Republic of the Philippines
Department of Education
Regional Office IX, Zamboanga Peninsula
Science Grade 8
Quarter 4 - Module 8
Human Impact on the
Environment
Z
est forP
rogressZ
eal ofP
artnership8
Name of Learner: ___________________________
Grade & Section: ___________________________
Name of School: ___________________________
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Module
8 Human Impact on the Environment
What I Need to Know
This module was designed and written with you in mind. It is here to help you master the concepts about minimizing the human impact on the environment (S8-LT-IVj-25). 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 textbook you are now using. After going through this module, you are expected to:
1. identify the farming methods that affect food chains and food webs; 2. suggest ways to minimize human impact on the environment; and 3. differentiate organic farming and inorganic farming.
What’s In
All organisms need the energy to sustain life. Every activity that organisms do in ecosystems like breathing running, burrowing, and growing requires energy. Producers and consumers make possible the flow of energy through food chains and food webs.
Guide Questions:
1. What is the difference between consumer and producer? 2. How important is the flow of energy in an ecosystem?
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What’s New
Direction: Arrange the jumbled letters based on the short description below.
1. It is a chemical substance that is spread on land or soil to make plants grow better.
2. It is a farming method that could kill weeds.
3. It is a farming practice that could kill an insect pests.
4. It is a cultivation of a single crop in large areas.
5. It is a form or type of agriculture in which more than one species is grown simultaneously in the same place in imitation of the diversity of a natural ecosystem.
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TIFERREZLI
REHEDCIBI
INTISECEDCI
ONMOERTULUC
LYOPERUTLUC
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What Is It
How do Human Activities Affect the Ecosystem?
Humans are the top consumers in many food pyramids. They use methods that affect food chains and food webs to increase food production. Some of the widely used farming practices are described below:
Monoculture. This involves the cultivation of a single crop in large areas. Vast tracts of land are converted to rice farms, sugar farms, and coconut farms.
People deprive many animals of their homes and food by limiting the cultivation of different kinds of plants. These animals move to other places and some of which feed on insect pests. Only the insect pests that eat the monocrop remain in the area. If uncontrolled, these pests can wipe out the monocrop in a short period of time.
Also, eliminating these plants can be harmful to the microorganisms because some soil microorganisms depend on specific plants for food. The cycling of nutrients for the reuse of plants will be disturbed since microorganisms are responsible for returning plant nutrients to the soil.
Herbicides and Insecticides. Farmers spray their crops with herbicides to kill weeds and with insecticides to kill insect pests. However, other organisms, including beneficial insects and soil organisms, which help in decay, will also be destroyed by the chemicals.
One traditional classification of pesticides places them in one of two groups: organic and inorganic. Organic pesticides are based on chemicals having carbon as the basis of their molecular structure. These more complex than those of inorganic pesticides and usually do not dissolve easily in water. Inorganic pesticides are simpler compounds. They have a crystalline, salt-like appearance are environmentally stable, and usually dissolve in water.
Malathion is a type of pesticide that is known as an acetylcholinesterase inhibitor. Agent orange is a weedicide containing dioxin. Also, use with caution is an appropriate way to describe a relatively low toxicity pesticide product to the customer.
Insecticides move up the food pyramid and accumulate in the body of organisms. The smallest concentration of the chemical is at the base of the pyramid occupied by producers. The amount increases towards the top. The greatest concentration is found in the top consumers, such as birds, mammals, and humans.
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Many insect pests become resistant to chemicals, which may lead to the use of increased amounts of pesticides.
Chemical Fertilizers. Monocrops usually require large amounts of chemical fertilizers. Continuous and uncontrolled use of chemical fertilizers may increase soil acidity, thus destroying soil structure. Findings show that more fertilizers are needed for the same amount of yield after years of monoculture. Fertilizers may run off to rivers, ponds, and lakes. Accumulation of fertilizers may cause the death of these bodies of water.
Azospirillum is an excellent example of organic fertilizer that improves phosphorus uptake.
Azolla and BGA is the best pair of biofertilizer.
Fertilizers in the water will cause an increase in the growth of some algae and other water plants. The passage of oxygen will be blocked when they cover the water's surface. Thus, less oxygen is dissolved in water. Also, when algae and aquatic plants die, decay microorganisms use oxygen. When the dissolved oxygen becomes insufficient, fishes and other marine animals will die.
The following practices may disrupt a food chain or food web: 1. monoculture
2. use of pesticides 3. use of fertilizers
Some desirable practices to conserve the environment are described below.
1. Grow a variety of crops instead of only one crop. Polyculture is a form of agriculture in which more than one species is grown simultaneously in the place in imitation of the diversity of a natural ecosystem. It is the opposite of monoculture in which only members of one plant or animal species are cultivated together.
2. Use insects to fight other insects. This is known as biological control of insect pests. It is a method of controlling pests such as insects, mites, weeds, and plant diseases using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms but typically also involves an active human management role. The release of parasitic wasps to control aphids is an example of biological control. Aphids, which are a pest of plants, cause huge damage to plants as they remove nutrients from the plant.
3. Try organic farming using natural fertilizers for crops instead of chemical fertilizers. Animal manure and compost are some of the common natural fertilizers. Organic farming is a technique that involves the rearing of animals and the cultivation of plants in natural ways. It involves using biological materials, avoiding synthetic substances to maintain soil fertility and ecological balance, thereby minimizing pollution and wastage.
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What’s More
Activity 5:
Match and Connect!
Directions: Match the words found in column A to their description in column B. Draw a line to connect them.
A B
1. Monoculture A. It is a good example of organic fertilizer which improves phosphorus uptake.
2. Polyculture B. It is based on chemicals having carbon as the basis of their molecular structure.
3. Organic Farming C. It is a cultivation of a single crop in large areas.
4. Azospirillum D. It is a technique which involves the cultivation of plants and rearing of animals in natural ways.
5. Malathion E. It is a type of pesticide that is known as an acetylcholinesterase inhibitor.
6. Organic Pesticides F. It is a chemical substance that is spread on land or soil to make plants grow better.
7. Pesticides G. It is a farming method that could kill weeds.
8. Herbicides H. It is a method of controlling pests such as insects, mites, weeds, and plant diseases using other organisms. 9. Fertilizer I. It is a substance used for destroying insects or other
organisms harmful to cultivated plants or to animals. 10. Biological
Control
J. It is a form of agriculture in which more than one species is grown at the same time and place in imitation of the diversity of natural ecosystem.
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What I Have Learned
Activity 5: Let’s see what you have learned!
Direction: Answer each question inside the box.
Answer:
Differentiate organic farming and inorganic farming.
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Suggest ways to minimize human impact on the environment.
Answer:
What is the difference between herbicide and pesticide?
Answer:
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What I Can Do
Activity 6: You can do more!
Directions: Make at least two paragraphs about organic farming based on the guide questions and criteria given. Write your answer in the box below and discuss it with your family. Guide questions:
1. As a student, what can you do to minimize human impact on the environment? 2. How would promote organic farming?
3. Differentiate organic farming and inorganic farming.
4. Explain the following practices that may disrupt a food chain or food web: a) monoculture
b) use of pesticides c) use of fertilizers
25
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Criteria 5 4 3 2
Content Collects and
contributes accurate content
Collects and contributes mostly accurate content
Collects and contributes somewhat accurate content
Collects and contributes inaccurate content Organization Very well
organized and informative
Clear words are used
Some pieces of information are not clear and is hard to follow
Arrangement of words is unclear and illogical
Neatness Exceptionally neat in terms of penmanship and presentation.
Attractive in terms of design, layout, and neatness.
Acceptably attractive
though it may be a bit messy.
Distractingly messy or very poorly in terms of penmanship and
presentation.
Assessment (Set A)
Directions. Encircle the letter of the best answer.
1. Which of the following is known as an acetylcholinesterase inhibitor? A. Malathion C. Azospirillum
B. Fertilizer D. None of the above
2. What do you call on a farming method that could kill weeds? A. Insecticide C. Fertilizer
B. Herbicide D. None of the above
3. Which of the following statements is true about the difference between organic and inorganic farming?
A. Organic farming is a technique that involves the cultivation of plants and rearing of animals in natural ways, while inorganic farming uses a synthetic substance that disrupts the soil fertility and ecological balance.
B. Organic farming is a technique that applies herbicides and pesticides, while inorganic farming applies natural ways that maintain soil fertility.
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C. Inorganic farming is the cultivation of a single crop in large areas. In contrast, organic farming involves the cultivation of more than one species simultaneously in the same place in imitation of the diversity of a natural ecosystem.
D. None of the above
4. Which of the following suggest ways to minimize human impact on the environment? A. Monoculture is the best practice.
B. Farmers should use fertilizers to increase the growth of algae and other water plants.
C. Organic farming using natural fertilizers for crops instead of chemical fertilizers. D. All of the above
5. What do you call on a chemical substance that is spread on land or soil to make plants grow better?
A. Insecticide C. Fertilizer
B. Herbicide D. None of the above
6. Which of the following is a type of agriculture in which more than one species is grown simultaneously in the same place in imitation of the diversity of a natural ecosystem?
A. Monoculture C. Organic farming
B. Polyculture D. Inorganic farming
7. Which of the following practices may disrupt food chain or food web?
A. Insecticide C. Fertilizer
B. Herbicide D. None of the above
8. Which of the following farming practices could kill insect pests?
A. Insecticide C. Fertilizer
B. Herbicide D. None of the above
9. What do you call on a method of controlling pests such as insects, mites, weeds, and plant diseases using other organisms?
A. Biological control B. Monoculture C. Polyculture D. None of the above 10. What is agent orange?
A. color used in fluorescent lamps C. a biodegradable insecticide
B. a weedicide containing dioxin D. a hazardous chemical used in luminous paints
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Assessment (Set B)
Direction: Match the words found in column A to their description in column B. Draw a line to connect them.
A B
1Malathion A. It is a good example of organic fertilizer which improves phosphorus uptake.
2. Azospirillum B. It is based on chemicals having carbon as the basis of their molecular structure.
3. Herbicides C. It is a cultivation of a single crop in large areas.
4. Polyculture D. It is a technique which involves the cultivation of plants and rearing of animals in natural ways.
5. Monoculture E. It is a type of pesticide that is known as an acetylcholinesterase inhibitor.
6. Organic Pesticides F. It is a chemical substance that is spread on land or soil to make plants grow better.
7. Biological Control
G. It is a farming method that could kill weeds.
8. Organic Farming H. It is a method of controlling pests such as insects, mites, weeds, and plant diseases using other organisms.
9. Fertilizer I. It is a substance used for destroying insects or other organisms harmful to cultivated plants or to animals. 10. Pesticides J. It is a form of agriculture in which more than one species
is grown at the same time and place in imitation of the diversity of natural ecosystem.
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Additional Activities
Activity 7: Let’s add more!
Directions: Write True if the statement is correct and False if the statement is incorrect.
_______1. Azospirillum is a substance used for destroying insects or other organisms harmful to cultivated plants or animals.
_______2. Fertilizer is a farming method that could kill weeds.
_______3. A monoculture is a form of agriculture wherein two or more species are grown simultaneously in the same place in imitation of the diversity of a natural ecosystem.
_______4. Polyculture is a cultivation of a single crop in large areas.
_______5. Biological control is a method of using other organisms to control pests such as insects, mites, weeds, and plant diseases.
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Answer Key- Science
Wha t’s New
1. FER TILI ZER
2. HER BIC ID E
3. IN SEC TICID E
4. MONO
CU LTU RE
5. POLY CU LTU RE
Wha t’s More
1.c 2. j 3. d 4. a 5. e 6. b 7. i 8. g 9. f 10. h
Assessm ent S et A
1. A
2. B
3. A
4. C
5. C
6. B
7. B
8. A
9. A
10.B
Additiona l Acti
vities
1. False
2. False
3. False
4. False
5. True
Assessm ent S et B
1. E
2. A
3. G
4. J
5. C
6. B
7. H
8. D
9. F
10.I
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References
Books:
Campo, Pia C., May R. Chavez, Maria Helen D. H. Catalan, Leticia V. Catris, Marlene B. Ferido, Ian Kendrich C. Fontanilla, Jacqeline Rose M. Gutierrez, Shirley R. Jusayan, Michael Anthony B. Mantala, Cerilina M. Maramag, Marie Paz E. Morales, Eligio C. Obille, Jr., Digna Paningbatan, Genevieve Faye Pasamonte, Ma. Dulcelina O. Sebastian, Rolando M. Tan, and Rodolfo S. Treyes. "Unit 4 Module 2. Interactions." In Science - Grade 8 Learner's Module, First Edition, 288-289. Pasig City, Philippines: Department of Education, 2013.
Electronic Resources: N/A
Development Team Region IX Hymn
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Zamboanga del Sur NHS Reviewer: MILA P. ARAO
EPS - Science Management Team:
DANNY B. CORDOVA, Ed.D., CESO VI Schools Division Superintendent
MARIA COLLEEN L. EMORICHA, Ed.D., CESE Assistant Schools Division Superintendent MARIA DIOSA Z. PERALTA
CID Chief
MA. MADELENE P. MITUDA, Ed.D. Education Program Supervisor – LRMDS MILA P. ARAO
Education Program Supervisor - Science
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