Chapter 1

1. Chapter 1 The Science of Biology

2. What is Science? • Science-an organized way of using evidence to learn about the natural world. • Goals of science: • Investigate & understand the natural world. • Explain events in the natural world. • Make predictions.

3. Why science works: • Only deals w/ the natural world. • Scientists collect & organize info in a careful, orderly way. • Scientists look for patterns & connections b/t events. • Scientists explanations can be tested!

4. Thinking Like a Scientist: • To think like a scientist you must do a few things: • Observe • Collect data • Make an inference

5. Observations use senses to get info. • Info is called data. • Data can be quantitative or qualitative. • Quantitative -counted or measured. • Example: there are 12 inches in a foot. • Qualitative -can’t be counted. • Example: “the scar on a manatee looks old”

6. Once scientists have data, they make inferences. • Inference –a logical interpretation based on prior knowledge or experience. • Example: • You observe smoke coming from a building. • You infer that “where there is smoke there is fire”.

7. Explaining & Interpreting Evidence: • Example: • Many people contract an unknown disease after attending a public concert. • Public health officials will likely use the scientific method to try & solve why this happened.

8. After making observations scientists will propose 1 or more hypothesis. • Hypothesis –a proposed scientific explanation for a set of observations. • It uses prior knowledge • Logical inferences • A creative imagination

9. Possible hypothesis’ could be that: • The disease spread from person to person via contact. • It spread by insect bites. • Or, it spread through air, food, or water.

10. A hypothesis must be able to be tested. • Hypothesis can be tested by: • Controlled experiments or • Gathering more data

11. Science as a way of Knowing: • Science is always changing. • New tools, techniques, & discoveries lead to new understandings. • Good scientists are skeptics: • You question everything? • You must be open minded. • Be open to new ideas & hypothesis.

12. Science & Human Values: • Science is in many of the questions of today. • How should chemical wastes be disposed of? • Who should be responsible for their disposal? • Should our electricity come from nuclear or hydroelectric? • Should the info in your genes be kept private?

13. All of these question involve science in a way. • But, science can’t answer them. • Science makes recommendations. • Society has the final decision. • We consider our laws & moral principles, then we make a decision.

14. Section 2 How Scientists Work

15. Designing an Experiment: • Some old ideas about living things… • P. 8 • Fig. 1.7

16. Required Steps in a Good Experiment: • Ask a question: • How, why? • Forming a Hypothesis: • Years ago people thought living things came from nonliving things. • This idea was called spontaneous generation.

17. Ex: • mice spontaneously appear in stored grain • maggots spontaneously appear in meat. • Spontaneous generation was a hypothesis. • Remember! • Hypotheses must be tested. • The idea that maggots came from meat was tested by Francesco Redi. • To test it, Redi needed an experiment. • So, he devised a controlled exp.

18. Setting Up a Controlled Experiment: • Factors that can be changed in an exp. are called variables. • Examples: • Equipment used • Type of materials • Amount of materials • Temp. • Light • Time

19. Hypotheses are tested in an experiments. where only 1 variable is changed at a time. • This is called a controlled exp. • Controlled exp. have 2 types of variables: • Manipulated variable • Variable that is deliberately changed. • Responding variable • Variable changes in response to the manipulating variable. • Refer to Redi’s Exp. Fig. 1-8

20. OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Uncovered jars Covered jars Controlled Variables: jars, type of meat, location, temperature, time Manipulated Variables: gauze covering that keeps flies away from meat Several days pass Responding Variable: whether maggots appear Maggots appear No maggots appear CONCLUSION:Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

21. Recording & Analyzing Results: • Scientists keep records of their observations, experements, or data. • These records are kept in: • Journals • Notebooks • Drawings Fig. 1-8 • Computers • Did Redi keep records? • Yes

22. Drawing Conclusions: • Evidence from a exp. either supports or disproves a hypothesis. • Did Redi’s exp. support his hypothesis? • Yes, it disproved the theory of spontaneous generation.

23. Repeating Investigations • Often, scientists place their procedures & findings of an experiments in scientific journals. • They do this so other scientists can repeat their work. • Why? • Scientists can confirm or deny other scientists findings.

24. Designing an Experiment State the Problem Analyze Results Form a Hypothesis Draw a Conclusion Set Up a Controlled Experiment Publish Results Record Results

25. Let’s look at some scientists who questioned Redi’s findings: • P. 11-13 • Needham fig. 1-10 • Spallanzani fig. 1-10 • Pasteur fig. 1-11

26. Needham’s ExperimentFig. 1-10Spallanzani’s Experiment:fig. 1-10

27. Pasteur's Experiment: fig. 1-11 Broth is boiled. Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.

28. When Experiments Are Not Possible: • You can’t always do an exp. to test a hypothesis. • When this happens you can do: • Field studies & more observations • Enables us to study animal behavior • Fig 1-12 • Medical studies & testing • Usually on volunteers

29. How a Theory Develops: • Theory -A very well tested explanation that unifies a broad range of observations. • Examples of theories: • Theory of Biogenesis • All living things come from other living things. • Verified by Pasteur • Theory of Evolution • The Cell Theory • Big Bang theory

30. Some explanations in life need more than one theory. • Fig. 1-13 • Examples: • Theory of Evolution • Cell Theory • Theory of Plate Tectonics

31. Section 3 Studying Life

32. What is biology? • study of life • Biology–understanding the living world.

33. Characteristics of Living Things • All living things share these characteristics: • made of cells • reproduce • a genetic code (DNA) • grow & develop • use materials & energy • respond to their environment • maintain their internal env. (homeostasis) • evolve • Fig. 1-14

34. Made up of cells: • Cell–a collection of living matter enclosed by a barrier that separates it from its surroundings. • Cell -the smallest unit of life. • Cells -complex & highly organized.

35. Orgs. can be unicellular or multicellular. • Unicellular –single celled • Ex: bacteria • Multicellular–many celled • Ex: humans • Fig. 1-15

36. Reproduction: • There are 2 types of reproduction: • Asexual • “A” before a word means w/out. • The new org. has a single parent. • Offspring are exact duplicates of the parent. (clones) • Fig. 1-16 shows “budding” of a hydra. • Sexual • Cells from 2 different parents unite to make the 1st cell of the org.

37. Based on Genetic Code: • Offspring resemble their parents. • All living orgs. have DNA. • DNA =Deoxyribonucleic Acid • Determines the traits of every org. on Earth.

38. Growth & Development: • All living things grow to some extent. • Growth = increase in size. • However, multicellular orgs. go through development. • Development involves cells dividing & becoming specialized or “differentiated”. • Ex: Stem cells can become: • nerve cells • skin cells • liver cells • brain cells • Fig. 1-17

39. Need for Materials & Energy: • Metabolism–set of chem. reactions through which an org. builds up/breaks down materials. • All orgs. need energy (E). • Plants, some bacteria, & most algae get E from the sun. • Animals get E from food.

40. Response to the Env: • All orgs. sense & respond to stimuli in their env. • Stimulus –a signal to which an org. responds. • Ex: plant seeds respond to warmth & water.

41. Maintaining Internal Balance: • Homeostasis–process by which orgs. maintain a relatively stable internal env. • Ex: home heating/cooling system. • Another example, the bird in fig. 1-19. • When it is cold it hunches down & adjusts its feathers for maximum insulation.

42. Evolution: • Evolution –process by which modern orgs. have descended from ancient orgs. over long periods of time.

43. Characteristics of Living Things: Characteristic Examples Living things are made up of units called cells. Many microorganisms consist of only a single cell. Animals and trees are multicellular. Living things reproduce. Maple trees reproduce sexually. A hydra can reproduce asexually by budding. Living things are based on a universal genetic code. Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees. Living things grow and develop. Flies begin life as eggs, then become maggots, and then become adult flies. Living things obtain and use materials and energy. Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat. Leaves and stems of plants grow toward light. Living things respond to their environment. Despite changes in the temperature of the environment, a robin maintains a constant body temperature. Living things maintain a stable internal environment. Taken as a group, living things change over time. Plants that live in the desert survive because they have become adapted to the conditions of the desert.

44. Branches of Biology: • Some branches of biology: • Zoology –study animals • Botany-study plants • Paleontology-study of ancient life • Molecular/Cell biologists- study of the smallest life forms. • Population biologists & ecologists –study of the largest systems on Earth.

45. Organism Individual living thing Bison Tissues, organs, and organ systems Groups of Cells Nervous system Brain Nervous tissue Smallest functional unit of life Cells Nerve cell Groups of atoms; smallest unit of most chemical compounds Molecules DNA Water

46. Biosphere The part of Earth that contains all ecosystems Biosphere Ecosystem Community and its nonliving surroundings Hawk, snake, bison, prairie dog, grass, stream, rocks, air Community Populations that live together in a defined area Hawk, snake, bison, prairie dog, grass Population Group of organisms of one type that live in the same area Bison herd

47. Biology in Everyday Life: • Read this section in class…

48. Section 4 Tools & Procedures

49. A Common Measurement System: • Scientists use the metric system for data & performing experiments. • Metric system: • -a decimal system of measurements w/ units that are based on multiples of 10. • International System of Units–revised version of the metric system. • Abbreviated as SI • Les Systeme International d’unites (French)