Chapter 1

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 1Chapter 1

Themes in the Study of Life


• 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


Themes of Biology:

• Evolution

• Ecosystems

• Biological organization

• Cells

• DNA

• Feedback mechanisms


• Life’s basic characteristic is a high degree of order

• Each level of biological organization has emergent properties

Video: Seahorse CamouflageVideo: Seahorse Camouflage


• The study of life extends from molecules and cells to the entire living planet

• Biological organization is based on a hierarchy of structural levels


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


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

Ecosystems

The biosphere

Organisms

Populations

Communities

Cells

Organelles

Molecules

Tissues

Organs and organ systems

Cell1 µm

Atoms

10 µm

50 µm


A Closer Look at Ecosystems

• Each organism interacts with its environment

• Both organism and environment affect each other


Ecosystem Dynamics

• 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


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

Heat

Chemicalenergy

Consumers(including animals)

Producers(plants and otherphotosynthetic

organisms)


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

LE 1-5

25 µm


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

LE 1-6

Sperm cell

NucleicontainingDNA

Egg cell

Fertilized eggwith DNA fromboth parents

Embryo’s cells With copies of inherited DNA

Offspring with traits inherited from both parents


• 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

LE 1-7

DNA double helix Single strand of DNA

Nucleotide

Cell

Nucleus DNA


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)


Feedback Regulation in Biological Systems

• Regulatory systems ensure a dynamic balance in living systems

• Chemical processes are catalyzed (accelerated) by enzymes

• Many biological processes are self-regulating: the product regulates the process itself


• In negative feedback, the accumulation of a product slows down the process itself

• In positive feedback (less common), the product speeds up its own production

Animation: Negative FeedbackAnimation: Negative Feedback Animation: Positive FeedbackAnimation: Positive Feedback

LE 1-11

Enzyme 1

A A

BB

C C

DD

D

DD

D

D

D

DDD

Enzyme 2

Enzyme 3

Negativefeedback

Enzyme 1

LE 1-12

W

Enzyme 4

W

XX

Y Y

ZZ

ZZ

Z ZZ

ZZ Z

Enzyme 5

Enzyme 6

Positivefeedback

Enzyme 4

Enzyme 6

Enzyme 5

Z

Z Z Z

Z

Z

Z

ZZ


• Biologists explore life across its great diversity of species

• Biologists have named about 1.8 million species

• Estimates of total species range from 10 million to over 200 million


Grouping Species: The Basic Idea

• Taxonomy is the branch of biology that names and classifies species into a hierarchical order

• Kingdoms and domains are the broadest units of classification

LE 1-14

Ursidae

Ursus

Carnivora

Mammalia

Chordata

Animalia

Eukarya

Species Genus Family Order Class Phylum Kingdom DomainUrsusamericanus(Americanblack bear)


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 PlantaeProtists

Kingdom AnimaliaKingdom FungiArchaea


Unity in the Diversity of Life

• Underlying life’s diversity is a striking unity, especially at lower levels of organization

• In eukaryotes, unity is evident in details of cell structure

LE 1-16a

Cilia of windpipe cellsCilia of Paramecium

15 µm 5 µm

LE 1-16b

Cilia of windpipe cellsCilia of Paramecium

Cross section of cilium,as viewed with anelectron microscope

0.1 µm


• Evolution accounts for life’s unity and diversity

• The history of life is a saga of a changing Earth billions of years old


• The evolutionary view of life came into sharp focus in 1859, when Charles Darwin published On the Origin of Species by Natural Selection


• The Origin of Species articulated two main points:

– Descent with modification (the view that contemporary species arose from a succession of ancestors)

– Natural selection (a proposed mechanism for descent with modification)

• Some examples of descent with modification are unity and diversity in the orchid family


Natural Selection

• Darwin inferred natural selection by connecting two observations:

– Observation: Individual variation in heritable traits

– Observation: Overpopulation and competition

– Inference: Unequal reproductive success

– Inference: Evolutionary adaptation

LE 1-20

Evolution of adaptationsin the population

Differences inreproductive success

Overproductionand competition

Populationof organisms

Hereditaryvariations


• An example is the effect of birds preying on a beetle population

LE 1-21

Population with varied inherited traits

Elimination of individuals with certain traits

Reproduction of survivors

Increasing frequency of traits that enhancesurvival and reproductive success


• Natural selection is often evident in adaptations of organisms to their way of life and environment

• Bat wings are an example of adaptation

Video: Soaring HawkVideo: Soaring Hawk


Hypothesis-Based Science

• In science, inquiry usually involves proposing and testing hypotheses

• Hypotheses are hypothetical explanations


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

LE 1-25a

Hypothesis #1:Dead batteries

Hypothesis #2:Burnt-out bulb

Observations

Question

LE 1-25b

Hypothesis #1:Dead batteries

Hypothesis #2:Burnt-out bulb

Test prediction

Test falsifies hypothesis

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction

Test does not falsify hypothesis


A Closer Look at Hypotheses in Scientific Inquiry

• A scientific hypothesis must have two important qualities:

– It must be testable

– It must be falsifiable


• 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

LE 1-26

Flower fly (nonstinging)

Honeybee (stinging)


• 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 coralsnake

Scarlet king snake

Key

Range of scarlet king snake

NorthCarolina

Range of easterncoral snake

SouthCarolina


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 snakeswere absent, most attacks

were on artificial king snakes.

LE 1-29

% of attacks onartificial king snakes

% of attacks onbrown artificial snakes

Field site withartificial snakes

83%

NorthCarolina

SouthCarolina

17%

16%

84%

Key


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


Theories in Science

• A scientific theory is much broader than a hypothesis

• A scientific theory is:

– broad in scope

– general enough to generate new hypotheses

– supported by a large body of evidence


Science, Technology, and Society

• The goal of science is to understand natural phenomena

• Technology applies scientific knowledge for some specific purpose

Chapter 1

Documents

Transcript of Chapter 1