1. Invitation to Biology
Chapter 1

2. 1.1 Life’s Levels of Organization
We understand life by thinking about nature at different levels of organization
Nature’s organization begins at the level of atoms, and extends through the biosphere
The quality of life emerges at the level of the cell

3. Making Sense of the World
Nature is everything in the universe except what humans have manufactured

4. A Pattern in Life’s Organization
Atoms
Fundamental building blocks of all substances
Molecules
Consisting of two or more atoms
Cell
The smallest unit of life
Organism
An individual consisting of one or more cells

5. A Pattern in Life’s Organization
Population
Individuals of the same species in the same area
Community
Populations of all species in the same area
Ecosystem
A community and its environment
Biosphere
All regions of the Earth where organisms live

6. Levels of Organization in Nature

7. Levels of Organization in Nature

8. Emergent Properties
Each level of organization in nature has emergent properties – a characteristic of a system that does not appear in any of its component parts

9. 1.1 Key Concepts: Levels of Organization
We study the world of life at different levels of organization, which extend from atoms and molecules to the biosphere
The quality of “life” emerges at the level of cells

10. 1.2 Overview of Life’s Unity
All living things have similar characteristics
Continual inputs of energy and the cycling of materials maintain life’s complex organization
Organisms sense and respond to change
DNA inherited from parents is the basis of growth and reproduction in all organisms

11. Energy and Life’s Organization
The capacity to do work
Nutrients
Atoms or molecules essential in growth and survival that an organism cannot make for itself

12. Producers and Consumers
Acquire energy and raw materials from the environment
Make their own food (photosynthesis)
Consumers
Cannot make their own food
Get energy by eating producers and other organisms

13. Organisms Sense and Respond to Change
Organisms sense and respond to change both inside and outside the body by way of receptors
Receptor
A molecule or cellular structure that responds to a specific form of stimulation

14. Homeostasis Homeostasis
Organisms use receptors to help keep conditions in their internal environment within ranges that their cells can tolerate

15. Organisms Grow and Reproduce
Organisms grow, develop, and reproduce using information in their DNA, a nucleic acid inherited from parents
Information encoded in DNA is the source of an individual’s distinct features (traits)

16. Same Materials, Many Products
20 amino acids are the building blocks used to build a great variety of proteins

17. 1.2 Key Concepts: Life’s Underlying Unity
All organisms consist of one or more cells, which stay alive through ongoing inputs of energy and raw materials
All sense and respond to change; all inherited DNA, a type of molecule that encodes information necessary for growth, development, and reproduction

18. 1.3 Overview of Life’s Diversity
Of an estimated 100 billion kinds of organisms that have ever lived on Earth, as many as 100 million are with us today

19. Scientific Naming
Each type of organism is given a two-part name that includes genus and species names
Genus
A group of species that share unique features
Species
Individuals that share one or more heritable traits and can interbreed (if sexually reproducing)

20. Classification Systems
Classification systems group species by their shared, heritable traits
All organisms are classified into three domains
Bacteria, archaea, and eukaryotes
Eukaryotes include plants, animals, protists and fungi

21. Comparison of Life’s Three Domains

22. 1.3 Key Concepts: Life’s Diversity
Many millions of kinds of organisms, or species, have appeared and disappeared over time
Each kind is unique in some aspects of its body form or behavior

23. One-Way Flow of Energy and Cycling of Materials through an Ecosystem

24. 1.4 An Evolutionary View of Diversity
A theory of evolution by natural selection is an explanation of life’s diversity

25. Variation and Mutation
Information encoded in DNA is the basis of traits an organism shares with others of its species
Mutations are the original source of variation in traits

26. Adaptation
Some forms of traits are more adaptive than others, so their bearers are more likely to survive and reproduce
Over generations, adaptive traits tend to become more common in a population; less adaptive forms of traits become less common or are lost

27. Evolution and Natural Selection
Evolution is change in a line of descent
Traits that characterize a species can change over generations in evolving populations
Natural selection is an evolutionary process
Differential survival and reproduction among individuals that vary in the details of their shared, heritable traits

28. 1.4 Key Concepts: Explaining Unity in Diversity
Theories of evolution, especially a theory of evolution by natural selection, help explain why life shows both unity and diversity
Evolutionary theories guide research in all fields of biology

29. 1.5 Critical Thinking and Science
Critical thinking is judging the quality of information
Science is limited to that which is observed
Helps minimize bias in judgments by focusing on testable ideas about observable aspects of nature

30. A Guide to Critical Thinking

31. 1.6 How Science Works
Scientists make and test potentially falsifiable predictions about how the natural world works

32. Observations, Hypotheses, and Tests
Researchers make observations, form hypotheses (testable assumptions), and make predictions about what might occur if the hypothesis is correct

33. A Scientific Approach

34. About the Word “Theory”
A hypothesis that is inconsistent with results of scientific tests (evidence) is modified or discarded
A scientific theory is a long-standing hypothesis that is used to make useful predictions

35. Examples of Scientific Theories

36. Some Terms Used in Experiments
Tests that can support or falsify a prediction
Variable
A single characteristic in a set of individuals that differs from the control group in an experiment

37. Some Terms Used in Experiments
Experimental group
Group with a single variable characteristic to be tested against a control group in an experiment
Control group
Group identical to the control group, except for the variable

38. 1.7 The Power of Experimental Tests
Researchers unravel cause and effect in complex natural processes by studying the effects of one variable at a time

39. Potato Chips and Stomach Aches
Researchers tested the prediction that Olestra® in potato chips causes cramps
Experimental group: Olestra chips
Control group: regular chips

40. Experiment: Olestra and Stomach Cramps

41. Butterflies and Birds
Why does the peacock butterfly flick its wings when birds are near?
Researchers tested two hypotheses
Wing spots deter predatory birds
Hissing and clicking sounds deter predatory birds

42. Results: Peacock Butterfly Experiment

43. Asking Useful Questions
Scientists try to design single-variable experiments that yield quantitative results
When studying humans, isolating a single variable is not often possible

44. 1.8 Sampling Error in Experiments
Researchers experiment on subsets of a group
Results may differ from results of the same experiment performed on the whole group
Sampling error is a difference between results from a subset and results from the whole
Small sample size increases the likelihood of sampling error in experiments

45. A) Natalie, blindfolded, randomly plucks a jelly bean from a jar
A) Natalie, blindfolded, randomly plucks a jelly bean from a jar. There are 120 green and 280 black jelly beans in that jar, so 30 percent of the jelly beans in the jar are green, and 70 percent are black.
B) The jar is hidden from Natalie’s view before she removes her blindfold. She sees only one green jelly bean in her hand and assumes that the jar must hold only green jelly beans.
C) Blindfolded again, Natalie picks out 50 jelly beans from the jar and ends up with 10 green and 40 black jelly beans.
Figure 1.12
Demonstration of 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). The 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 will come close to knowing the actual ratio.
Stepped Art
Fig. 1-12, p. 16

46. Summary of Life’s Characteristics

47. 1.5-1.8 Key Concepts: How We Know
Biologists make systematic observations, predictions, and tests in the laboratory and in the field
They report their results so others may repeat their work and check their reasoning