Hssttx2

HigH ScHool Science Today

Textbook

Second year

HigH ScHool Science Today Second YearTextbook

Philippine Copyright 2009 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the Philippines

Editorial, design, and layout by University Press of First Asia

No part of this publication may be reproduced or transmitted in any form or by any means electronic or mechanical, including photocopying, recording, or any information storage and retrieval 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 978-971-46-0099-7

reviewer

Annalee 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 University of the Philippines−Los Baños under the UP-NSDB scholarship grant. Prof. Hadsall is an Assistant Professor 7 at the Institute of Biological Sciences of the University of the Philippines–Los Baños. She has been involved in writing laboratory manuals in biodiversity and general botany for UPLB and biology modules for the UP Open University.

Preface

Discoveries in science and technology in recent years have had a profound impact on our society. We are now able to communicate easier with the use of the Internet and cellular phones. We have found ways to replace damaged body parts through prostheses and organ transplants. People are continually developing new medicines to treat diseases that were once fatal. Scientists have been able to clone animals, find alternative fuel sources, explore the far reaches of outer space, and develop better materials for construction. Even the way we entertain ourselves has been affected by discoveries in science.

With all these fascinating discoveries, it is important that you understand the scientific principles behind such advancements. The High School Science Today series has been developed with two objectives in mind: to explain key scientific concepts clearly and accurately within a context of unifying themes; and to introduce you to the technology and research 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 the implications these developments have on our global community.

Understanding science requires that you observe the things around you, perform experiments to solve problems, and explain the reasons for your observation. Each textbook contains activities that will help you develop the skills necessary in learning science concepts meaningfully. These activities will provide you with hands-on learning experiences. You will be asked to predict, hypothesize, describe, make models, form conclusions, 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—into the future and beyond.

Table of conTenTS

UniT 1 biology: THe Science of life

Chapter 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 ............................................................................ 11

Chapter 2 Technology and People2.1 Biotechnology ................................................................................................................................... 152.2 Some Local and Foreign Biologists .................................................................................................. 182.3 Careers Related to Biology ................................................................................................................ 21

Chapter 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 .......................................................................................... 29

UniT 2 THe PUzzle PieceS of life

Chapter 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 ............................................................................................................ 43

Chapter 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 ................................................................................................. 54

UniT 3 ProceSSeS of bioenergeTicS

Chapter 6 What a Leaf Is6.1 The Different Parts of a Leaf............................................................................................................. 586.2 Chloroplasts in Leaves ..................................................................................................................... 606.3 Chlorophyll in Plants ........................................................................................................................ 61

Chapter 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 ................................................................................... 70

Chapter 8 Cellular Respiration8.1 ATP ..................................................................................................................................................... 748.2 The Process of Cellular Respiration .................................................................................................. 758.3 Interdependence among Living Things for Important Gases ......................................................... 79

UniT 4 THe organ SySTemS

Chapter 9 Hierarchy in Organisms9.1 Levels of Organization ...................................................................................................................... 849.2 Organized System ............................................................................................................................. 85

Chapter 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

Chapter 11 Controlling and Regulating Body Systems 11.1 The Nervous System ......................................................................................................................... 9711.2 The Different Sense Organs and Their Parts .................................................................................... 10111.3 The Endocrine System ...................................................................................................................... 104

Chapter 12 Protective Body Systems12.1 The Integumentary System .............................................................................................................. 11112.2 The Muscular System ........................................................................................................................ 11512.3 The Skeletal System .......................................................................................................................... 117

Chapter 13 Energy Producing and Distributing Systems13.1 The Digestive System ........................................................................................................................ 12113.2 The Respiratory System .................................................................................................................... 12513.3 The Circulatory System ..................................................................................................................... 129

Chapter 14 Waste Elimination System14.1 The Excretory System ....................................................................................................................... 133

UniT 5 reProdUcTive PaTTernS

Chapter 15 Division of Cells15.1 The Cell Cycle and Mitosis ................................................................................................................ 14015.2 Meiosis ............................................................................................................................................... 14415.3 Meiosis in Humans ........................................................................................................................... 146

Chapter 16 Plant Reproduction16.1 Asexual Reproduction in Plants ....................................................................................................... 14816.2 Sexual Reproduction in Plants ......................................................................................................... 150

Chapter 17 Animal Reproduction17.1 Asexual Reproduction in Animals ................................................................................................... 15817.2 Sexual Reproduction in Animals ..................................................................................................... 160

Chapter 18 Human Reproduction 18.1 The Male Reproductive System ....................................................................................................... 16318.2 The Female Reproductive System ..................................................................................................... 16418.3 Fertilization ....................................................................................................................................... 166

Chapter 19 Problems and Issues Concerning Human Reproduction19.1 Infertility .......................................................................................................................................... 17219.2 Birth Control .................................................................................................................................... 17319.3 Sexually Transmitted Diseases (STDs) ............................................................................................ 175

UniT 6 HerediTy

Chapter 20 The Chemical Basis of Inheritance20.1 The DNA Molecule ............................................................................................................................ 18020.2 The Role of Protein Synthesis in Inheritance .................................................................................. 18220.3 DNA Replication ............................................................................................................................... 186

Chapter 21 Chromosomes and Genes21.1 Mutation in Chromosomes and Genes ........................................................................................... 18921.2 Human Chromosome Mutations Due to Nondisjunction ............................................................. 193

Chapter 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 ........................................................................................................................... 204

Chapter 23 Non-Mendelian Genetics23.1 Other Types of Dominance .............................................................................................................. 20823.2 Chromosomes Determine Sex ......................................................................................................... 21123.3 Non-Mendelian Traits Involving Gender ........................................................................................ 212

Chapter 24 Effects of Environment and Technology on Heredity24.1 Effects of the Environment on the Expression of Traits ............................................................... 21724.2 Modern Technology and Genetics ................................................................................................... 219

UniT 7 HiSTory of living organiSmS

Chapter 25 Theories of Evolution25.1 Some Theories of Evolution ............................................................................................................. 22425.2 Patterns in Evolution ....................................................................................................................... 230

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 .................................................................. 243

Chapter 27 Human Evolution27.1 Humans and Primates ..................................................................................................................... 24627.2 Races .................................................................................................................................................. 250

UniT 8 claSSifying living THingS

Chapter 28 Milestones in Biological Classification28.1 Basic Aspects of Taxonomy ............................................................................................................. 25428.2 Different Levels of Classification .................................................................................................... 257

Chapter 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 .............................................................................................................................................. 280

Chapter 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 .............................................................................................. 291

Chapter 31 Some Organisms and Their Importance31.1 Importance of Organisms................................................................................................................. 29431.2 Conserving Economically Important Organisms ........................................................................... 295

UniT 9 Science in naTUre

Chapter 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 ....................................................................................................................... 307

Chapter 33 Interrelationships in an Ecosystem33.1 Habitats and Lifestyles in a Community ......................................................................................... 31133.2 The Different Biotic Relationships .................................................................................................. 312

Chapter 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 ..................................................................................................... 320

Chapter 35 Different Natural and Man-made Ecosystems35.1 Terrestrial Biomes ............................................................................................................................ 32335.2 Aquatic Biomes ................................................................................................................................. 32635.3 Interdependent Ecosystems ............................................................................................................ 32835.4 Man-made Ecosystems .................................................................................................................... 329

Chapter 36 Threats to the Ecosystems36.1 Natural Threats ................................................................................................................................. 33236.2 Man-made Threats ........................................................................................................................... 33336.3 Saving Our Ecosystems .................................................................................................................... 337

Glossary .............................................................................................................................................................................. 341Bibliography ............................................................................................................................................................................ 343Index .............................................................................................................................................................................. 345

Unit1

Earth occupies a unique place in the solar system. Some scientists hypothesize that Earth is the only planet that can sustain life.

Living things such as the forests, seas, grasslands, and man-made communities abound in our planet. The study of life, therefore, has become a continuing human endeavor. This unit hopes to inspire you to study Biology—the science of life.

Biology: The Science of life

High School Science Today II �

Chapter 1inTroducTion To Biology

Over the last few years, you have studied various organisms through their characteristics. This is part of studying biology. You have also studied biology when you identified the function of each major organ system in the human body. And it is biology at work when you put food coloring in water to see capillary action in a lettuce stem. You cannot get away from biology because you observe and participate in biological processes every day as you eat, sleep, study, and play.

In an age when breakthroughs in the field of biological science are being made more public, it is important that you, as a student, are aware of the implications of these recent discoveries to society. But before you can begin to appreciate them, you should be able to understand and learn the basic concepts involved in the study of life.

Fig. 1.1 We encounter biology every day.

1.1The need To STudy 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 a scientific discipline as well as the general characteristics of living things.

Biology: The Science of Life �

Biology is the study of life. It comes from the Greek words bios meaning “life” and logos meaning “study.” Biology is divided into a number of specific fields of study. These are the major branches of biology:

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.

Evolutionary biology is the study of the change in organisms over time.

Botany is the study of plants.

Zoology is the study of animals.

Genetics is the study of genes and patterns of inheritance (heredity).

Microbiology is the study of microorganisms and viruses.

Ecology is the study of relationships between organisms and their environment.

Biology

1.2 The differenT BrancheS of Biology


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.

Although the branches of biology deal with different fields of study, they share the following 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.

1.3 The unifying ideaS in Biology


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 Collage

Materials

scissors,paste,oldmagazines,newspapers

Procedure 1. Makeacollageshowingtheunifyingideasofbiologicalsciences.Youcanuse

picturesfromoldmagazines. 2. Onacleansheetofpaper,writeashortparagraphexplainingyourartworkand

relatingitwiththeunifyingideasofthebiologicalsciences. 3. Sharewiththeclasswhatyouhavewritten.Explainthecollagetotheclass.


Fig. 1.� The mating season marks the start of reproduction in some organisms.

Reproduction

One distinction between living and nonliving things is the ability of living things to reproduce their own kind. Only living things are capable of reproduction. Through reproduction, the characteristics of the parents are passed on from one generation to the next generation.

What will happen if living things do not reproduce?

Growth and Development

Living things exhibit growth and development. A germinating seed grows and develops into a plant. It increases in size, and eventually forms distinct parts such as roots, stems, and leaves.

Can you tell if something is living or not? Things are said to be living if they have the following 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.

1.4living ThingS and Their characTeriSTicS

An organism grows as its body processes food. Growth can be exhibited by an increase in size, height, weight, or in the amount of materials in an organism. Development is marked by the changes an organism undergoes throughout its life span.


This can be related to a human being that started as a single cell developing in a mother’s womb. From that single cell, thousands of different kinds of cells grew and developed.

Do nonliving things also exhibit growth? How? Give an example.

Fig. 1.� Physical changes are natural results of growth.

Response to Stimuli (Irritability)

All living things are affected by both internal and external factors. What happens to your body temperature when 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?

Evolutionary Adaptation

Response is basically a short-term reaction. However, since an organism’s environment does not change drastically, organisms need to adapt. Evolutionary adaptation refers to the traits an organism possesses as a consequence of surviving in the environmental 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 body shapes minimize the drag caused by swimming.

Fig. 1.� Makahiya leaves fold once touched. It takes about 10 minutes for the plant to open its leaves again.


atoms → molecules → organelles → cells

organ system ← organs ← tissues

organism → population → community

biome ← ecosystem

All living things should adapt themselves to their habitats, climates, food sources, and ways of life.

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.

Phylogenetic Tree of Life

High Degree of Organization

In biology, scientists study life and its processes following levels of organizations.

Fig. 1.� All living things are made up of atoms which form molecules. Molecules form larger structures.

The cell, the basic functional unit of life, is a highly organized structure. Cells are composed of biomolecules such as nucleic acids, lipids or fats, proteins, and carbohydrates. These biomolecules help the cell perform essential functions such as reproduction, digestion, and respiration.

Different kinds of cells that are grouped together make up a tissue. Tissues are organized to form a more complex structure called an organ. Organs that are grouped together form

Bacteria Archaea EucaryaGreen

Filamentousbacteria

Grampositive

Spirochetes

ProteobacteriaCyanobacteria

Planctomyces

BacteroidesCytophaga

Thermotoga

Aquifex

Methanosarcina

HalophilesMethanobacteriumMethanococcus

T. celerThermoproteusPyrodicticum

EntamoebaSlime molds Animals

Fungi

Plants

Ciliates

Flagellates

Trichomonads

Microsporidia

Diplomonads


an organ system. Organ systems make up an organism. Each organ performs specific functions necessary for the survival of an organism. The structure of an organ is developed to suit a particular function. For example, your stomach has folded structures to increase its surface area. A large surface area allows more food substances to be exposed to digestive juices.

Metabolism

All living things obtain the materials and energy they need from the environment to be 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 raw materials (carbon dioxide, water) into food. Animals and other living things are capable of converting stored energy from food into a usable form of energy through cellular respiration. Cellular respiration releases the stored energy from food like in plants. Energy is then used by the cells to be able to perform various activities.

The process of converting and releasing energy is called metabolism. Only living things are capable of undergoing metabolic activities. Metabolism enables living things to break down food into simpler forms to release the stored energy in the process called catabolism. Living things are also capable of anabolism which allows them to synthesize new products such as proteins and nucleic acids.

Homeostasis

Living things have the ability to maintain the condition of their internal environment within 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 a temperature of 37oC. If this temperature rises, the human body perspires. The evaporation of perspiration cools the body.

1.5The imporTance of The ScienTific meThod

As with all sciences, biology is not solely a visual experience—it requires all five senses to collect, analyze, and use information. Like any field of study, biology requires patience and systematic ways of solving problems.

High School Science Today II 10

Scientists perform activities based on observation, data gathering and analysis, and experimentation. The logical way used by scientists to solve their problems or to answer their questions is called the scientific method. The method starts with the identification of the problem. When scientists notice some occurrences in their surroundings, they start to ask questions. They gather information about the problem from the previous works of other scientists. Then, they come up with possible answers or hypotheses. Hypotheses are intelligent guesses derived from observations. The hypothesis should contain the problem or the subject being studied and two possible consequences or results. The two possible consequences may be positive or negative. These consequences are used to denote the possible result of the study. Hypotheses are tested by conducting experiments. The organization and analysis of the experimental results follow after experimentation. Results may 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 investigation may be communicated to the scientific community through the publication of scientific papers, 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 following experiment.

Materials

threePetridishes,pondoragedtapwater,threedozenplanarians,threesheetsof whitepaper,threesheetsofblackpaper,lampshade,andtwoshoeboxes

Procedure 1. PlacetheblackandwhitesheetsofpaperundereachPetridishsuchthateach

sheetiscoveredbyhalfofthebottomofthedish. 2. PourpondoragedtapwaterintoeachPetridish.

ACTIVITY 1.� Come into the Light

Biology: The Science of Life 11

3. PlaceadozenplanariansineachofthePetridishes. 4. PlacetwoofthePetridishesintwoseparateshoeboxes. 5. FocusthelightofthelampshadeononeofthePetridishes. 6. Positionallthreedishessidebyside.Observethebehavioroftheplanarians.

Questions 1. Towhichsideofthedishdidtheplanariansmove? 2. Howwouldyouaccountforthemovementoftheplanarians? 3. Whichofthesetupsisexperimental?Whichisthecontrol? 4. Whatarethevariablesusedintheactivity?

Checkwhetheryouhaveidentifiedthevariablescorrectly.Readthenextlesson.

Variables in a Scientific Investigation

You have learned the systematic way of solving problems. Now, you are ready to observe other important factors involved in conducting a scientific investigation. The factors 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 called the independent variable. The dependent variable is the result which is observed to change due to the independent variable. In Activity 1.2, the movement of the planarians is the dependent variable. The shoe boxes and light from the lampshade used for each dish are the independent variables.

1.6The ScienTific Way of conducTing inveSTigaTionS

(a) (b) (c)

High School Science Today II 1�

I. Enriching Your Science Vocabulary

A. Choose the words in the box that will complete the sentences below.

Chapter Review

In conducting a scientific investigation, there are always two kinds of setups—the experimental and the control. The experimental setup is characterized by the presence of 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 under the lampshade are the experimental setups. The control setup is the one which does not contain any independent variable and is the basis by which the experimental result should be evaluated. Thus, one Petri dish with planarians was not exposed to changes in lighting conditions 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 experiment based on the problem. Make an outline of your experimental design following the scientific method. Identify the independent and dependent variables and the control and experimental 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 through publication of academic journals. The results of an investigation remain largely insignificant to society unless reported.

Scientific investigations allow scientists to explore other fields of science, work with different people, gain more knowledge, and learn and develop new ideas.

bios entomologylogos herpetologycell 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 _______________.

Biology: The Science of Life 1�

Column A

______ 1. Your heart is made up of special kinds of muscles working together.

______ 2. A flower that has been pollinated becomes a fruit.

______ 3. You try to block very bright light from your field of vision.

______ 4. A mosquito lays thousands of eggs in stagnant water.

______ 5. Your body breaks down food so it can be used by your cells.

Column B

a. reproduction b. growth and development c. irritability d. metabolism e. organization f. evolution

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.

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.

High School Science Today II 1�

Experiment: 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.

Datagatheredaftersevendays:

SetupLength of Stem (cm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7Plant without fertilizer 3 3.5 3.5 3.75 4 4.25 4.5

Plant with fertilizer 3 3.5 4 4.25 4.75 5 5.5

______ 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.

Biology: The Science of Life 1�

Technology and people

Technology refers to the practical application of knowledge to society. Scientists often need to have a firm background on a body of knowledge before coming up with an invention or an innovation.

Technology is the application of scientific principles. Many technological breakthroughs and innovations have had significant implications on the way we live today. Can you imagine how we can store food if the refrigerator were not invented? We have come to depend on the benefits of technology. It is important that we understand the underlying scientific principles behind them.

Chapter 2

Biotechnology is defined in two ways. First, it is concerned with the processing of living organisms to produce useful products for human consumption. The second definition refers 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 for human consumption. Examples of these are the production of powdered shrimp heads, soy sauce, 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.

2.1BioTechnology

Hssttx2

Technology

science of lifechapter

key science concepts

evolving world of science

key scientific concepts

scientific studies3

scientific method

scientific way

scientific research