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1.1 Ecosystems: Everything Is Connected
1.2 The Diversity of Living Things
1.3 Classifications
Classroom Catalyst
4.1 Ecosystems: Everything is Connected
 Distinguish between the biotic and abiotic factors in
an ecosystem.
 Describe how a population differs from a species.
 Explain how habitats are important for organisms.
Defining an Ecosystem
 Ecosystems are communities of organisms and their
abiotic environment.
 Examples are an oak forest or a coral reef.
 Ecosystems do not have clear boundaries.
 Things move from one ecosystem to another. Pollen
can blow from a forest into a field, soil can wash from a
mountain into a lake, and birds migrate from state to
Organization in an Ecosystem
The Components of an Ecosystem
 In order to survive, ecosystems need certain basic
components: energy, mineral nutrients, water, oxygen,
and living organisms.
 Plants and rocks are components of the land
ecosystems, while most of the energy of an ecosystem
comes from the sun.
 If one part of the ecosystem is destroyed or changes,
the entire system will be affected.
Biotic and Abiotic Factors
 Biotic factors are environmental factors that are
associated with or result from the activities of living
organisms which includes plants, animals, dead
organisms, and the waste products of organisms.
 Abiotic factors are environmental factors that are not
associated with the activities of living organisms which
includes air, water, rocks, and temperature.
 Scientists can organize these living and nonliving
things into various levels.
 Organisms are living things that can carry out life
processes independently.
 You are an organism, as is an ant, and ivy plant, and
each of the many bacteria living in your intestines.
 Every organism is a member of a species.
 Species are groups of organisms that are closely
related can mate to produce fertile offspring.
 Members of a species may not all live in the same
place. Field mice in Maine will not interact with field
mice in Texas. However, each organism lives as part of
a population.
 Populations are groups of organisms of the same
species that live in a specific geographical area and
 For example, all the field mice in a corn field make up
a population of field mice.
 An important characteristic of a population is that its
members usually breed with one another rather than
with members of other populations
 For example, bison will usually mate with another
member of the same herd, just as wildflowers will
usually be pollinated by other flowers in the same
 Communities are groups of various species that live
in the same habitat and interact with each other.
 Every population is part of a community.
 The most obvious difference between communities is
the types of species they have.
 Land communities are often dominated by a few
species of plants. These plants then determine what
other organisms can live in that community.
 Habitats are places where an organism usually lives.
 Every habitat has specific characteristics that the
organisms that live there need to survive. If any of
these factors change, the habitat changes.
 Organisms tend to be very well suited to their natural
habitats. In fact, animals and plants usually cannot
survive for long periods of time away from their
natural habitat.
1.1 Section Review Questions
Describe a population not mentioned in this section.
2. Describe which factors of an ecosystem are not part
of a community
3. Explain the difference between a population and a
1.2 The Diversity of Living Things
 Name the three domains and four kingdoms of
organisms and list characteristics of each.
 Explain the importance of bacteria and fungi in the
 Describe the role of protists in the ocean
 Describe how organisms interact and depend on each
other for survival.
The Diversity of Living Things
 Most scientists classify organisms into three domains
and six kingdoms based on different characteristics.
 Members of the three domains get their food in
different ways and are made up of different types of
cells, the smallest unit of biological organization.
 The cells of animals, plants, fungi, and protists all
contain a nucleus. While cells of bacteria, fungi, and
plants all have cell walls.
Levels of Classification
Archaea and Bacteria
 Archaea differ from bacteria in their genetics and the
makeup of their cell wall.
 Bacteria are microscopic, unicellular organisms that
usually have a cell wall and reproduce by cell division.
 Unlike all other organisms, bacteria and archaea lack
 Bacteria and archaea live in every habitat on Earth,
from hot springs to the bodies of animals.
Bacteria and the Environment
 Some kinds of bacteria break down the remains and
wastes of other organisms and return the nutrients to
the soil.
 Others recycle nutrients, such as nitrogen and
 Certain bacteria can convert nitrogen from the air into
a form that plants can use. This conversion is
important because nitrogen is the main component of
proteins and genetic material.
Bacteria and the Environment
 Bacteria also allow many organisms, including
humans, to extract certain nutrients from their food.
 The bacterium, Escherichia coli or E. coli, is found in
the intestines of humans and other animals and helps
digest food and release vitamins that humans need.
 A fungus is an organism whose cells have nuclei, rigid
cell walls, and no chlorophyll and that belongs to the
kingdom Fungi.
 Cell walls act like mini-skeletons that allow fungi to
stand up right.
 A mushroom is the reproductive structure of a fungus.
The rest of the fungus is an underground network of
fibers that absorb food from decaying organisms in the
 Fungi get their food by releasing chemicals that help
break down organic matter, and then absorbing the
 The bodies of most fungi are huge networks of threads
that grow through the soil, dead wood, or other
material on which the fungus is feeding.
 Like bacteria, fungi play an important role in breaking
down the bodies of dead organisms.
 Some fungi, like some bacteria, cause disease. Athlete’s
foot is an example of a condition caused by fungi.
 Other fungi add flavor to food as in blue cheese. The
fungus gives the cheese both its blue color and strong
 Yeasts are fungi that produce the gas that makes bread
 Protists are diverse organisms that belong to the
kingdom Protista.
 Some, like amoebas, are animal-like. Others are
plantlike, such as kelp, and some resemble fungi.
 Most protists are unicellular, microscopic organisms,
including diatoms, which float on the ocean surface.
 Another protist, Plasmodium, is the unicellular
organism that causes the disease malaria.
 From an environmental standpoint, the most
important protists are algae.
 Algae are plantlike protists that can make their own
food using light energy from the sun.
 They range in size from the giant kelp to the
unicellular phytoplankton, which are the initial source
of food in most ocean and freshwater ecosystems.
 Plants are multicellular organisms that make their own
food using light energy from the sun and have cell
 Most plants live on land where they use their leaves to
get sunlight, oxygen, and carbon dioxide from the air.
While absorbing nutrients and water from the soil
using their roots.
 Leaves and roots are connected by vascular tissue,
which has thick cell walls and serves is system of tubes
that carries water and food.
 Plants with no vascular tissue are called nonvascular
 Nonvascular plants lack specialized conducting
tissues, roots, stems, and leaves, so water must move
from the environment throughout the plant.
 Nonvascular plants such as mosses, live in damp
 Gymnosperms are woody vascular seed plants whose
seeds are not enclosed by an ovary or fruit.
 Conifers, such as pine trees, are gymnosperms that
bear cones.
 Much of our lumber and paper comes from
 Gymnosperms have several adaptations that allow
them to live in dry conditions.
• They can produce pollen, which protects and moves
sperm between plants.
• These plants also produce seeds, which protect
developing plants from drying out.
• A conifer’s needle-like leaves also lose little water.
 Angiosperms are flowering plants that produce seeds
within fruit. Most land plants are angiosperms.
 The flower is the reproductive structure of the plant.
Some angiosperms, like grasses, have small flowers,
that use wind to disperse their pollen.
 Other angiosperms have large flowers to attract insects
and birds. Many flowering plants depend on animals
to disperse their seeds and carry their pollen.
 Most land animals are dependent on flowering plants.
 Most of the food we eat, such as wheat, rice, beans,
oranges, and lettuce comes from flowering plants.
 Building materials and fibers, such as oak and cotton,
also come from flowering plants.
 Animals cannot make their own food. They must take
it in from the environment.
 Animal cells have no cell walls, so their bodies are soft
and flexible. Although, some animals have evolved
hard skeletons against which their muscles can pull to
move their bodies.
 As a result, animals are much more mobile than
plants. All animals move around in their environment
during at least one stage in their lives.
 Invertebrates are animals that do not have
 Many live attached to hard surfaces in the ocean and
filter their food out of the water, such as corals, various
worms, and mollusks.
 These organisms are only mobile when they are larvae.
At this early stage in their life they are part of the
ocean’s plankton.
 Other invertebrates, including squid in the ocean and
insects on land, actively move in search of food.
 More insects exist on Earth than any other type of
 Insects are successful for many reasons: they have a
waterproof external skeleton, can move and reproduce
quickly, most insects can fly, and their small size
allows them to live on little food and to hide from
enemies in small places.
 Many insects and plants have evolved together and
depend on each other to survive.
 Insects carry pollen from male fruit parts to fertilize a
plant’s egg, which develops into fruits such as
tomatoes, cucumbers, and apples.
 Insects are also valuable because they eat other insects
that we consider to be pests.
 However, insects and humans are often enemies.
 Bloodsucking insects transmit human diseases such as
malaria, sleeping sickness, and West Nile virus.
 Insects do most damage indirectly by eating our crops.
 Vertebrates are animals that have a backbone, and
includes mammals, birds, reptiles, amphibians, and
 The first vertebrates were fish, but today most
vertebrates live on land.
 The first land vertebrates were reptiles. These animals
were successful because they have an almost
waterproof egg which allows the egg to hatch on land,
away from predators in the water.
 Birds are warm-blooded vertebrates with feathers.
They keep their hard-shelled eggs and young warm
until they have developed insulating layers of fat and
 Mammals are warm-blooded vertebrates that have fur
and feed their young milk.
 Birds and mammals have the ability to maintain a high
body temperature which allows them to live in cold
areas, where other animals cannot live.
1.2 Section Review Questions
Describe how animals and angiosperms depend on
each other. Write a short paragraph to explain your
2. Describe the importance of protists in the ocean.
3. Name the four kingdoms of life, and give two
characteristics of each.
4. Explain the importance of bacteria and fungi in the
 Identify the main criterion that Linnaeus used to
classify organisms.
 List the characteristics that distinguish between the
 Explain why taxonomic systems continue to change.
Classifying Organisms
 Every year thousands of new species are discovered all
over the world, both on land and in water.
 Scientists attempt to classify these organisms in
meaningful ways.
 Over the centuries, the classifications systems have
 Taxonomy is the science of describing, naming, and
classifying organisms.
 Any particular group within a taxonomic system is
called a taxon.
 The Greek philosopher Aristotle, classified organism
into two taxa-either plants or animals over 2,400 years
 Early naturalists realized that common names would
not work to identify organism, because these names
varied from place to place.
 Ladybugs or Ladybirds?
The Linnaean System
Developed by Carolus Linnaeus over 200 years ago
Grouped organisms according to their form and structure.
His system had seven levels.
Modern Linnaean System
Binomial Nomenclature
 Organisms were given a species name or scientific
name with two parts: the genus name followed by a
species identifier.
 This two part naming is known as binomial
 Examples
 Humans – Homo sapiens
 Gorillas – Gorilla gorilla
 Scientists refer to variations of species that live in
different geographic areas as subspecies
 Phylogenetics – the analysis of evolutionary or
ancestral relationships among taxa
 Phylogenetic diagram (phylogenetic tree) – looks like a
family tree and has a branching pattern that indicates
how closely related a subset of taxa are thought to be.
Phylgenetic Tree
 Cladistics – a system of phylogenetic analysis that uses
shared and derived characters as the only criteria for
grouping taxa
 Cladogram is a type of phylogenetic diagram
Modern Classification
 Domain
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
 Three domains
 Archaea
 Bacteria
 Eukarya
 Small, single-celled prokaryotes
 Cell membranes that contain peptidoglycan
 Reproduce by binary fission
 Prokaryotes
 Extremophiles
 Cell membranes that do not contain peptidoglycan
Domain Eukarya
 Have membrane bound organelles and nucleus
 Larger cells
 Can be unicellular or multicellular
Kingdom Eubacteria (Bacteria)
 “true bacteria”
 Gram negative, Gram positive
Kingdom Archaebacteria
 “ancient bacteria”
 Most live in extreme environments
 Autotrophs
Kingdom Protista
 Eukaryotes that are not plants, animals, or fungi
 Most are unicellular
Kingdom Fungi
 Eukaryotes
 Heterotrophic
 Unicelluar and multicellular
 Absorb rather than ingest nutrients
Kingdom Plantae
 Eukaryotes
 Multicellular
 Except for a few parasitic varies they are autotrophs
 Photosynthetic
 Develop from embryos
 Most live on land
Indian Pipe (Monotropa uniflora)
Kingdom Animalia
 Eukaryotes
 Multicellular
 Heterotrophs
 Develop from embryos
 Most have symmetrical body organization
 Move around during one stage of life
Review Questions
 List and briefly describe the kingdoms of
 Why are protists, fungi, plants, and animals under one