Welcome to Biology 160&

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Moses Logan
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1 Welcome to Biology 160&

2 Course goals Know what ALL living things are made of Cells and cellular machinery. How do they work? Understand the genetic basis of evolutionary change Why so many organisms? How did they get here? Know the history and diversity of life on Earth Who, when, where? How do organisms interact with their environment and with each other? Learn a new language Learn to think critically and systematically, like a natural scientist

3 Two types of questions Proximate: How does it work? Mechanistic explanation. What are the parts & how do they interact? Ultimate: Why does it work that way? How does a structure, function or behavior increase an organism s chances of surviving or reproducing?

4 Scope Levels of Organization Matter & Energy flow through these levels

5 Interconnections: Matter Everything is built of matter: atoms & subatomic particles. ALL matter is recycled Producers Autotrophs; Algae, Plants & Cyanobacteria Consumers Heterotrophs; Animals & Bacteria Decomposers Saprotrophs; Fungi & Bacteria

6 Interconnections: Energy Energy flows through the lithosphere Producers harness it & make high energy molecules Consumers eat those producers for their energy Decomposers digest the remainders & the undigestable molecules Energy is lost as heat along the way

7 All life is interconnected What atoms are you mostly made of? Where did those atoms come from? Is there turnover of these atoms as you age? Where did the energy that you re using to scribble notes come from?

8 Life is Unified, yet Diverse All life shares a common origin But All life connotes tremendous diversity

9 Unified, yet Diverse Ex: Triangles Unity: 3 sides, 3 points, Area = 1/2(b x h) Diversity: right, equilateral, scalene, etc.

10 Life is Unified, yet Diverse Ex: Mammals Fur, 2 sets teeth; Milk nourish young; 3 middle ear bones K-rats (hoppers), whales (swimmers), sloths, anteaters, howler monkeys (brachiators), bats (flyers)

11 Characteristics of Life Anything alive is composed of cells (1-100 billion) Autonomous, self-replication Pass on copies of genetic material (DNA/RNA) Make energy (ATP) Grow/develop Make Carbon-containing molecules (all organic molecules have lots of carbon; C)

12 Diversity of life Bacteria & Archaea are prokaryotes - single celled; simple structure; no nucleus Eukarya are eukaryotes - nucleus; lots of specialized organelles

13 Evolution explains Unity & Diversity of Life Evolution: descent with modification Evolution is the process by which diversity is generated: Fossil Record Extinctions Transitional forms Environmental/Geological change Apparent relatedness of species Genetic similarity

14 Development of hypotheses Hypothesis: A statement of belief about how the world works, based on observation or experimentation Prediction: An if then statement that suggests/presents a test of that hypothesis

15 Example Observation: My flashlight will not illuminate. Hypothesis 1 (H 1 ): My flashlight will not illuminate because the batteries are dead. Prediction? H 2 : The bulb is burned out.

16 Clicker Q H 2 : My flashlight will not illuminate because the bulb is burned out. Which of the following is a prediction that logically stems from that hypothesis? 1. The battery s acid exploded the bulb 2. If I replace the bulb, then the flashlight will illuminate. 3. If the bulb is burned out, then the flashlight will not illuminate

17 What makes science different from other ways of understanding? Attempts to discover natural explanations for events (processes) and patterns that we observe Hypotheses ARE these explanations They lead to predictions on the outcomes of future events, observations or experiments Hypotheses must be testable (falsifiable) by further observation or experimentation If predictions are incorrect, we reject the hypothesis If predictions are correct, the hypothesis is supported and accepted (for now) but it may or may not be TRUE

18 Process of science The Scientific Method Observation Hypothesis Prediction Experiment Results Interpretations

19 Observations: Both cactus mice and thrashers eat chiles (fruits + seeds). Chile seeds eaten by thrashers germinate; those eaten by mice do not. Some species of chiles contain capsaicin (spice).

20 Question & Hypothesis Does capsaicin deter some predators but not others? H 1 : Capsaicin deters cactus mice (predators) but not thrashers (dispersers) H 0 (null): Capsaicin deters both cactus mice & thrashers OR capsaicin deters neither cactus mice nor thrashers.

21 Prediction: If then, both will eat hackberry, but only thrashers will eat pungent (hot) chiles. Prediction null: If then, there will be no difference between thrashers & mice in fruit consumed.

22 Results & Interpretation Result: Cactus mice do not eat pungent chiles; thrashers do. Interpretation?

23 Clicker Q Does capsaicin deter some predators and not others? 1. Yes, because because mice do not eat pungent chiles but thrashers do. 2. No, because there is no difference between mice & thrashers 3. No, because mice & thrashers both eat NP chiles.

24 Does rejection of a hypotheses represent a failure of science? There may be a limit to what the human mind can figure out about our universe. But how presumptuous it would be for me to claim that if I can't solve a problem, neither can any other person who has ever lived or who will ever be born. Neil degrasse Tyson, The Perimeter of Ignorance

25 Are there limits to the explanatory power of science? If our hypotheses accurately predict the outcome of 10, 20, even 30 experiments, can we say that we ve proven it true? If not, how many accurately predicted outcomes will prove it true?

26 Truth of Hypotheses? They are simply our best explanation of how the world works They are only TRUE in that they have always, in the past, accurately predicted outcomes They are hopefully TRUE in that they accurately describe all the mechanisms and processes that produce those outcomes Because we cannot know the results ahead of time, we can only disprove hypotheses

27 What makes science so powerful? 1. It s always changing! Every theory, law, rule, assumption, etc. is subject to rejection at any time if its predictions conflict with observational or experimental evidence. 2. Anyone can test predictions of a hypothesis 3. Hypotheses are worthless (& not hypotheses at all) unless they can be tested.

Chapter 1 Biology: Exploring Life

Chapter 1 Biology: Exploring Life PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Lecture by Edward J. Zalisko Figure 1.0_1 Chapter 1: