01 exploring biology text

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

Sample Free Response Question:

• The rate of photosynthesis may vary with changes that occur in environment temperature, wavelength of light, and light intensity. Using a photosynthetic organism of your choice, choose only ONE of the three variables (temperature, wavelength of light, or light intensity) and for this variable

– Design a scientific experiment to determine the effect of the variable on the rate of photosynthesis for the organism;

– Explain how you would measure the rate of photosynthesis in your experiment;

– Describe the results you would expect. Explain why you would expect these results.


What is Life?

• The phenomenon we call life

– Defies a simple, one-sentence definition

Figure 1.1

We recognize life

By what living things

do


• Some properties of life

Figure 1.2

(c) Response to the environment

(a) Order

(d) Regulation

(g) Reproduction (f) Growth and development

(b) Evolutionary adaptation

(e) Energy processing


• Biologists explore life from the microscopic to the global scale

• The study of life

– Extends from the microscope scale of molecules and cells to the global scale of the entire living planet

The hierarchy of lifeExtends through many levels of biological organization


• From the biosphere to organisms

Figure 1.3

1 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


A Closer Look at Ecosystems

• Each organism

– Interacts with its environment

• Both organism and environment

– Are affected by the interactions between them


Ecosystem Dynamics

• The dynamics of any 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 (autotrophs) to consumers (heterotrophs)


Energy Conversion

• Activities of life

– Require organisms to perform work, which depends on an energy source

The exchange of energy between an organism and its surroundings

Often involves the transformation of one form of energy to another


• Energy flows through an ecosystem

– Usually entering as sunlight and exiting as heat

Producers

(plants and other

photosyntheticorganisms)

Consumers(including animals)

Sunlight

Chemical

energy

Heat

Heat

Ecosystem

Figure 1.4


A Closer Look at Cells

• The cell

– Is the lowest level of organization that can perform all activities required for life

25 µmFigure 1.5


The Cell’s Heritable Information

• Cells contain chromosomes made partly of DNA, the substance of genes

– Which program the cells’ production of proteins and transmit information from parents to offspring

Egg cell

Sperm cell

NucleicontainingDNA

Fertilized eggwith DNA fromboth parents

Embyro’s cells with copies of inherited DNA Offspring with traits

inherited fromboth parentsFigure 1.6


• The molecular structure of DNA

– Accounts for it information-rich nature

DNA

Cell

Nucleotide

ACTA

T

A

CC

G

G

TA

TA

(b) Single strand of DNA. These geometric shapes and letters are simple symbols for the nucleotides in a small section of one chain of a DNA molecule. Genetic information is encoded in specific sequences

of the four types of nucleotides (their names are abbreviated here as A, T, C, and G).

(a) DNA double helix. This model shows

each atom in a segment of DNA.Made up of two long chains of building blocks called nucleotides, a DNA molecule takes the three-dimensional form of a double helix.

Figure 1.7

Nucleus


Two Main Forms of Cells

• All cells share certain characteristics

– They are all enclosed by a membrane

– They all use DNA as genetic information

• There are two main forms of cells

– Eukaryotic

– Prokaryotic


• Eukaryotic cells

– Are subdivided by internal membranes into various membrane-enclosed organelles


• Prokaryotic cells

– Lack the kinds of membrane-enclosed organelles found in eukaryotic cells

EUKARYOTIC CELL

Membrane

Cytoplasm

Organelles

Nucleus (contains DNA) 1 µm

PROKARYOTIC CELL

DNA

(no nucleus)Membrane

Figure 1.8


• Biological systems are much more than the sum of their parts

• A system

– Is a combination of components that form a more complex organization


The Power and Limitations of Reductionism

• Reductionism

– Involves reducing complex systems to simpler components that are more manageable to study

Irreducibly Complexity or WPP (Whole Package Phenomenon)


• The study of DNA structure, an example of reductionism

– Has led to further study of heredity, such as the Human Genome Project

Figure 1.9


• In feedback regulation

– The output, or product, of a process regulates that very process


• In negative feedback

– An accumulation of an end product slows the process that produces that product

B

A

C

D

Enzyme 1Enzyme 1

Enzyme 2

Enzyme 3

DD D D

D

D

DD

DD

C

B

A Negative feedback

Figure 1.11

In Biology, this process (generally biochemical) is often referred to as Homeostasis; from the regulating of body temperature, to the regulating of blood glucose levels.


• In positive feedback

– The end product speeds up production

WW

X

Y

Z

ZZ

ZZ

Z

Z Z Z

Z Z Z Z

Z

ZZ Z

ZZ

Y

X

Enzyme 4

Enzyme 5

Enzyme 6

Enzyme 4

Enzyme 5

Enzyme 6

Positivefeedback

Figure 1.12

For another example, imagine an ecosystem with only one species and an unlimited amount of food. The population will grow at a rate proportional to the current population, which leads to an accelerating increase, i.e., positive feedback. This has a de-stabilizing effect, so left unchecked, does not result in homeostasis. In some cases (if not controlled by negative feedback), a positive feedback loop can run out of control, and can result in the collapse of the system.


• Biologists explore life across its great diversity of species

• Diversity is a hallmark of life

Figure 1.13


Grouping Species: The Basic Idea

• Taxonomy

– Is the branch of biology that names and classifies species according to a system of broader and broader groups


• Classifying lifeSpecies Genus Family Order Class Phylum Kingdom Domain

Mammalia

Ursusameri-canus(Americanblack bear)

Ursus

Ursidae

Carnivora

Chordata

Animalia

EukaryaFigure 1.14


The Three Domains of Life

• At the highest level, life is classified into three domains

– Bacteria

– Archaea

– Eukarya


• Domain Bacteria and domain Archaea

– Consist of prokaryotes

• Domain Eukarya, the eukaryotes

– Includes the various protist kingdoms and the kingdoms Plantae, Fungi, and Animalia


• Life’s three domains

Figure 1.15

100 µm

0.5 µm

4 µmBacteria are the most diverse and widespread prokaryotes and are now divided among multiple kingdoms. Each of the rod-shapedstructures in this photo is a bacterial cell.

Protists (multiple kingdoms)are unicellular eukaryotes and their relatively simple multicellular relatives.Pictured here is an assortment of protists inhabiting pond water. Scientists are currently debating how to split the protistsinto several kingdoms that better represent evolution and diversity.

Kingdom Plantae consists of multicellula eukaryotes that carry out photosynthesis, the conversion of light energy to food.

Many of the prokaryotes known as archaea live in Earth‘s extreme environments, such as salty lakes and boiling hot springs. Domain Archaea includes multiple kingdoms. The photoshows a colony composed of many cells.

Kindom Fungi is defined in part by thenutritional mode of its members, suchas this mushroom, which absorb nutrientsafter decomposing organic material.

Kindom Animalia consists of multicellular eukaryotes thatingest other organisms.

DOMAIN ARCHAEA


Unity in the Diversity of Life

• As diverse as life is

– There is also evidence of remarkable unity

Cilia of Paramecium.The cilia of Parameciumpropel the cell throughpond water.

Cross section of cilium, as viewedwith an electron microscope

15 µm

1.0 µm

5 µm

Cilia of windpipe cells. The cells that line the human windpipe are equipped with cilia that help keep the lungs clean by moving a film of debris-trapping mucus upward.Figure 1.16


Continuity and Discontinuity

• God created organisms with enough continuity (similarities) to know that only ONE God was the Creator, yet with enough discontinuity (differences) to know that organisms could not have created (or evolved) themselves.


• The evolutionary view of life

– Came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection

Figure 1.18


• The Origin of Species articulated two main points

– Descent with modification

– Natural selection

Figure 1.19


• Natural selection is the evolutionary process that occurs

– When a population’s heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others

1 Populations with varied inherited traits

2 Elimination of individuals with certain traits.

3 Reproduction of survivors.

4 Increasing frequency of traits that enhance survival and reproductive success. Figure 1.21


• Darwin proposed that natural selection

– Could enable an ancestral species to “split” into two or more descendant species, resulting in a “tree of life”

Large

ground finchSmallground

finch

Geospiza

magnirostris

Seed eater

Sharp-beaked

ground finch

Camarhynchus

psitacula

Green

warbler

finch

Large

tree finchLarge cactusground finch

Ground finches Tree finches

Insect eaters Bud eater

Warbler finches

Common ancestor fromSouth American mainland

Gray

warbler

finch

Certhidea

olivacea

Certhidea

fuscaGeospiza

difficilis

Cactus flowereater

Geospizascandens

Seed eater

Geospiza

conirostris

Geospiza

fortis

Mediumground

finch

Geospizafuliginosa

Mangrovefinch

Cactospiza

heliobates

Cactospizapallida

Woodpecker

finch

Mediumtree finch

Camarhynchuspauper

Small tree finch

Vegetarianfinch

Camarhynchusparvulus

Platyspizacrassirostris

Cactusground finch

Figure 1.23

Macro vs. Micro

Changes


Creation and Evolution: Major Beliefs

Topic Evolutionists believe….. Creationists believe….

Date of the Earth

The Earth is at least 4.6 billion years old. Evolutionists must have vast amounts of time in order for mutations to accumulate; otherwise the variations we see today would not have had enough time to accumulate.

Creationists are divided on the age of the Earth; however, a straight forward reading of the book of Genesis indicates a young Earth. Using the generations from Adam to Jesus we deduce approximately 4,000 years have passed and from Jesus to the present another 4,000 years. Approximate age of the Earth taken from scripture is between 6,000-7,000 years old.

Mutation Mutations have always existed since the first organism evolved. Mutations are believed to be the major element and contributing factor causing the enormous quantity of variations we see in organisms today.

Mutations originated at the fall of man (Genesis) and have accumulated from this point, however, mutations are not considered to be the major cause of variations within organisms, rather, variations were created by God and then selected to best fit an environment. Mutations are most often negative and therefore could not have produced the organisms and variations we see today.


Creation and Evolution: Major Beliefs Topic Evolutionists believe….. Creationists believe….

Natural Selection A process that selects from existing traits and variations and fits organisms to their environment. Evolutionists extrapolate this observable process and belief that natural selection had the ability to guide evolving organisms through innumerable changes and alterations and to produce the organisms we see in the present. Natural selection (being a process) must act on living organisms and couldn’t have in itself functioned before organisms evolved.

A process that selects from existing traits and variations and fits organisms to their environment. Creationists see natural selection as a process that was instituted by God after the fall in order to preserve variations and to fit organisms to their changing environment. Creationists view natural selection as a method of preservation rather than a method of selection. Creationists insist that natural selection explains the “survival of the fittest” but not the “arrival of the fittest”.

Tree of Life

All organisms are related to an ancestral organism. The tips of the branches are modern day species and the trunk represents the first organism that evolved. New evidence is continually altering major branches.

All organisms are not related. Instead of a tree, Creationists envision a lawn or orchard, where the tips represent modern day species and the base represents God’s Created Kinds (barmins, Genesis). Creationists would agree that the connections of the branches in the evolutionary tree of life are not real relationships rather are only hypothesized and undocumented relationships.



Species

Species are finely tuned organisms to their environments that have the capabilities of reproducing with those in their same species. Evolutionists believe that new species are constantly forming due to geographic isolation, etc.

Species are viewed as finely tuned to their environment through natural selection, however, not all Creationists agree with the modern view of fixed species. Creationists instead view all modern day species as descendants of a Biblical Kind, sometimes still being able to breed with others of the same Biblical Kind.

Information (DNA and RNA)

DNA had to accumulate over the vast eons (4.6 bya). The first organism had little information compared to modern day species with vast quantities of information. Evolutionists believe that the quantity of DNA has increased through mutational events.

DNA was created by God as the instructions for each Biblical Kind. Written into the DNA are variations. Creationists do not believe that new and novel DNA can be produced through mutations and have challenged evolutionists with the problem of DNA complexity.



Variation Variations are a result of mutational events.

Variations were written into the DNA code by God. New variations are possible through mutational events but they are almost always harmful or not beneficial. Creationists would argue that mutations are incapable of producing all of the variations we see in the Biblical Kinds.

Missing-links

They are fossilized organisms that exhibit a transitional form between (usually) a more ancient species and a more modern species. Archaeopteryx is an example of a supposed missing-link between reptiles and birds.

Would suggest that missing-links do not exist and are still missing. Creationists would view missing-links as an evolutionary forced relationship between two organisms that are in fact distinct species.



Microevolution Small incremental changes in the frequency of alleles within a species.

Creationists would agree that microevolution occurs but would credit the frequency of alleles within a species as being selected from variation that was created by God rather than solely produced by mutation. Creationists would also emphasize that microevolution fluctuates within a population.

Macroevolution

Evolutionists would extrapolate the small changes found in microevolution as accumulating to produce a much larger event, incorporating all of life into a large continuum.

Creationists would suggest that microevolution is not possible nor has been observed and that any extrapolation by evolutionists to prove macroevolution is hypothetical rather than actual. Creationists believe that macroevolution is not possible because God set natural limitations between the Biblical Kinds.



Darwin The first scientist that united various preconceived ideas to make a whole realm of thought, which later came to be known as evolution. Some scientist credit Darwin with allowing them to become “intellectually fulfilled atheists”, but not all evolutionists agrees with this view.

Creationists do not generally vilify Darwin but disagree with his final conclusion; that all life evolved in a continuum without the need of an intelligent designer. Creationists view Darwin as a scientist who was a product of his time, making misguided extrapolations based on somewhat good reasoning but spoiling that good reasoning with unsubstantiated hypothetical reasoning. Creationists often claim that Darwin made conclusions based on faith rather than true science.

Human Evolution Evolutionists include humans in the overarching evolutionary scenario, claiming that humans descended from ape-like organisms.

Creationists reject human evolution entirely, based on the belief that humans were created in the image of God (Genesis). Creationists believe that humans were created (Adam and Eve) fully formed with the ability to communicate with each other and with God from the beginning and reject any step-by-step process of human evolution.


1 The heavens declare the glory of God; the skies proclaim the work of his hands.

2 Day after day they pour forth speech; night after night they display knowledge.

3 There is no speech or language where their voice is not heard.

4 Their voice goes out into all the earth, their words to the ends of the world.

Psalm 19: 1-4

My Presupposition


• Eleven themes that unify biology

Table 1.1

01 exploring biology text

Education

dna molecule

segment of dna

study of dna structure

form of energy

rate of photosynthesis

cells production of

main forms of cellsall

b single strand of dna