Chp 1 Biology: Exploring Life 1.10 Biology, Technology, & Society are Connected What current Biology-related news topics have you read/heard about? 1
1.1 All Life Forms Share Common Properties What common property of life does each picture display? Sunflower, Macaques, tadpole, hummingbird feeding, dragonfly on Venus flytrap, Jackrabbit s ears, Ptarmigan coloration 2
1.2 In Life s Hierarchy of Organization, New Properties Emerge at Each Level Biology is the study of (at any of its many levels of organization) 18th Century illustration of the bizarre world of microorganisms 3
Biosphere Biosphere Ecosystem Florida coast Community Organism Community All organisms on the Florida coast Biology s Levels of Organization Population Group of brown pelicans Organism Brown pelican 4
Organ system Spinal cord Organism Brown pelican Organ system Nervous system Organ Tissue Nerve Brain Organ Brain Cell Tissue Nervous tissue Atom Atom Cell Nerve cell Nucleus Organelle Nucleus Molecule DNA 5
The upper tier is a global perspective of life - all the environments on Earth that support life - all the organisms and the physical factors of a particular area - all of the organisms living in a particular ecosystem - all the individuals of a particular species within a specific area 6
The middle tier is characterized by the organism, an individual living thing, which is composed of - have specific functions; are composed of multiple organs - provide specific functions for the organism; composed of multiple - composed of groups of similar cells 7
Life emerges at the level of the cell, the lower tier, which is composed of - living entities distinguished from their environment by a membrane; fundamental unit of life - membrane-bound structures within a cell that has specific functions - clusters of atoms bonded together 8
1.3 Cells are the Smallest Units of Life Two distinct types of cells exist on our planet Prokaryotic cells Simple and small Bacteria are examples of cells Eukaryotic cells Possess organelles surrounded by a Plants, animals, and fungi are composed of cells 9
Prokaryotic cell DNA (no nucleus) Eukaryotic cell Membrane Nucleus (contains DNA) Organelles 10
EVOLUTION IS THE CORE THEME IN BIOLOGY 1.6 Diversity of Life is Arranged into 3 Domains The 3 (categories) of life Bacteria prokaryotic, and most are unicellular and microscopic Archaea like bacteria, are, and most are unicellular and microscopic Eukarya are and contain a nucleus and organelles 11
Domain Bacteria Domain Eukarya Bacteria (multiple kingdoms) Protists (multiple kingdoms) Kingdom Plantae Domain Archaea Archaea (multiple kingdoms) Kingdom Fungi Kingdom Animalia 12
Tree of life: Based on analyzing chemical components of organisms Earliest living cells were, then multicellular organisms evolved 13
1.7 Evolution Explains Unity & Diversity of Life In 1859, published On the Origin of Species by Means of Natural Selection The book accomplished two things Presented evidence to support the idea of evolution Proposed a mechanism for evolution called Charles Darwin (1809-1882) 14
Natural selection is an editing process Individuals within a have inherited variations Population exposed to outside factors that favor reproductive success of some individuals over others Over time, this results in a change in the = biological evolution (1) Population with varied inherited traits (2) Elimination of individuals with certain traits (3) Reproduction of survivors Figure 1.6B Natural selection 15
Evolution = descent with modification History of life resembles a multi-branched tree of tree are current living species, twigs and limbs are lines of descent, branches are Living species are descendants of ancestral species 16
THE PROCESS OF SCIENCE 1.8 Scientific Inquiry Asks and Answers Questions About Nature 2 approaches to understand natural causes for natural events Inductive reasoning- draw general conclusions from many observations reasoningcome up with ways to test a hypothesis and see if results support the hypothesis Science: A method of inquiry 17
In Science, Hypothesis & Theory are Different Hypothesis - a proposed explanation for a set of observations Theory - an explanatory idea that is 1) in scope 2) Supported by a large body of and 3) Widely What is an example of a hypothesis, and a theory Science seeks natural causes for natural events Limits scope to those structures/processes that Can be and 18
1.9 Scientists Form and Test Hypotheses Case study Flashlight failure Observations A that has been tested and not falsified is tentatively accepted Hypothesis # 1: Dead batteries Prediction: Replacing batteries will fix problem Question Hypothesis # 2: Burnt-out bulb Prediction: Replacing bulb will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis Figure 1.8A The hypothesis-based scientific method 19
Scientists Conduct Controlled Experiments Each factor that might influence a process is a variable To evaluate hypotheses about one variable, all other variables must be kept constant The experimental group has one variable altered. In the group, that variable is not altered All other aspects the two groups are identical Controls are used to make the results of an meaningful 20
Case study: Spider mimicry What is the hypothesis? Zebra spider and snowberry fly. Pounce rate (% of trials in which spider jumped on fly) What do these results tell you about the hypothesis? Control group (untreated flies) Experimental group (wing markings masked) 21
Objective Checklist! Name the common properties of all life! Describe life s hierarchy of organization! Describe the two types of cells and name some of their structural features! Explain the theory of evolution by natural selection and how current species are descendants of ancestral species! Describe the process of hypothesis-based science! Describe the difference between a hypothesis and a theory 22