1 CHAPTER 1 BIOLOGY EXPLORING LIFE Introduction o Snowy owls exhibit adaptations for life in their frozen barren habit including feathers that provide insulation in subzero weather and keen vision and acute hearing that help owls locate prey o Snowy owls are the result of evolution the process that has transformed life from its earliest beginnings o THEMES IN THE STUDY OF BIOLOGY o BIG IDEAS I Themes in the Study of Biology II Evolution the Core Theme of Biology III The Process of Science I THEMES IN THE STUDY OF BIOLOGY 1 1 All forms of life share common properties o Biology is the scientific study of life o Properties of life include Order the highly ordered structure that typifies life Reproduction the ability of organisms to reproduce their own kind Growth and development consistent growth and development controlled by inherited DNA Energy processing the use of chemical energy to power an organism s activities and chemical reactions ex caterpillar use the energy stored in plant Regulation an ability to control an organism s internal environment within limits that sustain life ex lizard sunbathing to help raise its body temp Response to the environment an ability to respond to environmental stimuli ex venus trap closing in response to the stimulus Evolutionary adaptation adaptations evolve over many generations as individuals with traits best suited to their environments have greater reproductive success and pass their traits to offspring ex snowy owls sharp talons facilitate prey capture and its feathered feet keep it warm in its cold habitat Question how would you define life Answer Life can be defined by a set of common properties such as those described in this module 1 2 In life s hierarchy of organization new properties emerge at each level o Biological organization unfolds as follows Biosphere all of the environments on Earth that support life Include most regions of land bodies of water and the lower atm 2 Ecosystem all the organisms living in a particular area and the physical components with which the organisms interact such as air soil water and sunlight Community the entire array of organisms living in a particular ecosystem Alligators snakes herons egrets myriads and other SPCIES Population all the individuals of a species living in a specific area Organism an individual living thing Organ system several organs that cooperate in a specific function Organ a structure that is composed of tissues Tissue a group of similar cells that perform a specific function Organelle a membrane enclosed structure that performs a specific Cell the fundamental unit of life function within a cell such as the nucleus Molecule a cluster of small chemical units called atoms held together by chemical bonds o Emergent properties are new properties that arise in each step upward in the hierarchy of life from the arrangement and interactions among component parts Question Which of these levels of biological organization includes all others in the list Cell Molecule organ and tissue Answer organ 1 3 Cells are the structural and functional units of life o Cells are the level at which the properties of life emerge o A cell can regulate its internal environment take in and use energy respond to its environment develop and maintain its complex organization and give rise to new cells o All cells are enclosed by a membrane that regulates the passage of materials between the cell and its surroundings and use DNA as their genetic information They were the first to evolve are simpler and are usually smaller than o There are two basic forms of cells Prokaryotic cells eukaryotic cells No nucleus but have a DNA Ex bacteria Eukaryotic cells are found in plants animals fungi and protists are subdivided by membranes into various functional compartments or organelles including a nucleus that houses the DNA Evolved from prokaryotic cells 3 o Systems biology is the study of a biological system and the modeling of its dynamic behavior ranging from the functioning of the biosphere to the complex molecular machinery of an organelle o Cells illustrate another theme in biology the correlation of structure and function o Structure is related to function at all levels of biological organization Question Why are cells considered the basic unit of life Answer They are the lowest level in the hierarchy of biological organization at which the properties of life emerge 1 4 Organisms interact with their environment exchanging matter and energy o Living organisms interact with their environments which include other organisms as well as physical factors o In most ecosystems Decomposers Plants are the producers that provide the food Consumers chemicals that plants can absorb and use eat plants and other animals and Ex fungi and bacteria in the soil act as recyclers changing complex matter into simpler o The dynamics of ecosystems include two major processes the recycling of chemical nutrients from the atmosphere and soil through producers consumers and decomposers back to the air and soil and Some of chemical necessary for life CO2 O2 H2O and minerals the one way flow of energy through an ecosystem entering as sunlight and exiting as heat 1 Inflow of light energy from the sun Plants absorb light energy and convert it to chemical energy 4 2 These chemical energy such as glucose is passed through a series of consumers and eventually to decomposers 3 Energy is converted to heat Question Explain how the photosynthesis of plants functions in both the cycling of chemicals and the flow of energy in an ecosystem Answer photosynthesis uses light energy to convert CO2 and water to energy rich food making it the pathway by which both chemical and energy become available to most organisms II Evolution the Core Theme of Biology 1 5 The unity of life is based on DNA and a common genetic code All cells have DNA the chemical substance of genes Genes The unit of inheritance that transmit information from parents to offspring They are grouped into very long DNA molecules called chromosomes and control the activities of a cell Molecule structure of DNA DNA molecule is made up of 2 long strands coiled together into a double helix The strands are made up of 4 kinds of chemical building blocks called nucleotides The letters are A T C G The DNA of genes provides the blueprints for making proteins that serve as the tools that build and maintain the cell and its activity Protein serve as the tools that actually build and maintain the cell and