The lives of gray-headed flying foxes are closely entwined with the lives of the eucalyptus trees that form their habitat –Eucalyptus trees provide food and roosting sites for the flying foxes –Flying foxes aid in eucalyptus pollination and help disperse the resulting seeds

Flying foxes are becoming an endangered species, partly because of habitat destruction

Biology is the scientific study of life Interactions between different kinds of organisms affect the lives of all –Recall the example of flying foxes and eucalyptus trees

ECOSYSTEM LEVEL Eucalyptus forest COMMUNITY LEVEL All organisms in eucalyptus forest POPULATION LEVEL Group of flying foxes ORGANISM LEVEL Flying fox ORGAN SYSTEM LEVEL Nervous system ORGAN LEVEL Brain Brain Spinal cord Nerve TISSUE LEVEL Nervous tissue CELLULAR LEVEL Nerve cell MOLECULAR LEVEL Molecule of DNA At the top of life’s hierarchy is the ecosystem ECOSYSTEM LEVEL Eucalyptus forest COMMUNITY LEVEL All organisms in eucalyptus forest POPULATION LEVEL Group of flying foxes ORGANISM LEVEL Flying fox ORGAN SYSTEM LEVEL Nervous system ORGAN LEVEL Brain Brain Spinal cord Nerve TISSUE LEVEL Nervous tissue CELLULAR LEVEL Nerve cell Figure 1.1 Ecosystems include: –all the organisms in an area, which make up a community –interbreeding organisms of the same species, a population

A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology An ecosystem consists of: –all organisms living in a particular area –all nonliving physical components of the environment that affect the organisms (soil, water)

The theory of natural selection applies to all levels in life’s hierarchy In an ecosystem, these interactions make up a complex web of relationships –The functional aspects of an ecosystem come from the structure of the ecosystem’s web

A web of interactions in a rain forest ecosystem

Plants, or plant products, are the ultimate sources of food in an ecosystem –This African sunbird is consuming nectar, a plant product

–Energy flows in and out constantly Figure 1.7C Sun Inflow of light energy AirChemical energy Cycling of chemical nutrients Organisms Soil ECOSYSTEM Chemical nutrients cycle within an ecosystem’s web

Biology is connected to a great number of important issues –Environmental problems and solutions –Genetic engineering –Medicine Figure 1.8A

Evaluating everyday reports in the press about a large range of subjects requires critical thinking and some familiarity with many areas of biology –In order to understand how rain forest destruction impacts global climate, it is important to understand biology from the molecular to the ecosystem level Many technological advances stem from the scientific study of life

Grouping organisms by fundamental features helps make the vast diversity of life manageable for study Scientists classify organisms into a hierarchy of broader and broader groups

Figure 1.4A, B Most classification schemes group organisms into three domains: –Domain Bacteria Domain Archaea

Domain Eukarya

All organisms share a set of common features, signs of unity in life’s vast diversity –All are made of cells –All have DNA as their genetic blueprint These orchids show the variety possible within one species

DNA is made of chemical units called nucleotides Each species has its own nucleotide sequence

The genetic information in DNA underlies all of the features that distinguish life from nonlife –Order and regulation –Growth and development –Use of energy from the environment –Response to environmental stimuli –Ability to reproduce –Evolutionary change

Charles Darwin is a central figure in biology He synthesized the theory of evolution by natural selection –A theory in science is a comprehensive idea with broad explanatory power Evolution is the core theme of biology

The theory of natural selection explains the main mechanism whereby all species of organisms change, or evolve

Evolution happens when populations of organisms with inherited variations are exposed to environmental factors that favor the success of some individuals over others –Natural selection is the editing mechanism –Evolution is based on adaptations

Chapter 1 Vocabulary Adaptation Biology Development Energy Environment Evolution Growth Homeostasis Organism Organization Reproduction Response Species Stimulus