Life in the Trees --- Discovery Science

1. What is Biology????How does a scientist learn about living things????Most scientists practice discovery science and hypothesis driven science.

2. Life in the Trees --- Discovery Science • The lives of gray-headed flying foxes are closely entwined with the lives of the eucalyptus trees that form their habitat • Eucalyptus trees provide food and roosting sites for the flying foxes • Flying foxes aid in eucalyptus pollinationand help disperse the resulting seeds

3. Flying foxes are becoming an endangered species, partly because of habitat destruction

4. In discovery science, scientists describe some aspect of the world and use inductive reasoning to draw general conclusions • Example: scientists have described how newborn flying foxes cling to their mother’s chest for the first weeks of life • The scientists have made observations and reasoned to a generalization. Figure 1.2

5. Discovery Science Utilizes Inductive ReasoningVerifiable observations and measurements are the data of discovery science.Discovery science can lead to important conclusions based on a type of logic called inductive reasoning.This type of reasoning derives general principles from a large number of specific observations.“All living things are made from cells.” That induction was made with over two centuries of observations in which biologists discovered cells in every biological specimen they observed through microscopes.

6. Hypothesis Driven Science • In hypothesis-driven science, scientists use the “scientific method” • They propose a hypothesis • They make deductions leading to predictions • They then test the hypothesis by seeing if the predictions come true • The use of “danger” calls by flying foxes helps them evade the tree climbing pythons that prey upon them.

7. If the flying foxes don’t call out “danger,” then they will be more subject to predation.

8. Case study: flashlight failure • Based on research and past experience…my hypothesis is that the batteries are dead. • If a hypothesis is correct, and we test it, then we can expect a particular outcome • If I replace the batteries then the flashlight should work. • From general premises we extrapolate to the specific results we should expect if the premises are true. • Deductive reasoning is used in testing hypotheses Figure 1.3B

9. Hypothesis driven science utilizes deductive reasoning.Ifall organisms are made of cells(premis 1), and humans are organisms (premis 2), then humans are composed of cells (deduction about a specific case). This deduction can be tested by examining human tissue under the microscope.

10. SummaryScientists use two main approaches in their efforts to understand nature, In discovery science, they describe some aspect of the world and use inductive reasoning to draw general conclusions. In hypothesis driven science, scientists use the “Scientific Method.” They propose a hypothesis ( a tentative answer to a question), make deductions leading to predictions, and then test the hypothesis by seeing if the predictions come true.

11. The Tools of Hypothesis Driven Science • Hypothesis driven science utilizes the scientific method. • The scientific method uses the 5 senses to make observations. • The most extensive work, while utilizing the scientific method, is the gathering of background information in order to formulate a hypothesis using acceptable premises. • The scientific method uses deductive reasoning.

12. 1.3 With the scientific method, we pose and test hypotheses Observation • The main steps of the scientific method Search &Question Hypothesis Prediction Test does notsupport hypothesis; revise hypothesis or pose new one Test supports hypothesis; make additional predictions and test them Test: Experiment oradditionalobservation Figure 1.3A

13. Control groups must be tested along with experimental groups for the meaning of the results to be clear • A control group and an experimental group differ by only one variable. • The control group provides a basis for comparison, enabling researchers to draw meaningful conclusions from their experiments. • Experiments designed to test hypotheses must be controlled experiments

14. Zebra Jumping Spider 

15. Snowberry fly

16. Case study: spider mimicry by snowberry fly jumping spider snowberry fly If the flies wing markings are masked with a dye then jumping spiders should pounce on the experimental flies more often than they do on control flies with normal wings. Pounce rate (% of trials in which spider jumped on fly) Control group(untreated flies) Experimental group(wing markings masked) Figure 1.3D

17. Another test of the spider mimic hypothesis: wing transplants from spider mimics (snowberry flies) to houseflies Number of stalk andattack responsesby spiders Wingmarkings Wingwaving Housefly withmimic wing transplant (no waving) Normalspidermimic Mimic withmimic wing transplant Mimic withhousefly wing transplant Normalhousefly Figure 1.3E Controls Experimentals

18. The Tools of Science Include Technology • Tools can be implements such as microscopes. • Science and technology are an indivisible pair.

19. Science vs Technology • TECHNOLOGYGoal: the creation of artfacts and systems to meet people's needs • SCIENCEGoal: the pursuit of knowledge and understanding for its own sake • “ . . . practical usable criteria for making sharp neat distinctions between science and technology do not exist.” • “ . . . ‘contrivance’ technology exemplified by many gifted engineers in the last century who worked with no formal scientific understanding of their problems, and ‘applied science’ technology in which one increasingly needs to grasp the conceptual science even to understand the problem, let alone explore solutions " • “Neither is sufficient on its own; some problems require more of one approach, some more of the other.”

21. THE SCOPE OF BIOLOGY • Biology is the scientific study of life • Interactions between different kinds of organisms affect the lives of all • Recall the example of flying foxes and eucalyptus trees

22. organ systems • organs • tissues • cells • molecules ECOSYSTEM LEVELEucalyptus forest • Organisms are made up of: COMMUNITY LEVELAll organisms ineucalyptus forest POPULATION LEVELGroup of flying foxes ORGANISM LEVELFlying fox Brain Spinal cord ORGAN SYSTEM LEVELNervous system ORGAN LEVELBrain Nerve TISSUE LEVELNervous tissue CELLULAR LEVELNerve cell MOLECULAR LEVELMolecule of DNA Figure 1.1

23. 1.1 Life’s levels of organization define the scope of biology • A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology • An ecosystem consists of: • all organisms living in a particular area • all nonliving physical components of the environment that affect the organisms (soil, water)

24. ECOSYSTEM LEVELEucalyptus forest • Ecosystems include: • all the organisms in an area, which make up a community • interbreeding organisms of the same species, a population • At the top of life’s hierarchy is the ecosystem COMMUNITY LEVELAll organisms ineucalyptus forest POPULATION LEVELGroup of flying foxes ORGANISM LEVELFlying fox Brain Spinal cord ORGAN SYSTEM LEVELNervous system ORGAN LEVELBrain Nerve TISSUE LEVELNervous tissue CELLULAR LEVELNerve cell MOLECULAR LEVELMolecule of DNA Figure 1.1