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Invitation to Biology
Chapter 1
Biology
Scientific study of life
Lays the foundation
for asking basic questions about life
and the natural world
What is Alive?
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Acquire and use energy
Grow and Develop
Reproduce using DNA
Respond to Stimuli
Maintain Homeostasis
Organization
Have the ability to evolve
Energy Flow
• Usually starts with energy from the
sun
• Transfers from one organism to
another
• Flows in one direction
• Eventually is lost as heat
Life’s Underlying Unity
• Life’s organization extends from the
molecular level to the biosphere
• Shared features at the molecular level
are the basis of life’s unity
atom
Smallest unit of an element that still retains the
element’s properties. Electrons, protons, and
neutrons are its building blocks. This hydrogen
atom’s electron zips around a proton in a
spherical volume of space
Fig. 1-1a, p.2
molecule
Two or more joined atoms of the
same or different elements. The
“molecules of life” are complex
carbohydrates, lipids, proteins,
DNA, and RNA. In today’s world only
living cells make them
Fig. 1-1b, p.2
cell
Smallest unit that can live
and reproduce on its own
or as part of a multicellular
organism. It has an outer
membrane, DNA, and
other components
Fig. 1-1c, p.2
tissue
Organized cells and
substances that interact
in a specialized activity.
Many cells (white) made
this bone tissue from
their own secretions
Fig. 1-1d, p.2
organ
Two or more tissues interacting in some task. A parrotfish eye, for
example, is a sensory organ used in vision
Fig. 1-1e, p.2
organ system
Organs interacting physically, chemically, or both in some task
Parrotfish skin is an organ system with tissue layers, organs such
as glands, and other parts
Fig. 1-1f, p.2
multicelled organism
Individual made of different types of cells
Cells of most organisms, including this Red Sea parrotfish, are
organized as tissues, organs, and organ systems
Fig. 1-1g, p.3
population
Group of single-celled or multicelled individuals of the same
species occupying a specified area
This is a fish population in the Red Sea
Fig. 1-1h, p.3
community
All populations of all species
occupying a specified area
This is part of a coral reef
in the Gulf of Aqaba at the
northern end of the Red Sea
Fig. 1-1i, p.3
ecosystem
A community that is
interacting with its physical
environment
It has inputs and outputs of
energy and materials
Reef ecosystems flourish in
warm, clear seawater
throughout the Middle East
Fig. 1-1j, p.3
the biosphere
All regions of the Earth’s waters, crust, and atmosphere that hold
organisms
Earth is a rare planet; without its abundance of free-flowing water,
there would be no life
Fig. 1-1k, p.3
Molecules of Life
• Atoms are the basic units of matter
• Living things are made up of a certain
subset of molecules:
– Nucleic acids
– Proteins
– Carbohydrates
– Lipids
DNA (deoxyribonucleic acid)
• Signature molecule of life
• Molecule of inheritance
• Directs assembly of amino acids
DNA and Inheritance
• Inheritance
– Acquisition of traits through
transmission of DNA from parent to
offspring
• Reproduction
– Mechanism by which parents transmit
DNA to offspring
Interdependencies among Organisms
Producers
Make their own food
Consumers
Obtain energy by eating other
organisms
Decomposers
Break down remains and wastes
Energy
input,
from
sun
Producers
plants, and other
self-feeding organisms
Nutrient
Cycling
Consumers
animals, most fungi,
many protists, many bacteria
Energy output (mainly metabolic heat)
Fig. 1-3, p.5
Sensing and Responding
• Organisms sense and respond to
changes in their environment
• Receptors detect specific forms of
energy (stimuli)
• Sensing and responding helps to
maintain homeostasis
Sensing and Responding
Homeostasis
• Organisms maintain certain conditions
in their internal environment
• A defining feature of life
Unity of Life
All organisms
– Consist of one or more cells
– Have the capacity to reproduce based
on instructions in DNA
– Engage in metabolism
– Sense and respond to the environment
Levels of Organization
Cell
Multicelled organism
Population
Community
Ecosystem
Biosphere
Life’s Diversity
• Millions of living species
• Millions more now extinct
• Each species has some
unique traits
Scientific Names
Two-part name
– Humphead parrotfish is Scarus gibbus
– First part (Scarus) is genus name
– Second name is a particular species within
the genus
Classification Systems
• Organisms are grouped into three
domains:
Eubacteria
(Bacteria)
Archaebacteria
(Archaea)
Eukaryotes
(Eukarya)
Major Groups
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Prokaryotes
Eukaryotes
• Single celled
• Single- or multicelled
• No nucleus
• Nucleus
• Smaller, less
complex
• Archaebacteria,
eubacteria
• Larger, more
complex
• Fungi, protistans,
plants, animals
Bacteria
• The most common prokaryotes
Archaea
• Prokaryotes
Protists
Protists
Plants
• Generally
photosynthetic
Fungi
• Decomposers, parasites and pathogens
Animals
• Multicelled eukaryotes
Mutation: Source of Variation
• Mutation = change in structure of DNA
• Basis for variation in heritable traits
• May be harmful, neutral, or beneficial
Evolution
• Heritable change in a line of descent
over time
• Changes in populations result in
diversity
Natural Selection
• Individuals vary in some heritable traits
• Different forms of heritable traits are
most helpful under different conditions
• Natural selection is an outcome of
differences in survival and reproduction
among individuals that vary in their traits
Scientific Method
• Observe phenomenon
• Develop hypotheses
• Make predictions
• Devise test of predictions
• Carry out test and analyze results
Role of Experiments
• Study a phenomenon under known
conditions
• Tests the prediction of the hypothesis
• Can never prove a hypothesis 100%
correct
Experimental Design
• Control group
– A standard for comparison
– Identical to experimental group except for
variable being studied
• Experimental group
– Includes one variable being studied
Scientific Theory
• An explanation of the causes of a wide
range of related phenomena
• Is consistent with all collected data
• Used to make predictions
• Still can be disproved