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Section 1: Ecosystems: Everything is Connected
Objectives:
 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
A. Definitions
1. Ecosystem: a community of organisms and their abiotic environment; all the organisms
living in an area together with their physical environment
2. Biotic factor: an environmental factor that is associated with or results from the activities of
living organisms
3. Abiotic factor: an environmental factor that is not associated with the activities of living
organisms
4. Organism: a living thing; anything that can carry out life processes independently
5. Species: a group of organisms that are closely related and can mate to produce fertile
offspring; also the level of classification below genus and above subspecies
6. Population: a group of organisms of the same species that live in a specific geographical
area and interbreed
7. Community: a group of various species that lie in the same habitat and interact with each
other
8. Habitat: the place where an organism usually lives
B. Ecosystems are connected
1. Seemingly unconnected things in nature can be linked together in a complex web.
Example: Gypsy moths kill oak trees. Scientists removed mice, which eat gypsy moths from
an oak forest. Young moths increased dramatically. Scientists then added acorns, which
attracted mice. The mice population increased and the gypsy moth population decreased.
Acorns also attracted deer, which carry ticks. Ticks infested the mice and picked up the
organism that causes Lyme disease from the mice. Ticks can bite and infect humans.
2. Oak forest ecosystem – mice, deer, moths, oak trees, and ticks
3. Other ecosystems examples – coral reef, vacant lot
4. People often think of ecosystems as isolated from each other, but ecosystems do not have
clear boundaries.
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C. The components of an Ecosystem
1. In order to survive, ecosystems need five basic components:
a. energy – majority comes from the sun
b. mineral nutrients
c. water
d. oxygen
e. living organisms
2. Biotic and Abiotic Factors
a. Biotic factors are the living and once living parts of an ecosystem, which includes
dead organisms, dead parts of organisms, such as leaves, and the organisms’ waste
products.
b. Abiotic factors are the nonliving parts of the ecosystem, which includes air, water,
rocks, sand, light, and temperature.
3. Various levels to the organization of living things:

Biosphere – ecosystem – community – population – organism
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4. Organisms – an individual living thing
a. History Connection: Swedish naturalist, Carolus Linnaeus, was the father of the
binomial system used to identify species today. A species has a two-part Latin name:
genus and species.
b. All humans belong to the species Homo sapiens.
5. Populations
a. Important characteristic of a population – members usually breed with one another
rather than with members of other populations
b. example: bison in the same herd will mate or wildflowers in the same field will
pollinate with others nearby
6. Communities
a. An organism does not live alone and neither does a population. Every population is
part of a community.
b. Example: Pond community includes all the populations of plants, fish, and insects
that live in and around the pond.
c. Most obvious difference between communities – types of species in them
d. Land communities are often dominated by a few species of plants. Example:
Colorado forest – ponderosa pine trees ; Louisiana swamp – bald cypress trees
C. Habitat
1. Examples of different habitats: pine forest for squirrel; rain forest for howler monkey;
desert for cactus; pond for waterlily; damp forest floor for salamander
2. You can think of a habitat as an organism’s address.
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3. Every habitat has specific characteristics that organisms need to survive. If any of these
factors change, then the habitat changes.
4. Organisms tend to be very well suited to their habitats and cannot survive for long periods
of time away from their natural habitat.
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Section 2: Evolution
Objectives:
 Explain the process of evolution by natural selection
 Explain the concept of adaptation
 Describe the steps by which a population of insects becomes resistant to a
pesticide
1. Definitions:
a. natural selection: the process by which individuals that have favorable variations and
are better adapted to their environment survive and reproduce more successfully
than less well adapted individuals do
b. evolution: a change in the characteristics of a population from one generation to the
next; the gradual development of organisms from other organisms since the
beginnings of life
c. adaptation: the process of becoming adapted to an environment; an anatomical,
physiological, or behavioral change that improves a population’s ability to survive
d. artificial selection: the selective breeding of organisms (by humans) for specific
desirable characteristics
e. resistance: in biology, the ability of an organism to tolerate a chemical or diseasecausing agent
2. Organisms tend to be well suited to where they live and what they do. How do they become
so well suited to their environments?
a. Evolution is a change in a genetic characteristic of a population from one generation
to another. Evolution can happen in several ways:
 Natural selection
 Artificial Selection
 Resistance
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3. Evolution by Natural Selection

In 1859, English naturalist Charles Darwin proposed an answer. He observed that
organisms in a population differ slightly from each other in form, function, and
behavior. His case study is called Darwin’s Finches.
o Some of the difference is hereditary that is passed from parent to offspring.
o Darwin also believed that the environment played a very strong role over which
offspring would survive.
o Darwin used the term natural selection to describe the unequal survival and
reproduction that results from the presence or absence of particular traits.

He proposed that natural selection causes characteristics of populations to change.
o Darwin thought that nature selects the traits that will go on for survival.
o Example: Species adapt and those that adapt survive.
Deer in north have thicker fur than deer in South: Believed that southern deer strayed from
group and only the deer with the thicker fur survived the winters in the north. These deer
kept having offspring with thicker fur.
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o Darwin’s finches: The finches that survived the drought survived because their
bills were stronger and longer. They could dig for food, so their offspring had
larger bills. They survived.

Organisms evolve adaptations to other organisms as well as to their physical
environment. The process of two species evolving in response to long-term interactions
with each other is called coevolution.
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o Example: The Hawaiian honeycreeper used its curved beak to sip nectar from a
lobelia flower which has evolved structures that ensure the bird gets pollen on it
head.
4. Evolution by Artificial Selection
a. Many populations of plants and animals do not live in the wild by instead are cared
for by humans.
People control how these plants and animals reproduce and
therefore how they evolve.
b. The selective breeding of organisms by humans for specific characteristics is called
artificial selection.
c. Examples: Humans have bred ancestors of today’s wolves to produce the variety of
dog breeds we have today and saved seeds from the largest, sweetest fruits and most
nutritious grains.
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5. Evolution of Resistance
a. Sometimes humans cause populations of organisms to evolve unwanted adaptations.
Examples: insect pests resistant to pesticides or bacterial resistant to antibiotics
b. Resistance is the ability of one or more organisms to tolerate a particular chemical
designed to kill it.
c. Survivors happen to have a gene that protects them from the pesticide and this gets
passed on to their offspring.
d. The faster an organism reproduces, the faster its populations can evolve.
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Section 3: The Diversity of Living Things
Objectives:
 Name the six kingdoms of organisms and identify two characteristics of each
 Explain the importance of bacteria and fungi in the environment
 Describe the importance of protists in the ocean environment
 Describe how angiosperms and animals depend on each other
 Explain why insects are such successful animals
1. Definitions:
a. bacteria: extremely small, single-celled organisms that usually have a cell wall and
reproduce by cell division
b. fungus: an organism whose cells have nuclei, rigid cell walls, and no chlorophyll and
that belongs to the kingdom Fungi
c. protist: an organism that belongs to the kingdom Protista
d. gymnosperm: a woody vascular seed plant whose seeds are not enclosed by an ovary
or fruit
e. angiosperm: a flowering plant that produces seeds within a fruit
f. invertebrate: an animal that does not have a backbone
g. vertebrate: an animal that has a backbone; includes mammals, birds, reptiles,
amphibians, and fish
2. The Diversity of Living Things
a. Scientist classify organisms into six kingdoms based on different characteristics.
1. Archaebacteria
2. Eubacteria
3. Fungi
4. Protista
5. Plantae
6. Animalia
b. The cells of animals, plants, fungi, and protists contain a nucleus (membrane bound
organelle containing the cell’s genetic material).
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c. A characteristic shared by bacteria, fungi, and plants is the cell wall (a structure that
surrounds a cell and provides it with rigid support).
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1. Bacteria
a. Characteristics:
1. single-celled organisms
2. lack nuclei
3. reproduce by dividing in half
4. usually have cell walls
5. live in every habitat on Earth (hot springs to animal bodies)
b. Two main kinds
1. Archaebacteria – live in extreme environments; methanogens,
thermophiles, halobacteria
2. Eubacteria – most bacteria, including disease-causing and soil-dwelling
c. Role in environment
1. break down the remains and wastes of other organisms and return nutrients
to soil
2. recycle mineral nutrients, such as nitrogen and phosphorous
3. converting nitrogen in the air into a usable form for plants – Nitrogen is a
main component in proteins and genetic material.
4. Escherichia coli (E. coli) – found in the human intestine – helps digest food
and release vitamins that humans need
2. Fungi
a. Characteristics
1. Have nuclei, cell walls, and no chlorophyll (the pigment that makes plants
green)
2. Absorb their food from their surroundings by releasing chemicals that help
break down organic matter (decaying organisms)
3. Huge network of threads that grow through the soil, dead wood, or other
material
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b. Examples
1. Yeast
2. Mushrooms
3. Molds
4. Mildews
c. Roles in Environment
1. Break down the bodies and body parts of dead organisms
2. Some cause disease, such as athlete’s foot
3. Add flavor to food, such as taste of blue cheese
4. Used in cooking, mushrooms for flavor, yeast produces gas that makes
bread rise or used in fermentation process at a brewery
3. Protists
a. Characteristics
1. most are unicellular, but some are multicellular
2. most live in water
b. Examples
1. Amoeba – animallike unicellular organism
2. Diatoms – float on the ocean’s surface
3. Plasmodium – unicellular organism that
causes malaria
4. Algae – plantlike organisms that produce
their own food from the sun’s energy:
kelp, pond “scum”, seaweed,
phytoplankton (initial source of food in
most ocean and freshwater ecosystems)
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4. Plants
a. Characteristics
1. multicellular
2. make their own food by photosynthesis
3. have cell walls
b. Examples
1. lower plants

ferns

mosses
2. trees
3. herbs
4. grasses
c. Plants have a vascular tissue, which is a system of tubes that carry water and food
from the roots to the leaves and act as a support for the plant.
d. Plants have roots that tap mineral and water resources from underground; and
leaves that intercept light, oxygen, and carbon dioxide from the air.
e. Pine trees and other evergreens are common examples of gymnosperms. Pine trees
are called conifers because they bear cones.
f. Gymnosperm adaptations
1. produce pollen – protects and moves sperm between plants
2. produce seeds – protect developing plants from drying out
3. conifer’s needle-like leaves lose little water
g. Most land plants are angiosperms. The flower is the reproductive structure of the
plant.
1. Grasses have small flowers that produce pollen carried by the wind.
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2. Large flowers of other angiosperms attract insects or birds that carry their
pollen to other plants.
h. Most land animals are dependent on flowering plants for food. We eat wheat, rice,
beans, oranges, and lettuce, which come from flowering plants. Building materials
and fibers, such as oak or cotton, also come from flowering plants.
5. Animals
a. Characteristics
1. multicellular
2. no cell walls
3. ingest their food from their environment
4. live on land and in water
b. Two kinds
1. Invertebrates
2. Vertebrates
c. Insects are the most successful type of animal on Earth.
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d. Reasons why insects are so successful:
1. waterproof external skeleton
2. move quickly
3. reproduce quickly
4. most can fly
5. need little food and can hide from enemies in small spaces due to their size
e. Many insects and plants have evolved together and depend on each other to survive.
Example: insect pollination
f. Insects eat other insects that we consider pests.
g. Humans and insects are often enemies. Example: mosquitoes transmit human
disease like malaria, sleeping sickness, and West Nile virus. They also eat our crops.
h. Vertebrate adaptations:
1. amphibians partially aquatic – return to water to lay their eggs
2. reptiles – 1st land vertebrate – have an almost waterproof egg, which allows
the egg to hatch on land away from predators in the water
3. birds – warm-blooded – have hard shell eggs
4. mammals – warm-blooded – have fur and feed their young milk
5. High body temperature allows birds and mammals to live in cold areas,
where other animals cannot survive.
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The Organization of Life
An ecosystem
is made of
biotic factors
abiotic factors
which include
populations
of different
species
which live in
habitats
that form a
community
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