This is the Grade 8 Science self-learning module for Quarter 4, Module 9: Cycling of Materials in the Ecosystem. It was developed by DepEd Caraga Region (Alternative Delivery Mode, First Edition, 2020) for learners studying at home or in school. After working through it, learners should be able to name the processes in the water cycle, the oxygen-carbon dioxide cycle, and the nitrogen cycle, and explain how materials move through an ecosystem.
On this page 6 sections
What learners will learn
The module has one lesson, Lesson 1: Cycling of Materials in the Ecosystem. After going through it, learners are expected to:
- Identify the processes involved in the cycling of materials in the ecosystem, such as the water cycle, the oxygen-carbon dioxide cycle, and the nitrogen cycle.
- Explain how materials cycle in an ecosystem (MELC Week 9, S8LT-IVi-23).
Why materials must be recycled
The elements that living things need flow from the non-living (abiotic) parts of the environment, such as soil, water, and air, to the living (biotic) parts, such as plants and animals, and back again. These elements are used in metabolism, in forming amino acids, in respiration, and in building tissues. Because the supply is limited, living things can survive only if these materials are recycled continuously.
The three cycles in this module
Water cycle
The water cycle, also called the hydrological cycle, is the continuous movement of water through the atmosphere, land, and bodies of water. Energy from the sun drives it.
| Process | What happens |
|---|---|
| Evaporation | Water in oceans, lakes, streams, and even soil changes from liquid to water vapor and rises into the air. |
| Transpiration | Water taken in by plant roots moves up to the leaves and escapes as water vapor through the stomata (tiny openings in leaves). |
| Condensation | Water vapor cools in the troposphere and turns back into liquid droplets on dust, smoke, and sea salt particles, forming clouds. |
| Precipitation | Water falls back to Earth because of gravity as rain, snow, hail, fog, or sleet. In the Philippines, most precipitation is rain. |
| Infiltration | Some water seeps into the soil and becomes groundwater stored in aquifers, underground rock layers that can be reached by wells. |
| Surface runoff | Water that cannot soak into the ground flows over the land into lakes, rivers, and the ocean, where most of Earth’s water is stored. |
Oxygen-carbon dioxide cycle
This cycle depends on two processes:
- Photosynthesis: Plants use the sun’s energy to combine water and carbon dioxide into sugar. They give off oxygen through the stomata, where carbon dioxide enters.
- Respiration: Animals take in oxygen, and their cells use it to break down sugar for energy. They give off carbon dioxide, which plants use again.
The module also links this cycle to everyday life. Deforestation and the burning of fossil fuels add carbon dioxide to the air and contribute to global warming, an increase in Earth’s air temperature. Trees absorb carbon dioxide, so planting trees helps reduce it.
Nitrogen cycle
Earth’s atmosphere is nearly 78% nitrogen gas, but plants and animals cannot use it in that form. It must first be changed into usable forms such as nitrates, nitrites, and ammonium. The module describes five processes, which do not always happen in order:
- Nitrogen fixation: Nitrogen gas is changed into nitrates or ammonia. Lightning does this during thunderstorms. Bacteria do most of it, about 90%, including bacteria that live on the roots of legumes such as the mongo plant.
- Nitrogen assimilation: Plants absorb nitrates from the soil through their roots and use them to make proteins and nucleic acids.
- Ammonification: When organisms die or release waste, fungi and bacteria break down the remains and return nitrogen to the environment as ammonia or ammonium.
- Nitrification: Soil bacteria change ammonia into nitrites and then into nitrates, which plants can use.
- Denitrification: Bacteria in soil change nitrates back into nitrogen gas, returning it to the atmosphere.
How to use this module
The module follows the usual parts of a DepEd self-learning module. Write all answers on a separate sheet of paper, not on the module.
- What I Know: a 15-item pretest to check what you already know.
- What’s In: Activity 1 (Arrange Me!), a quick review of energy flow from Module 8.
- What’s New: Activity 2 (Where Do I Belong?), sorting processes into the three cycles.
- What is It: the main discussion of the three cycles.
- What’s More: Activities 3 to 7, including matching water cycle processes, labeling the water cycle and nitrogen cycle diagrams, and completing an oxygen-carbon dioxide concept map.
- What I Have Learned: a 10-item fill-in-the-blanks review.
- What I Can Do: Activity 8 (Let’s Combine!), drawing a small ecosystem from your surroundings that shows all three cycles.
- Assessment: a 15-item post-test.
- Additional Activities: Activity 9 (Share Us), on why planting trees matters and how farmers can farm without harming the environment.
Learners: Take the pretest first, then go through each part in order. Use the answer key honestly, only after you have answered.
Parents: Help your child find a quiet place to work, and ask the teacher if a task is unclear.
Teachers: Written explanations and the drawing task are scored with 0-to-3 rubrics printed in the module. The answer key at the end covers the pretest, activities, and post-test.
Frequently asked questions
What grade and quarter is this Science module for?
It is for Grade 8 Science, Quarter 4, Module 9. It covers the MELC for Week 9, code S8LT-IVi-23.
What cycles does the module cover?
It covers the water cycle, the oxygen-carbon dioxide cycle, and the nitrogen cycle, and explains how each moves materials between living and non-living parts of an ecosystem.
Does the module have an answer key?
Yes. The answer key at the end covers the pretest, the activities, What I Have Learned, and the 15-item assessment.
What are the five processes of the nitrogen cycle?
Nitrogen fixation, nitrogen assimilation, ammonification, nitrification, and denitrification. The module notes that these steps do not always happen in order.
What are the two main processes in the oxygen-carbon dioxide cycle?
Photosynthesis and respiration. Plants use carbon dioxide and give off oxygen during photosynthesis, while animals take in oxygen and give off carbon dioxide during respiration.
Full text of the module
The text below is a transcription of the PDF above, as printed.
Science Quarter 4 – Module 9: Cycling of Materials in the Ecosystem
[illustration: learners reading and studying outdoors and indoors, with a teacher and a globe]
CO_Q4_Science 8_ Module 9
Science– Grade 8 Alternative Delivery Mode Quarter 4 – Module 9: Cycling of Materials in the Ecosystem First Edition, 2020
Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalties.
Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this module are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them.
Published by the Department of Education Secretary: Leonor Magtolis Briones Undersecretary: Diosdado M. San Antonio
Development Team of the Module
Writers: Honey R. Bolo, John Rey L. Baradero, Jenile Y. Orias, Adelita I. Escudero, Jocelle B. Bañares
Editor: Ana Rubi L. Sereño
Reviewers: Bernabe L. Linog, Corazon P. Roa, Juvy B. Luna, Arlene L. Abala, Kathyleen S. Torculas
Illustrator: Rose Mia L. Pontillo, Jenile Y. Orias
Layout Artists: Celeste Faith R. Almanon, Jay S. Ayap, Eldiardo E. de la Peña
Management Team: Francis Cesar B. Bringas, Isidro M. Biol Jr., Maripaz F. Magno, Josephine Chonie M. Obseñares, Gregoria T. Su, Marvilyn C. Francia, Jay S. Ayap, Nonita C. Patalinghug
Printed in the Philippines by ________________________
Department of Education – Caraga Region
Office Address: Teacher Development Center J.P. Rosales Avenue, Butuan City, Philippines 8600 Telefax: (085) 342-8207/ (085) 342-5969 E-mail Address: caraga@deped.gov.ph
8
Science Quarter 4 – Module 9: Cycling of Materials In the Ecosystem
Introductory Message
This Self-Learning Module (SLM) is prepared so that you, our dear learners, can continue your studies and learn while at home. Activities, questions, directions, exercises, and discussions are carefully stated for you to understand each lesson.
Each SLM is composed of different parts. Each part shall guide you step-by-step as you discover and understand the lesson prepared for you.
Pre-tests are provided to measure your prior knowledge on lessons in each SLM. This will tell you if you need to proceed on completing this module or if you need to ask your facilitator or your teacher’s assistance for better understanding of the lesson. At the end of each module, you need to answer the post-test to self-check your learning. Answer keys are provided for each activity and test. We trust that you will be honest in using these.
In addition to the material in the main text, Notes to the Teacher are also provided to our facilitators and parents for strategies and reminders on how they can best help you on your home-based learning.
Please use this module with care. Do not put unnecessary marks on any part of this SLM. Use a separate sheet of paper in answering the exercises and tests. And read the instructions carefully before performing each task.
If you have any questions in using this SLM or any difficulty in answering the tasks in this module, do not hesitate to consult your teacher or facilitator.
Thank you.
What I Need to Know
This module was designed and written with you in mind. It is here to help you master the cycling of materials in the ecosystem. The scope of this module permits it to be used in many different learning situations. The language used recognizes the diverse vocabulary level of students. The lessons are arranged to follow the standard sequence of the course. But the order in which you read them can be changed to correspond with the learner’s material you are now using.
The module contains:
- Lesson 1 – Cycling of Materials in the Ecosystem
After going through this module, you are expected to:
- Identify the processes involved in the cycling of materials in the ecosystem such as water cycle, oxygen-carbon dioxide cycle, and nitrogen cycle; and
- Explain how materials cycle in an ecosystem. (MELC Week 9 S8LT-IVi-23)
What I Know
Directions: Choose the letter of the correct answer. Write your answers on a separate sheet of paper.
Which stage of the water cycle changes water vapor into droplets in the air, forming clouds?
- A. Condensation
- B. Evaporation
- C. Groundwater
- D. Precipitation
Where Earth’s water is mostly stored?
- A. creeks
- B. lakes
- C. oceans
- D. rivers
How does water vapor in the atmosphere return to the earth’s surface?
- A. It condenses and evaporates.
- B. It evaporates and condenses.
- C. It condenses and precipitates.
- D. It precipitates and evaporates.
Which of the following statements BEST describes evaporation?
- A. Water is absorbed and stored into plants.
- B. Water has reached its freezing point and becomes ice.
- C. Water vapor meets hot air and changes back to liquid.
- D. Water gets warm and changes from liquid to water vapor.
The following explains the importance of sunlight to water cycle EXCEPT:
- A. It gives energy to drive the water cycle.
- B. It changes the state of water from liquid to gas.
- C. It affects the temperature of water in the atmosphere.
- D. It breaks the bonds between hydrogen and oxygen of water vapor in the atmosphere.
Which is the result of photosynthesis?
- A. It changes sugar into energy.
- B. It converts carbon dioxide into sugar.
- C. It releases nitrogen into the atmosphere.
- D. It gives off carbon dioxide into the atmosphere.
What are the two main processes involved in Oxygen-Carbon dioxide cycle?
- A. Respiration and Transpiration
- B. Respiration and Photosynthesis
- C. Photosynthesis and Transpiration
- D. Photosynthesis and Condensation
Why is carbon dioxide important to living things?
- A. It is used in respiration.
- B. It is used by animals to produce oxygen.
- C. It is used by plants to produce sugar and starch.
- D. It is given off by plants when they break down food.
Which statement is TRUE about the process of respiration?
- A. It uses Oxygen and releases Carbon dioxide.
- B. It utilizes Carbon dioxide and produces energy.
- C. It utilizes Carbon dioxide and produces Oxygen.
- D. It consumes energy and produces Carbon dioxide.
Which of the following best explains the process of photosynthesis and respiration in Oxygen-Carbon Dioxide cycle in the ecosystem?
- A. Plants use oxygen for both photosynthesis and respiration.
- B. Animals breathe in carbon dioxide during both respiration and photosynthesis.
- C. Plants use carbon dioxide to produce oxygen during photosynthesis, while animals take in oxygen and give off carbon dioxide during respiration.
- D. Animals use carbon dioxide to produce oxygen during photosynthesis, while plants take in oxygen and give off carbon dioxide during respiration.
In which process is nitrogen circulated and recycled?
- A. Carbon cycle
- B. Nitrogen cycle
- C. Nitrogen fixation
- D. Water cycle
What do bacteria convert during the process of nitrification?
- A. ammonium into nitrates
- B. ammonium into nitrogen
- C. nitrogen into nitrous oxide
- D. nitrous oxide into nitrogen
Which of the nitrogen compound is taken up by plants?
- A. Ammonia
- B. Ammonium
- C. Nitrate
- D. Nitrite
Which stage in the nitrogen cycle is nitrogen converted into ammonium?
- A. Ammonification
- B. Denitrification
- C. Nitrogen fixation
- D. Nitrification
Nitrogen is considered a limiting element because _____.
- A. it easily escapes out of the soil into the ground water
- B. plants are generally made of nitrogen and they need much of it
- C. it stays suspended in the atmosphere and cannot get to the roots
- D. abundant forms of nitrogen that are available cannot be used by plants
Lesson 1: Cycling of Materials in the Ecosystem
In the ecosystem, essential elements or substances of living matter are circulated. These elements flow in different forms from non-living (abiotic) to a living (biotic) component of the environment and back. For the biotic components of the ecosystem to survive, all the important elements must be recycled continuously.
What’s In
In Module 8, you have learned about the flow of energy in an ecosystem. Let us have a quick review of your understanding in the previous module!
Activity 1. Arrange Me!
Directions: Arrange the jumbled letters inside the parenthesis to reveal the term referred by the given statement. Write your answers on a separate sheet of paper.
- It traps energy from the sun and converts it in the form of chemical energy for food. (SNPLAT)
- The total dry mass of organisms in a food chain and food web. (SSMAIOB)
- Organisms that eat plants. (HREVOBIRE)
- It is the source of energy used by plants for photosynthesis. (SNU)
- The trend in the amount of the biomass as it is transferred from one trophic level to another. (ECRSINGEAD)
What’s New
Activity 2. Where Do I Belong?
In this activity you will gain understanding on the different processes involved in water, oxygen-carbon dioxide and nitrogen cycle.
Directions: Complete the table below by indicating the processes involved in the different cycles. Write your answers on a separate sheet of paper.
Ammonification / Fixation / Precipitation Condensation / Nitrification / Respiration Evaporation / Photosynthesis
| Water Cycle | Oxygen-Carbon dioxide Cycle | Nitrogen Cycle |
|---|---|---|
What is It
Many elements including carbon, oxygen, and nitrogen cycle through ecosystems between biotic (e.g. plants and animals) and abiotic (e.g. soil, water, and air) components. These are used in essential processes, such as metabolism, the formation of amino acids, respiration and building of tissues. The Ecosystem depends on the recycling of these elements, such as water cycle, oxygen-carbon dioxide cycle and nitrogen cycle, to sustain life.
Water Cycle
Most part of the Earth is covered with water. It supports life, drains harmful substances and arbitrates day to day activities. The continuous movement of water through the atmosphere, land, and bodies of water is called Water Cycle, which is also called the hydrological cycle. The water cycle is composed of different processes namely: evaporation, condensation, precipitation, transpiration, surface runoff and infiltration. See Figure 1. Solar energy drives the water cycle through evaporation and transpiration, moving water from the earth’s surface, and even plant parts, to the atmosphere.
Figure 1. Water Cycle
[chart: diagram; Figure 1. Water Cycle] Labels: Condensation; Condensation; Precipitation; Precipitation; Snow Run-off; Transpiration; Evaporation; Surface Run-off; Plant Uptake; Evaporation; Infiltration; Ground Water Flow Illustrated by: Jenile Y. Orias
Evaporation
It takes place in oceans, lakes, streams, icebergs and even in soil and rocks. It is the physical change of water from liquid phase into gaseous phase known as water vapor that rises into the atmosphere. This process is driven by the warmth and energy from the sun.
Transpiration
Water moves into the different parts of the plants and evaporates through the process called transpiration. The water absorbed by the roots is pulled towards the leaves for photosynthesis. The excess water escape through the stomata (tiny openings of the leaves) into the environment as water vapor. This pulling mechanism in plants is driven by the energy from the sun.
Condensation
Water vapor rises into the atmosphere where it condenses to form clouds. The cooler temperature in the troposphere causes the water vapor to lose its heat and turn back to liquid water, which is known as condensate, in the process called condensation. In much colder temperatures, the condensate turns into ice.
Water vapor condenses with the help of some particles such as dust, smoke, sea salts and other matter that assist in cloud formation. The tiny particles of water
vapor condense into liquid on the surfaces of dust particles in the air. A cloud forms as more water vapor condenses into water droplets. Clouds form massive condensate in the sky. This happens when smaller water droplets combine to make bigger ones due to wind or temperature change.
Precipitation
Precipitation is water or liquid that forms in the atmosphere that falls back to earth as precipitates because of gravity, either in a rain, snow, hail, fog or sleet. In the Philippines, most precipitation occurs as rain.
Infiltration
Some of the water that precipitates seep through the pores of the soil and forms the groundwater in the aquifers. The flow of water from the surface into the soil is called infiltration. Aquifers are underground layers of rocks that hold groundwater. When water seeps down, it will increase the level of groundwater table. Groundwater can be accessed by drilling or digging through the ground into an aquifer as in the case of artesian wells.
Surface Runoff
Surface runoff is the manner by which water moves across the ground or land. It occurs when water can no longer infiltrate the ground because of water-impermeable rocks or when the ground is already saturated with water. Water flows through the surfaces and become part of a lake, river or ocean. Most of the Earth’s water is stored in the ocean.
Oxygen-Carbon Dioxide Cycle
In the ecosystem, organisms consume and produce oxygen and carbon dioxide during the process of photosynthesis and respiration. These important gases flows through the organisms and the environment through a cyclic process called oxygen-carbon dioxide cycle.
Plants produce oxygen through the process called photosynthesis to manufacture their own food. In this process, plants use the energy of the sun to combine water and carbon dioxide to sugar molecules that give them the energy to live and grow. Oxygen is given off by plants through the stomata where carbon dioxide enters.
All animals need oxygen to survive. They take in oxygen and give off carbon dioxide through the process called respiration. Animals get energy from the food they eat. During respiration, cells use oxygen to break down sugar to obtain energy. Animals use this energy to grow, reproduce, and to perform other functions. They give off carbon dioxide into the atmosphere which in turn is used by the plants during photosynthesis.
Plants need the carbon dioxide released by animals when they manufacture their own food, while animals need oxygen for respiration. The release of oxygen by
the plants and carbon dioxide by the animals into the atmosphere constitute oxygen-carbon dioxide cycle. (See Figure 2 below).
[chart: diagram; Figure 2. The Oxygen-Carbon dioxide Cycle] Labels: Oxygen; Photosynthesis; Carbon dioxide; Respiration; Respiration Illustrated by: Rose Mia L. Pontillo
Figure 2. The Oxygen-Carbon dioxide Cycle
The exchange of oxygen and carbon dioxide through photosynthesis and respiration helps cycle these gases. Human activities such as deforestation and burning of fossils contribute to carbon dioxide emissions in the atmosphere resulting to global warming. Global warming is an increase in the earth’s air temperature.
Trees play significant role in mitigating global warming by absorbing carbon dioxide, that is why planting of trees and other plants are necessary to reduce carbon dioxide in the atmosphere.
Nitrogen Cycle
Many processes in the ecosystem, such as plant and animal growth, are limited by the available supply of nitrogen. The earth’s atmosphere contains nearly 78% of nitrogen gas. However, for it to be available to organisms, it must be changed first into usable forms. One of the many importance of nitrogen is for plant growth. Through a series of nitrogen-transformations, nitrogen is made available to plants. Nitrates (N03), Nitrites (NO2), and Ammonium (NH4) are forms of nitrogen that results of the nitrogen cycle.
There are five processes of Nitrogen cycle that happen in the environment. The steps which are not necessarily sequential include nitrogen fixation, nitrogen assimilation, ammonification, nitrification, and denitrification (Figure 3).
Figure 3. Nitrogen Cycle: Its Agents and processes
[chart: diagram; Figure 3. Nitrogen Cycle: Its Agents and processes] Labels: N2 ATMOSPHERIC NITROGEN; nitrogen fixation; denitrification; ammonification; assimilations; nitrification Text in diagram: “Is the process of making nitrogen usable by plants where bacteria change nitrogen into ammonium.”; “Extra nitrogen in the soil gets put back out into the air. There are special bacteria that perform this task as well.”; “The decaying process where the nitrogen turns into ammonium so it can re-enter the nitrogen cycle.”; “The process by which ammonia gets change into nitrates.”; “This is how plants get nitrogen. They absorb nitrates from the soil into their roots. Then nitrogen gets used in the amino acids, nucleic acids, and chlorophyll.” Illustrated by: Rose Mia L. Pontillo
Nitrogen fixation is the process in which nitrogen gas is converted into nitrates or ammonia. Lightning fixation is one type of nitrogen fixation wherein nitric oxide (NO) is formed in the air from nitrogen gas (N2) and oxygen (02) during thunderstorms by lightning. Nitric oxide (NO) oxidizes further to nitrogen dioxide (NO2) and later reacts with water forming nitric acids. Acids fall to the ground during rain and form nitrates (NO3) and nitrites (NO2 -) in the soil.
Another way of nitrogen fixation is the bacterial fixation which is estimated to harness 90% of nitrogen gas into its usable forms. Some genera of bacteria have the ability to fix atmospheric nitrogen. Most are free-living, but some form symbiotic relationships with the roots of legumes such as the mongo plant. Only the symbiotic bacteria fix enough nitrogen to be of a major role in nitrogen production. Nitrogen fixing bacteria act as a link between the nitrogen in the atmosphere and the nitrogen in land.
Nitrogen assimilation is the process by which nitrates and ammonia formed from nitrogen fixation are combined into the specific tissue compounds of algae and higher plants. Plants absorb nitrates from the soil through the roots and integrate them into plant protein and nucleic acids. The nitrates become one of the many components of the nutrient-rich water absorbed by the plants which will be utilized by it for growth and development.
Ammonification is the process of making ammonia or ammonium ions (NH4+) by living things. Ammonium ions are produced as a waste material of animals and some bacteria and during the decomposition of organic nitrogenous materials by bacteria. For example, some bacteria can convert nitrate into ammonia in soils. When an organism dies or eliminate waste, the nitrogen in its tissues is in the form of organic nitrogen. Many fungi and other unicellular organisms then decompose the tissue and release inorganic nitrogen back into the environment as ammonia in the process of ammonification. The majority of ammonium ions are rapidly used up in soil and water by microorganisms and plants. At different points in the food web, ammonium ions are released back to the environment.
Nitrification is a process by which soil ammonia are converted to nitrites then to nitrates, compounds usable by plants. This process is mediated by two distinct groups of microorganisms that live particularly in areas where ammonia is present in large amounts, such as areas of ammonification and in sewage. The ammonia-oxidizing bacteria (nitrosifyers) mediate the first step by oxidizing ammonia into nitrites. The second group, the nitrite-oxidizing bacteria (or nitrifying bacteria) such as Rhizobium in the roots of legumes, catalyze the second step, by oxidizing nitrites into nitrates, to complete the nitrification process.
Denitrification is the process wherein nitrate is converted into nitrogen gas (N2) or other gaseous nitrogen compounds such as N2O and NO by different bacteria in soils during anaerobic respiration. Denitrification reduces nitrate to nitrogen gas, thus, replenishing the atmospheric nitrogen that was once used, returning it to the atmosphere, the reservoir.
What’s More
Activity 3. Match Me!
This activity will enable you to identify the different processes involved in the water cycle.
Directions: Match column A with column B. Write your answers on a separate sheet of paper.
| Column A | Column B |
|---|---|
| 1. Condensation | A. Water droplets fall on the earth’s surface because of gravity, either in the form of rain, snow, hail, fog or sleet. |
| 2. Evaporation | B. The water seeps into the ground part of the soil where it becomes groundwater. |
| 3. Infiltration | C. Water from the ocean rises in the atmosphere and turns into water vapor. |
| 4. Precipitation | D. Water is absorbed by the roots and is given off in a form of water vapor through the stomata of the plant. |
| 5. Surface Runoff | E. Water vapor changes to liquid phase and form into clouds. |
| 6. Transpiration | F. The water that falls to the earth reaches the ground, moves along the surface and becomes part of a lake, river or ocean |
Activity 4. Where Am I?
This activity will help you recognize and explain the essential elements of the water cycle.
Directions: Complete the water cycle using the words from the box and briefly answer the question below. Write your answers on a separate sheet of paper.
Condensation / Infiltration / Surface runoff Evaporation / Ocean / Transpiration Groundwater / Precipitation
[illustration: water cycle landscape with numbered blanks 1 to 8; blanks are labeled 1., 2., 3., 4., 5., 6., 7., 8.] Illustrated by: Rose Mia L. Pontillo
Question:
Explain how water cycle happens in the ecosystem?
Scoring Rubric 3 – Discussion has no misconceptions with complete scientific evidence. 2 – Discussion has no misconceptions with incomplete scientific evidence. 1 – Discussion has misconceptions and without scientific evidence. 0 – No discussion.
[transcriber’s note: the printed page numbers on these pages read 13 to 20; the markers below follow the page numbering requested for this file, 17 to 24]
Activity 5. Understanding Oxygen-Carbon Dioxide Cycle
This activity is designed to allow you to dig deeper understanding on how oxygen and carbon dioxide flow through the ecosystem
Directions: Study the diagram of Oxygen-Carbon dioxide cycle. Answer the questions that follow. Write your answers on a separate sheet of paper.
[chart: cycle diagram; unnumbered diagram of the Oxygen-Carbon Dioxide cycle. Labels: Photosynthesis (arrow from a tree to Oxygen), Oxygen (arrow from the tree to an animal), Respiration (beside the animal), Carbon dioxide (arrow from the animal back to the tree). A sun is drawn above the tree.]
Illustrated by: Rose Mia L. Pontillo
Questions:
- What gas is needed by plants for photosynthesis? What gas is given off?
- During respiration, what do animals absorb? What gas do they give off?
- Explain how oxygen-carbon dioxide cycle occurs in the ecosystem?
Scoring Rubric for number 3
3 – Discussion has no misconceptions with complete scientific evidence.
2 – Discussion has no misconceptions with incomplete scientific evidence.
1 – Discussion has misconceptions and without scientific evidence.
0 – No discussion.
Activity 6. Complete Me!
This activity will help you analyze the components of oxygen-carbon dioxide cycle.
A. Directions: Complete the Oxygen-Carbon dioxide cycle concept map using the terms inside the box. Write your answers on a separate sheet of paper.
Animals Oxygen Plants Carbon dioxide Photosynthesis Respiration
[chart: concept map; Activity 6 Oxygen – Carbon Dioxide Cycle concept map. Root box: “Oxygen – Carbon Dioxide Cycle”.]
- Left branch: “photosynthesis” → “takes place in” → “2. _____________” → “take in” → “carbon dioxide”; “give off” → “3. ___________”
- Right branch: “1. _______________” → “takes place in” → “animals” → “take in” → “4. ___________”; “give off” → “5. ___________”
Activity 7. Fill Me Up!
You are challenged here to explore and explain the chemical processes that occur within the nitrogen cycle.
Directions: Complete the Nitrogen cycle using the words from the box and answer the question that follows. Write your answers on a separate sheet of paper.
Assimilation Denitrification Nitrogen-fixation Ammonification Nitrification
[chart: nitrogen cycle diagram; unnumbered diagram of the nitrogen cycle with blanks numbered 1 to 5. Labels: N2 ATMOSPHERIC NITROGEN (top); 1. _____________ (upper left); 2. _____________ (lower left); 3. _____________ (lower center); 4. _____________ (lower right); 5. _____________ (upper right); “ammonia” (circle at left); “nitrifying bacteria” (circle); “nitrates” (circle); “denitrifying bacteria” (circle at right).]
Illustrated by: Rose Mia L. Pontillo
Question:
Explain the different processes of nitrogen cycle.
A. Nitrogen Fixation
B. Assimilation
C. Ammonification
D. Nitrification
E. Denitrification
Scoring Rubric
3 – Discussion has no misconceptions with complete scientific evidence.
2 – Discussion has no misconceptions with incomplete scientific evidence.
1 – Discussion has misconceptions and without scientific evidence
0 – No discussion.
What I Have Learned
Directions: Complete the statement by writing the appropriate word or phrase on the blank. Write your answers on a separate sheet of paper.
Water moves through the atmosphere to the earth’s surface and back through the process called _________________.
Evaporation happens when liquid phase of water is transformed into _______________ which rises into the atmosphere.
The precipitate falls to the surface as _________________.
_________________is water that flows to across the ground or land surface.
The production of oxygen and carbon dioxide flows through the organisms and in the environment through a cyclic process called _______________.
The process of manufacturing food by plants is called _______________.
Animals give off _______________ to the atmosphere during respiration, which in turn will be absorbed and used by plants in manufacturing food.
The gas that consists nearly 78% in the Earth’s atmosphere is _____________.
Nitrogen fixation is the process in which nitrogen gas is converted into _______________ and ammonia.
In the _______________ process, nitrate is converted into nitrogen gas (N2) or other gaseous nitrogen compounds such as N2O and NO by different bacteria in soils during anaerobic respiration.
What I Can Do
Activity 8. Let’s combine!
In the ecosystem, water cycle, oxygen-carbon dioxide cycle and nitrogen cycle play vital role in maintaining the cycle of essential nutrients needed by all plants and animals. Regardless of the type of environment, these cycles occur.
Directions: Draw small ecosystem that you can see in your environment and incorporate the diagram of the three cycles.
Draw it here:
[transcriber’s note: empty bordered box for the learner’s drawing]
| Scoring Rubrics: | |
|---|---|
| 3 points | The illustration shows complete scientific concepts on the three cycle. |
| 2 points | The illustration shows limited scientific concepts on the three cycle. |
| 1 point | The illustration fails to show scientific concepts on the three cycle. |
| 0 point | No illustration. |
Assessment
Directions: Choose the letter of the correct answer. Write your answers on a separate sheet of paper.
Which stage of water cycle changes water into water vapor?
- A. condensation
- B. evaporation
- C. precipitation
- D. transpiration
Which is the source of energy that drives water cycle?
- A. clouds
- B. rain
- C. sun
- D. wind
A girl on her way home noticed a puddle of water on the road. As she passed by the next day, the water was gone. What has happened to the water? It has _____________.
- A. condensed
- B. evaporated
- C. precipitated
- D. transpired
Which process involves water to move across the ground or land and becomes part of the oceans, lakes and other bodies of water?
- A. condensation
- B. evaporation
- C. surface runoff
- D. transpiration
Which of the following is true about water vapor?
- A. It can be counted.
- B. It is solid and visible.
- C. It is liquid and visible.
- D. It is gaseous and invisible.
Which process of water cycle is exhibited when water is absorbed by the roots and is given off as water vapor through the stomata of the plant?
- A. condensation
- B. evaporation
- C. precipitation
- D. transpiration
Which gas is given off by animals that is needed by plants?
- A. Carbon dioxide
- B. Carbon monoxide
- C. Nitrogen
- D. Oxygen
Which gas is needed by plants to manufacture food?
- A. Carbon dioxide
- B. Carbon monoxide
- C. Nitrogen
- D. Oxygen
Which of the following provides available natural oxygen?
- A. animal
- B. decomposers
- C. plant
- D. water
What happens during the process of respiration?
- A. Carbon dioxide is changed into oxygen.
- B. Oxygen and sunlight are converted to sugar.
- C. Oxygen is used up and carbon dioxide is released.
- D. Carbon dioxide and water form energy and oxygen.
Which of the following is the effect of carbon dioxide build-up in the atmosphere?
- A. The amount of available oxygen decreases.
- B. There is less amount of solar energy reaching the earth.
- C. Global temperature increases that affect the weather patterns.
- D. Global air pressure increases making more difficult for plants and animals to breathe.
Which of the following processes of nitrogen cycle releases nitrogen gas (N2) back to the atmosphere?
- A. Ammonification
- B. Denitrification
- C. Fixation
- D. Nitrification
Which of the processes of nitrogen cycle changes dead plants and animals into ammonium?
- A. Ammonification
- B. Denitrification
- C. Fixation
- D. Nitrification
Where do plants obtain nitrogen they need?
- A. atmosphere
- B. ecosystem
- C. soil
- D. water
Can the Earth’s nitrogen be utilized directly by plants? Why?
- A. No, because nitrogen gas cannot be converted to other forms.
- B. Yes, because majority of the Earth’s nitrogen is stored in land and water.
- C. No, most of it exists as inorganic nitrogen gas and is not usable by plants.
- D. Yes, because there is sufficient available nitrogen gas in the atmosphere and is usable to most organisms.
Additional Activities
Activity 9. Share Us
This activity will help you relate and apply the different cycle in a real life scenario.
Directions: Answer the questions below. Write your answers on a separate sheet of paper.
- What is the importance of planting trees in relation to the Oxygen-Carbon dioxide cycle?
- With your knowledge about the Nitrogen cycle, what suggestions can you give to farmers in your community to enhance their farming practices without destroying the environment?
Scoring Rubric
3 – Discussion has no misconceptions with complete scientific evidence.
2 – Discussion has no misconceptions with incomplete scientific evidence.
1 – Discussion has misconceptions and without scientific evidence
0 – No discussion.
[transcriber’s note: this page is printed as page 21 of the module]
Answer Key
What I Know
- A
- C
- C
- D
- D
- B
- B
- C
- A
- C
- B
- A
- C
- C
- D
What’s In
Activity 1
- Plants
- Biomass
- Herbivore
- Sun
- Decreasing
What’s New
Activity 2: Where I Belong?
Water Cycle
- *Condensation
- *Evaporation
- *Precipitation
Oxygen- Carbon dioxide Cycle
- *Photosynthesis
- *Respiration
Nitrogen Cycle
- *Ammonification
- *Fixation
- *Nitrification
What’s More
Activity 3: Match Me!
- E
- C
- B
- A
- F
- D
Activity 4. Where Am I?
- Condensation
- Precipitation
- Evaporation
- Transpiration
- Surface runoff
- Infiltration
- Groundwater
- Ocean
What’s More
Activity 4. Where Am I?
Explanation:
Water from soil and bodies of water (such as ocean, river, lake, etc.) evaporates as water vapor, condenses to form clouds and falls back to the earth surface as rain or snow. The liquid water flows across land (runoff) and becomes part of the oceans, lakes, rivers and other bodies of water. Some water that precipitates seep into the soil, becomes groundwater where it taken up by plants (plant uptake) and evaporates from plants into the atmosphere through transpiration and photosynthesis.
Activity 5. Understanding Oxygen-Carbon dioxide Cycle
- Carbon dioxide, Oxygen
- Oxygen, Carbon dioxide
- *Plants use Oxygen through the process called Photosynthesis. They use the energy from the sun to combine Carbon dioxide and water into sugar molecules that’s give them energy to live and grow and provide food for other organisms. Oxygen is given off as a waste product of photosynthesis. Animals breathe in the oxygen released by plants and released Carbon dioxide in the process called respiration. During this process animals cells combine food molecules to oxygen with obtain energy. They release CO2 into the air as a waste product which in turn is used by plants for photosynthesis.
[transcriber’s note: this page is printed as page 22 of the module]
What’s More
Activity 6. Complete Me!
- Respiration
- Plants
- Oxygen
- Oxygen
- Carbon dioxide
Activity 7. Fill Me Up!
There are five processes of Nitrogen cycle that happen in the environment, which are not necessarily sequential are the following:
- Nitrogen Fixation is the process in which nitrogen gas is converted into nitrates and ammonia.
- Ammonification is the process of making ammonia or ammonium ions (NH4+) by living things.
- Assimilation is the process by which plants are able to absorb nitrates as a water soluble substance from the soil through the roots.
- Nitrification is a process by which soil ammonia and nitrites are converted to nitrates, compounds usable by plants.
- Denitrification is the process wherein nitrate is converted back into nitrogen gas (N2) or into other gaseous nitrogen compounds.
[illustration: nitrogen cycle diagram showing a plant, a cow, clouds, and labeled nitrogen processes]
What I have Learned
- Water Cycle
- Gaseous phase/water vapor
- rain, snow, hail, or sleet
- Surface runoff
- Oxygen-Carbon dioxide cycle
- Photosynthesis
- Carbon dioxide
- Nitrogen
- Nitrates
- Denitrification
What I Can Do
Activity 8. Let’s combine!
[illustration: sample illustration of the water, oxygen-carbon dioxide, and nitrogen cycles]
Illustrated by: Honey R. Bolo
Assessment
- B
- C
- B
- C
- D
- D
- A
- A
- C
- C
- C
- B
- A
- C
- C
Additional Activities
Activity 9. Share Us!
- *Learn to reuse and recycle water.
*Turn off faucet when not in use.
*Observe proper waste disposal.
*Join/organize tree planting activities.
*Advocate reforestation and conduct campaign against illegal logging. - *Help balance oxygen-carbon Dioxide in the ecosystem.
* Help absorb CO2, thus prevent global warming. - *Advise the farmers to use organic fertilizers.
*Planting leguminous plants.
*Avoid burning hay after harvest.
*Avoid using inorganic herbicide.
[transcriber’s note: this page is printed as page 23 of the module]
References
Development Team of the Learner’s Module, Grade 8 Science Learner’s Module, DepEd, Pasig City Philippines: Vibal Publishing House, Inc, 2013.
Lourdes R. Carale, Aida Dasallas, Zenaida Lopez Dee, Elvira R. Galvez, Gerardo Luna, Ma. Dulcelina O. Sebastian, Esther Sebua, Merle C. Tan, Guadalupe Yap, Mabel Ypil and Risa L. Reyes, Science and Technology II Revised Edition Quezon City, Philippines: ISMED, 2004.
[transcriber’s note: this page carries no printed page number]
For inquiries or feedback, please write or call:
Department of Education – Bureau of Learning Resources (DepEd-BLR)
Ground Floor, Bonifacio Bldg., DepEd Complex Meralco Avenue, Pasig City, Philippines 1600
Telefax: (632) 8634-1072; 8634-1054; 8631-4985
Email Address: blr.lrqad@deped.gov.ph * blr.lrpd@deped.gov.ph
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