This document provides an introduction to cell structure and the major systems of the human body for 9th grade students. It begins with an overview of cell organelles such as the cell membrane, cytoplasm, mitochondria, vacuoles, chloroplasts, and nucleus. It then compares and contrasts plant and animal cells. The second topic covers the main human body systems, including the digestive, circulatory, respiratory, musculoskeletal, nervous, and reproductive systems. For each system, the document discusses its overall function and key structural components. The book concludes with acknowledgments and a reference section.

1. By O. Mantyi
S P A R K C U R I O S I T Y.
NATURALSCIENCES
GRADE-9
By O. Mantyi

2. TABLE OF CONTENT
INTRODUCTION ………………………………………………………………………………………………. i
BACKGROUND ……………………………………………....................................................... ii
TOPIC 1: CELL STRUCTURE………………………………………………………………………………. 1
Organelles……………………………………………………………………………………………………2
Organelles ……………………………………………………………………………………………………. 3
Organelles …………………………………………………………………………………………………… 4
Organelles……………………………………………………………………………………………………..5
What did you learn? ……………………………………………………………………………………………6
Differences between plant and animal cell………………………………………………………..7
Differences between plant and animal cell ………………………………………………………..8
TOPIC 2: SYSTEMS IN THE HUMAN BODY……………………………………………………………….9
Digestive system………………………………………………………………………………………………10
Structure of a digestive system………………………………………………………………………………11

3. Circulatory system……………………………………………………………………………………………..12
Structure of the circulatory system…………………………………………………………………….13
Respiratory system ………………………………………………………………………………………………………14
Structure of the respiratory system……………………………………………………………………………..15
Musculoskeletal system…………………………………………………………………………………………….16
Structure of the musculoskeletal system …………………………………………………………………..17
Nervous system……………………………………………………………………………………………………….18
Reproductive system………………………………………………………………………………………………...19
What did you learn…………………………………………………………………………………………………..20
ACKNOWLEDGMENTS……………………………………………………………………………………………………21
REFERENCES…………………………………………………………………………………………………………………22
THE END……………………………………………………………………………………………………….……23

4. INTRODUCTION
Welcome to an exciting journey into the
microscopic world of cells and the intricately
woven systems that make up our human bodies!
This book is designed specifically for Grade 9
students, curious minds eager to explore the
fundamental building blocks of life and how they
come together to form the complex machinery
that keeps us alive and thriving.
In this book, we will embark on a captivating
adventure to uncover the mysteries of cells, the
basic units of life, and delve into the remarkable
body systems that function to maintain our health
and well-being. From the tiniest organelles to the
most elaborate network Cells of organs, we will
uncover sophistication of the human body
systems.
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5. BACKGROUND
Cells are the building blocks of all living organisms, and the human body is no exception. At the core of every living being,
including humans, lies an intricate system of cells working in harmony to perform essential functions. Understanding the
structure and function of cells is crucial to comprehending the complexities of the human body's various systems.
At the cellular level, learners will discover the fascinating world of organelles – the tiny structures within cells that carry out
specific functions. They will learn about the cell membrane, cytoplasm, nucleus, and other organelles that play critical roles
in maintaining cell health and enabling cellular processes.
Moving beyond cells, we will venture into the realm of body systems. The human body is an intricate network of systems
that work together to regulate physiological processes, respond to environmental changes, and maintain internal balance.
We will explore systems such as the circulatory system, respiratory system, digestive system, nervous system, and more. Each
system will be examined in detail, highlighting its specific functions, key organs, and how they interact with one another.
Throughout this book, learners will be introduced to captivating illustrations, interactive diagrams, and engaging activities to
reinforce their understanding and stimulate their curiosity. Whether you aspire to become a biologist, or doctor, or simply
wish to grasp the wonders of life, this book is your gateway to the captivating world of cells and body systems. So, let's
embark on this enlightening voyage of discovery, where science meets wonder and where the microscopic becomes
magnificent! ii

6. Topic1: CELL STRUCTURE
1
Figure 1.1
A cell is a fundamental base of any life and everything, a functional
unit of life of anything and living or non-living.

7. ORGANELLES
Cell membrane
The cell membrane forms the outer boundary of the cell. It surrounds the contents
of the cell. The membrane is selectively permeable. This means that it controls
which materials pass into or out of the cell.
Cytoplasm
Cells are filled with a jelly-like substance called cytoplasm. It consists of water with
a complex collection of structures and materials that are either dissolved or
suspended in it. The cytoplasm provides a liquid medium for all the chemical
reactions that take place inside the cell (Lange & Gull, 2000).
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8. ORGANELLES
Mitochondria
Mitochondria are found in both plant
and animal cells. Respiration, the
metabolic reaction that releases energy
from glucose, takes place in the
mitochondria(Darnell, 1998)
3
Figure 1.2

9. ORGANELLES
Vacuoles
Vacuoles are fluid-filled sacs that are surrounded by a membrane. They are used to
store substances which can then be used by the cell. Animal cells usually have
several small vacuoles or no vacuoles at all while plant cells usually have one or two
large vacuoles which store substances such as sugar, salts, and water for the cell
(Conduit & Wainman, 2015)
Chloroplast
Chloroplasts are only found in plant cells. Photosynthesis takes place in
chloroplasts.
4

10. Organelles
Nucleus
The nucleus is a double-membraned organelle that contains the genetic material
and other instructions required for cellular processes. It is exclusively found in
eukaryotic cells and is also one of the largest organelles (Showalter, 2003).
Nucleolus
The nucleolus is considered as the brain of the nucleus, covering nearly 25%
volume of the nucleus (Showalter, 2003). Primarily, it takes part in the production
of subunits that unites to form ribosomes. Hence, nucleolus plays an important role
in the synthesis of proteins and in the production of ribosomes in eukaryotic cells
5

11. What did you learn?
Activity 1
1. Name the organelles, which help provide cells with energy and release energy.
2. Which organelle would you not find in an animal cell and why do they need it?
3. Write some Features of cells.
Activity 2
https://quizlet.com/783677171/test/embed?i=5013sd&x=1jj1
6

12. Differences between plant & animal cell
ANIMAL CELL PLANT CELL
7
Figure 1.3 Figure 1.4

13. Differences of Animal & Plant cells
• They have a cell wall that surrounds the cell on the outside of the cell membrane.
It is made of cellulose, which is a rigid material. The cell wall provides the cell
with support and protection. (Bacic, Harris, & Stone, 2018)
• Animal cells do not have a cell wall because organisms are usually supported and
protected by their skeleton.
• They usually have one or two large vacuoles. In contrast, animal cells usually do
not have vacuoles or if they are present, they are very small (Bacic, Harris, &
Stone, 2018)
• https://youtu.be/q__DDE-n4sc Find more differences!
8

14. Topic2: Systems in the
human body
Six body systems:
Digestive system
Circulatory system
Respiratory system
Musculoskeletal system
Excretory system
Nervous system
Reproductive system
9

15. Digestive system
Function
The digestive system breaks down food
into dissolved nutrients that can be
absorbed into the bloodstream and
transported to cells throughout the
body. A nutrient such as glucose is an
ingredient that nourishes the body
(Svihus, 2014).
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16. STRUCTURE OF A
DIGESTIVE SYSTEM
The main components include the mouth,
oesophagus, stomach, intestines and liver
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Figure 2.1 -

17. Circulatory
system
Function
The circulatory system transports substances around the body. Blood carries
nutrients and oxygen to cells and removes waste products from cells. The
nutrients and oxygen are used by the cells for respiration and as raw materials
for growth. Waste products are transported in the blood to the excretory
organs such as the kidneys and the skin (Chindongo, 2021).
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18. structure
The main components of the
circulatory system are the heart,
blood vessels, and blood. The heart
is a muscular organ that pumps
blood around the body. Humans
shave a closed blood system. That
means the blood flows around the
body contained in blood vessels
13
Figure 2.2 -
hyperlinked

19. Function
The respiratory system is responsible
for supplying oxygen to the body and
for removing carbon dioxide. You
learned in Grade 8 that respiration
takes place in living cells. Respiration
needs oxygen to take place and carbon
dioxide is given off. In this unit, you are
going to learn how oxygen reaches the
cells and how carbon dioxide is taken
away from the cells (Dungworth &
Mohr, 2012).
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20. STRUCTURE
The main components of the
respiratory system include the nose
and mouth, trachea and other
passageways, lungs, and blood. The
trachea is the tube through which
the air travels to the lungs. It splits
into the left and right bronchi which
branch into smaller and smaller
tubes. They eventually end in tiny
hollow cavities called alveoli.
15
Figure 2.3

21. Musculoskeletal
Function
The skeleton protects the body, provides support and
enables movement. The skeleton keeps the body
upright. However, bones cannot move on their own.
Muscles can move and are required to produce body
movement. Look at Figure 14. Notice that muscles
are attached to the outside of the skeletal bones.
Muscles and bones work together to create body
movement (Chindongo, 2021).
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22. STRUCTURE OF
HUMAN SKELETON
The main components of the musculoskeletal system include
muscles, bones, cartilage, tendons and ligaments.
Learn more - https://youtu.be/gSW2ryFmihk
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Figure 2.4 Figure 2.5

23. NERVOUS
SYSTEM
Function
The nervous system receives and helps the body respond to
stimuli. A stimulus is a change in the environment that causes a
reaction in a living organism.
Structural components
The main components of the human nervous system include the
brain, spinal cord, nerves, ears, nose, eyes, skin, and tongue (sense
organs). The sense organs have specific cells that detect stimuli in
the environment. These cells are called receptors. The receptors
convert the stimuli to impulses. Impulses are signals that travel
along nerve cells, called neurons. The impulses travel along the
spinal cord to and from the brain. The brain is the main organ that
coordinates and controls nerve activity. In this way, information is
transmitted through the nervous system (Chindongo, 2021).
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Figure 2.6 -
hyperlinked

24. REPRODUCTIVE SYSTEM
Function
The reproductive system produces sex cells for the purpose of the
continuation of the species. The male sex cells are the sperm cells.
The female sex cells are the egg cells. These cells need to fuse to
ensure that new babies are born. In this way, the human species
continue to live from generation to generation (Heffner & Schust,
2010)
Structure
The main components of the human reproductive system include the
testes, ovaries, and the uterus. Men have testes that produce sperm
cells which are the male sex cells. Women have ovaries that produce
egg cells which are the female sex cells. The uterus is the place where
the baby will grow until it is ready to be born.
Figure 2.7
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25. WHAT DID YOU LEARN?
ACTIVITY 1
TO COMPLETE THIS ACTIVITY
Visit https://www.Socrative.com and enter room name ’MANTYI’ OR SCAN THIS
PICTURE!
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26. Creating a comprehensive Grade 9 book on cells and body systems has been an exciting and challenging endeavor, and it
would not have been possible without the support, dedication, and contributions of numerous individuals. I would like to
express my deepest gratitude to all the people that showed the support.
Our Teachers and Educators: We extend our heartfelt thanks to the passionate and knowledgeable teachers and educators
who have been the guiding lights throughout this journey. Your expertise, insights, and feedback have been invaluable in
shaping the content and ensuring its alignment with the Grade 9 curriculum.
Our Reviewers: A special thank you to the experts and reviewers who meticulously examined the content, providing
valuable suggestions and constructive criticism. Your attention to detail and commitment to academic excellence have
significantly enhanced the quality of this book.
Our Editors and Proofreaders: A big thank you to the meticulous editors and proofreaders who diligently checked and
refined the content, ensuring accuracy, clarity, and coherence throughout the book.
Lastly, we express our gratitude to the young readers themselves. Your curiosity and enthusiasm for learning are the driving
force behind our commitment to education. We hope this book will ignite a lifelong passion for science and inspire you to
explore the remarkable world of cells and body systems further. With sincere appreciation to all who contributed, we present
this Grade 9 book on cells and body systems, hoping that it will inspire the next generation of scientists, doctors, and
scholars to unravel the mysteries of life and contribute to the betterment of humanity.
Thank you all!
[O. Mantyi] and S P A R K C U R I O S I T Y. Development Team
ACKNOWLEDGMENTS
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27. REFERENCES
Lange, B. M., & Gull, K. (2000). Structure and function of the centriole in animal cells: progress and questions. Trends in
cell biology, 6(9), 348-352.
Darnell Jr, J. E. (1998). Ribonucleic acids from animal cells. Bacteriological reviews, 32(3), 262-290.
Conduit, P. T., Wainman, A., & Raff, J. W. (2015). Centrosome function and assembly in animal cells. Nature reviews
Molecular cell biology, 16(10), 611-624.
Showalter, A. M. (2003). Structure and function of plant cell wall proteins. The plant cell, 5(1), 9.
Knox, J. P. (2008). Revealing the structural and functional diversity of plant cell walls. Current opinion in plant
biology, 11(3), 308-313.
Gunning, B. E., & Steer, M. W. (1996). Plant cell biology: structure and function. Jones & Bartlett Learning.
Bacic, A. N. T. O. N. Y., Harris, P. J., & Stone, B. A. (2018). Structure and function of plant cell walls. The biochemistry of
plants, 14, 297-371.
Chindongo, I. C. (2021). Teachers’ Pedagogical Beliefs on the use of Youtube Videos for Teaching and Learning Grade 9
Life Science Concepts. University of Johannesburg (South Africa).
Svihus, B. (2014). Function of the digestive system. Journal of Applied Poultry Research, 23(2), 306-314.
Jones, T. C., Dungworth, D. L., & Mohr, U. (Eds.). (2012). Respiratory system. Springer Science & Business Media.
Heffner, L. J., & Schust, D. J. (2010). The reproductive system at a glance (Vol. 23). John Wiley & Sons.
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copyright laws by not reproducing, scanning, or distributing any part of it in any form without
permission. You support writers and allow authors to continue publishing books for every
reader.
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