Science
8
Science – Grade 8
Quarter 4 – Module 10: Levels of Biodiversity
First Edition, 2020
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Published by the Department of Education - Schools Division of Pasig City
Development Team of the Self-Learning Module
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Science
8
Quarter 4
Self-Learning Module 15
Energy Flow in an Ecosystem
Introductory Message
For the Facilitator:
Welcome to the Science 8 Self-Leaning Module the Levels of Biodiversity!
This Self-Learning Module was collaboratively designed, developed and
reviewed by educators from the Schools Division Office of Pasig City headed by its
Officer-in-Charge Schools Division Superintendent, Ma. Evalou Concepcion A.
Agustin, in partnership with the City Government of Pasig through its mayor,
Honorable Victor Ma. Regis N. Sotto. The writers utilized the standards set by the K
to 12 Curriculum using the Most Essential Learning Competencies (MELC) in
developing this instructional resource.
This learning material hopes to engage the learners in guided and independent
learning activities at their own pace and time. Further, this also aims to help learners
acquire the needed 21st century skills especially the 5 Cs, namely: Communication,
Collaboration, Creativity, Critical Thinking, and Character while taking into
consideration their needs and circumstances.
In addition to the material in the main text, you will also see this box in the
body of the module:
Notes to the Teacher
This contains helpful tips or strategies that
will help you in guiding the learners.
As a facilitator you are expected to orient the learners on how to use this
module. You also need to keep track of the learners' progress while allowing them to
manage their own learning. Moreover, you are expected to encourage and assist the
learners as they do the tasks included in the module.
For the Learner:
Welcome to the Science 8 Self-Leaning Module on the Levels of Biodiversity!
This module was designed to provide you with fun and meaningful
opportunities for guided and independent learning at your own pace and time. You
will be enabled to process the contents of the learning material while being an active
learner.
This module has the following parts and corresponding icons:
Expectations - This points to the set of knowledge and skills
that you will learn after completing the module.
Pretest - This measure your prior knowledge about the lesson
at hand.
Recap - This part of the module provides a review of concepts
and skills that you already know about a previous lesson.
Lesson - This section discusses the topic in the module.
Activities - This is a set of activities that you need to perform.
Wrap-Up - This section summarizes the concepts and
application of the lesson.
Valuing - This part integrates a desirable moral value in the
lesson.
Posttest – This measure how much you have learned from the
entire module.
EXPECTATIONS
From the previous lesson, you have learned that the stability of the ecosystem
is depending on how high or low the biodiversity. The Higher the biodiversity, the
higher the stability or the ecosystem, meaning, the higher the chance of survival. In
vice versa, the lower the biodiversity, the lower the chance of survival in an ecosystem
since the stability is low.
An ecosystem must contain both biotic (living things) and abiotic (non-living)
factor to sustain its stability or mode of balance where different organisms have a
shelter and enough source of food to ensure the survival of their species. But how
does the interaction between biotic and abiotic factor helps maintain the balance in
the ecosystem?
For this lesson, we are going to learn about the energy pyramid and on how
energy transfer takes place through the trophic levels.
At the end of the lesson, learners are expected to:
1. Describe the flow of energy transfer in an ecosystem;
2. Construct a food pyramid and interpret how energy transfer takes place
through the trophic levels; and
3. Recognize the importance of energy transfer in an ecosystem.
PRETEST
Instructions: Read each item carefully. Then, choose the letter of the correct
answer.
1. It refers to a graphical representation, showing the flow of energy at each trophic
level in an ecosystem.
a. trophic level
b primary consumers
c. producers
d. energy pyramid
2. What do you call the hierarchal levels in an ecosystem, in which organisms
share the same function and nutritional relationship within the food chain?
a. trophic level
b. primary consumers
c. primary consumers
d. energy pyramid
3. The first order consumers include the producers. Producers are also called
autotrophs. What do autotrophs mean?
a. organisms that eat plants
b. organisms that depend on other organisms for food
c. organisms that can manufacture their own food
d. organisms that eat meat
4. A 10 percent law of energy flow states that when the energy is passed on from
one trophic level to another. Suppose the producers store energy of 30, 000
kcal/m2/year, how much energy will go to the first consumers?
a. 30 kcal/m2/year
b. 300 kcal/m2/year
c. 30, 000 kcal/m2/year
d. 3, 000 kcal/m2/year
5. Human plays an important role in maintaining the healthy environment. Which
of the following human activities will give a positive impact to our environment?
a. Deforestation
b. Be a responsible steward of this planet by protecting wildlife.
c. Throwing garbage anywhere
d. Ignoring some campaign on environmental protection.
RECAP
In your previous grade level, you learned about the food chain and the food
web. Describe the food chain below by following the arrows.
Figure A. Food Chain
https://byjus.com/biology/energy-flow-in-ecosystem/
LESSON
A food chain is a linear sequence of organisms through which nutrients and
energy pass as one organism eats another.
All organisms are dependent to one another and to the environment where it
belongs in order to survive. The process of who will be eaten and who will eat
established the balance and flow of energy in an ecosystem. The one that being eaten
gives energy to those dependent on them and eventually the one receives the energy
will bring back the energy to the ecosystem the time it decomposes.
Figure B. Energy Pyramid
https://en.wikipedia.org/wiki/Ecological_pyramid
An energy pyramid (sometimes called a trophic pyramid or an ecological
pyramid) is a graphical representation, showing the flow of energy at each trophic
level in an ecosystem.
Trophic Level – refers to the hierarchal levels in an ecosystem, in which
organisms share the same function and nutritional relationship within the food
chain. The width of each bar represents the units of energy available within each
trophic level; the height is always the same. The flow of energy moves through the
layers of the energy pyramid from the bottom-up and is gradually reduced as energy
is used up by the organisms at each level.
The first trophic level is the base of the energy pyramid which indicates the
energy available within the PRODUCERS. Producers, also known as autotrophs, are
organisms which create their own food by taking their energy from non-living sources
of energy. Plants being the producers absorb sunlight with the help of the
chloroplasts and a part of it is transformed into chemical energy in the process of
photosynthesis.
The second trophic level consists of PRIMARY CONSUMERS. These are the
herbivores that feed solely on primary producers. The energy stored in various
organic products in the plants and passed on to the primary consumers in the food
chain when the HERBIVORES consume the plants as food. Then conversion of
chemical energy stored in plant products into kinetic energy occurs, degradation of
energy will occur through its conversion into heat.
The third trophic level are the secondary consumers. When these herbivores
are ingested by carnivores or omnivores of the first order (secondary consumers)
further degradation will occur. CARNIVORES are also known as “meat eater”, is an
animal whose food and energy requirements derive solely from animal tissue or meat.
OMNIVORES are an animal that has the ability to eat and survive on both
plant and animal matter. Carnivores and omnivores are HETEROTROPHS – an.
organisms that obtain their nutrition from the other organisms.
Finally, when tertiary consumers consume the carnivores or the omnivores,
energy will again be degraded. Thus, the energy flow is unidirectional in nature.
The 10 percent law of energy flow states that when the energy is passed on
from one trophic level to another, only 10 percent of the energy is passed on to the
next trophic level.
Figure C. Trophic Level
https://www.khanacademy.org/science/ap-biology/ecology-ap/energy-flowthrough-ecosystems/a/food-chains-food-webs
As an example, suppose that the primary producers of an ecosystem store
20,000 kcal/m2/year of energy as biomass. This is also the amount of energy per
year that's made available to the primary consumers, which eat the primary
producers. The 10% rule would predict that the primary consumers store only 2,000
kcal/ m2/year of energy in their own bodies, making energy available to their
predators—secondary consumers—at a lower rate.
The energy flow in the ecosystem is important to maintain an ecological
balance. The producers synthesize food by the process of photosynthesis. A part of
the energy is stored within the plants. The remaining energy is utilized by the plants
in their growth and development. This stored energy is transferred to the primary
consumers when they feed on the producers. This energy is further passed on to the
secondary consumers when they feed on the primary consumers, and so on.
ACTIVITY 1
Matching Type
Match the terms in Column A with their descriptions in Column B. Write the
letters only.
A
_______1. Producers
B
A. Linear sequence of organisms
through which nutrients and energy
pass as one organism eats another.
________2. Energy pyramid
________3. Omnivores
B. Refers to the hierarchal levels in an
ecosystem.
C. The base of the energy pyramid
________4. First trophic level
D. Also known as autotrophs.
________5. Carnivores
E. Consists of primary consumers.
________6. Trophic level
F. Plant eaters
________7. Second trophic level
G. Secondary consumers.
________8. Herbivores
H. Meat eaters
________9. Food chain
I. Feed on both plants and animals
________10. Third trophic level
J. A graphical representation, showing
the flow of energy at each trophic level
in an ecosystem.
ACTIVITY 2
Energy Pyramid
Complete the food pyramid by supplying the correct components. Use the
word bank below for your answer.
Producers
100 kcal/m2/yr.
Primary consumers
Eagle
Sun
1, 000 kcal/m2/yr.
Mouse
Secondary consumers
Grasshopper
Tertiary consumers
WRAP-UP
ACTIVITY 3
Fill in blanks.
Fill in the blanks with the correct words to complete the paragraph. Use the picture
as your guide.
Figure C. Energy Flow in an Ecosystem
https://sites.google.com/a/canacad.ac.jp/sl-hl-2-biology-2-ferguson/12ecology/4-2-energy-flow
The1. ________________ in the ecosystem is important to maintain an ecological
balance. The 2. _________________synthesize food by the process of 3. ______________.
A part of the energy is stored within the plants. The remaining energy is utilized by
the plants in their growth and development. This stored energy is transferred to the
4.________________ when they feed on the producers. This energy is further passed
on to the 5. _________________when they feed on the primary consumers, and so on.
VALUING
One factor in maintaining the ecological balance or stability is the energy flow
in an ecosystem. Human as component of ecosystem plays a major role in
maintaining a healthy environment.
How will explain the saying “Be a responsible steward of this planet” in your
word?
.
POSTTEST
Instructions: Read each item carefully. Then, choose the letter of the correct answer.
1. It refers to a graphical representation, showing the flow of energy at each trophic
level in an ecosystem.
a. trophic level
b. energy pyramid
c. producers
d. biodiversity
2. What do you call the hierarchal levels in an ecosystem, in which organisms
share the same function and nutritional relationship within the food chain?
a. secondary consumers
b. energy pyramid
c. primary consumers
d. trophic level
3. The first order consumers include the producers. Producers are also called
autotrophs. What do autotrophs mean??
a. organisms that can manufacture their own food
b. organisms that depend on other organisms for food
c. organisms that eat plants
d. organisms that eat meat
4. A 10 percent law of energy flow states that when the energy is passed on from
one trophic level to another. Suppose the producers store energy of 30, 000
kcal/m2/year, how much energy will go to the first consumers?
a. 30 kcal/m2/year
b. 300 kcal/m2/year
c. 3, 000 kcal/m2/year
d. 3, 300 kcal/m2/year
5. Human plays an important role in maintaining the healthy environment. Which
of the following human activities will give a positive impact to our environment?
a. Be a responsible steward of this planet by protecting wildlife.
b. Deforestation
c. Throwing garbage anywhere
d. Ignoring some campaign on environmental protection
REFERENCES
a. Internet Sources
https://www.globalissues.org/article/170/why-is-biodiversity-important-who cares
https://education.seattlepi.com/biodiversity-high-places-but-low-others-4475.html
https://byjus.com/biology/energy-flow-in-ecosystem/
https://en.wikipedia.org/wiki/Ecological_pyramid
https://www.khanacademy.org/science/ap-biology/ecology-ap/energy-flowthrough-ecosystems/a/food-chains-food-webs
https://sites.google.com/a/canacad.ac.jp/sl-hl-2-biology-2-ferguson/12ecology/4-2-energy-flow
https://en.wiki pedia.org/wiki/Ecological_pyramid
https://www.khanacademy.org/science/high-school-biology/hs-ecology/trophiclevels/a/energy-flow-and-primary-productivity?modal=1