Biology: Exploring Life Chapter 1 Biology: Exploring Life

A Big-Billed Bird Rebounds A Big-Billed Bird Rebounds Brown pelicans Are part of the web of life in their environment

The brown pelicans’ proximity to humans Has meant trouble for the species The brown pelicans’ connection to the environment Sets the stage for the study of biology

THE SCOPE OF BIOLOGY 1.1 Life’s levels of organization define the scope of biology Life’s structural hierarchy Defines the scope of biology, the scientific study of life Biosphere Ecosystem Florida coast Community All organisms on the Florida coast Population Group of brown pelicans Organism Brown pelican Spinal cord Organ system Nervous system Brain Organ Brain Nerve Tissue Nervous tissue Figure 1.1 Cell Nerve cell Nucleus Atom Organelle Nucleus Molecule DNA

An ecosystem consists of all the organisms living in a par ticular area As well as the nonliving environmental components All the living organisms in an ecosystem Make up a community

A population Consists of a localized group of individuals of a species An individual living entity Is an organism

Life is organized in a hierarchical fashion. Life is organized in a hierarchical fashion. Molecule Cell Tissue Organ Organ system Organism Population Community Ecosystem

1.2 Living organisms and their environments form interconnecting webs 1.2 Living organisms and their environments form interconnecting webs Ecosystems are characterized by the cycling of chemical nutrients from the atmosphere and soil to producers to consumers to decomposers and back to the environment. Organisms exchange chemical nutrients that results in a change of energy. Ex. A consumer eating a producer represents a transfer of chemical nutrients and energy.

Energy flows one-way through an ecosystem Energy flows one-way through an ecosystem From the sun (the ultimate source of energy in an ecosystem) to producers to consumers and exits as heat Sun Air Inflow of light energy Loss of heat energy O2 CO2 CO2 Chemical energy Cycling of Chemical nutrients Producers Consumers Decomposers H2O Figure 1.2 Soil Ecosystem

1.3 Cells are the structural and functional units of life 1.3 Cells are the structural and functional units of life A cell is the basic unit of life Characteristics of cells: Cells respond to the environment.   Cells develop and maintain complex organization.   Cells take in and use energy.   Cells regulate their internal environment.  

New proper ties emerge from the complex organization of a system, such as a cell. The formation of systems typically results in the appearance of novel characteristics called emergent properties.

Lack membrane-enclosed organelles and a nucleus, but do have DNA Eukaryotic cells Contain membrane-enclosed organelles, including a DNA-containing nucleus Prokaryotic cells Lack membrane-enclosed organelles and a nucleus, but do have DNA Nucleus (contains DNA) Prokar yotic cell Eukar yotic cell DNA (no nucleus) Organelles Figure 1.3 25,000 

EVOLUTION, UNITY, AND DIVERSITY 1.4 The unity of life: All forms of life have common features DNA is the genetic information for constructing the molecules that make up cells and organisms Differences among organisms reflect different nucleotide sequences in their DNA.

Each species’ genetic instructions Each species’ genetic instructions Are coded in the sequences of the four building blocks making up DNA’s two helically coiled chains A C T A T A C C G T A G T A Figure 1.4A

All organisms share a common set of features: Complex organization All organisms share a common set of features: Complex organization Regulation of internal conditions (homeostasis) Figure 1.4B Figure 1.4C

Growth and development The ability to take in energy and use it Growth and development The ability to take in energy and use it   Response to environmental stimuli The ability to reproduce and evolve Figure 1.4D Figure 1.4E

1.5 The diversity of life can be arranged into three domains 1.5 The diversity of life can be arranged into three domains Organisms are classified into the prokaryotic domains Bacteria and Archaea and the eukaryotic domain Eukarya

Domains Bacteria and Archaea Domains Bacteria and Archaea All lack a nucleus and membrane bound organelles. SEM 3,250 Figure 1.5A SEM 25,000 Figure 1.5B

Domain Eukarya includes Protists-unicellular Domain Eukarya includes Protists-unicellular The kingdoms Fungi, Plantae, and Animalia are all multicellular Fungi-heterotrophic absorb food Plantae-autotrophic, cell wall made of cellulose Animalia-heterotrophic, no cell wall made of

1.6 Evolution explains the unity and diversity of life 1.6 Evolution explains the unity and diversity of life Charles Dar win synthesized the theory of evolution by natural selection. Evolution is a passive process Figure 1.6A

Darwin’s Mechanism of Natural Selection Individuals in a population exhibit variations, some of which are heritable.   Factors in the environment result in some organisms with better reproductive success than others. Natural selection is based in part on the overproduction of offspring. Natural selection can lead to the appearance of new species.  

Natural selection is an editing mechanism that occurs when populations or organisms, having inherited variations, are exposed to environmental factors that favor the reproductive success of some individuals over others 1 Populations with varied inherited traits 2 Elimination of individuals with certain traits Figure 1.6B 3 Reproduction of survivors

Evolution by natural selection relies upon: Heritable variation. All organisms have adaptations that have evolved by means of natural selection Evolution by natural selection relies upon: Heritable variation.   Overproduction of offspring. Struggle for existence.   Individual variation. Figure 1.6C

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 Science Is a way of knowing Seeks natural causes for natural phenomena

Discovery Science In discovery science Discovery Science In discovery science Scientists describe some aspect of the world and use inductive reasoning to draw general conclusions

Inductive reasoning is making a conclusion based on a set of data. Deductive reasoning starts with a general rule, then from that rule, we make a conclusion about something specific. Example: If all vertebrates have backbones, and turtles are vertebrates, then turtles have backbones. Inductive reasoning is making a conclusion based on a set of data. Example: All sheep that I've seen are white. All sheep must be white

Hypothesis-Based Science Hypothesis-Based Science In hypothesis-based science Scientists attempt to explain obser vations by testing hypotheses (a tentative answer to some question)

1.8 With hypothesis-based science, we pose and test hypotheses 1.8 With hypothesis-based science, we pose and test hypotheses To be scientifically valid, a hypothesis must be testable and falsifiable. Hypothesis-based science involves: Obser vations, questions, hypotheses as tentative answers to questions Deductions leading to predictions, and then tests of predictions to see if a hypothesis is falsifiable

A Case Study from Ever yday Life A Case Study from Ever yday Life Deductive reasoning is used in testing hypotheses as follows If a hypothesis is correct, and we test it, then we can expect a par ticular outcome 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 Figure 1.8A Test falsifies hypothesis Test does not falsify hypothesis

Percent of total attacks A Case Study of Hypothesis-Based Science In experiments designed to test hypotheses The use of control groups and experimental groups helps to control variables The role of a control in an experiment is to provide a basis of comparison to the experimental group. 100 Artificial king snakes 83% 84% 80 Artificial brown snakes 60 Percent of total attacks on artificial snakes Figure 1.8B Figure 1.8C 40 20 17% 16% Coral snakes absent Coral snakes present Figure 1.8E Figure 1.8D

BIOLOGY AND EVERYDAY LIFE CONNECTION 1.9 Biology is connected to our lives in many ways

Biology is connected to many impor tant issues in our lives Biology is connected to many impor tant issues in our lives Environmental problems and solutions Genetic engineering Medicine Figure 1.9

Many technological advances stem from scientific research The science-technology-society relationship is an impor tant aspect of a biology course Science-goal is to understand natural phenomena; “discoveries” Technology-goal is to apply scientific knowledge for some specific purpose; “inventions”