Name __________________________________________
Unit 25 Introduction
Readiness Standard 8.11(B)
Motivation Station: Scientific Fact
In the rainforest, many plants compete for sunlight. For
example, strangler fig seedlings begin growing on other trees,
wrapping roots around the host tree. When the roots reach the
ground, the strangler fig takes root in the soil and grows taller
than the host tree, taking nutrients from the host tree and
growing to the height of the rainforest canopy.
After this lesson I will be able to:
• Investigate how organisms and populations in an ecosystem depend on and may compete for biotic and
abiotic factors such as quantity of light, water, range of temperatures, or soil composition.
Comparative and Descriptive Investigations
Activity 1: Competition in Ecosystems
Organisms are dependent on their ecosystem for survival. Populations within ecosystems compete for the
available resources. A biotic factor is any living or once-living organism in an ecosystem. An abiotic factor is
any nonliving factor in the environment including rocks, air, water, and sunlight.
Follow the directions given by the teacher to learn about competition in ecosystems. Graph the results below.
Without Competition
13
12
12
11
4
Biotic and Abiotic Factors
f a iot
c t ic
or
s
he
r
bi
f a ot
c t ic
or
s
ot
ab
ac
r
he
nt
sh
fo
od
/n
u
tr
w
ie
at
er
f a iot
c t ic
or
ot
s
he
r
bi
f a ot
c t ic
or
s
r
he
r/
sp
ot
te
el
sh
ab
ac
ht
ig
nl
ie
tr
/n
u
od
su
nt
er
at
w
fo
e
1
s
2
1
e
3
2
r/
sp
3
5
ot
4
6
ht
5
7
te
6
8
ig
7
9
el
8
nl
9
10
s
10
su
Number Collected
11
Number Collected
With Competition
13
Biotic and Abiotic Factors
Key
blue – water
green – food/nutrients
yellow – sunlight
orange – shelter/space
red – other abiotic factors
purple – other biotic factors
Compare your results to the results of classmates. What can you conclude about competition in ecosystems?
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How do plants and animals compete differently for resources?
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