1. Chapter 1
Invitation to Biology

2. Biology: study of life, past and present

3. What is “Living”? What do All organisms have in common?
Characterizing Life
What is “Living”? What do All organisms have in common?

4. 1.1 How Do Living Things Differ From Nonliving Things?
Life is more than the sum of its parts
Complex properties, including life, emerge from the interactions of simple parts

5. How Do Living Things Differ From Nonliving Things? (cont’d.)

6. Life’s Organization Atom: fundamental building block of matter
Molecule: association of two or more atoms
Cell: smallest unit of life
Organism: consists of one or more cells

7. Life’s Organization (cont’d.)
Tissue: specialized cells organized to perform a collective function
Organ: grouping of tissues engaged in a collective task
Organ system: set of organs engaged in a collective task

8. Life’s Organization (cont’d.)
atom
Atoms are fundamental units of all substances, living or not. This image shows a model of a single atom. 1
organ
Structural unit of interacting
tissues. Flowers are the
reproductive organs of
many plants. 5
molecule
Atoms join other atoms in
molecules. This is a model of a
water molecule. The molecules
special to life are much larger
and more complex than water. 2
organ system
A set of interacting organs.
The shoot system of this
poppy plant includes its
aboveground parts: leaves,
flowers, and stems. 6
cell
The cell is the smallest unit
of life. Some, like this plant
cell, live and reproduce as
part of a multicelled organism;
others do so on their own. 3
Figure 1.1 An overall pattern in the way life is organized. New emergent properties appear at each successive level.
multicelled organism
Individual that consists of
more than one cell. Cells of
this California poppy plant
are part of its two organ
systems: aboveground shoots
and belowground roots. 7
tissue
Organized array of cells
that interact in a collective
task. This is epidermal tissue
on the outer surface of
a flower petal. 4

9. Organisms Require Energy and Nutrients
Nutrient: substance that an organism need for survival
Producers: organism that makes its own nutrients
Consumers: organism that gets energy and nutrients by feeding on other organisms
Molecules in organisms are recycled; Energy is not recycled.

10. Organisms Require Energy and Nutrients (cont’d.)
producer
acquiring energy
and nutrients from
the environment 1
consumer acquiring energy and nutrients by eating a producer 2
Figure 1.2 The one-way flow of energy and cycling of materials through the world of life.

11. Organisms Sense and Respond to Change
Every living thing has the ability to sense and respond to changes.
Homeostasis: process by which organism keeps its internal conditions within tolerable ranges

12. Organisms Use DNA
DNA carries hereditary information that guides cell function
Inheritance: DNA transmitted to offspring through reproduction
DNA is the basis of similarities in form and function among organisms

13. 1.3 How Are Living Things Different?
Biodiversity: scope of variation among living organisms
Organisms can be grouped on the basis of whether they have a nucleus (Eukaryote) or not (Prokaryote)

14. How Are Living Things Different? (cont’d.)
Bacteria: most diverse and well-known group of single-celled organisms that lack a nucleus
Archaea: organisms that lack a nucleus but are more similar to eukaryotes than to bacteria

15. How Are Living Things Different? (cont’d.)
A Prokaryotes are single-celled, and have no nucleus.
As a group, they are the most diverse organisms.
Figure 1.4 A few representatives of life’s diversity: A some prokaryotes; B some eukaryotes.
bacteria are the most numerous organisms on Earth. Top, this bacterium has a row of iron crystals that functions like a tiny compass; bottom, a resident of human intestines.
archaea resemble bacteria, but they are more closely related to eukaryotes. Top: two types from a hydrothermal vent on the seafloor. Bottom, a type that grows in sulfur hot springs.

16. How Are Living Things Different? (cont’d.)
B Eukaryotes consist of cells that have a nucleus. Eukaryotic cells are typically larger and more complex than prokaryotes.
Figure 1.4 A few representatives of life’s diversity: A some prokaryotes; B some eukaryotes.
protists are a group of extremely diverse eukaryotes that range from microscopic single cells (top) to giant multicelled seaweeds (bottom).
fungi are eukaryotic consumers that secrete substances to break down food outside their body. Most are multicelled (top), but some are single-celled (bottom).

17. How Are Living Things Different? (cont’d.)
Figure 1.4 A few representatives of life’s diversity: A some prokaryotes; B some eukaryotes.
plants are multicelled eukaryotes. Most are photosynthetic, and have roots, stems, and leaves.
animals are multicelled eukaryotes that ingest tissues or juices of other organisms. All actively move about during at least part of their life.

18. 1.4 What Is a Species? Species: unique type of organism
Taxonomy: the science of naming and classifying species
Taxon: group of organisms that share a unique set of traits

19. A Rose by Any Other Name . . . (cont’d.)
domain
Eukarya
kingdom
Plantae
phylum
Magnoliophyta
class
Magnoliopsida
order
Apiales
Rosales
family
Apiaceae
Cannabaceae
Rosaceae
genus
Daucus
Cannabis
Malus
Rosa
species
carota
sativa
domestica
acicularis
canina
common name
wild carrot
marijuana
apple
prickly rose
dogrose
Figure 1.5 Linnaean classification of five species that are related at different levels. Each species has been assigned to ever more inclusive
groups, or taxa: in this case, from genus to domain.

20. A Rose by Any Other Name . . . (cont’d.)
Bacteria
Archaea
Protists
Plants
Fungi
Animals A
Figure 1.6 Two ways to see the big picture of life. The lines in such diagrams indicate evolutionary connections.
A Six-kingdom classification system. The protist kingdom includes the most ancient multicelled and all single-celled eukaryotes.
B Three-domain classification system. The Eukarya domain includes protists, plants, fungi, and animals.
Bacteria
Archaea
Eukarya B

21. 1.5 How Does Science Work?

22. The Scientific Method
Science: study of the observable world and the knowledge obtained
Scientific method: making, testing, and evaluating hypotheses
Hypothesis: testable explanation of a natural phenomenon

23. The Scientific Method (cont’d.)
Inductive reasoning: drawing a conclusion based on observation
Prediction: statement, based on a hypothesis, about a condition that should exist if the hypothesis is correct
Deductive reasoning: using a general idea to make a conclusion about a specific case

24. The Scientific Method (cont’d.)
Experiment: test designed to support or falsify a hypothesis
Variable: a characteristic or event that differs among individuals or over time
Researchers often investigate causal relationships by changing variables

25. The Scientific Method (cont’d.)
Independent variable: condition or treatment controlled by the experimenter
Dependent variable: observed result that is influenced by the independent variable
Experimental group: receive a certain treatment or have certain characteristics
Control group: identical to an experimental group, but without exposure to the independent variable

26. 1.7 What Are Some Potential Pitfalls in Scientific Inquiry?
Sampling error: difference between results obtained from a subset, and results from the whole
Can be a substantial problem with a small subset
Experimenters start with a relatively large sample, and repeat their experiments

27. What Are Some Potential Pitfalls in Scientific Inquiry? (cont’d.)
Probability: chance that a particular outcome of an event will occur
Statistically significant: a result is very unlikely to have occurred by chance alone

28. What Are Some Potential Pitfalls in Scientific Inquiry? (cont’d.)
Figure 1.12 Example of error bars in a graph. This graph was adapted from the peacock butterfly research described in Section 1.6.
The researchers recorded the number of times each butterfly flicked its wings in response to an attack by a bird. The dots represent average frequency of wing flicking for each sample set of butterflies. The error bars that extend above and below the dots indicate the range of values—the sampling error.

29. Bias in Interpreting Results
Human beings are by nature subjective, and scientists are no exception
Experimenters risk interpreting their results in terms of what they want to find out
To minimize bias, experiments should yield quantitative results

30. What Is a Theory?
Scientific theory: hypothesis that has not been disproven after many years of rigorous testing
Consistent with all data ever gathered
Contributes to successful predictions about other phenomena

31. What Is a Theory? (cont’d.)
Table 1.5 Examples of Scientific Theories