communities - Houston ISD
Transcript communities - Houston ISD
Populations & Communities
Investigate and analyze how
organisms, populations, and
communities respond to
What is an organism?
• An individual living thing, such as
a bacterium, protist, fungi, plant,
What is a population?
• A group of one species of organisms
that live together in a certain area.
• Humans living in the city of Houston
• Tree frogs living in a forest
What is a community?
• A group of populations of different
species that interact with one another.
• Populations of tree frogs, snakes, birds,
as well as other animals and plants all
living together on a tropical island
What is an ecosystem?
• Communities in the environment
• Includes abiotic (non-living) and
biotic (living) factors.
Example: the tropical island
How do organisms respond to
• When a rabbit
senses that a
It runs away or hides in a burrow
• When a skunk feels threatened…
It sprays its attacker with a foulsmelling liquid
• When an opossum is attacked…
It curls into a ball, and pretends to
• Plants that grow as vines, such as
pumpkin and ivy, produce tendrils
that can wrap around surfaces
• Roots of
plants tend to
wet soil, while
How do populations respond to
• Predator & prey relationships
• Competition among predators
• Invasive species outcompete
• Asian carp were
Michigan lakes to
• Now introduced
native fish for
Pythons in the Everglades in Florida
How do communities respond to
What happens to
out due to
The Role Microorganisms
11C: Summarize the role of
microorganisms in both maintaining
and disrupting the health of both
organisms and ecosystems.
What is a microorganism?
• Any organism that cannot be seen
without the aid of a magnifying glass
• Examples – bacteria, protists, fungi
• Found in almost every habitat on Earth
How can microorganisms maintain
the health of other organisms?
• Microorganism gains benefits such as
a warm environment to inhabit and
• Animal or plant may gain benefits
such as protection from other
microorganisms or a supply of
enzymes they need but cannot
• Example – bacteria living in guts of
termites & cows to produce enzymes
to digest cellulose
• Example - Fungi & plants form
relationship called mycorrhizae.
• The Fungi collect water & minerals
and deliver them to plant roots
• The Plants provide the fungi with
nutrients made through
• Example – Plants called legumes
contain bacteria of the genus
Rhizobium in structures on their
roots called nodes.
• The Rhizobium fixes atmospheric
nitrogen so that is is available for
plants to use.
How can microorganisms disrupt
the health of organisms?
• Some microorganisms causes diseases
in a host. These microorganisms are
• Pathogens cause a disease by killing
the host cells, releasing toxins, or
interfering with the processes within
the host’s body.
• Caused by at least three species of bacteria
belonging to the genus Borrelia.
• Caused by the bacteria Clostridium tetani.
• Caused by the bacteria Streptococcus
How do microorganisms maintain
the health of ecosystems?
• Microorganisms recycle nutrients.
Decomposers break down organic
matter of dead plants & animals.
• Some bacteria living on the ocean floor
feed on oil that seeps from the ground.
How do microorganisms disrupt
the health of ecosystems?
• Pathogens (microorganisms that
cause disease) can kill off large
numbers of a plant or animal species
that is important to the health of the
• In oak forests, many animals depend
on the acorns that fall each autumn
• What would happen if a pathogen
infected the oak trees and prevented
them from producing acorns?
Caused by the fungus
• Algal blooms in aquatic ecosystems such as
oceans can block sunlight and cause death of
plants along with organisms that eat the
• Bacteria populations rise because of an
increase in food supply of dead organic
• Oxygen levels drop because of the bacteria
population increase. Fish and other organisms
then die. These areas are called dead zones.