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The Science of Biology

Chapter 1

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Definition of Life

Living organisms:

are composed of cells

are complex and ordered

respond to their environment stimuli - sensitivity can grow and reproduce

are able to obtain and use energy

maintain internal balance - homeostasis allow for evolutionary adaptation

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Living things show hierarchical

organization

Cellular level: Atoms Molecule Macromolecule Organelle Cell

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Tissuegroups of similar cells that acts as functional unit.

Organseveral different tissues that act as a structural and functional unit

Organ systema group of related organs, such as nerve system

Organismal Level: Cell Tissue Organ Organ System Organism

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Populationa group of organisms of the same species living in the same place.

Speciesall population of particular kind of organism

Communityall populations of different species living together in one place

Ecosystema biological community and its physical habitat

Populational Level: Organism Population Species Community

Ecosystem Biosphere

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The Nature of Science

Much of science is descriptive throughobservation

The study of biodiversity

Science uses both deductive and inductivereasoning. Deductive reasoninguses general principles to make

specific predictions.

Inductive reasoninguses specific observations to

develop general conclusions.

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How Science Is Done

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An Example of Scientific Inquiry:

Darwin and Evolution

Were species created and unchangeable

overtime?

Darwin studied a wide variety of plants and

animals around coastal South America and

observed differences in related organisms

Used many observations to develop his ideas.

Proposed that evolution occurred by naturalselection.

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Voyage of the Beagle

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Natural Selection- Individuals with superior

physical or behavioral characteristics are more

likely to survive and reproduce than those

without such characteristicsArtificial selectionaccording to humans will

Evolution- modification of a species over

generations

-descent with modification

Natural Selection and Evolution

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Darwins Evidence for Natural Selection

Why finches have different beaks?- food availability

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The predictions of natural selection have

been tested

Fossil record shows intermediated links between

the groups of organisms. For example, between

fishes and the amphibian, reptiles and birds

The age of earthusing evidence obtained by

studying the rate of radioactive decay, we now

know that earth was formed about 4.5 BYA.

The mechanism of heredity help understandDarwins theory

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Comparative anatomy have provide evidence for

Darwins theory

- Homologous structureshave same evolutionary origin,but different structure and function.

-Analogous structureshave similar structure and

function, but different evolutionary origin. (example:

wings of butter flies and birds)

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Molecular Evidence

- Study of DNA and protein structures has led to thedevelopment of more accurate phylogenetic trees.

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Unifying Themes in Biology

Cell theory describes the organization of livingsystem

All living organisms are made of cells, and all living cells

come from preexisting cells.

Two types of cells: prokaryotic and Eukaryotic cells

Molecular basis of inheritance explains the

continuity of life

DNA encodes genes which control living organisms and

are passed from one generation to the next.

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Function of molecules and cells is depends

on structure.

Cells surface receptor for insulin in human and

other animals has the similar molecular structure

The diversity of life arises by evolutionary

changes. Organisms can be classified into three domains:

Eukaryainclude four kingdoms: Plantea, Fungi,

Animalia, and protista, which have complex cellular

structure

Archaeaprokaryotes living in extreme environment

Bacteria - prokaryotes

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Evolutionary conservation explains the unity

of living system

The storage of hereditary information in DNA iscommon to all organisms

Cells are information-processing systemsDNA used for to direct synthesis of cellular

components

Living systems exist in a nonequilibrium

state

Constant supply and uses of energy