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

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 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 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 Themes Connect Biological Concepts

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

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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

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

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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

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

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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

LE 1-15 Bacteria 4 µm 100 µm 0.5 µm Kingdom Plantae Protists Kingdom Animalia Kingdom Fungi Archaea

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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 In science, inquiry usually involves proposing and testing hypotheses Hypotheses are hypothetical explanations Hypothesis-Based Science

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 Hypothesis #2: Burnt-out bulb

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

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

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

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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

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

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

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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