HigH ScHool Science Today        Second year         Textbook
HigH ScHool Science TodaySecond YearTextbookPhilippine Copyright 2009 by DIWA LEARNING SYSTEMS INCAll rights reserved. Pri...
P r e fa c e     Discoveries in science and technology in recent years have had a profound impact onour society. We are no...
Table of conTenTSUniT 1       biology: THe Science of lifeChapter 1    Introduction to Biology1.1          The Need to Stu...
Chapter 11   Controlling and Regulating Body Systems11.1         The Nervous System .........................................
Chapter 26                         Evidences of Evolution26.1                               Fossils .........................
Biology:                                                                               Unit                               ...
Chapter             1                               inTroducTion        To   Biology      Simply put, biology is the study...
1 . 2	 		The differenT BrancheS of Biology     Biology is the study of life. It comes from the Greek words bios meaning “l...
11.   Ichthyology − the study of fishes.    12.   Mammalogy − the study of mammals.    13.   Marine ecology − the study of...
2.   The science of life can be studied through a variety of structural levels and         functions.              Even th...
1 . 4		living ThingS and Their characTeriSTicS     Can you tell if something is living or not? Things are said to be livin...
This can be related to a humanbeing that started as a single celldeveloping in a mother’s womb. Fromthat single cell, thou...
All living things should adapt themselves to their habitats, climates, food sources, andways of life.                     ...
an organ system. Organ systems make up an organism. Each organ performs specificfunctions necessary for the survival of an...
Scientists perform activities based on observation, data gathering and analysis, andexperimentation. The logical way used ...
3.	   Place	a	dozen	planarians	in	each	of	the	Petri	dishes.	       4.	   Place	two	of	the	Petri	dishes	in	two	separate	sho...
In conducting a scientific investigation, there are always two kinds of setups—theexperimental and the control. The experi...
5. Scientists that specialize in cell structure, function, and processes are experts in          the field of ____________...
E     	 xperiment:            a. Paulo got two young plants of the same kind, size, and vigor.            b. He placed equ...
Chapter                2                              Technology        and    people     Technology refers to the practic...
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  1. 1. HigH ScHool Science Today Second year Textbook
  2. 2. HigH ScHool Science TodaySecond YearTextbookPhilippine Copyright 2009 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the PhilippinesEditorial, design, and layout by University Press of First AsiaNo part of this publication may be reproduced or transmitted in any form or by any meanselectronic or mechanical, including photocopying, recording, or any information storage andretrieval systems, without permission in writing from the copyright owner. Exclusively distributed by DIWA LEARNING SYSTEMS INC 4/F SEDCCO 1 Bldg. 120 Thailand corner Legazpi Streets Legaspi Village, 1229 Makati City, Philippines Tel. No.: (632) 893-8501 * Fax: (632) 817-8700 ISBN 978-971-46-0099-7reviewerAnnalee S. Hadsall has a bachelor’s degree in Biology (cum laude) from the Philippine Normal College.She has a master’s degree in Botany, with specialization in Plant Systematics, from the Universityof the Philippines−Los Baños under the UP-NSDB scholarship grant. Prof. Hadsall is an AssistantProfessor 7 at the Institute of Biological Sciences of the University of the Philippines–Los Baños. Shehas been involved in writing laboratory manuals in biodiversity and general botany for UPLB andbiology modules for the UP Open University.
  3. 3. P r e fa c e Discoveries in science and technology in recent years have had a profound impact onour society. We are now able to communicate easier with the use of the Internet and cellularphones. We have found ways to replace damaged body parts through prostheses and organtransplants. People are continually developing new medicines to treat diseases that wereonce fatal. Scientists have been able to clone animals, find alternative fuel sources, explorethe far reaches of outer space, and develop better materials for construction. Even the waywe entertain ourselves has been affected by discoveries in science. With all these fascinating discoveries, it is important that you understand thescientific principles behind such advancements. The High School Science Today series hasbeen developed with two objectives in mind: to explain key scientific concepts clearly andaccurately within a context of unifying themes; and to introduce you to the technology andresearch techniques which have resulted from the application of these scientific concepts. The topics in each textbook are organized to keep key science concepts in clear view.In each chapter, you will find discussions on specific technological breakthroughs and theimplications these developments have on our global community. Understanding science requires that you observe the things around you, performexperiments to solve problems, and explain the reasons for your observation. Eachtextbook contains activities that will help you develop the skills necessary in learningscience concepts meaningfully. These activities will provide you with hands-on learningexperiences. You will be asked to predict, hypothesize, describe, make models, formconclusions, calculate, and measure with accuracy and precision. As such, High School Science Today will enable you to keep pace with the ever-evolving world of science and technology. We invite you to take this journey with us—intothe future and beyond.
  4. 4. Table of conTenTSUniT 1 biology: THe Science of lifeChapter 1 Introduction to Biology1.1 The Need to Study Biology .............................................................................................................. 21.2 The Different Branches of Biology .................................................................................................. 31.3 The Unifying Ideas in Biology........................................................................................................... 41.4 Living Things and Their Characteristics........................................................................................... 61.5 The Importance of the Scientific Method ........................................................................................ 91.6 The Scientific Way of Conducting Investigations ............................................................................ 11Chapter 2 Technology and People2.1 Biotechnology ................................................................................................................................... 152.2 Some Local and Foreign Biologists .................................................................................................. 182.3 Careers Related to Biology................................................................................................................ 21Chapter 3 Tools Used in Scientific Studies3.1 The Microscope ................................................................................................................................. 243.2 A Detailed Look at the Compound Microscope ............................................................................... 263.3 Other Tools Used in Scientific Research .......................................................................................... 29UniT 2 THe PUzzle PieceS of lifeChapter 4 Cells in Living Things4.1 Early Cell Discoveries........................................................................................................................ 324.2 The Different Parts of a Cell ............................................................................................................. 344.3 Organisms Can Be Unicellular, Colonial, or Multicellular .............................................................. 414.4 Prokaryotes and Eukaryotes ............................................................................................................ 43Chapter 5 Passing across the Cell Membrane5.1 The Fluid Mosaic Model of the Cell Membrane ............................................................................... 455.2 The Mechanisms for Cell Membrane Transport .............................................................................. 475.3 The Transport of Large Particles through Cell Membranes ............................................................ 505.4 Cell Size.............................................................................................................................................. 515.5 Research and Technology Related to Cells....................................................................................... 535.6 Importance of Some Cell Processes ................................................................................................. 54UniT 3 ProceSSeS of bioenergeTicSChapter 6 What a Leaf Is6.1 The Different Parts of a Leaf............................................................................................................. 586.2 Chloroplasts in Leaves ..................................................................................................................... 606.3 Chlorophyll in Plants ........................................................................................................................ 61Chapter 7 The Process of Photosynthesis7.1 The Photosynthetic Reaction ........................................................................................................... 647.2 The Light Reaction ........................................................................................................................... 657.3 The Dark Reaction ............................................................................................................................ 667.4 Factors Affecting Photosynthesis .................................................................................................... 697.5 Scientific Explanation of Farming Practices ................................................................................... 70Chapter 8 Cellular Respiration8.1 ATP..................................................................................................................................................... 748.2 The Process of Cellular Respiration .................................................................................................. 758.3 Interdependence among Living Things for Important Gases ......................................................... 79UniT 4 THe organ SySTemSChapter 9 Hierarchy in Organisms9.1 Levels of Organization...................................................................................................................... 849.2 Organized System ............................................................................................................................. 85Chapter 10 The Organ Systems of Plants10.1 Cell and Tissue Types Found in Plants ............................................................................................ 8810.2 Factors Affecting the Growth of Plants ........................................................................................... 9310.3 The Response of Plants to the Environment ................................................................................... 94
  5. 5. Chapter 11 Controlling and Regulating Body Systems11.1 The Nervous System ......................................................................................................................... 9711.2 The Different Sense Organs and Their Parts.................................................................................... 10111.3 The Endocrine System ...................................................................................................................... 104Chapter 12 Protective Body Systems12.1 The Integumentary System .............................................................................................................. 11112.2 The Muscular System ........................................................................................................................ 11512.3 The Skeletal System .......................................................................................................................... 117Chapter 13 Energy Producing and Distributing Systems13.1 The Digestive System ........................................................................................................................ 12113.2 The Respiratory System .................................................................................................................... 12513.3 The Circulatory System ..................................................................................................................... 129Chapter 14 Waste Elimination System14.1 The Excretory System ....................................................................................................................... 133UniT 5 reProdUcTive PaTTernSChapter 15 Division of Cells15.1 The Cell Cycle and Mitosis ................................................................................................................ 14015.2 Meiosis............................................................................................................................................... 14415.3 Meiosis in Humans ........................................................................................................................... 146Chapter 16 Plant Reproduction16.1 Asexual Reproduction in Plants ....................................................................................................... 14816.2 Sexual Reproduction in Plants ......................................................................................................... 150Chapter 17 Animal Reproduction17.1 Asexual Reproduction in Animals ................................................................................................... 15817.2 Sexual Reproduction in Animals ..................................................................................................... 160Chapter 18 Human Reproduction18.1 The Male Reproductive System ....................................................................................................... 16318.2 The Female Reproductive System..................................................................................................... 16418.3 Fertilization ....................................................................................................................................... 166Chapter 19 Problems and Issues Concerning Human Reproduction19.1 Infertility .......................................................................................................................................... 17219.2 Birth Control .................................................................................................................................... 17319.3 Sexually Transmitted Diseases (STDs) ............................................................................................ 175UniT 6 HerediTyChapter 20 The Chemical Basis of Inheritance20.1 The DNA Molecule ............................................................................................................................ 18020.2 The Role of Protein Synthesis in Inheritance .................................................................................. 18220.3 DNA Replication ............................................................................................................................... 186Chapter 21 Chromosomes and Genes21.1 Mutation in Chromosomes and Genes ........................................................................................... 18921.2 Human Chromosome Mutations Due to Nondisjunction ............................................................. 193Chapter 22 Principles and Laws of Genetics by Mendel22.1 Mendel’s Laws of Genetics ............................................................................................................... 19622.2 The Use of Punnet Squares .............................................................................................................. 19922.3 Genetic Reasoning ........................................................................................................................... 204Chapter 23 Non-Mendelian Genetics23.1 Other Types of Dominance .............................................................................................................. 20823.2 Chromosomes Determine Sex ......................................................................................................... 21123.3 Non-Mendelian Traits Involving Gender ........................................................................................ 212Chapter 24 Effects of Environment and Technology on Heredity24.1 Effects of the Environment on the Expression of Traits ............................................................... 21724.2 Modern Technology and Genetics ................................................................................................... 219UniT 7 HiSTory of living organiSmSChapter 25 Theories of Evolution25.1 Some Theories of Evolution ............................................................................................................. 22425.2 Patterns in Evolution ....................................................................................................................... 230
  6. 6. Chapter 26 Evidences of Evolution26.1 Fossils ............................................................................................................................................... 23226.2 Embryonic Development ................................................................................................................. 23526.3 Biochemical Evidences ..................................................................................................................... 23726.4 Effects of Technology on the Evolution of Organisms .................................................................. 243Chapter 27 Human Evolution27.1 Humans and Primates ..................................................................................................................... 24627.2 Races .................................................................................................................................................. 250UniT 8 claSSifying living THingSChapter 28 Milestones in Biological Classification28.1 Basic Aspects of Taxonomy ............................................................................................................. 25428.2 Different Levels of Classification .................................................................................................... 257Chapter 29 The Six-kingdom Scheme of Classification29.1 An Overview of the Six Kingdoms .................................................................................................. 26129.2 Archaebacteria .................................................................................................................................. 26329.3 Eubacteria ......................................................................................................................................... 26329.4 Protista ............................................................................................................................................. 26429.5 Fungi ................................................................................................................................................. 26729.6 Plantae .............................................................................................................................................. 26729.7 Animalia ............................................................................................................................................ 27229.8 Viruses .............................................................................................................................................. 280Chapter 30 Adaptive Mechanisms of Living Organisms30.1 Adaptations of Animals ................................................................................................................... 28630.2 Adaptations of Plants ...................................................................................................................... 28830.3 Defense Adaptations ........................................................................................................................ 28830.4 Adaptation for Preserving Offspring .............................................................................................. 291Chapter 31 Some Organisms and Their Importance31.1 Importance of Organisms................................................................................................................. 29431.2 Conserving Economically Important Organisms ........................................................................... 295UniT 9 Science in naTUreChapter 32 The Ecosystem32.1 Ecosystem: An Interactive Community .......................................................................................... 30032.2 The Ecosystem and Its Components ............................................................................................... 30232.3 The Need for Natural Balance in an Ecosystem .............................................................................. 30332.4 The Three Important Biogeochemical Cycles in an Ecosystem ...................................................... 30332.5 Ecological Succession ....................................................................................................................... 307Chapter 33 Interrelationships in an Ecosystem33.1 Habitats and Lifestyles in a Community ......................................................................................... 31133.2 The Different Biotic Relationships .................................................................................................. 312Chapter 34 Energy Flow in an Ecosystem34.1 Energy Supply .................................................................................................................................. 31634.2 Energy Level ..................................................................................................................................... 31634.3 Food Chains ...................................................................................................................................... 31734.4 The Pyramid of Productivity ............................................................................................................ 31934.5 Energy Requirement of Humans ..................................................................................................... 320Chapter 35 Different Natural and Man-made Ecosystems35.1 Terrestrial Biomes ............................................................................................................................ 32335.2 Aquatic Biomes ................................................................................................................................. 32635.3 Interdependent Ecosystems ............................................................................................................ 32835.4 Man-made Ecosystems .................................................................................................................... 329Chapter 36 Threats to the Ecosystems36.1 Natural Threats ................................................................................................................................. 33236.2 Man-made Threats ........................................................................................................................... 33336.3 Saving Our Ecosystems .................................................................................................................... 337Glossary .............................................................................................................................................................................. 341Bibliography ............................................................................................................................................................................ 343Index .............................................................................................................................................................................. 345
  7. 7. Biology: Unit 1The Science of life Earth occupies a unique place in the solar system. Some scientists hypothesize that Earth isthe only planet that can sustain life. Living things such as the forests, seas, grasslands, and man-made communities abound inour planet. The study of life, therefore, has become a continuing human endeavor. This unit hopesto inspire you to study Biology—the science of life.
  8. 8. Chapter 1 inTroducTion To Biology Simply put, biology is the study of life. Anything living and to some extent, once-living,fall under the domain of biology. This chapter will introduce the fundamentals of biology as ascientific discipline as well as the general characteristics of living things. 1.1 The need To STudy Biology Over the last few years, you have studied various organisms through theircharacteristics. This is part of studying biology. You have also studied biology when youidentified the function of each major organ system in the human body. And it is biologyat work when you put food coloring in water to see capillary action in a lettuce stem. Youcannot get away from biology because you observe and participate in biological processesevery day as you eat, sleep, study, and play. In an age when breakthroughs in the field of biological science are being made morepublic, it is important that you, as a student, are aware of the implications of these recentdiscoveries to society. But before you can begin to appreciate them, you should be able tounderstand and learn the basic concepts involved in the study of life. Fig. 1.1 We encounter biology every day. High School Science Today II
  9. 9. 1 . 2 The differenT BrancheS of Biology Biology is the study of life. It comes from the Greek words bios meaning “life” andlogos meaning “study.” Biology is divided into a number of specific fields of study. These arethe major branches of biology: Biology Botany is the Genetics is the Microbiology Evolutionary biology study of plants. study of genes is the study of is the study of the and patterns microorganisms change in organisms of inheritance and viruses. over time. (heredity). Zoology is the Ecology is the study study of animals. of relationships between organisms and their environment. Here are some of the specific fields of Biology. 1. Anatomy − the study of the morphology (form and structure) of organisms and their elements. 2. Bacteriology − the study of bacteria. 3. Biochemistry − the study of the molecules within the cell and the chemical composition of living things. 4. Cytology − the study of the formation, structure, and function of cells. 5. Embryology − the study of the formation, early growth, and development of organisms. 6. Entomology − the study of insects. 7. Epidemiology − the study of patterns of diseases within a certain population, determining causes of diseases and how they spread. 8. Ethnobotany − the study of the way plants are identified, classified, and used by various cultures. 9. Herpetology − the study of reptiles and amphibians. 10. Histology − the study of the minute structures of plant and animal tissues. Biology: The Science of Life
  10. 10. 11. Ichthyology − the study of fishes. 12. Mammalogy − the study of mammals. 13. Marine ecology − the study of the interrelationships of marine organisms with their environment. 14. Mycology − the study of fungi. 15. Ornithology − the study of birds. 16. Paleontology − the study of fossils. 17. Parasitology − the study of parasites. 18. Pathology − the study of the nature of diseases and their causes. 19. Phycology − the study of seaweeds and algae. 20. Physiology − the study of typical life processes, functions, and activities of organisms. 21. Terrestrial ecology − the study of the interrelationships of land organisms with their environment. 22. Virology − the study of viruses and viral diseases. 1 . 3 The unifying ideaS in Biology Although the branches of biology deal with different fields of study, they share thefollowing principles: 1. Life on Earth is both diverse and united through continuous interactions among life forms. Recall the concept of the food chain and the food web you have learned. All the organisms in the food web are connected to each other in a feeding relationship. You can also be a part of the food web. How do you think this is possible? Similarly, people, animals, and plants are connected to each other in a different way other than in a feeding relationship. Animals give off a gas which plants need. Plants, in turn, release a gas which is necessary for the survival of animals. List some interactions between living organisms that you usually observe. High School Science Today II
  11. 11. 2. The science of life can be studied through a variety of structural levels and functions. Even though living systems are complex, there is an underlying degree of order which is basic to life. Your body is a very good example that shows the order of structural levels. Your body is made up of organs. These organs are then made up of smaller parts. Each part works together with other parts. Take eating as an example. You use different body parts to chew and digest the food, but these parts work toward a single function—to make the energy stored in food available for your body to use. 3. The basic unit of structure and function is the cell, and as such it is at the core of all levels of biological organization. The cell is the basic unit of life. You will learn more about the cell in Unit II of this book. ACTIVITY 1.1 My Biology CollageMaterials scissors, paste, old magazines, newspapersProcedure 1. Make a collage showing the unifying ideas of biological sciences. You can use pictures from old magazines. 2. On a clean sheet of paper, write a short paragraph explaining your artwork and relating it with the unifying ideas of the biological sciences. 3. Share with the class what you have written. Explain the collage to the class. Biology: The Science of Life
  12. 12. 1 . 4 living ThingS and Their characTeriSTicS Can you tell if something is living or not? Things are said to be living if they have thefollowing characteristics: • They are able to reproduce. • They exhibit growth and development. • They have the ability to respond to stimuli (irritability) and adapt themselves to changing environmental conditions. • They evolve. • They have a high degree of organization. • They undergo the process of metabolism. • They exhibit homeostasis.Reproduction One distinction between living andnonliving things is the ability of living thingsto reproduce their own kind. Only livingthings are capable of reproduction. Throughreproduction, the characteristics of the parentsare passed on from one generation to the nextgeneration. What will happen if living things do notreproduce?Growth and Development Living things exhibit growth and Fig. 1. The mating season marks the start ofdevelopment. A germinating seed grows and reproduction in some organisms.develops into a plant. It increases in size, andeventually forms distinct parts such as roots,stems, and leaves. An organism grows as its body processes food. Growth can be exhibited by an increasein size, height, weight, or in the amount of materials in an organism. Development ismarked by the changes an organism undergoes throughout its life span. High School Science Today II
  13. 13. This can be related to a humanbeing that started as a single celldeveloping in a mother’s womb. Fromthat single cell, thousands of differentkinds of cells grew and developed. Do nonliving things also exhibitgrowth? How? Give an example.Response to Stimuli (Irritability) All living things are affected byboth internal and external factors. What Fig. 1. Physical changes are natural results ofhappens to your body temperature when growth.the weather gets cold? Your brain responds internally to the change in temperature by giving certain signals to specific organs. You then respond to the external factor, such as the cold weather, by wearing a jacket or sweater. Other living things also display the ability to respond to stimuli. Take for example the makahiya plant (Mimosa pudica), whose leaves fold once you touch them. What will happen to living things if they cannot respond to changes in the environment?Fig. 1. Makahiya leaves fold once touched. It takes about 10 minutes for the plant to open its leaves again.Evolutionary Adaptation Response is basically a short-term reaction. However, since an organism’senvironment does not change drastically, organisms need to adapt. Evolutionaryadaptation refers to the traits an organism possesses as a consequence of surviving in theenvironmental conditions. Living things should adapt to their environment so that they will continue to exist.Fish adapt to living in water. They have fins which enable them to maneuver and their bodyshapes minimize the drag caused by swimming. Biology: The Science of Life
  14. 14. All living things should adapt themselves to their habitats, climates, food sources, andways of life. Phylogenetic Tree of Life Bacteria Archaea Eucarya Green Filamentous Slime bacteria Entamoeba molds Animals Spirochetes Methanosarcina Fungi Gram Methanobacterium positive Halophiles Plants Proteobacteria Methanococcus Cyanobacteria T. celer Ciliates Thermoproteus Planctomyces Flagellates Pyrodicticum Bacteroides Trichomonads Cytophaga Microsporidia Thermotoga Diplomonads Aquifex Fig. 1. One good way of showing relationships among organisms is by making a phylogenetic tree. The phylogenetic tree shows how organisms diverged from their common ancestor because of evolution. The phylogenetic tree above shows the relationships among the major groups of organisms.High Degree of Organization In biology, scientists study lifeand its processes following levels oforganizations. The cell, the basic functional unitof life, is a highly organized structure.Cells are composed of biomolecules suchas nucleic acids, lipids or fats, proteins,and carbohydrates. These biomoleculeshelp the cell perform essentialfunctions such as reproduction, atoms → molecules → organelles → cellsdigestion, and respiration. organ system ← organs ← tissues Different kinds of cells that are organism → population → communitygrouped together make up a tissue.Tissues are organized to form a more biome ← ecosystemcomplex structure called an organ.Organs that are grouped together form Fig. 1. All living things are made up of atoms which form molecules. Molecules form larger structures. High School Science Today II
  15. 15. an organ system. Organ systems make up an organism. Each organ performs specificfunctions necessary for the survival of an organism. The structure of an organ is developedto suit a particular function. For example, your stomach has folded structures to increaseits surface area. A large surface area allows more food substances to be exposed to digestivejuices.Metabolism All living things obtain the materials and energy they need from the environment tobe able to perform the different life processes such as nutrition, movement, respiration,excretion, growth, circulation, and reproduction. Plants have the capacity to obtain and utilize light energy from the sun to convert rawmaterials (carbon dioxide, water) into food. Animals and other living things are capableof converting stored energy from food into a usable form of energy through cellularrespiration. Cellular respiration releases the stored energy from food like in plants. Energy isthen used by the cells to be able to perform various activities. The process of converting and releasing energy is called metabolism. Only livingthings are capable of undergoing metabolic activities. Metabolism enables living thingsto break down food into simpler forms to release the stored energy in the process calledcatabolism. Living things are also capable of anabolism which allows them to synthesize newproducts such as proteins and nucleic acids.Homeostasis Living things have the ability to maintain the condition of their internal environmentwithin tolerable limits. This regulatory mechanism is called homeostasis. This is evident,for example, in the regulation of body temperature in humans which is maintained at atemperature of 37oC. If this temperature rises, the human body perspires. The evaporationof perspiration cools the body. 1 . 5 The imporTance of The ScienTific meThod As with all sciences, biology is not solely a visual experience—it requires all five sensesto collect, analyze, and use information. Like any field of study, biology requires patienceand systematic ways of solving problems. Biology: The Science of Life
  16. 16. Scientists perform activities based on observation, data gathering and analysis, andexperimentation. The logical way used by scientists to solve their problems or to answertheir questions is called the scientific method. The method starts with the identificationof the problem. When scientists notice some occurrences in their surroundings, they startto ask questions. They gather information about the problem from the previous works ofother scientists. Then, they come up with possible answers or hypotheses. Hypothesesare intelligent guesses derived from observations. The hypothesis should contain theproblem or the subject being studied and two possible consequences or results. The twopossible consequences may be positive or negative. These consequences are used to denotethe possible result of the study. Hypotheses are tested by conducting experiments. Theorganization and analysis of the experimental results follow after experimentation. Resultsmay be presented in graphs, charts, or tables. The results become the basis for a conclusion,which might prove or disprove the hypotheses. The results of the scientific investigationmay be communicated to the scientific community through the publication of scientificpapers, conventions, symposiums, and conferences. In summary, these are the steps of the scientific method: 1. State the problem. 2. Gather information about the problem. 3. Formulate a hypothesis. 4. Test the hypothesis through experimentation. 5. Analyze the data gathered from the experiment. 6. Formulate a conclusion. 7. Communicate the results. Practice how to state a problem and formulate a hypothesis by doing the followingexperiment. ACTIVITY 1. Come into the Light Materials three Petri dishes, pond or aged tap water, three dozen planarians, three sheets of white paper, three sheets of black paper, lampshade, and two shoe boxes Procedure 1. Place the black and white sheets of paper under each Petri dish such that each sheet is covered by half of the bottom of the dish. 2. Pour pond or aged tap water into each Petri dish.10 High School Science Today II
  17. 17. 3. Place a dozen planarians in each of the Petri dishes. 4. Place two of the Petri dishes in two separate shoe boxes. 5. Focus the light of the lampshade on one of the Petri dishes. 6. Position all three dishes side by side. Observe the behavior of the planarians. (a) (b) (c) Questions 1. To which side of the dish did the planarians move? 2. How would you account for the movement of the planarians? 3. Which of the setups is experimental? Which is the control? 4. What are the variables used in the activity? Check whether you have identified the variables correctly. Read the next lesson. 1.6 The ScienTific Way of conducTing inveSTigaTionSVariables in a Scientific Investigation You have learned the systematic way of solving problems. Now, you are ready toobserve other important factors involved in conducting a scientific investigation. Thefactors affecting the results of a study are called variables. Variables are of two kinds:dependent and independent. The factor that causes changes in the result of a study is calledthe independent variable. The dependent variable is the result which is observed tochange due to the independent variable. In Activity 1.2, the movement of the planarians isthe dependent variable. The shoe boxes and light from the lampshade used for each dish arethe independent variables. Biology: The Science of Life 11
  18. 18. In conducting a scientific investigation, there are always two kinds of setups—theexperimental and the control. The experimental setup is characterized by the presenceof independent variables which can be manipulated. This setup is the subject of your study.In the case of the experiment in Activity 1.2, the Petri dishes in the shoe boxes and underthe lampshade are the experimental setups. The control setup is the one which does notcontain any independent variable and is the basis by which the experimental result shouldbe evaluated. Thus, one Petri dish with planarians was not exposed to changes in lightingconditions to represent the normal situation. From Activity 1.2, you have learned to identify the control and experimental setups.Think of a problem with some help from your group mates. Design a simple experimentbased on the problem. Make an outline of your experimental design following thescientific method. Identify the independent and dependent variables and the control andexperimental setups in your experiment. You can always have two or more groups of setups while testing a single hypothesis.What do you think is the significance of having several setups? The outcome of scientific findings should be reported to the community throughpublication of academic journals. The results of an investigation remain largely insignificantto society unless reported. Scientific investigations allow scientists to explore other fields of science, work withdifferent people, gain more knowledge, and learn and develop new ideas. Chapter ReviewI. Enriching Your Science Vocabulary A. Choose the words in the box that will complete the sentences below. bios entomology logos herpetology cell bacteriology cytology 1. Scientists do not consider the virus as a living thing because it has no _____, which is the basic unit of structure and function. 2. A scientist studying the life cycle of moths and flies to effectively limit their population is a specialist in the field of _________________. 3. The word biology comes from the words _______________ meaning “life” and _______________ meaning “study.” 4. Scientists who study the nature of microscopic organisms, especially bacteria, are experts in the field of _______________.1 High School Science Today II
  19. 19. 5. Scientists that specialize in cell structure, function, and processes are experts in the field of ___________________. B. Match the situations in column A with the characteristics of living things in column B. Write the letter of your answer on the blank space. Column A Column B ______ 1. Your heart is made up of a. reproduction special kinds of muscles b. growth and development working together. c. irritability ______ 2. A flower that has been d. metabolism pollinated becomes a fruit. e. organization ______ 3. You try to block very bright light from your field of vision. f. evolution ______ 4. A mosquito lays thousands of eggs in stagnant water. ______ 5. Your body breaks down food so it can be used by your cells.II. Assessing Your Knowledge A. Answer the following questions briefly. 1. Why do you think Biology is a required subject in high school? 2. Which branch of biology do you think is the most exciting? Why do you say so? B. Choose the letter of the best answer. Write your answer on the blank space. ______ 1. Which of the following can be accepted or not depending on the results obtained after the experiment? a. variable b. hypothesis c. problem d. conclusion For numbers 2–5: Paulo wanted to show the relationship between plant growth and the presence of fertilizer. Problem: Will plants grow faster in soil with fertilizer? Hypothesis: Plants grown in soil with fertilizer will grow faster than plants grown in soil without fertilizer. Biology: The Science of Life 1
  20. 20. E xperiment: a. Paulo got two young plants of the same kind, size, and vigor. b. He placed equal amounts of loam soil in two identical containers. He planted one plant in a container without fertilizer. He planted the other plant in a container with fertilizer. c. He placed the two plants in the garden, making sure that both plants get the same amount of sunlight. d. Every morning, he gave the plants the same amount of water. e. He recorded the length of the stem of both plants for a week.Data gathered after seven days: Length of Stem (cm) Setup Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7Plant without 3 3.5 3.5 3.75 4 4.25 4.5fertilizerPlant with 3 3.5 4 4.25 4.75 5 5.5fertilizer ______ 2. In the experiment, what is the independent variable? a. application of fertilizer b. amount of water given c. length of the stems d. number of days ______ 3. What is the dependent variable? a. presence of fertilizer b. amount of water given c. length of the stems d. number of days ______ 4. Which is the experimental setup? a. plant with fertilizer b. plant without fertilizer c. two plants d. fertilizer ______ 5. If Paulo were to base his hypothesis on the results, should he accept his hypothesis? a. Yes, the results of the experiment support his hypothesis. b. Yes, the observations support the variable. c. No, the results of the experiment do not support his hypothesis. d. No, the observations are not enough to be conclusive.1 High School Science Today II
  21. 21. Chapter 2 Technology and people Technology refers to the practical application of knowledge to society. Scientists oftenneed to have a firm background on a body of knowledge before coming up with an inventionor an innovation. Technology is the application of scientific principles. Many technological breakthroughsand innovations have had significant implications on the way we live today. Can you imaginehow we can store food if the refrigerator were not invented? We have come to depend on thebenefits of technology. It is important that we understand the underlying scientific principlesbehind them. 2.1 BioTechnology Biotechnology is defined in two ways. First, it is concerned with the processing ofliving organisms to produce useful products for human consumption. The second definitionrefers to the technique of using deoxyribonucleic acid (DNA) sequence, cell, enzymes,and other molecular components of a living organism to produce commercial products.Biotechnology uses concepts in microbiology, biochemistry, and chemical engineering.Biotechnology applies these concepts to manufacture useful products. The first definition of biotechnology involves the production of useful products forhuman consumption. Examples of these are the production of powdered shrimp heads, soysauce, patis and bagoong, nata de coco, and dairy products. 1. Powdered shrimp heads − The Philippines is one of the world’s major exporters of shrimps, but exporters and processors face the problem of how to lengthen the shelf life of their products. Shrimp heads release a foul odor because of the rapid degradation of enzymes. Hence, exporters and processors remove the shrimps’ heads before they are exported. Not only does the foul odor affect the export quality of the shrimps, but a great amount of shrimps’ heads is wasted. To be able to maximize the use of shrimps, the Food and Nutrition Research Institute (FNRI) has developed a technology that converts shrimps’ heads into a usable product. This product is a concentrated powder which provides a good source of protein and flavor for various food products. 2. Soy sauce − Traditionally, fermentation in soy sauce making lasts from 1 to 3 h and requires a temperature of 37oC. However, recent studies have established that good quality soy sauce needs to be fermented for a month at 40oC. Scientists use the salt-tolerant acid bacterium, Lactobacillus delbrueckii. They have also discovered that mongo beans are a good substitute for soy beans. Biology: The Science of Life 1

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