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population
community
ecosystem
biosphere
SCIENCE STAAR NOTEBOOK
BIOLOGY - CATEGORY 5
Interdependence within
Environmental Systems
Change in Ecosystems over Time

Succession- transition in
species composition over time;
can take years or decades, and
usually after a disturbance

Primary Succession- Begins
with a virtually lifeless area
without soil, then comes…
1) bacteria
2) lichens & mosses
3) grasses
4) shrubs
5) Trees
(Bacteria, lichens, and mosses
make soil for the other
plants)

Secondary Successionsuccession in a habitat that
has previously supported
growth.
The picture above is an example of
secondary succession.
Example of Succession
Glacier Bay
An example of
primary succession
is the receding
glacier of Glacier
Bay, Alaska. Land
is continually being
exposed and
colonized as the
face of the glacier
moves back.
Photo: www.usastatestravel.com
STAAR Question
Succession can lead to….
species diversity
greater biodiversity = greater stability

Greater biodiversity
offers:
– more food
resources
– more habitats
– more resilience
in face of
environmental change
Diversity can lead to…
Better Adaptations

Examples:
- Plants deep in the rain
forest with larger leaves
can capture more
sunlight for
photosynthesis.
- Birds on the
Galapagos Islands with
pointy beaks can reach
in deeper holes for
food.
- Snow shoe hare can
easily hide from their
predators because of
their camouflage.
Photo: http://www.wild-facts.com/tag/snowshoe-hare-facts
/
Interactions in an Ecosystem:
Symbiosis

Symbiosis: the relationship organisms have with each other.

Examples:
– Parasitism – one organism, the parasite, benefits while the other
organism, the host, is hurt. (not necessarily killed)
 Ex: a tick feeding on the blood of a dog
– Commensalism – when one organism benefits and the other organism
is not effected.
 Ex: sea anemone rides on the shell of crab for a free ride
– Mutualism – both organisms benefit.
 Ex: an orchid being pollinated by a nectar collecting wasp
– Predation – one animal hunts and eats another animal or organism.
STAAR Question
Interactions in an Ecosystem:
Food Chains, Food Webs, and Pyramids
 To
illustrate the flow of energy in an
ecosystem we use food chains, food
webs, and pyramids.
– The consumers in a food chain:
–Carnivore – eats meat
–Herbivore – eats plants
–Omnivore – eats plants and meat
Interactions in an Ecosystem:
Food Chains, Food Webs, and Pyramids
The sun is the ultimate source of energy.
 The sun drives the flow of energy in an ecosystem.
 Trophic levels – different feeding levels of an ecosystem.
As you go up the different trophic levels energy decreases.


Organisms lose energy in the form of HEAT.
sunlight
producer
consumer 1
consumer 2
Interactions in an Ecosystem:
Food Chains, Food Webs, and Pyramids
The arrows in a food chain point in a
direction of energy flow.
Chicken
Human
Interactions in an Ecosystem:
Food Chains, Food Webs, and Pyramids

Test Taking Tip:
– Use a simple numbering system
to answer test questions!
3
2
 Place a P on the producer and count
upwards once for each arrow.
 There should be a 1 on the primary
consumer; 2 on the secondary
consumer; a 3 on the tertiary
consumer.
1
– This method will work every time
as long as you start counting with
a P on the producer.
– DON’T FORGET THAT PLANTS
ARE PRODUCERS.
P
1
2
2
3
1, 2
P
STAAR Question
Interactions in an Ecosystem:
Food Chains, Food Webs, and Pyramids
Pyramids show the amount of energy at
each trophic (feeding) level.
 Producers are usually at the bottom
because they are the most abundant and
have the most energy. But why?????

STAAR Question
The Texas blind salamander (Eurycea rathbuni) lives in the Edwards
Aquifer region around San Marco. Along with other species the salamander
lives in total darkness in the underground crevices and caves of the aquifer
region. The table lists some of the organisms that live in this environment
and their food sources.
In an energy pyramid for these aquifer cave dwellers, which of the
following would be placed at the bottom?
A Snails
B Blind Shrimp
C Protozoa
D Texas blind salamanders
Long-Term Survival
The long-term
survival of a species
is dependent on the
changes of
resources in different
trophic levels.
 When one level is
affected the other
parts of the
ecosystem are
affected as well.

X
X
X
X
Bacteria
 Some bacteria benefit humans
 Helps with digestion and vitamin
absorption
 Aids with fermentation of
cellulose in a cows digestive
system
 Some bacteria are harmful
 Causes dental cavities
 Cooking food properly helps to
protect against some harmful
bacteria (ex: salmonella in
chicken)
Salmonella attacking a
cultured human cell.
 Some bacteria are
decomposers
 Some bacteria are used to
produce foods such as yogurt,
cheese, and pickles
 There is a multitude of
bacteria. Most do not have a
direct effect on humans
STAAR Question
Bacteria are present in the digestive tract of some
herbivores. The bacteria break down plant cellulose,
making it possible for the herbivore to digest plant
material. These bacteria live in a stable environment with
sufficient food and water. The herbivore and the bacteria in
this relationship –
A. benefit each other
B. compete for survival
C. are producers
D. are secondary consumers
Carbon Cycle
CO2 in Atmosphere
animal respiration
factory
soil and
organism
respiration
assimilation
by plants
plant respiration
photosynthesis
by algae
respiration
by algae
and aquatic
animals
litter
limestone
decomposition
fossil fuels
coal, gas, petroleum
oceans,
lakes
STAAR Question
NITROGEN CYCLE
Simplified
Free N2 in
Atmosphere
denitrifying
bacteria
RIP
Organic
material
nitrogen-fixing
bacteria
NITRATES
STAAR Question
Look
carefully,
the
answer is
in the
picture!!
Environmental Stability
The cycling of all these substances and
nutrients helps maintain the ecosystem,
and if humans or natural occurrences
effect any part of those it can effect the
availability of the resources.
 Recycling: use many times = less waste

STAAR Question
The overgrowth of algae poses a major problem
for coral reefs. Intensive fishing is one factor that
contributes to algae overgrowth because it does
which of the following?
A Allows more sunlight to be available to algae
B Inhibits the spread of pathogens in algae
colonies
C Reduces the number of organisms that feed on
algae
D Increases the competition between different
algae species