chapter one the science of biology. chapter 1 – the science of biology biology is the study of...

Chapter One

The Science of Biology

Chapter 1 – The Science of Biology

• Biology is the study of living things

• Living things are diverse

• There are enough similarities among some living things that they can be grouped into the same kingdom

• Members of different kingdoms are usually very different from each other

Kingdoms

• Life on planet Earth is broken down into six groups called Kingdoms.• Bacteria• Archaea• Protista• Fungi• Plantae• Animalia

BACTERIA EUKARYA

Bacteria Archaea Protista Plantae Fungi Animalia

ARCHAEA

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Archaea. This kingdom of prokaryotes(the simplest of cells that do not havenuclei) includes this methanogen, whichmanufactures methane as a result of itsmetabolic activity.

Animalia. Organisms in this kingdom arenonphotosynthetic multicellular organismsthat digest their food internally, such as thisram.

Protista. Most of the unicellular eukaryotes(those whose cells contain a nucleus) aregrouped into this kingdom, and so are themulticellular algae pictured here.

Fungi. This kingdom containsnonphotosynthetic organisms, mostlymulticellular, that digest their foodexternally, such as these mushrooms.

Bacteria. This group is the second of thetwo prokaryotic kingdoms. Shown here arepurple sulfur bacteria, which are able toconvert light energy into chemical energy.

Plantae. This kingdom containsphotosynthetic multicellular organisms that are terrestrial, such as the flowering plantpictured here.

(Achaea): © R. Robinson/Visuals Unlimited; (bacteria): © Alfred Pasieka/Science Photo Library/Photo Researchers; (protista, plantae): © Corbis RF; (fungi, animalia): © Getty RF

Diversity of Life

• The living world is very diverse – many different types of living organisms – but all living things share many key properties.

Properties of Life

• What does it mean to be alive?• Complexity (computers are complex)• Movement (clouds, ocean waves move)• Response to stimulation (soap bubble pops if

touched)

• Let’s look at five more properties of life:

Properties of Life

• Cellular Organization – All living things are composed of one or more cells.• Cell – tiny compartment surrounded by a

membrane.• Cells may have simple or complex interiors.• All can grow and reproduce.

Properties of Life

• Metabolism – All living things use energy.• Energy comes from the

sun.• Energy is captured by

plants and algae.• Plants turn energy from

the sun into a form that can be used by the plants and by organisms that eat the plants.

• The chemical process that extracts energy from a food source is called metabolism.

Properties of Life

• Homeostasis – All living things maintain stable internal conditions.• Environment is variable.• Organisms keep interior relatively constant –

homeostasis.• Body temperature is one example.

Properties of Life

• Reproduction – All living things reproduce. • The simplest organisms (bacteria) simply split

in two.• More complex organisms have more

complicated forms of reproduction.

Properties of Life

• Heredity – All organisms possess a genetic system that is based on the replication and duplication of a long molecule called DNA (deoxyribonucleic acid).• The order of the subunits that

make up DNA provide the information needed to determine what an organism will be like.

Properties of Life

• Each set of instructions within the DNA is called a gene.

• Transmission of characteristics from parent to offspring is a process called heredity.

The Organization of Life

• Organisms function and interact with each other on many levels.

• Hierarchy of increasing complexity• Within cells• Within multicellular organisms• Among organisms

Fig. 1.4left-1


1Atoms(Hydrogen,carbon,nitrogen)

CELLULAR LEVEL

Fig. 1.4left-2


1

2Molecule(Adenine)

Atoms(Hydrogen,carbon,nitrogen)

CELLULAR LEVEL

Fig. 1.4left-3


1

2Molecule(Adenine)


CELLULARLEVEL

3Macromolecule

(DNA)

Fig. 1.4left-4


1

2

4Organelle(Nucleus)

Molecule(Adenine)


CELLULARLEVEL

3Macromolecule

(DNA)

Fig. 1.4left-5


1

2

4Organelle(Nucleus)

Molecule(Adenine)


CELLULARLEVEL

3Macromolecule

(DNA)

5 Cell(Nervecell)


1

2

4Organelle(Nucleus)

Molecule(Adenine)


ORGANISMAL LEVEL

CELLULARLEVEL

3Macromolecule

(DNA)

5 Cell(Nervecell)

6 Tissue(Nerve tissue)


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2

4Organelle(Nucleus)

Molecule(Adenine)


ORGANISMAL LEVEL

CELLULARLEVEL

3Macromolecule

(DNA)

5 Cell(Nervecell)


7Organ(Brain)


1

2

4Organelle(Nucleus)

Molecule(Adenine)


ORGANISMAL LEVEL

CELLULARLEVEL

3Macromolecule

(DNA)

5 Cell(Nervecell)


78

Organ(Brain)

Organ system(Nervous system)


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4Organelle(Nucleus)

Molecule(Adenine)


ORGANISMAL LEVEL

CELLULARLEVEL

3Macromolecule

(DNA)

5 Cell(Nervecell)


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Organ(Brain)

Organ system(Nervous system)

Organism

Fig. 1.4right-1


POPULATIONAL LEVEL

(goose & crane): © Jim Bailey; (geese on lake): © Raymond Gehman/Corbis; (cranes on lake): © Corbis RF; (ecosystem): © Winfried Wisniewski/zefa/Corbis

Fig. 1.4right-2


POPULATIONAL LEVEL

Population

Species

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11


Fig. 1.4right-3


POPULATIONAL LEVEL

Community

Population

Species

12

10

11


Fig. 1.4right


POPULATIONAL LEVEL

EcosystemCommunity

Population

Species

12 13

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Organization of Life

• At higher levels of the living hierarchy, new properties become apparent that were absent at the lower levels

• These emergent properties result from the interaction of diverse but simpler components

• Many higher order processes that are hallmarks of life are emergent properties• metabolism• consciousness

Biological Themes

• Evolution – The change in species over time. Charles Darwin proposed the mechanism by which this change takes place – natural selection.• Organisms that are better able to respond to

challenges in the environment are more likely to survive, reproduce, and pass on their genes to the next generation.

Evolution

• Artificial Selection• Darwin was familiar

with variation in domestic animals and that breeders select animals with desired characteristics and breed them to obtain offspring with the desired or exaggerated characteristics.

Evolution

• The characteristics selected are passed on through the generations because DNA is transmitted from parent to offspring.

• Darwin extended the idea of artificial selection to the natural world.

• Thus, the many forms of life we see today reflect a long history of natural selection.

Biological Themes

• The flow of energy – All organisms require energy for the activities of living.• All of the energy used by most organisms

originally comes from the sun.• This energy gets used up as it passes through

an ecosystem.

The Flow of Energy

• Green plants and photosynthetic protists (algae, seaweed) capture energy from the sun using a process called photosynthesis.

• Plants serve as the energy source for the animals who eat them.

The Flow of Energy

• Other animals eat the plant-eaters.

• At each stage, some energy is used, some is transformed, and much is lost.

The Flow of Energy

• The flow of energy is very important in shaping ecosystems:• What kind of organisms live there?• How many of each?

Biological Themes

• Cooperation has played a critical role in the evolution of life on Earth.• Coevolution of

insects & flowering plants

• Fungi helped plants first invade land from the sea.• Barnacles living on gray whales are carried around exposing them to fresh supply of food.

Biological Themes

• Structure determines function – At every level of organization, structures are well suited to their functions.

Biological Themes

• Homeostasis – maintaining a relatively constant internal environment is essential for complex organisms.• Body temperature• Ph• Water balance

The Nature of Science

• Science is a particular way of investigating the world.

Deductive Reasoning

• Deductive reasoning involves making individual decisions by applying accepted general principles.• Math• Philosophy• Politics• Ethics

DEDUCTIVE REASONINGAn Accepted General Principle

DEDUCTIVEREASONING

Traveling at the speed limit,you approach eachIntersection anticipating thatthe red light will turn green asyour each the intersection.

Using a GeneralPrinciple toMake EverydayDecisions

When traffic lights along city streets are "timed“ to change at thetime interval it takes traffic to pass between them, the result will bea smooth flow of traffic.

The Nature of Science

• Where do these general principles come from?• Religious & ethical principles may have a

religious foundation.• Political principles reflect social systems.• Some general principles come from observing

the world around us.• Science is based on this type of general principle

Inductive Reasoning

• Science is devoted to discovering general principles that govern the operation of the physical world.

• Discovering general principles by careful examination of specific cases is called inductive reasoning.

Observations ofSpecific Events

INDUCTIVEREASONING

Maintaining the same speed,you observe the same event atthe next several intersections:the traffic lights turn green justas you approach theintersections. When you speedup, however, the light doesn't change until after you reach theintersection.

You conclude that the traffic lights along this street are "timed“ tochange in the time it takes your car, traveling at the speed limit, totraverse the distance between them.

Driving down the street at thespeed limit, you observe that thered traffic light turns green justas you approach theintersection.

INDUCTIVE REASONING

Formation of a General Principle

Inductive Reasoning

• 400 years ago Isaac Newton, Francis Bacon, and others began conducting experiments and inferring general principles about how the world works from their results.

• Simple observations (such as Newton’s apple) are very important in science.

Inductive Reasoning

• Newton started by simply dropping an apple from his hand.

• He then performed other simple experiments.

• Using his results, Newton inferred that all objects fall toward the center of the Earth.

• This is a hypothesis about how the world works.

Inductive Reasoning

• Today, scientists still formulate hypotheses to explain how the world works.

• Observations are the materials that they use to build their hypotheses.

How Science is Done

• Scientists start by making observations concerning a particular problem.

• A hypothesis is then formed.• Hypothesis – a proposition that might be true,

an educated guess.

• Experiments are performed to eliminate alternate hypotheses.

How Science is Done

• Hypotheses that are not rejected are retained because they fit known facts.

• Hypotheses are often revised or replaced as new data become available.

• Hypotheses that are well supported by many experiments over time are known as theories.

01.04 Scientific Method

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The Scientific Process

• Scientific investigations can be broken down into six stages.

Observation

• Observation is the key to any successful scientific investigation.

• Scientists take note of many details and keep careful records of these details.

Observation - Science in Action: A Case Study

• Example – Scientists in the Antarctic kept careful record of temperature, light and levels of chemicals. They realized the level of ozone was dropping.

Hypothesis

• A hypothesis is a guess that might be true – a potential explanation for the observations that have been made.

• Antarctic scientists guessed that CFCs may be responsible for ozone depletion.• Chlorine from the CFCs reacts with O3 producing

O2.

Hypothesis

• Scientists form several alternate hypotheses when they have more than one guess about what they observe.

Predictions

• If a hypothesis is correct, several consequences might be predicted.

• Prediction – what you would expect to happen if a hypothesis is true.

Predictions

• If the CFC hypothesis is true, it should be possible to detect CFCs in the upper Antarctic atmosphere as well as the chlorine released from CFCs that attack the ozone.

Testing

• The next step is to verify the prediction.• A test of a hypothesis is an experiment.

Testing

• To test the CFC hypothesis, atmospheric samples were collected 6 miles over the Antarctic.• CFCs were found as predicted.• Free chlorine & fluorine were also found

confirming breakdown of CFCs.• These results support the hypothesis.

Controls

• A factor that might influence a process that we are interested in is called a variable.

• To evaluate alternative hypotheses about one variable, all others must be held constant so that we are not misled.

Controls

• Carry out 2 experiments in parallel:• In one, a variable is altered in a known way to

test a particular hypothesis.• In the other, the variable is not altered. This is

called a control experiment.• The two experiments are identical in every way

except for the one variable under consideration.

Controls

• In our example, scientists set up experiments reconstructing conditions in the upper atmosphere.• In one set-up they added CFCs.• In the other they added no CFCs.

• Ozone levels only dropped in the set-up containing the added CFCs.

Conclusion

• A hypothesis that has been tested and not rejected is tentatively accepted.

• A collection of related hypotheses that have been tested many times is called a theory.

Conclusion

• The hypothesis that CFCs released into the atmosphere are destroying the Earth’s protective ozone shield is now supported by a great deal of experimental evidence and is widely accepted as a theory.

Theory and Certainty

• Hypotheses that are often tested and never rejected are sometimes combined into general statements called theories.

• A Theory is a unifying explanation for a broad range of observations.• Theory of gravity• Theory of evolution• Theory of the atom


• Theories represent the ideas of which scientists are most certain.

• There is no absolute truth in science, only varying degrees of certainty.• It is always possible that new information will

surface causing a theory to be revised.


• Very active areas of science are often full of controversy.• Not a sign of poor science.• Push & pull that is the heart of the scientific

process.

• Example – global warming due to excessive production of CO2.

The Scientific “Method”

• A scientist does not follow a fixed method to form a hypothesis.

• Judgment and intuition are also very important to the process of science.

Limitations of Science

• Scientific study is limited to organisms and processes that we are able to observe and measure.

• Supernatural and religious phenomena are completely outside the realm of science.

Limitations of Science

• Science can point us toward solutions to problems only when those solutions exist.• Science can not restore extinct animals.• Science may not be able to fix all problems

created by polluting the environment and using up resources.

Four Theories Unify Biology as a Science

• 1. The Cell Theory

• 2. The Gene Theory

• 3. The Theory of Heredity

• 4. The Theory of Evolution

The Cell Theory: Organization of Life

• Robert Hooke, 1665• Discovered cells

• Anton van Leeuwenhoek, 1670s• Discovered single-celled life

• Matthias Schleiden & Theodor Schwann, 1839• All living organisms are composed of cells• Cells are the basic units of life

• Later the third tenet of the theory was added • All cells come from other cells

• Genetic information is encoded in molecules of deoxyribonucleic acid (DNA)

• Genes can encode specific proteins or RNA, or they can act to regulate other genes

• The proteins and RNA encoded by an organism’s genes determine what it will be like in terms of form and function

The Gene Theory: Molecular Basis of Inheritance

Figure 1.12 The gene theory


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MACROPHAGE

NERVE CELL

INTESTIONAL CELL

Nucleus

Chromosomes

Genesbeingused

MUSCLE CELL

Chromosome Gene

DNA double helix

Nucleotides

All cells contain the sameset of genes, but different kindsof cells use different genes.Theproduction of specific proteinscoded for by these genesdetermines what the cell is like.

A typical humanchromosome can containup to a thousand genes,arrayed along a linearpiece of DNA.

Each gene is composed of a sequence of several hundredto many thousands of DNA nucleotides and functions as adiscrete unit of information.

A human cell has 46chromosomes, containingsome 3 billion nucleotidesof DNA.

1 A human bodycontains over 100different kinds of cells.

• Genes are passed down in generations as discrete units.• Mendel’s theory of heredity gave rise to the

field of genetics.• The chromosomal theory of inheritance

located Mendelian genes on chromosomes.

The Theory of Heredity: Unity of Life

• Charles Darwin’s theory of evolution explains the unity and diversity of life as “descent with modification”.

• Advances in genetics have helped scientists understand precisely how changes in genes can result in adaptation and evolution.

The Theory of Evolution: Diversityof Life

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