Chapter 1 Invitation to Biology

1. Chapter 1Invitation to Biology

2. 1.1The Secret Life of Earth • Biology • The scientific study of life • We have found only a fraction of the organisms on Earth • Scientists constantly discover new species • Extinction rates are accelerating • Example: New Guinea’s Foja Mountains

3. “Pinocchio Frog” Extinction is happening at 1000x faster than normal, thanks to us humans!

4. Life’s Levels of Organization • Atom • Fundamental building block of all matter • Molecule • An association of two or more atoms • Cell • Smallest unit of life • Organism • An individual; consists of one or more cells

5. Life’s Levels of Organization • Population • Group of individuals of a species in a given area • Community • All populations of all species in a given area • Ecosystem • A community interacting with its environment • Biosphere • All regions of Earth that hold life

6. ANIMATED FIGURE: Life’s levels of organization To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

7. What is Life?1.3 How Living Things Are Alike • Life is organized in successive levels with new properties emerging at each level. • All living things have similar characteristics • Require energy and nutrients • Sense and respond to change • Reproduce with the help of DNA

8. Organisms Require Enery and Nutrients • Energy • The capacity to do work • Nutrient • Substance that is necessary for survival, but that an organism can’t make for itself

9. Organisms and Energy Sources • Producers • Organisms that make their own food using energy and simple raw materials from the environment • Example:photosynthesis in plants • Consumers • Organisms that get energy and carbon by feeding on tissues, wastes, or remains of other organisms • Example: animals

10. ANIMATED FIGURE: One-way energy flow and materials cycling To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

11. Organisms Sense and Respond to Change • Homeostasis • Set of processes by which an organism keeps its internal conditions within tolerable ranges by sensing and responding to change

12. Organisms Grow and Reproduce • Organisms grow, develop, and reproduce based on information encoded in DNA, which they inherit from parents • Growth • Increase in size, volume, and number of cells in multicelled species • Development • Multistep process by which the first cell of a new individual becomes a multicelled adult

13. Organisms Grow and Reproduce • Reproduction • Process by which parents produce offspring • Inheritance • Transmission of DNA from parents to offspring • DNA (Deoxyribonucleic acid) • Carries hereditary information that guides development and functioning

14. 1.4 How Living Things Differ • Living things differ in observable characteristics, or traits ie. Biodiversity (Scope of variation among living organisms)

15. Classification Systems • Organisms can be grouped based on whether they have a nucleus • Nucleus • Sac with two membranes that encloses a cell’s DNA • One system sorts all organisms into one of three domains: Bacteria, Archaea, and Eukarya

16. Prokaryotes • Prokaryotes • Single celled organisms in which DNA is not contained in a nucleus. Examples include • Bacterium • Archaeon • More closely related to eukaryotes than to bacteria Collectively, the most diverse representatives of life!

17. Bacteria and Archaea A) Bacteria are the most numerous organisms on Earth. Left, a bacterium with a row of iron crystals that acts like a tiny compass; right, spiral cyanobacteria.

18. Bacteria and Archaea B) Archaea may resemble bacteria, but they are more closely related to eukaryotes. These are two types of archaea from a hydrothermal vent on the seafloor.

19. Eukaryotes • Eukaryotes • Organisms whose cells typically have a nucleus • These can be single or multi-celled and are usually larger, and more complex than prokaryotes • Examples include • Fungus • Eukaryotic consumer that obtains nutrients by digestion and absorption outside the body • Protists • Eukaryotes that are not plants, animals, or fungi

20. Eukaryotes • Examples continued… • Animals • Multi-celled consumer that develops through a series of embryonic stages and moves about during all or part of the life cycle • Plant • Typically a multi-celled, photosynthetic producer

21. Some Eukaryotes

22. 1.5 What is a “Species?” • Taxonomy is the science of naming and classifying species • A species is a unique kind of organism • A genus is a group of species that share unique traits • Every species is given a unique two-part scientific name consisting of its genus and species • Example: Lion: Panthera leo

23. Taxa • Each rank, or taxon is a group of organisms that share a unique set of traits • Morphological (structural) traits • Biochemical traits • Behavioral traits (response to stimuli) • Each taxon consists of a group of the next lower taxon • Species, genus, family, order, class, phylum, kingdom, and domain • “Dumb kids playing catch on freeways get smashed “

24. Taxonomic Classification domain kingdom phylum class order family genus species commonname Eukarya Eukarya Eukarya Eukarya Eukarya Plantae Plantae Plantae Plantae Plantae Magnoliophyta Magnoliophyta Magnoliophyta Magnoliophyta Magnoliophyta Magnoliopsida Magnoliopsida Magnoliopsida Magnoliopsida Magnoliopsida Apiales Rosales Rosales Rosales Rosales Apiaceae Cannabaceae Rosaceae Rosaceae Rosaceae Daucus Cannabis Malus Rosa Rosa carota sativa domestica acicularis canina wild carrot marijuana apple prickly rose dog rose

25. Identifying Species • How do we decide if similar-looking organisms belong to different species or not? • Early naturalists classified species according to what they looked like and where they lived • Today’s biologists compare biochemical traits such as DNA sequence

26. Four butterflies, two species

27. Biological Species Concept • “Biological species concept” • Ernst Mayr defined a species as one or more groups of individuals that potentially can interbreed, produce fertile offspring, and do not interbreed with other groups

28. ANIMATED FIGURE: Classification systems To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

29. The Scientific Method

30. The Scientific Method • Prediction • Statement, based on a hypothesis, about a condition that should exist if the hypothesis is correct • Model • Analogous system used for testing hypotheses • Experiment • Test designed to support or falsify a prediction

31. The Scientific Method • Variable • Characteristic that differs among individuals or over time • Experimental group • Group of individuals who are exposed to a variable • Control group • Group not exposed to the variable being tested. • Data • Factual information from experiments or surveys

32. Experiment: Potato Chips and Stomachaches

33. 1.7 Analyzing Experimental Results • Researchers experiment on subsets of a group, which may result in sampling error • Sampling error • Difference between results derived from testing an entire group of events or individuals, and results derived from testing a subset of the group

34. Sampling Error A) Natalie, blindfolded, randomly plucks a jelly bean from a jar. The jar contains 120 green and 280 black jelly beans, so 30 percent of the jelly beans in the jar are green, and 70 percent are black.

35. Sampling Error B) The jar is hidden from Natalie’s view before she removes her blindfold. She sees one green jelly bean in her hand and assumes that the jar must hold only green jelly beans.

36. Sampling Error C) Still blindfolded, Natalie randomly picks out 50 jelly beans from the jar. She ends up picking out 10 green and 40 black ones.

37. Sampling Error D) The larger sample leads Natalie to assume that one-fifth of the jar’s jelly beans are green (20 percent) and four-fifths are black (80 percent). This sample more closely approximates the jar’s actual green-to-black ratio of 30 percent to 70 percent. The more times Natalie repeats the sampling, the greater the chance she has of guessing the actual ratio.

38. Probability • Researchers try to design experiments carefully in order to minimize sampling error • Probability • The measure, expressed as a percentage, of the chance that a particular outcome will occur • Statistically significant • Refers to a result that is statistically unlikely to have occurred by chance

39. Bias in Interpreting Results • Researchers risk interpreting their results in terms of what they want to find out (bias) • Science is a self-correcting process because scientists continuously retest and recheck each other’s ideas

40. ANIMATION: Height Graph To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

41. 1.8 The Nature of Science • Scientific theory • Hypothesis that has not been disproven after many years of rigorous testing • Can never be proven absolutely • Can be disproven by a single observation or result that is inconsistent with it

42. Law of Nature • A scientific theory differs from a law of nature • Law of nature • Generalization that describes a consistent natural phenomenon for which there is incomplete scientific explanation • Example: Laws of thermodynamics

43. 1.9 The Secret Life of Earth (revisited) • Earth hosts at least 100 million species • Recently discovered species include a leopard in Borneo; a wolf in Egypt; a dolphin in Australia; and spiders in California • You can find information about the 1.8 million species we know about in the Encyclopedia of Life (www.eol.org)

44. A new species of trapdoor spider