1

A View of Life

Lecture 1

2

Define: metabolism, homeostasis, heredity, species, natural selection, evolution, ecology

Outline and describe the properties of life. Describe evolution and its importance. Define and list, in order, the levels of

organization from the simplest to the most complex.

3

•Compare and contrast the flow of energy and materials through an ecosystem.•List some ways in which human activities are modifying ecosystems•Explain how and why taxonomists classify organisms.•List the stages of the scientific process and explain how these steps are used. Note the use of controlled studies.

Objectives

Living things:

◦ Comprised of the same chemical elements e.g. Carbon, Hydrogen, and Oxygen

◦ Obey the same physical and chemical laws

◦ Living organisms consist of cells (Unicellular or Multi-cellular). The cell is the basic structural and functional unit of all living

things e.g. plants, animals, and fungus Cells are produced from preexisting cells Cells are the smallest units that perform all vital physiological

functions

4

5

Living organisms can be Microscopic:

Bacteria

Paramecium

Living organisms can be Macroscopic (Multi-cellular):

Snow goose

HumansCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(Bacteria): © Dr. Dennis Kunkel/Phototake; (Paramecium): © M. Abbey/Visuals Unlimited; (Morel): © Royalty-Free Corbis; (Sunflower): © Photodisc Green/Getty Images; (Snow goose): © Charles Bush Photography

Bacteria Paramecium Morel Sunflower Snow goose

Each level of organization has Emergent Properties

Levels range from extreme micro (e.g. Atoms, Molecules and Cells) to global (e.g. Community, Ecosystem and Biosphere)

Each level of organization is more complex than the level preceding it

◦ Emergent properties:

Interactions between the parts making up the whole

All emergent properties follow the laws of physics and chemistry

6

7

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

OrganComposed of tissues functioning

together for a specific task

TissueA group of cells with a common

structure and function

CellThe structural and functional

unit of all living things

MoleculeUnion of two or more atoms ofthe same or different elements

AtomSmallest unit of an element composed of

electrons, protons, and neutrons

BiosphereRegions of the Earth’s crust,

waters, and atmosphereinhabited by living things

Ecosystem A community plus

the physical environment

CommunityInteracting populations in a

particular area

PopulationOrganisms of the same

species in a particular area

OrganismAn individual; complex

individuals contain organ systems

Organ SystemComposed of several organs

working together

Energy – required to maintaining organization and conducting life-sustaining processes

◦ The sun:

Ultimate source of energy for nearly all life on Earth

Certain organisms, such as plants, capture solar energy to carry on photosynthesis

Photosynthesis transforms solar energy into chemical energy (Organic Molecules)

Chemical energy is used by other organisms e.g. animals

◦ Metabolism is all the chemical reactions that occur in a cell or in an organism.

Homeostasis - Maintenance of internal conditions within certain boundaries

8

Living things interact with the environment and respond to changes in the environment

Response ensures survival of the organism and it often results movement

◦ Vulture can detect and find carcass a mile away and soar toward dinner

◦ Monarch butterfly senses approach of fall and migrates south

◦ Microroganisms can sense light or chemicals

◦ Even leaves of plants follow sun

Activities as a result of Responses are termed behavior

9

Organisms live and die

All living organisms must reproduce to ensure continued existence and maintain population

In most multicellular organisms reproduction:

◦ Begins with union of sperm and egg (fertilization)

◦ Followed by cell division and differentiation

◦ Developmental instructions encoded in genes

Composed of DNA

Long spiral molecule in chromosomes

10

Adaptation

◦ Any modification that makes an organism more suited to its way of life

◦ Organisms become modified over long period time

Respond to environmental changes by developing new adaptations

◦ However, organisms very similar at basic level

Suggests living things descended from same ancestor

Descent with modification - Evolution

Caused by natural selection11

Despite diversity, organisms share the same basic characteristics

◦ Composed of cells organized in a similar manner

◦ Their genes are composed of DNA

◦ Carry out the same metabolic reactions to acquire energy

This suggests that they are descended from a common ancestor

12

Taxonomy:◦ Discipline of identifying and classifying

organisms according to certain rules

◦ Hierarchical levels (taxa) based on hypothesized evolutionary relationships

◦ Levels are, from least inclusive to most inclusive: Species, genus, family, order, class, phylum, kingdom,

and domain

A level (e.g. phylum) includes more species than the level below it (e.g. class), and fewer species than the one above it (e.g. kingdom)

13

14

Bacteria

◦ Microscopic unicellular prokaryotes

Archaea

◦ Bacteria-like unicellular prokaryotes

◦ Extreme aquatic environments

Eukarya

◦ Eukaryotes – Familiar organisms

15

16

17

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

BACTERIA

ARCHAEA

EUKARYA

Protists

commonancestor(first cells)

cell with nucleus

Past

Time

Present

Photosyntheticprotist

HeterotrophicProtist

Plants

Fungi

Animalscommon ancestor

18

Methanosarcina mazei, an archaeon 1.6 m

• Prokaryotic cells of various shapes• Adaptations to extreme environments• Absorb or chemosynthesize food• Unique chemical characteristics

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

© Ralph Robinson/Visuals Unlimited

19

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Prokaryotic cells of various shapes• Adaptations to all environments• Absorb, photosynthesize, or chemosynthesize food• Unique chemical characteristics

Escherichia coli, a bacterium 1.5 m

© A.B. Dowsett/SPL/Photo Researchers, Inc.

Archaea – Kingdoms still being worked out

Bacteria - Kingdoms still being worked out

Eukarya

◦ Kingdom Protista

◦ Kingdom Fungi

◦ Kingdom Plantae

◦ Kingdom Animalia

20

21

KINGDOM: Fungi

Coprinus, a shaggy mane mushroom

Protists

Paramecium, a unicellular protozoan

• Molds, mushrooms, yeasts, and ringworms• Mostly multicellular filaments with specialized, complex cells• Absorb food1

• Algae, protozoans, slime molds, and water molds• Complex single cell (sometimes filaments, colonies, or even multicellular)• Absorb, photosynthesize, or ingest food1 m

KINGDOM: Plants

r

Vulpes, a red fox

KINGDOM: Animals

• Certain algae, mosses, ferns, conifers, and flowering plants• Multicellular, usually with specialized tissues, containing complex cells• Photosynthesize food

• Sponges, worms, insects, fishes, frogs, turtles, birds, and mammals• Multicellular with specialized tissues containing complex cells• Ingest food

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(Protist): © Michael Abby/Visuals Unlimited; (Plant): © Pat Pendarvis; (Fungi): © Rob Planck/Tom Stack; (Animal): © Royalty-Free/Corbis

Binomial nomenclature (two-word names)- used to assign each organism with two part name e.g. Homo Sapience

Universal Latin-based

◦ First word represents genus of organism e.g. Homo

◦ Second word is specific epithet of a species within the genus e.g. Sapience

◦ Always italicized as a Genus species (Homo sapiens)

◦ Genus may be abbreviated e.g. Escherichia Coli as E. Coli

22

23

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Some plants within a population exhibit variation in leaf structure.

Deer prefer a diet of smooth leaves over hairy leaves. Plants withhairy leaves reproduce more than other plants in the population.

Generations later, most plants within the population have hairyleaves, as smooth leaves are selected against.

Population - Members of a species within an area

Community - A local collection of interacting populations

Ecosystem – A community plus its physical environment

How chemicals are cycled and re-used by organisms

How energy flows, from photosynthetic plants to top predators

24

25

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

WASTE MATERIAL, DEATH,AND DECOMPOSITION

heat

heat

heat

heat

heat

solarenergy

Chemical cycling

Energy flow

heat

26

1975 Minimal coral death

b.

a. Healthy coral reef

1985 Some coral death with no fish present

1995 Coral bleaching with limited chance of recovery

2004 Coral is black from sedimentation; bleaching still evident

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a: © Frank & Joyce Burek/Getty Images; b (All): © Dr. Phillip Dustan

Humans modify ecosystems◦ Humans negative impact on ecosystems:

Destroy forest or grassland for agriculture, housing, industry, etc.

Produce waste and contaminate air, water, etc.

However, humans depend upon healthy ecosystems for◦ Food

◦ Medicines

◦ Raw materials

◦ Other ecosystem processes27

Biodiversity is the zone of air, land, and water where organisms exist

◦ Abundance of species estimated about 15 million.

◦ The variability of their genes, and

◦ The ecosystems in which they live

Extinction is:

◦ The death of the last member of a species

◦ Estimates of 400 species/day lost worldwide

28

Scientific method is a standard series of steps in gaining new knowledge through research.◦ Begins with observation

Scientists use their five senses e.g. use visual sense to observe animal behavior

Instruments can extend the range of senses e.g. use microscope to see microorganisms

Take advantage of prior studies

◦Hypothesis A tentative explanation for what was observed

Developed through inductively reasoning from specific to general

29

30

Observation

New observationsare made, and previous

data are studied.

Hypothesis

Input from varioussources is used to formulate

a testable statement.

Conclusion

The results are analyzed,and the hypothesis issupported or rejected.

Scientific Theory

Many experiments andobservations support a

theory.

Experiment/Observations

The hypothesis istested by experiment

or further observations.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Courtesy Leica Microsystems Inc.

Experimentation◦ Purpose is to challenge the hypothesis

◦ Designed through deductively reasoning from general to specific

◦ Often divides subjects into a control group and an experimental group

◦ Predicts how groups should differ if hypothesis is valid If prediction happens, hypothesis is unchallenged If not, hypothesis is unsupportable

31

The results are analyzed and interpreted

Conclusions are what the scientist thinks caused the results

Findings must be reported in scientific journals

Peers review the findings and the conclusions

Other scientists then attempt to duplicate or dismiss the published findings

32

Results or Data

◦ Observable, objective results from an experiment

◦ Strength of the data expressed in probabilities

◦ The probability that random variation could have caused the results

Low probability (less than 5%) is good

Higher probabilities make it difficult to dismiss random chance as the sole cause of the results

33

Scientific Theory:

◦ Joins together two or more related hypotheses

◦ Supported by broad range of observations, experiments, and data

Scientific Principle / Law:

◦ Widely accepted set of theories

◦ No serious challenges to validity

34

Experimental (Independent) variable

◦ Applied one way to experimental group

◦ Applied a different way to control group

Response (dependent) variable

◦ Variable that is measured to generate data

◦ Expected to yield different results in control versus experimental group

35

Observations:

◦ Nitrate fertilizers boost grain crops, but may damage soils by altering its properties

◦ When grain crops are rotated with pigeon pea it adds natural nitrogen

Hypothesis:

◦ Pigeon pea rotation will boost crop production as much as nitrates

◦ Pigeon pea rotation will NOT damage soils36

37

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

© Dr. Jeremy Burgess/Photo Researchers, Inc.

nodules

Experimental Design◦ Control Group

Winter wheat planted in pots without fertilizer

◦ Experimental Groups 1-Winter wheat planted in pots with 45 kg/ha nitrate

2-Winter wheat planted in pots with 90 kg/ha nitrate

3-Winter wheat planted in pots that had grown a crop of pigeon peas

◦ All groups treated identically except for above

38

39

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

= Pigeon pea/winter wheat rotation

15

20

10

5

0year 1 year 2 year 3

= no fertilization treatment

= 45 kg of nitrogen/ha

Control Pots

Test Pots

= 90 kg of nitrogen/ha

Wh

eat

Bio

mas

s (g

ram

s/p

ot)

b. Results

a. Control pots and test pots of three types

Test pots

90 kg of nitrogen/ha

Test pots

Pigeon pea/winter wheat rotation

Control pots

no fertilization treatment

Test pots

45 kg of nitrogen/ha

(All): Courtesy Jim Bidlack

Experimental Prediction:◦ Wheat production following pigeon pea rotation will

be equal or better than following nitrate fertilizer

Results◦ 45 kg/ha produced slightly better than controls

◦ 90 kg/ha produced nearly twice as much as controls

◦ Pigeon pea rotation did not produce as much as the controls

40

Conclusion

◦ Research hypothesis was not supported by results

◦ However, research hypothesis was not proven false by negative results

Revised experiment

◦ Grow wheat in same pots for several generations

◦ Look for soil damage in nitrate pots and improved production in pigeon pea pots

41

Results◦ After second year:

Production following nitrates declined Production following pigeon pea rotation was greatest of

all

◦ After third year Pigeon pea rotation produced 4X as much as controls

Revised conclusions◦ Research hypothesis supported

◦ Pigeon pea rotation should be recommended over nitrates

42

Defining Life - Emergent Properties

◦ Materials and Energy

◦ Reproduction and Development

◦ Adaptations and Natural Selection

Biosphere Organization

◦ Human Population

◦ Biodiversity

Classification

The Scientific Method

43