2. Smart Science
GRADE 5
TEXTBOOK
Philippine Copyright 2009 by DIWA LEARNING SYSTEMS INC
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ISBN: 978–971–46–0093–5
REVIEWER
Marina Balce was a former assistant dean and associate professor at the College of Education, La
Salle College–Antipolo. She taught biological sciences for Psychology students and thesis writing for
graduating Education students in the same college. She was also a Trainee of the Japan International
Cooperation Agency (JICA) at the Aichi University in Nagoya, Japan, where she attended a special
training on Practical Work in Elementary School Science. Dr. Balce finished her bachelor’s degree in
Secondary Education major in Biology at the University of the East–Manila. She has a master’s degree
in Biology Education from the De La Salle University–Manila and a doctorate in Science Education
major in Biology from the University of the Philippines–Diliman.

3. To the Learner
Do you ask yourself questions about the world you live in? Do you
wonder about what lies beyond the blue skies or what rests below the
seas? Do you ask questions about the blooming trees and colorful flowers
you see, the heat and cold you feel, or the various scents you smell? Do
you wonder about the sun, the moon, and the stars? Your young, active
mind has so many questions because you are curious about so many
things.
This book will help you discover the answers to the questions you
have about yourself, the world, and everything beyond it. This book will
be your constant companion as you unlock the many mysteries of life
through various learning experiences. Moreover, this book will teach you
how to apply the wonders of science to your day-to-day activities.
Let this book help you find the answers to the questions you have
about yourself, your world, and your universe. Let this take you a step
closer to understanding life and in discovering the wonders of science!

4. Unit 1 The Reproductive, Respiratory, and Urinary Systems
Chapter 1 The Human Reproductive System
Lesson 1 The Male and the Female Reproductive Systems .........................................2
Lesson 2 Changes during Puberty ..............................................................................7
Lesson 3 Menstrual Cycle ........................................................................................11
Lesson 4 Taking Care of Your Reproductive Organs ................................................15
Think Back .................................................................................................................17
Measure Up! .................................................................................................................18
Chapter 2 The Human Respiratory System
Lesson 1 Parts and Functions of the Human Respiratory System ..............................19
Lesson 2 Inhalation and Exhalation ..........................................................................25
Lesson 3 Common Respiratory Ailments..................................................................29
Think Back .................................................................................................................33
Measure Up! .................................................................................................................33
Chapter 3 The Human Urinary System
Lesson 1 Parts and Functions of the Human Urinary System ....................................35
Lesson 2 How the Urinary System Works ................................................................39
Lesson 3 Some Urinary Ailments .............................................................................43
Think Back .................................................................................................................47
Measure Up! .................................................................................................................47
Unit 2 Animal and Plant Groups
Chapter 4 The Animal Group
Lesson 1 What Animals Eat .....................................................................................50
Lesson 2 Body Parts That Animals Use in Eating ......................................................54
Lesson 3 Animal Adaptations ..................................................................................58
Lesson 4 Vertebrates................................................................................................63
Lesson 5 Invertebrates .............................................................................................70
Think Back .................................................................................................................76
Measure Up! .................................................................................................................76
Chapter 5 The Plant Group
Lesson 1 The Needs of Plants to Produce Food ........................................................78
Lesson 2 Photosynthesis ..........................................................................................85
Lesson 3 Importance of Plants .................................................................................89
Lesson 4 Plant Adaptations ......................................................................................93
Lesson 5 Classifying Plants ......................................................................................97

5. Think Back ...............................................................................................................101
Measure Up! ...............................................................................................................102
Unit 3 Matter, Energy, and Machines
Chapter 6 Changes in Matter
Lesson 1 Physical Changes ....................................................................................106
Lesson 2 Chemical Changes ..................................................................................114
Lesson 3 Agents Causing Changes in Matter ..........................................................118
Lesson 4 The Changing Environment .....................................................................122
Lesson 5 Controlling the Destructive Changes in the Environment.........................127
Think Back ...............................................................................................................131
Measure Up! ...............................................................................................................131
Chapter 7 Electric Energy
Lesson 1 Static Electricity.......................................................................................133
Lesson 2 Electric Circuit ........................................................................................139
Lesson 3 Series Connection and Parallel Connection .............................................143
Lesson 4 Generation of Electric Energy ..................................................................147
Lesson 5 Electricity and Magnetism .......................................................................151
Lesson 6 Using Electric Energy Wisely ...................................................................155
Think Back ...............................................................................................................158
Measure Up! ...............................................................................................................159
Chapter 8 Machines
Lesson 1 Levers .....................................................................................................161
Lesson 2 Classes of Levers .....................................................................................166
Lesson 3 Inclined Planes .......................................................................................170
Lesson 4 Wedges ..................................................................................................173
Lesson 5 Screws ....................................................................................................176
Lesson 6 Wheel and Axle ......................................................................................179
Lesson 7 Pulleys ....................................................................................................182
Lesson 8 Proper Use of Machines ..........................................................................185
Think Back ...............................................................................................................187
Measure Up! ...............................................................................................................187
Unit 4 Earth and Its Weather
Chapter 9 Rocks and Soil
Lesson 1 Characteristics of Rocks ..........................................................................190
Lesson 2 Igneous Rocks: The “Hot” Rocks .............................................................195

6. Lesson 3 Sedimentary Rocks: The “Cool” or “Wet” Rocks......................................199
Lesson 4 Metamorphic Rocks: The “Changed” Rocks ............................................204
Lesson 5 Rock Cycle .............................................................................................207
Lesson 6 Weathering and Soil Formation ...............................................................211
Think Back ...............................................................................................................214
Measure Up! ...............................................................................................................214
Chapter 10 Weather Conditions
Lesson 1 Water Cycle ............................................................................................216
Lesson 2 Sunlight and Weather .............................................................................220
Lesson 3 Tropical Cyclones ...................................................................................225
Lesson 4 Before, During, and After a Cyclone .......................................................230
Lesson 5 Public Storm Warning Signals .................................................................233
Lesson 6 Safety Precautions ...................................................................................237
Think Back ...............................................................................................................240
Measure Up! ...............................................................................................................240
Unit 5 Our Solar System
Chapter 11 About the Sun
Lesson 1 The Sun, a Star ........................................................................................244
Lesson 2 Sunspots .................................................................................................249
Lesson 3 Uses of Solar Energy ...............................................................................251
Think Back ...............................................................................................................253
Measure Up! ...............................................................................................................254
Chapter 12 The Solar System
Lesson 1 Members of the Solar System ..................................................................255
Lesson 2 The Planets in Orbit ................................................................................260
Lesson 3 Planets and Their Distances from the Sun................................................263
Lesson 4 Planets and Their Periods of Revolution ..................................................266
Lesson 5 Asteroids, Meteoroids, and Comets .........................................................269
Think Back ...............................................................................................................273
Measure Up! ...............................................................................................................274
Glossary .............................................................................................................................. 276
Bibliography ........................................................................................................................ 279
Index ................................................................................................................................... 281

7. Unit 1 The Reproductive,
Respiratory, and
Urinary Systems
The human body is able to perform many tasks. These tasks are
made possible by the different body systems. Although each body system
performs a specific function, the different body systems work in close
coordination with one another. They sustain and regulate different life
processes such as reproduction, adaptation, growth, and development.
In this unit, you will study three important body systems—the
reproductive, respiratory, and urinary systems. You will study the parts of
these body systems and their functions. You will also learn how to take
good care of them.

8. Chapter 1
The Human Reproductive System
Have you ever wondered how a new human being develops inside the female
body? As you proceed with the lessons in this unit, you will be amazed to find out
that life starts out as a fertilized cell. This cell is the result of the union of the male and
female sex cells.
Lesson 1
The Male and the Female Reproductive Systems
Find Out
1. What are the parts of the male and the female reproductive systems?
2. What are the functions of each part?
Humans, being living things, are able to reproduce offspring of their own kind.
No two offspring, however, are the same. The ability of humans to reproduce ensures
their continued existence on Earth.
Humans have body parts called organs that enable us to reproduce. These organs
have coordinated functions that form a body system, called the reproductive system.
In this lesson, you will learn about the structures of the reproductive organs and their
specific functions.
The reproductive system of males differs from that of females. Look at the two
illustrations below.
ureter bladder
ovum inside
fallopian tube the ovary
ovary
seminal vesicle
prostate gland
penis
Cowper’s gland
urethra wall of endometrium
foreskin epididymis
uterus uterus
scrotum
sperm inside sperm cervix ovum
the testis vagina
Male reproductive system Female reproductive system
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9. Each reproductive organ has a specific function in the reproductive process.
Table 1.1 lists the parts of the male reproductive system.
Table 1.1 Parts of the Male Reproductive System and Their Functions
Organ Description/Location Function
Testis (plural: testes) usually consists of a pair; each testis produces sperm cells and
consists of many highly coiled tubes secretes the male sex
or ducts surrounded by several hormone (testosterone)
layers of connective tissues; found
inside the scrotal sac or scrotum
Scrotal sac or external saclike structure with holds the testes
scrotum temperature slightly lower than that
of the rest of the body
Penis composed of spongy, erectile deposits sperm into the
tissues; its head is covered by a vagina
foreskin, which can be removed
during circumcision
Urethra a duct that runs through the length serves as a passageway for
of the penis and opens to the both sperm and urine; has
outside an opening that closes to
allow sperm and urine to
pass one at a time
Epididymis long, narrow, flattened, highly stores mature sperm and is
coiled convoluted ducts lying on the the site where the sperm
edge of the posterior border of the cells gain the ability to
testes move, which is necessary
for fertilization
Vas deferens a short muscular duct passageway of the sperm
(plural: vas deferentia) from the epididymis to the
urethra; stores sperm
Prostate gland thumb-sized gland; consists of secretes a fluid that
muscular and glandular tissues that neutralizes the acidity of
lie around the base of the bladder the vagina to ensure the
survival of the sperm; aids
in sperm motility
Cowper’s glands a pair of pea-sized glands found secrete a fluid that may
(bulbourethral glands) along the urethra and below the serve as a lubricant and
prostate gland urine neutralizer
Seminal vesicles a pair of glands found between the secrete a fluid that
bladder and the rectum contains fructose (energy
source for sperm)
The Reproductive, Respiratory, and Urinary Systems 3

10. Explore
The Male Reproductive System
Look at the diagram of the male reproductive system. Identify the different
organs of the system. Try to trace the path that sperm cells take as they travel from
the testes to the outside of the body. Write your answers on the blanks.
Head – bears half
from the testes of the male’s
characteristics
Midpiece – contains
substances that
provide the sperm
cells energy for
swimming
outside Tail – for moving the
sperm to reach
the egg
The male reproductive system is made up of different organs and glands. Some of
these parts are involved in the production of sperm cells, while some are involved in
the delivery of the sperm cells to the female reproductive system.
The human testes produce the male sex cells called the sperm. Sperm cells are
stored in the epididymis. Three glands provide secretions that mix with the sperm cells
to form the semen. These glands are the seminal vesicles, the prostate gland, and the
Cowper’s glands.
The ability to produce sperm cells does not necessarily mean the ability to
produce a new individual. The number and the quality of sperm cells also determine
the capability of sperm cells to unite with female egg cells. Smoking, excessive alcohol
intake, emotional stress, substance abuse, malnutrition, heredity, and exposure to toxins
and chemicals are some of the factors that affect sperm number and quality. At present,
there are products available to test sperm number and sperm quality. These products
can be administered at home without the aid of a physician.
The parts of the female reproductive system differ from those of the male. These
parts and their corresponding functions are listed in Table 1.2 on the following page.
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11. Table 1.2 Parts of the Female Reproductive System and Their Functions
Organ Description/Location Function
Ovaries small, flattened, elongated organs alternately produce the female
on both sides of the uterus sex cells (eggs or ova) and
secrete the female hormones
(estrogen and progesterone)
Fallopian tubes a pair of ducts leading from the serve as pathways where ova
or oviducts ovaries to the uterus travel from the ovary to the
uterus
Uterus pear-shaped muscular organ found receives and holds the
in the pelvic cavity fertilized ovum that eventually
develops into a fetus
Cervix neck of the uterus that opens to serves as the passageway for
the vagina menstrual flow; serves as a
passageway for sperm
Vagina a thin-walled passageway through serves as a passageway for
(also called the birth which the sperm can enter and menstrual flow; serves as
canal) swim to the fallopian tube the passageway of the baby
during birth
How much have you learned about the female reproductive system? Find out in
the next activity.
Explore
The Female Reproductive System a.__________
b.__________
c.__________
d.__________
e.__________
1. Use the illustration to identify the organs of the female reproductive system.
2. Tell the function of each part.
3. Using a marker, trace the path of the egg cell from the ovary to the uterus.
Draw arrows to indicate direction.
The Reproductive, Respiratory, and Urinary Systems 5

12. There are two ovaries where the
ova develop and mature. Each ovary is Language
connected to the ends of the fallopian
The word reproduce is a combination
tubes. The lower end or “neck” of the
of the prefix re-and the root word produce.
uterus is the cervix. The vagina is the birth
Re-means “again.” For example, to reproduce
canal through which a baby is normally means “to produce again,” as in “reproduce
delivered. the sound” or “reproduce the page.” Note that
when something is reproduced, the resulting
object is usually the same as the original.
In the life sciences, to reproduce means to
produce individuals of the same kind.
Keep in Mind You will later encounter scientific terms
with the prefix re-like regenerate and recycle.
Use context clues to determine their meanings.
• The fundamental male reproductive Also, try to make a list of scientific words with
organs are the testes. Other organs of the prefix re-.
the male reproductive system merely
store and transport sperm, which
include the following: scrotal sac,
epididymis, vas deferens, prostate gland, Cowper’s gland, urethra, and penis.
• The testes produce sperm.
• The fundamental female reproductive organs are the ovaries. Other organs of the
female reproductive system are the following: fallopian tubes or oviducts, uterus,
cervix, and vagina.
• The ovaries produce eggs.
Challenge Yourself
Your teacher will group the class into two. Each group will be given about two
to three illustrations of the male and female reproductive systems. You will also be
given a set of name cards of the female and the male reproductive organs. Find the
parts in each of the given illustrations. The first group to correctly sort them out will be
the winner.
6 Smart Science 5