Hnrs Biology CH 1- What is Life? 1

1.1 How to Define Life Biology is the scientific study of life. There is great diversity among living things. Living things:  are composed of the same chemical elements as nonliving things.  obey the same physical and chemical laws that govern everything in the universe. 2

Diversity of Life 3 Despite diversity, all living things share the same basic characteristics.

Characteristics of Life 1. Living things are organized. The levels of biological organization range from atoms to the biosphere. The cell is the basic unit of structure and function of all living things. As biological complexity increases, each level acquires new emergent properties. 4

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Biosphere Regions of the Earth’s crust, waters, and atmosphere inhabited by living things Ecosystem A community plus the physical environment Community Interacting populations in a particular area Population Organisms of the same species in a particular area Organism An individual; complex individuals contain organ systems Organ System Composed of several organs working together Organ Composed of tissues functioning together for a specific task Tissue A group of cells with a common structure and function Cell The structural and functional unit of all living things Molecule Union of two or more atoms of the same or different elements Atom Smallest unit of an element composed of electrons, protons, and neutrons oxygen methane plant cell epidermal tissue nerve cell nervous tissue leaves the brain shoot system nervous system treeelephant

Characteristics of Life 2. Living things acquire materials and energy.  Energy is required to maintain organization and conduct chemical reactions.  The sun is the ultimate source of energy for most life on Earth. 6

Characteristics of Life 3. Living things maintain homeostasis.  Feedback systems monitor internal conditions and make adjustments. 7

Characteristics of Life 8 4. Living things respond to stimuli.

Characteristics of Life 5. Living things reproduce and develop. Pass on copies of their genetic information (genes) to offspring  Genes determine the characteristics of an organism.  Genes are composed of DNA (deoxyribonucleic acid). 9

Characteristics of Life 6. Living things have adaptations. An adaptation is any modification that makes an organism better able to function in its environment. Diversity exists when organisms develope new adaptations in response to changing environments Evolution is the change in a population over time to become more suited to the environment. 10

1.2 Evolution, the Unifying Concept of Biology The theory of evolution explains the diversity and unity of life.  The theory of evolution explains how all living things descended from a common ancestor.  Common descent with modification 11

Evolutionary Tree of Life 12 An evolutionary tree traces the ancestry of life on Earth to a common ancestor.

Organizing Diversity Taxonomy- identifies, names, and classifies organisms. Systematics- study of evolutionary relationships between organisms. Classification categories (least inclusive- most inclusive) Species, genus, family, order, class, phylum, kingdom, and domain 13

Levels of Classification

Domains Domain Bacteria  unicellular prokaryotes  live in all environments Domain Eukarya  Unicellular & multicellular  Have membrane-bound nucleus. 15

Domain Archaea 16 Methanosarcina mazei, an archaean 1.6 m Adaptations to extreme environments Absorb or chemosynthesize food Unicellular

Domain Bacteria 17 Prokaryotic cell Adaptations to all environments Absorb, photosynthesize, or chemosynthesize food Escherichia coli, a bacterium1.5m

Fig. 1.8 Passiflora, passion flower, a flowering plant Domain Eukarya: Protists Algae, protozoans, slime molds, and water molds Complex single cell (sometimes filaments, colonies, or even multicellular) Absorb, photosynthesize, or ingest food Paramecium, a unicellular protozoan 1 µm Domain Eukarya: Kingdom Fungi Molds, mushrooms, yeasts, and ringworms Mostly multicellular filaments with specialized, complex cells Absorb food Amanita, a mushroom Domain Eukarya: Kingdom Plantae Certain algae, mosses, ferns, conifers, and flowering plants Multicellular, usually with specialized tissues, containing complex cells Domain Eukarya: Kingdom Animalia Sponges, worms, insects, fishes, frogs, turtles, birds, and mammals Multicellular with specialized tissues containing complex cells Ingest food Vulpes, a red fox Photosynthe size food a: © Michael Abby/Visuals Unlimited; b: © Pat Pendarvis; c: © Tinke Hamming/Ingram Publishing RF; d: © Corbis RF Domain Eukarya

Scientific Names Universal Latin-based Binomial nomenclature  Carolus Linneaus  Italicized, two-part name  First word: genus, second word: species Ex: Homo sapiens (humans), Zea mays (corn) 19

20 Natural Selection Mechanism of evolutionary proposed by Charles Darwin Individuals w/ favorable traits produce the greater numbers of offspring that survive & reproduce.  Increases the frequency of those traits in population Mutations fuel natural selection.

Some plants within a population exhibit variation in leaf structure. Deer prefer a diet of smooth leaves over hairy leaves. Plants with hairy leaves reproduce more than other plants in the population. Generations later, most plants within the population have hairy leaves, as smooth leaves are selected against. Example:

1.3 How the Biosphere Is Organized Biosphere- zone of air, land, and water where organisms exist. Population- all members of a species in an area. Community- collection of interacting populations within an environment. Ecosystem- community plus its physical environment. 22

Ecosystems Ecosystems are characterized by chemical cycling and energy flow. Energy from the sun flows through plants to other members of the food chain as one population feeds on another. 23

The Human Population Ecosystems have been negatively impacted by human populations. Destruction of:  forest or grassland for agriculture, housing, industry  coastal wetlands by waste and other pollutants Humans depend upon healthy ecosystems for:  Food  Medicines  Raw materials 24

The Effect of Human Activities on Coral Reefs Minimal coral deathb. a. Healthy coral reef 1985 Some coral death With no fish present 1995 Coral bleaching with limited chance of recovery 2004 Coral is black from sedimentation; bleaching still evident

Biodiversity Biodiversity is the total number and relative abundance of species, the variability of their genes, and the ecosystems in which they live.  Estimated to be as high as 15 million species Less than 2 million have been named and identified Extinction is the death of the last member of a species or larger classification category.  Estimates of 400 species/day lost due to human activities 26

1.4 The Process of Science Scientific method- standard series of steps used in gaining new knowledge through research. Observation Hypothesis Experiments and Data Collection Conclusion 27

The Scientific Method 1. Observation Scientists use senses to gather information about a phenomenon or natural event. 2. Hypothesis A tentative explanation for observation Developed through inductive reasoning Testable 28

The Scientific Method 3. Experiments and Data Collection Experiment- series of procedures designed to test a hypothesis.  Utilizes deductive reasoning to make a prediction or expected outcome A good experimental design ensures that the experimental (independent) variable is the factor being tested 29

The Scientific Method 3. Experiments and Data Collection (cont’d) Test group- exposed to the experimental variable. Control group- goes through all aspects of the experiment but is not exposed to the experimental variable. The data are the observable and objective results of an experiment. 30

The Scientific Method 4. Conclusion The data are analyzed and interpreted to determine whether the hypothesis is supported or not.  If prediction happens, hypothesis is supported.  If not, hypothesis is rejected. Findings are reported in scientific journals Peers review the findings Other scientists then attempt to duplicate or dismiss the published findings 31

Observation New observations are made, and previous data are studied. Hypothesis Input from various sources is used to formulate a testable statement. Conclusion The results are analyzed, and the hypothesis is supported or rejected. Scientific Theory Many experiments and observations support a theory. Experiment/Observations The hypothesis is tested by experiment or further observations. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Courtesy Leica Microsystems Inc.

Scientific Theory Scientific Theory: a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method, repeatedly tested and confirmed through observation and experimentation Scientific Principle / Law: a statement based on repeated experimental observations that describes some aspects of the universe  do not give a mechanism or explanation of phenomena 33

34 Basic Theories of Biology

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. = Pigeon pea/winter wheat rotation year 1year 2year 3 = no fertilization treatment = 45 kg of nitrogen/ha Control Pots Test Pots = 90 kg of nitrogen/ha Wheat Biomass (grams/pot) b. Results a. Control pots and test pots of three types Test pots 90 kg of nitrogen/ha Test pots Pigeon pea/winter wheat rotation Control pots no fertilization treatment Test pots 45 kg of nitrogen/ha (All): Courtesy Jim Bidlack Using the Scientific Method: Pigeon Pea/Winter Wheat Rotation Study

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Scientist making observations b. Normal mountain bluebird nesting behavior c. Resident male attacking a male model near nest resident male female mate male bluebird model d. Observation of two experimental nests provided data for graph Approaches per Minute nest construction first egg laid hatching of eggs Stage of Nesting Cycle Approaches to male model Approaches to female mate nest 2 nest 1 © Erica S. Leeds Using the Scientific Method: A Field Study