Biology: Exploring Life Chapter 1 Biology: Exploring Life

A Big-Billed Bird Rebounds Some core themes underlie all of biology: evolution, cells as the fundamental unit of life, a nearly universal genetic code, the relation of structure and function The brown pelican is an example of the connection between organisms and their environment

1.1 Life’s levels of organization define the scope of biology These levels represent a hierarchy Starting with the biosphere, each level is less inclusive than the one below it

Biosphere: all the environments of Earth that support life Ecosystem: All the living and nonliving components of a particular environment Community: All the living organisms in an ecosystem Population: an interacting group of individuals of one species Organism: An individual living entity

The hierarchy continues downward with Organ systems Organs Tissues Cells Organelles Molecules Atoms

Biosphere Ecosystem Florida coast Community All organisms on the Florida coast Population Group of brown pelicans Organism Brown pelican Organ system Nervous system Organ Brain Spinal cord Nerve Tissue Nervous tissue Nucleus Cell Nerve cell Organelle Molecule DNA Atom

1.2 Living organisms and their environments form interconnecting webs Producers-photosynthetic organisms-use energy from the sun to produce food Consumers are ultimately dependent on producers for food Decomposers break down dead organic material, which is recycled

The dynamics of an ecosystem include two major processes: The cycling of chemical nutrients The one-way flow of energy, entering as sunlight and leaving as heat

LE 1-2 Inflow of light Loss energy of heat energy Chemical energy Sun Air Inflow of light energy Loss of heat energy O2 CO2 CO2 Chemical energy Cycling of chemical nutrients Consumers Producers Decomposers H2O Soil Ecosystem

1.3 Cells are the structural and functional units of life Cells perform all functions necessary for life Regulate their internal environment Take in and use energy Respond to the local environment Develop and maintain their complex organization Divide to form new cells

Theme of emergent property "The whole is greater than the sum of its parts" The combination of the parts that form a more complex organization is called a system

Two basic types of cells: prokaryotes and eukaryotes Prokaryotes are smaller and less complex than eukaryotes and lack a nucleus and other organelles Eukaryotes are generally larger and more complex and contain a nucleus and other organelles

LE 1-3 Nucleus (contains DNA) Eukaryotic cell Prokaryotic cell DNA (no nucleus) Organelles 25,000 

EVOLUTION, UNITY, AND DIVERSITY 1.4 The unity of life: All forms of life have common features Genetic information within all cells is coded in DNA molecules Each DNA molecule is made up of chains of four chemical "building blocks"

Other common properties of organisms: Order Regulation Growth and development Energy use Response to the environment Reproduction Evolution

1.5 The diversity of life can be arranged into three domains Scientists have identified about 1.8 million species-particular types of organisms Taxonomy classifies species into a hierarchy of increasingly broad groups

Three domains are the most overarching groups: Domain Bacteria, unicellular prokaryotes (cells that lack a nucleus) Domain Archaea, unicellular prokaryotes Domain Eukarya, unicellular and multicellular eukaryotes (cells with a nucleus), including protists, plants, animals, and fungi

LE 1-5c Kingdom Fungi Kingdom Animalia Protists (multiple kingdoms) 275 Kingdom Animalia Protists (multiple kingdoms) Kingdom Plantae

1.6 Evolution explains the unity and diversity of life Charles Darwin proposed the theory of evolution by natural selection Species evolved from ancestors through "descent with modification" Natural selection occurs as heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others The product of natural selection is adaptation

Population with varied inherited traits LE 1-6b Population with varied inherited traits Elimination of individuals with certain traits Reproduction of survivors

1.7 Scientists use two main approaches to learn about nature THE PROCESS OF SCIENCE 1.7 Scientists use two main approaches to learn about nature Discovery science Primarily describes nature through verifiable observations and measurements Hypothesis-driven science Attempts to explain nature by studying questions drawn from observations made during "discovery science" Hypothesis: a tentative answer to a problem or question that is being asked

1.8 With hypothesis-based science, we pose and test hypotheses Hypothesis-based science applies the five steps of the scientific method: (1) Observations from others or results of earlier tests (2) Questions about unclear aspects of the observations: How? Why? When?

(3) Hypotheses or tentative explanations of a phenomenon Must be testable Must be falsifiable (4) Predictions developed by the use of deductive reasoning (if...then) (5) Tests of predictions to determine if the predictions are supported or falsified.

A Case Study from Everyday Life Following the scientific method to discover why a flashlight doesn't work Using deductive reasoning to test alternative hypotheses If a hypothesis is correct, and we test it, then we can expect a particular outcome

Observations Question LE 1-8a-1 Observations Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb

LE 1-8a-2 Observations Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem

Test falsifies hypothesis Test does not falsify hypothesis LE 1-8a-3 Observations Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis

A Case Study of Hypothesis-Based Science Following the scientific method to test an hypothesis about the function of biological mimicry Predict that mimicry should protect coral snakes in the areas where king snakes live Develop a controlled experiment using artificial snakes Summarize results confirming prediction in a graph

Percent of total attacks LE 1-8e 100 Artificial king snakes 83% 84% 80 Artificial brown snakes 60 Percent of total attacks on artificial snakes 40 20 17% 16% Coral snakes absent Coral snakes present

BIOLOGY AND EVERYDAY LIFE CONNECTION 1.9 Biology is connected to our lives in many ways Technology applies scientific knowledge for a specific purpose Biology and technology affect our everyday lives Environmental problems and solutions Genetic engineering Medicine