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Chapter 1: The Science of Biology.

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Presentation on theme: "Chapter 1: The Science of Biology."— Presentation transcript:

1 Chapter 1: The Science of Biology

2 Section 1-1: What is Science

3 Thinking about the Nature of Science
What is science? What makes science powerful? What characteristics must something have in order for it to be science? How does one “do” science?

4 What is Science? What is biology?
Science – an organized way of using evidence to learn about the natural world Biology – the study of the living world

5 How Scientists Work What are your ideas about what specifically makes science the most powerful method we have for understanding nature?

6 How Scientists Work Using Scientific Method Ask a Question
Form a Hypothesis Test the Hypothesis Analyze the Results Draw Conclusions Communicate Results

7 Scientific Method “The Scientific Method” = umbrella term for a variety of methods of study. All rigorous, systematic, evidence-based, and objective means of testing explanations of the natural world. Steps not the same order every time.


9 Ask a Question Scientists form questions when they observe nature through their senses (sight, hearing, touch, smell) Examples: Some peaches are juicy and sweet. Others are spongy with very little flavor. What makes some peaches juicier than others? My neighbor has thick, green grass. Mine is brown in spots and is thin. What does grass need to be healthy?

10 Ask a Question Practice
Make observations and form a scientific question about the pictures below.

11 Form a Hypothesis Hypothesis – a proposed explanation for a set of observations or possible answer to a question Must be testable, or it’s not scientific Write the hypothesis as a clear statement, do not say “I think that ….” ATTENTION - It is okay for your hypothesis to be wrong! Never change your hypothesis after an experiment to make it correct. Prediction – what you expect to observe. The data the experiment will produce if the hypothesis is correct Can be written as an “If the hypothesis is correct, then…” statement.

12 Form a Hypothesis Example
Hypothesis: Apples develop thicker skins as a defense against cold temperatures. Prediction: If apples are exposed to cool temperatures, then they will have thicker skin than other apples.

13 Form A Hypothesis Practice
Write a possible hypothesis and prediction for each of the following observations. The plants in Mr. Smith’s living room are large, healthy and green but the plants in Mr. Smith’s dining room are small and yellowish in color. All of the fish in the classroom fish tank are healthy except for the algae eaters that keep dying.

14 Test the Hypothesis * Whenever possible, an experiment should be designed to have only ONE variable that is changed at a time. (AKA: Controlled Experiment) Controlled Variable/s – the variable/s that are purposely kept the same Manipulated Variable – the ONE variable that is deliberately changed (also called independent) Responding Variable – the variable that is observed and that changes in response to the manipulated variable (also called dependent) Experimental Group – the group in which the manipulated variable is changed Control or Control Group – the group used as a standard for comparison for the experimental group

15 Test the Hypothesis Practice
Hypothesis: Tomato plants given fertilizer will produce more tomatoes than plants that are not fertilized. Plant A Plant B * Both plants are given the same soil, amount of water and sun, temperature, pot size, and growth time. * Plant B is fertilized once a week. What are the controlled variables, the manipulated variable, and the responding variable? Which is the control and the experimental group?

16 Answers Controlled Variables – soil, amount of water and sun, temperature, pot size, and growth time Manipulated Variable – fertilizer Responding Variable – # of tomatoes Control – Plant A Experimental Group – Plant B

17 Why change only one variable?
Plant A 5 hours of sunlight per day l L of water every 4 days quart sized pot 30°C for 6 weeks no fertilization Plant B 7 hours of sunlight per day l L of water every 2 days gallon sized pot 35°C for 9 weeks fertilized once a week Can’t tell! Why did plant B grow more tomatoes? It’s the only way to know which manipulated variable caused the responding variable to change.

18 Test the Hypothesis Practice
Describe why the experiment below is poorly designed. Write a prediction for the hypothesis and then re-design the experiment to make it better. Identify all variables and groups. Hypothesis: Bacteria exposed to antibiotics will be killed. Plate B Stored in incubator (35° C) Given ampicillin Stored in dark Given nutrients Plate A Stored on counter (22° C) Given penicillin Stored in light Not given nutrients

19 Analyze the Results All experimental data must include units. (examples: 9cm, 20sec, 98°C) Tables and graphs are used to represent data and must be labeled with units and titles.

20 Analyze the Results Example
Notice the table below has units and clear labels. Effect of Storage Temperature on Seed Germination Storage Temperature Inside 68˚F Outside 25˚F Germinated Seeds 0% 80% 85%

21 Representing Data in Graphs
Effects of Storage Temperature on Seed Germination 100 80 60 40 20 Germinated Seeds (%) - Inside 68˚F - Inside 25˚F - Outside 25˚F Storage Temperature °F

22 Analyze the Results Practice
Add to the data table and graph to improve them. Hypothesis: Caffeine improves muscle performance. Prediction: Caffeinated frogs will jump farther than uncaffeinated frogs. Results: Frogs given caffeine jumped 27cm and frogs not given caffeine jumped 20 cm. Frog not given caffeine Frog given caffeine Distance of jump 20 27

23 Table needs units, labels, and title.
Graph needs a title, labels on X and Y axis, and a key. Table needs units, labels, and title. Effect of Caffeine on Frog Jumps Effect of Caffeine on Frog Jumps Amount of Caffeine No Caffeine Caffeine Distance of jump 20cm 27cm Distance of jump (cm) Amount of Caffeine

24 Table needs units, labels and a title.
Graph needs a title, labels on X and Y axis, and a key. Effect of Caffeine on Frog Jumps Amount of Caffeine No Caffeine Caffeine Distance of jump 20cm 27cm Effect of Caffeine on Frog Jumps Distance of jump (cm) Uniform scale: every line stands for exactly 5 cm, no “skips” Amount of Caffeine

25 Choosing Bar vs Line Graphs
Bar graph = Used for groups/categories, Line graph = Comparing two number scales Manipulated variable on X-axis, responding variable on Y-axis

26 Graph Examples Number of students per town… what kind of graph, bar or line? Town # of Students Canton 9 Stoughton 2 Norwood 1 Westwood 4 Dedham 3 Milton Randolph Sharon Hyde Park

27 Graph Examples Number of students at different heights… what kind of graph, bar or line? Height (cm) # of Students 150 2 151 152 3 153 6 154 5 155 156 1 157

28 Bar or Line Graph? Number of American Thrushes living in each of five forests 100 students’ choices for their favorite lunch Comparing the number of chromosomes to the number of genes The number of mates attracted by red vs yellow vs blue-beaked parrots The growth of a seedling (days old vs height)

29 Draw Conclusions Conclusion – a final summation of experimental results A conclusion’s main purpose is to evaluate your initial ideas (hypothesis & prediction) using your data A conclusion should do the following:

30 Draw Conclusions (Add your own notes)
State the purpose in your own words. Summarize the scientific idea the lab is about, and define any vocab words. Restate the hypothesis and prediction, not copying exactly how they were already written. Summarize (1-2 sentences) the procedure. State whether the results support or refute the hypothesis/prediction. Support the evaluation you made in step 5 with specific evidence (data). “The average height in group A was 2 cm higher than group B.” = Specific “Group A grew more.” = Not specific. Give a final concluding statement. If your hypothesis was supported, summarize that. If it was refuted, give a new and improved hypothesis.

31 Draw Conclusions Example
Label the paragraph with numbers, marking where each of the 7 steps occurs: The experiment was designed to test whether caffeine would increase the distance frogs could jump. Caffeine is a stimulant. Stimulants are psychoactive drugs, meaning that they affect the nervous system. Jumping involves the nervous and muscular systems, so it’s possible that caffeine could affect jumping. It was hypothesized that caffeine improves muscle action, and it was predicted that the more caffeine a frog has, the farther it will jump. To test this, some frogs were given caffeine and others were not, and the lengths of their jumps were measured. The results supported the hypothesis and prediction, showing that frogs given caffeine jumped an average of 7cm farther than frogs that were not given caffeine. Caffeine does indeed increase the distance that frogs can jump.

32 Draw Conclusions Practice
Examine the hypothesis and experimental results below, and write an appropriate conclusion. Hypothesis: Carrots require high nitrogen levels for best growth. Results: Effects of Nitrogen Levels on Carrot Growth Level of Nitrogen None Low High Average Carrot Length 6 in. 10 in. 4 in.

33 Communicate Results Scientists always report their results through journals and scientific papers. Allows others to repeat the investigation, skeptically evaluate the validity of the results, & can lead to further questions and investigations.

34 Scientific Language

35 Scientific Language The scientific process has a language of its own.
Sometimes, this language diverges from conversational English. “Science words” can be different from English words even when they look exactly the same.

36 Scientific Language For example: the words for different kinds of scientific outcomes and models. In English, an observation is… In Science, an observation is…

37 Scientific Language Observation (Science definition): A data point gathered by one of the five senses. An example of an observation in science: “After adding solution A to solution B, the mixture has a sharp sour smell.”

38 Scientific Language Fact:

39 Scientific Language Fact (Science definition): An observation that has been made repeatedly. Example: Two negative poles move away from each other.

40 Scientific Language Law:

41 Scientific Language Law (Science definition): A mathematical description of patterns in a relationship between two quantities. Example: p + q = 1, (p + q)2 (Hardy-Weinberg’s Law)

42 Scientific Language Theory:

43 Scientific Language Theory (Science Definition): A powerful explanation of numerous natural phenomena. Example: Matter is made up of atoms, properties of matter come from atomic behavior (Atomic theory)

44 Section 1-3 Studying Life

45 Characteristics of Living Things
made up of cells reproduce DNA grow and develop need materials and energy respond to the environment maintain a stable internal environment (homeostasis) evolve (as a group, change over time)

46 Living things are… made up of cells.
Cell – a collection of living matter enclosed by a barrier separating the cell from its surroundings Cells are the smallest units of life in all organisms. Unicellular organisms – single celled Multi-cellular organisms – composed of more than one cell

47 Living things… reproduce.
Reproduction – process where organisms produce new organisms or offspring Sexual Reproduction: two cells from different parents unite to produce first cell of new organism Asexual Reproduction: a single-celled organism divides in half to form two new organisms OR a portion of an organism splits off to form a new organism

48 Living things… contain DNA.
DNA (deoxyribonucleic acid) carries directions for inheritance. DNA determines the inherited traits of every organism on Earth.

49 Living things… grow and develop.
Growth – getting larger in size Unicellular: cell gets bigger Multicellular: create more cells Development – changes that occur during an organisms lifetime (life cycles)

50 Living things… need materials and energy.
Metabolism: organism’s chemical reactions building or breaking down materials Organisms vary in how they obtain energy: Autotrophs: capture energy from sun and convert it into food energy Heterotrophs: must take in food for energy

51 Living things… respond to the environment.
Organisms live in constantly changing environments (living and nonliving parts). Organisms respond or change to cope.

52 Living things… maintain internal balance.
Organisms maintain stable internal conditions (homeostasis) despite fluctuations in environment. temp, water content and food intake

53 Living things… evolve over time.
Populations of organisms evolve (change over time). Natural selection – organisms that have certain favorable traits are better able to successfully reproduce than organisms that lack these traits

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