops into an organism – How plants convert sunlight to chemical energy – How the human mind works – How living things interact in communities – How life’s diversity evolved from the first microbes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Life’s basic characteristic is a high degree of order • Each level of biological organization has emergent properties Video: Seahorse Camouflage Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Some Properties of Life Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Themes Connect Biological Concepts • Concept 1. 1: Biologists explore life from the microscopic to the global scale • The study of life extends from molecules and cells to the entire living planet • Biological organization is based on a hierarchy of structural levels Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The biosphere Ecosystems Organelles 1 µm Cells Atoms 10 µm Communities Molecules Tissues Populations Organisms 50 µm Organs and organ systems

A Hierarchy of Biological Organization 1. Biosphere: all environments on Earth 2. Ecosystem: all living and nonliving things in a particular area 3. Community: all organisms in an ecosystem 4. Population: all individuals of a species in a particular area 5. Organism: an individual living thing Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

A Hierarchy of Biological Organization (continued) 6. Organ and organ systems: specialized body parts made up of tissues 7. Tissue: a group of similar cells 8. Cell: life’s fundamental unit of structure and function 9. Organelle: a structural component of a cell 10. Molecule: a chemical structure consisting of atoms Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

A Closer Look at Ecosystems • Each organism interacts with its environment • Both organism and environment affect each other • The dynamics of an ecosystem include two major processes: – Cycling of nutrients, in which materials acquired by plants eventually return to the soil – The flow of energy from sunlight to producers to consumers Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Energy Conversion • Activities of life require work • Work depends on sources of energy • Energy exchange between an organism and environment often involves energy transformations • In transformations, some energy is lost as heat • Energy flows through an ecosystem, usually entering as light and exiting as heat Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

LE 1 -4 Sunlight Ecosystem Producers (plants and other photosynthetic organisms) Heat Chemical energy Consumers (including animals) Heat

A Closer Look at Cells • The cell is the lowest level of organization that can perform all activities of life • The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The Cell’s Heritable Information • Cells contain DNA, the heritable information that directs the cell’s activities • DNA is the substance of genes • Genes are the units of inheritance that transmit information from parents to offspring Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Each DNA molecule is made up of two long chains arranged in a double helix • Each link of a chain is one of four kinds of chemical building blocks called nucleotides Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Two Main Forms of Cells • Characteristics shared by all cells: – Enclosed by a membrane – Use DNA as genetic information • Two main forms of cells: – Eukaryotic: divided into organelles; DNA in nucleus – Prokaryotic: lack organelles; DNA not separated in a nucleus Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

LE 1 -8 EUKARYOTIC CELL PROKARYOTIC CELL DNA (no nucleus) Membrane Cytoplasm Organelles Nucleus (contains DNA) 1 µm

The Three Domains of Life • At the highest level, life is classified into three domains: – Bacteria (prokaryotes) – Archaea (prokaryotes) – Eukarya (eukaryotes) Eukaryotes include protists and the kingdoms Plantae, Fungi, and Animalia Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

LE 1 -15 Bacteria Archaea 4 µm 0. 5 µm Protists Kingdom Fungi 100 µm Kingdom Plantae Kingdom Animalia

• Concept 1. 4: Evolution accounts for life’s unity and diversity • The history of life is a saga of a changing Earth billions of years old Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Discovery Science • Discovery science describes nature through careful observation and data analysis • Examples of discovery science: – understanding cell structure – expanding databases of genomes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Data • Data are recorded observations • Two types of data: – Quantitative data: numerical measurements – Qualitative data: recorded descriptions Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Induction in Discovery Science • Inductive reasoning involves generalizing based on many specific observations Hypothesis-Based Science In science, inquiry usually involves proposing and testing hypotheses Hypotheses are hypothetical explanations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The Role of Hypotheses in Inquiry • In science, a hypothesis is a tentative answer to a well-framed question • A hypothesis is an explanation on trial, making a prediction that can be tested Observations Question Hypothesis #1: Dead batteries Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Hypothesis #2: Burnt-out bulb

LE 1 -25 b Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test falsifies hypothesis Test does not falsify hypothesis

Deduction: The “If…then” Logic of Hypothesis-Based Science • In deductive reasoning, the logic flows from the general to the specific • If a hypothesis is correct, then we can expect a particular outcome Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

A Closer Look at Hypotheses in Scientific Inquiry • A scientific hypothesis must have two important qualities: – It must be testable – It must be falsifiable Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The Myth of the Scientific Method • The scientific method is an idealized process of inquiry • Very few scientific inquiries adhere rigidly to the “textbook” scientific method Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations • In mimicry, a harmless species resembles a harmful species • An example of mimicry is a stinging honeybee and a nonstinging mimic, a flower fly Flower fly (nonstinging) Honeybee (stinging) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• This case study examines king snakes’ mimicry of poisonous coral snakes • The hypothesis states that mimics benefit when predators mistake them for harmful species • The mimicry 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

LE 1 -27 Scarlet king snake Key Range of scarlet king snake Range of eastern coral snake North Carolina Eastern coral snake South Carolina Scarlet king snake

Field Experiments with Artificial Snakes • To test this mimicry hypothesis, researchers made hundreds of artificial snakes: – An experimental group resembling king snakes – A control group resembling plain brown snakes • Equal numbers of both types were placed at field sites, including areas without coral snakes • After four weeks, the scientists retrieved the artificial snakes and counted bite or claw marks • The data fit the predictions of the mimicry hypothesis Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

LE 1 -28 (a) Artificial king snake (b) Artificial brown snake that has been attacked

LE 1 -29 17% In areas where coral snakes were absent, most attacks were on artificial king snakes. 83% Key North Carolina % of attacks on artificial king snakes % of attacks on brown artificial snakes Field site with artificial snakes South Carolina 16% 84% In areas where coral snakes were present, most attacks were on brown artificial snakes.

Designing Controlled Experiments • Scientists do not control the experimental environment by keeping all variables constant • Researchers usually “control” unwanted variables by using control groups to cancel their effects Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Limitations of Science • The limitations of science are set by its naturalism – Science seeks natural causes for natural phenomena – Science cannot support or falsify supernatural explanations, which are outside the bounds of science Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Theories in Science • A scientific theory is much broader than a hypothesis and has been rigorously investigated. • A scientific theory is: – broad in scope – general enough to generate new hypotheses – supported by a large body of evidence Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Science, Technology, and Society • The goal of science is to understand natural phenomena • Technology applies scientific knowledge for some specific purpose Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings