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First edition 2016
TABLE OF CONTENTS
LIFE AND LIVING THINGS
1
CELLS AS THE BASIC UNITS OF LIFE
2
SYSTEMS IN THE HUMAN BODY
THE DIGESTIVE SYSTEM
THE CIRCULATORY SYSTEM
THE RESPIRATORY SYSTEM
THE MUSCULOSKELETAL SYSTEM
THE EXCRETORY SYSTEM
THE NERVOUS SYSTEM
THE REPRODUCTIVE SYSTEM
1
15
21
28
35
41
45
57
3
HUMAN REPRODUCTION
59
4
CIRCULATORY AND RESPIRATORY SYSTEMS
77
5
DIGESTIVE SYSTEM
95
MATTER AND MATERIALS
6
COMPOUNDS AND CHEMICAL REACTIONS
THE PERIODIC TABLE
FORMULAS AND NAMES OF COMPOUNDS
CHEMICAL EQUATIONS TO REPRESENT REACTIONS
7
REACTIONS WITH OXYGEN
REACTIONS OF METALS WITH OXYGEN
REACTIONS OF NONMETALS WITH OXYGEN
106
112
119
125
130
MATTER AND MATERIALS
8
ACIDS AND BASES
ACIDS, BASES AND PH VALUE
REACTIONS OF ACIDS AND BASES
REACTIONS OF ACIDS WITH METALS
135
144
163
ENERGY AND CHANGE
9
FORCES
TYPES OF FORCES
FIELD FORCES: GRAVITATIONAL FORCE
FIELD FORCES: MAGNETIC FORCE
FIELD FORCES: ELECTROSTATIC FORCE
10
ELECTRIC CELLS AND CIRCUITS
ELECTRICAL CELLS AS ENERGY SYSTEMS
RESISTANCE
SERIES AND PARALLEL CIRCUITS
ENERGY AND THE NATIONAL ELECTRICITY NETWORK
THE COST OF ELECTRICAL POWER
167
173
179
189
195
200
206
230
240
PLANET EARTH AND BEYOND
11
THE EARTH, LITHOSPHERE AND MINING
THE EARTH AS A SYSTEM
THE LITHOSPHERE AND ROCK CYCLE
MINING OF MINERAL RESOURCES
MINING IN SOUTH AFRICA
12
245
250
258
270
ATMOSPHERE
COMPOSITION OF THE ATMOSPHERE
STRUCTURE OF THE ATMOSPHERE
THE GREENHOUSE EFFECT
BIRTH, LIFE AND DEATH OF A STAR
274
276
283
287
1
CELLS AS THE
BASIC UNITS OF LIFE
CELL STRUCTURE
• A cell is the basic structural and functional unit of all living organisms.
• Cells are microscopic and can not be observed with the naked eye.
• Cells can only be seen under a microscope.
• There are two types of cells; plant cells and animal cells.
• Plant and animal cells differ in shape and function, but have certain parts in common which are present in all plant
and animal cells.
Similarities between plant and animal cells
• The cells of plants and animals all have a cell membrane, nucleus, cytoplasm and organelles.
• Organelles, such as mitochondria and vacuoles, are structures that are present in the cytoplasm of the cell.
cytoplasm
cell membrane
nucleus
vacuole
mitochondrion
Three-dimensional
structure of an animal cell.
Three-dimensional
structure of a plant cell.
• Let us briefly look at the parts in plant and animal cells that are similar.
1. Cell membrane
Characteristic
- It is a thin, living and flexible membrane (layer or skin).
Function
- It encloses the contents of the cell (keeps the contents together).
- It is selectively/semi permeable, i.e. it only allows certain substances to move in and out of the cell.
2. Cytoplasm
Characteristics
- Is a jelly-like substance that fills the cell (fills the entire cavity).
- It contains a large variety of organelles and food particles.
Function
- It contains organelles (small, membrane-like structures) that fulfil specific functions.
- Chemical reactions take place here.
- It supports and maintains the shape of the cell.
3. Nucleus
Characteristics
- It is a spherical (round) structure that is present in all living cells.
- It is surrounded by the nuclear membrane.
- It contains a liquid known as the nucleoplasm.
- It has a smaller, dense body inside, which is called a nucleolus.
- In animal cells it is normally found close the centre of the cell.
- In plant cells the nucleus is found close to the edge of the cell.
Function
- It controls all the life activities of the cell.
- Is the part of the cell that is referred to as the ‘brain'.
- Contains DNA (deoxyribonucleic acid), which determines hereditary characteristics such as eye colour and
height.
(DNA contains the genetic code that is unique to every living organism. The information in DNA ensures that
a mouse is different from a hamster. The variations in DNA also make each one of us unique.)
LIFE AND LIVING
1
4. Organelles
- Organelles are structures in the cell’s cytoplasm that carry out cell functions.
- Organelles like mitochondria (singular: mitochondrion) and vacuoles are present in the cytoplasm of plant
and animal cells.
► Mitochondria
Characteristics
- Are small, spherical structures in the cytoplasm of plant and animal cells.
Function
- Are also referred to as the powerhouse of the cell as it breaks down food during breathing
(referred to as cellular respiration) to produce the energy needed for cells to carry out life
processes.
(The number of mitochondria that are present in a cell depends on the cell’s function.)
Breathing takes
place in the
(Muscle and liver cells contain a lot of mitochondria, because they require a lot of energy.)
mitochondrion.
► Vacuoles
- Vacuoles are organelles with large cavities and are mainly present in plant cells.
- Plant cells have large vacuoles, while animal cells contain small vacuoles.
- Vacuoles in plant cells are permanent.
- Vacuoles in animal cells are temporary or absent.
DIFFERENCE BETWEEN PLANT AND ANIMAL CELLS
• Plant cells differ from animal cells.
• Compare the following two figures that represent the structure of the plant cell and animal
cell:
cell wall
cell membrane
cell membrane
cytoplasm
nuclear membrane
nucleus
nucleolus
nucleoplasm
cytoplasm
nuclear membrane
nucleolus
nucleus
nucleoplasm
tonoplast
vacuole
cell sap
vacuole
mitochondrion
chloroplast
mitochondrion
Animal cell structure.
Plant cell structure.
• Plant cells have cell walls, chloroplasts and large vacuoles.
• These structures are not present in animal cells.
• We will briefly discuss the elements only present in plant cells.
1. Cell wall
Characteristics
- The outermost layer of the plant cell (sturdy outer framework of the cell).
- It is non-living, rigid and strong.
- It generally allows all soluble substances through.
- Mainly consists of cellulose (a type of carbohydrate).
Function
- Gives the cell its specific shape.
- Gives the cell sturdiness.
- Protects the inside of the cell against damage.
2. Chloroplasts
Characteristics
- Oval-shaped organelles (structures) found in the cytoplasm of plant cells.
- It occurs only in the green parts of the plant, such as the leaves and stems.
- Contains a pigment called chlorophyll, which gives the plant its green colour.
Function
- Chlorophyll captures the sun’s energy and produces, together with carbon dioxide and water, energy-rich
food (glucose and starch) for the plant.
- This process is referred to as photosynthesis.
2
LIFE AND LIVING
3. Large vacuoles
Characteristics
- There is normally only one large vacuole in plant cells.
- It is the space (cavity) in the cytoplasm that is surrounded by a membrane called tonoplast.
- The space within the vacuole is filled with a liquid referred to as cell sap.
Functions
- Gives support to the plant cell so that it can maintain its shape.
- Provides storage space for food and waste products.
(Vacuoles may be present in animal cells, but they are usually small and temporary.)
(There are also animal cells where vacuoles are completely absent.)
SUMMARY OF THE CELL STRUCTURE
• Similarities between plant and animal cells
Characteristics
Plant cell
Animal cell
Cell membrane
A cell membrane is present.
A cell membrane is present.
Cytoplasm
Contains cytoplasm.
Contains cytoplasm.
Nucleus
A nucleus is present.
A nucleus is present.
Mitochondria
There are mitochondria in the cytoplasm. There are mitochondria in the cytoplasm.
Vacuoles
A single large vacuole in the cytoplasm.
Numerous small vacuoles in the cytoplasm
(if vacuoles are present at all).
• Differences between plant and animal cells
Characteristics
Plant cells
Animal cells
Cell shape
Rigid and firm or sturdy shape
due to the presence of a cell wall.
Flexible or changeable shape due to
the absence of a cell wall.
Cell wall
Firm cell wall is present.
No cell wall present.
Chloroplasts
The chloroplasts in the cytoplasm are
responsible for photosynthesis.
Chloroplasts are not present in the
cytoplasm.
Vacuoles
A single large vacuole in the cytoplasm.
Normally no vacuole or numerous
smaller vacuoles in the cytoplasm.
CELLS IN TISSUE, ORGANS AND SYSTEMS
• Living things consist of different types of cells.
• These cells are found in many different shapes and sizes and carry out different functions.
Cellular differentiation and specialisation
• In plants (and other multicellular organisms) growth can only take place when the number of cells increases.
• The increase in cells takes place through a special process during which a mature cell divides into two daughter
cells, which in turn grows into maturity and subdivide.
• Not all the cells of a multicellular plant or animal are similar.
• During the early stages of cell division, enzymes (chemical substances that control different processes in cells)
ensure that cells develop in such as way that they differ from one another in structure.
• These differences are referred to as differentiation and are aimed at giving cells specific functions, in other
words, the cells are specialised.
• Cells are thus adapted and have different shapes and structures to perform different functions.
• Some cells protect the body against the invasion of germs, e.g. skin cells; some cells play an important role in
transporting substances, e.g. the red blood cells that transport oxygen; some cells carry impulses to and from the
brain, e.g. nerve cells (neurons); some cells can contract and relax, e.g. muscle cells, etc.
blood cells
surface epidermal cells
cardiac muscle cells
bone cell
skeletal muscle cells
Different types of cells.
nerve cell
smooth muscle cells
LIFE AND LIVING
3
Single-celled organisms
• Microscopic organisms such as bacteria, the amoeba and certain algae normally consist of a single cell and are
referred to as unicellular.
• These organisms carry out all of their life functions in a single cell.
• This means that digestion, secretion, respiration, reproduction and breathing all occur in one cell.
amoeba
bacteria
Multicellular organisms
algae
Examples of single-celled organisms.
• Macroscopic organisms such as people, animals and plants consist of a large number of cells, and are
known as multicellular.
• The cells of multicellular organisms such as plants and animals differ in shape and in the function that they carry
out.
• This means that the cells are specialised.
• In multicellular organisms, the complex processes that allow the body to function cannot take place in a single cell.
• Instead, the cells have to work together in an organised manner.
The organisation of cells
• A cell is a mass of cytoplasm and a nucleus that is surrounded by the cell membrane and, in plants,
surrounded by a cell wall.
• The contents of the cell consists of large numbers of atoms of various types.
• Atoms form molecules that are grouped together to form organelles.
• The cells of an organism differ from one another.
• Cells normally do not work individually in the body, but in groups.
• Cells are grouped together according to their shape and function.
• A group of cells that carry out a specific function forms tissue, a group of tissues makes up an organ, and organs
work together in groups to form systems, which finally form an organism.
• Tissue consists of a group of cells with the same structure, which works together to carry out a common function.
- Examples of tissue in humans are the muscle and nerve tissue.
• An organ is a structure of a specific shape and function that consists of more than one type of tissue.
- In humans, the heart is an organ that consists of muscle, nerve and support tissue.
• A system (or organ system) is a group of different organs working together to carry out a common function.
- Together, these organs form a system.
- The digestive system in the human body consists of various organs, such as the stomach, liver, pancreas, the
small intestine and the large intestine.
• An organism (human organism) has differentiated cells arranged in the tissue, organs and organ systems, i.e. an
independent body.
atoms
organ system
molecules
organelles
organ
cells
organism
tissue
How the body is organised.
4
LIFE AND LIVING
USE OF MICROSCOPES TO OBSERVE CELLS
History of the discovery of microscopes
• Before the seventeenth century very little was known about the structure of the cell because there was no apparatus available to examine these minute structures.
• Roughly in the year 1590, two Netherlanders, Hans and Zacharias Janssen, designed the first compound microscope
(a microscope that consists of more than one lens).
• Many years later, another Netherlander, Antonie van Leeuwenhoek (a spectacle maker, 1632-1723) built various
simple microscopes by using lenses that he ground himself. By using these microscopes, the blood flow in the
blood vessels of a fish’s tale could be observed.
• After van Leeuwenhoek, the English scientist, Robert Hooke (1635-1703), built an instrument that can be considered the forerunner of the modern compound light microscope. Hooke examined thin slices of cork under his
microscope. He saw small cavities, each surrounded by a wall.
It reminded him of the compartments in a honeycomb, and he named them cells.
The Jansens microscope.
Van Leeuwenhoeks microscope.
Hookes microscope.
Cork cells Hooke
observed with his
microscope.
Cork cells under a
modern light
microscope.
• Years later, in 1938, the Belgian botanist, Matthias Schleiden, and the German zoologist, Theodor Schwann, formulated the cell theory. They claimed that all organisms are made up of cells and their products, in other words,
that the cell is basically the smallest unit of life.
• Today this cell theory is accepted, while cells are continuously being examined to eventually obtain more knowledge
about these minute structures.
• In this study, microscopes are used, amongst other things.
Microscopes have improved a great deal since Hooke’s time.
• Today we have powerful microscopes, such as compound light microscopes, and even more
powerful microscopes, such as electron microscopes, which can magnify cells many times more
so that they can more easily be examined.
• A light microscope focuses light onto the object being examined to illuminate it, and can
magnify it up to 2 000 times.
• The electron microscope was developed in the 1950s and works by shooting an electron beam
at a small object that is covered with a thin layer of gold.
Electrons bounce off the thin layer of metal to form an image, which then appears on a
computer screen.
This type of microscope can magnify up to 500 000 times.
A modern electronmicroscope.
The light microscope
• When a microscope uses light to magnify an object, it is called a light microscope.
eyepiece or ocular lens
tube
coarse adjustment knob
revolving nosepiece
high power objective
low power objective
stage clips
stage
diaphragm
fine adjustment knob
arm
mirror or electrical light source
base
The light microscope.
LIFE AND LIVING
5
• Functions of the parts of the light microscope.
Part
Function
Eyepiece or ocular lens
It’s the lens that you place your eye against to magnify the object being examined,
normally 10 x.
Tube
Keeps the lenses of the eyepiece and objectives at the correct working distance
from one another.
Coarse adjustment knob
It moves the tube up and down to focus on the object being examined.
Fine adjustment knob
Is used for the final focus to get a clear image of the object.
Arm
Connects the base and stage with the tube and supports the adjustment knobs.
Revolving nosepiece
Holds the objectives with low and high power lenses closely to the rotating slide.
Objectives
Lenses of objectives assist in magnifying the image:
- the short lens gives a lower magnification (4 ×).
- the long lenses give a higher magnification (10 × and 40 ×).
Stage clips
Keeps the microscope slide firmly in position to examine the object.
Stage
Supports the microscope slide over the opening that allows light through from the
mirror or light source.
Diaphragm
Controls the amount of light that moves to and through the object; focuses light
beams from the mirror or electrical source onto the object.
Mirror or electrical light source Reflects the light upwards through the condenser to the opening in the stage.
Base
It is sturdy and supports the weight of the microscope.
• Magnification : If the magnifying power of the eyepiece is 10 ×, and that of the objective is 40 ×, then the total magnification of the object being examined is 10 × 40; or 400 ×.
• Microscope slide : Consists of a small object glass, the object (specimen) and a cover glass.
• Micrograph : Is a photo taken by a microscope.
STEM CELLS
• Stem cells are the small living cells that give birth to new tissue in a developing embryo.
• They are called embryonic stem cells.
• Stem cells are unspecialised cells that can divide (make photocopies of themselves) to form different specialised cells.
• Which means that stem cells can be used to repair damaged cells and organs, and even to make new ones.
• Thus stem cells have two specifically distinguishable characteristics.
duplicate itself
(i.e. can divide and form new stem cells)
A single stem cell can
or
differentiate in many other types of cells
(i.e. can develop into any
other type of cell).
• Bone marrow, brain cells and other types of tissue can be cultivated from stem cells and have the ability to repair
organs or tissues after damage caused by disease or chemotherapy.
• Stem cells are also present, for example, in the bone marrow of adults.
• Stem cells have also recently been discovered in the adult body, in the epidermis (skin), hair, eyes and the pulp
of teeth.
• Older patients can, however, get diseases that contaminate their stem cells and make them unfit for use.
• The quality and amount of stem cells decrease as people grow older.
• Stem cells are mainly harvested from human embryos and from the blood in the umbilical cord when a baby is born.
Ethical issues regarding stem cells
• The research destroys human embryos.
• Every living being started his/her life as an embryo – consequently the objection is that research that destroys
embryos, is murder.
• Stem cell research will possibly open the door for inhumane practices, such as embryo farms, cloned babies and
the use of foetuses for organ donation.
6
LIFE AND LIVING
Counter arguments on ethical issues
• Embryos can not be compared to living, fully-grown organisms.
• The moral status of an embryo can not be compared to that of, for example, a baby - hence the use of embryonic
stem cells can not be considered as murder.
• A few embryos will die, but many people can be cured of disease.
• Scientific knowledge can be advanced and many people can benefit from it.
PRACTICAL EXAMINATION 1
Goal: Making and examining a wet preparation of onion cells.
Method:
What you need
Step 1
Step 2
Step 3
Step 4
• Cut the onion into little
blocks of 1 square cm with
a sharp knife or scalpel.
• Place the thin film on the
object glass.
• Pull the thin film (layer of epidermal cells) on the
inside (hollow side) of the square using a tweezer.
• Place a drop of iodine
solution on the film.
Step 5
•
•
•
•
•
•
•
•
•
Onion
Scalpel or sharp knife
Dissecting needle
Tweezer
Object glass
Cover glasses
Tissue or filtration paper
Iodine solution
Light microscope
• Lower a cover glass carefully against an angle on
the film.
Step 6
• Try to wipe all the
excess liquid with a
tissue.
Step 7
• Place the object glass with the wet preparation on the
stage of a microscope.
• Move the slide until the light shines through the film.
• Carefully focus on the onion cells (epidermal cells) by using
the coarse and fine adjustment knobs.
Onion cells magnified 400 x.
Questions:
Draw three to four adjacent cells of an onion leaf next to each other and indicate the following:
cell wall, vacuole, nucleus and cytoplasm
LIFE AND LIVING
7
PRACTICAL EXAMINATION 2
Goal: Making and examining a wet preparation of cheek cells.
What you need
Method:
•
•
•
•
•
•
Step 1
Step 2
• Place the scraping on an object
glass.
• Throw the earbud (toothpick) in the
dustbin.
• Take a clean earbud or
toothpick and brush it lightly
against your cheek.
Step 3
• Add a drop of the bromothymol blue.
Step 4
• Cover with a cover glass.
Step 5
• Dry the glass.
Object glass
Cover glass
Clean earbud or toothpick
Tissue or filtration paper
Methylene blue solution
Light microscope
Safety!
• Never use somebody else’s
earbud or toothpick!!
Step 6
• Place the object glass
with the wet preparation on the stage of a
microscope.
Step 7
• Move the slide so that the light shines
through the solution.
• Find the cells using low and high magnifications.
A few cheek cells coloured with methylene blue.
Questions:
Draw three to four adjacent cheek cells and indicate the following: cell wall, nucleus and cytoplasm.
8
LIFE AND LIVING
BUILD A THREE-DIMENSIONAL (3D) MODEL OF A CELL
Build a three-dimensional model of a plant or animal cell that meets the following requirements:
• It must be approximately as big as an A4-page.
• Be creative in building the cell.
• Different types of sweets, material from nature, clay, paper maché or carton of different colours can be used.
• Visit the internet to get ideas.
Three-dimensional models of cells.
Exercise
CELLS AS BASIC UNITS OF LIFE
1. 1.1 What is a cell? _________________________________________________________________________
_____________________________________________________________________________________
1.2 Are cells macroscopic or microscopic? Explain your answer.
_____________________________________________________________________________________
__________________________________________________________________________________________
1.3 Between which two types of cells can we distinguish?
_____________________________________________________________________________________
2. Plant and animal cells have a cell membrane, cytoplasm, nucleus and organelles such as a mitochondrion and a
vacuole.
Look at the following figures and answer the questions that follow.
1
2
3
4
5
Figure 2
Figure 1
2.1 What are organelles? ____________________________________________________________________
2.2 Provide an appropriate heading for the above diagrams.
Figure 1 : _________________________________
Figure 2 : _________________________________
2.3 Provide captions for parts 1 to 5 in the above figure.
1. _______________________________________
2. _______________________________________
3. _______________________________________
4. _______________________________________
5. _______________________________________
LIFE AND LIVING
9
2.4 Name the parts in plant and animal cells that carry out the following functions as listed in the table below.
Function of the cell
Part of the cell
Jelly-like medium where many chemical reactions take place.
Contains DNA and controls all the life activities of the cell.
Is responsible for releasing energy from food during respiration.
Surrounds the contents of the cell and allows specific substances to
move in and out of the cell.
A space filled with liquid that is referred to as cell sap.
3. Complete the following table by making a tick ( U ) in the appropriate space.
Structure
Only in plant cells
Only in animal cells
In both plant and animal cells
Nucleus
Cytoplasm
Cell membrane
Mitochondria
Large vacuole
Chloroplasts
Cell wall
Flexible shape
4. 4.1 Do a simple sketch to represent an animal cell. Indicate the following in your sketch with captions:
cell wall, cell membrane, cytoplasm, nucleus, vacuole, chloroplasts, mitochondrion
4.2 Name the main function of each of the following parts in an animal cell.
4.2.1 Cell wall :________________________________________________________________________
________________________________________________________________________________
4.2.2 Chloroplasts :_____________________________________________________________________
________________________________________________________________________________
10
LIFE AND LIVING
5. 5.1 Do a simple sketch to represent the plant cell. Indicate the following in your sketch with captions:
cell membrane, cytoplasm, nucleus, vacuole, mitochondrion
5.2 Which part of the cell can be referred to as the 'brain'? Give a possible reason to motivate your answer.
_____________________________________________________________________________________
_____________________________________________________________________________________
5.3 Describe the main function of the following parts of the plant cell.
5.3.1 Cell membrane :__________________________________________________________________
________________________________________________________________________________
5.3.2 Cytoplasm :______________________________________________________________________
________________________________________________________________________________
5.3.3 Mitochondrion :___________________________________________________________________
________________________________________________________________________________
5.4 How do vacuoles differ in plant and animal cells?
_____________________________________________________________________________________
_____________________________________________________________________________________
6. Differentiate between microscopic and macroscopic organisms and give an example of each.
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
LIFE AND LIVING
11
7. Multicellular organisms are organisms with differentiated cells arranged in tissue, organs and organ systems,
i.e. an independent plant or animal body.
Levels of organisation
Cells
Tissue
Organs
Organ systems
Organism
Now explain the following concepts:
7.1 Cells:_________________________________________________________________________________
_____________________________________________________________________________________
7.2 Tissue:_______________________________________________________________________________
_____________________________________________________________________________________
7.3 Organs:_______________________________________________________________________________
_____________________________________________________________________________________
7.4 Organ system: _________________________________________________________________________
_____________________________________________________________________________________
7.5 Organism:____________________________________________________________________________
_____________________________________________________________________________________
8. This diagram shows a certain instrument. What is the name of this instrument and how
does it work?
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
9. Examine the diagrams below of the light microscope, which is regularly used in schools.
A
A
B
B
C
D
E
J
L
12
F
G
H
I
K
LIFE AND LIVING
F
G
H
J
K
E
I
C
D
L
9.1 Provide captions for each of the numbered parts of the microscope.
A
G
B
H
C
I
D
J
E
K
F
L
9.2 What is the function of each of the following parts of the microscope?
A
C
D
G
J
K
10. The following sketches represent different cells as seen through a light microscope. Provide each with the
correct heading and identify the parts that are numbered.
10.1 _____________________________________
(1)
10.2 _____________________________________
(1)
(2)
(2)
(3)
(4)
(1) __________________________________
(1) __________________________________
(2) __________________________________
(2) __________________________________
(3) __________________________________
(4) __________________________________
10.3 _____________________________________
(1)
10.4 _____________________________________
(1)
(2)
(3)
(2)
(3)
(1) __________________________________
(1) __________________________________
(2) __________________________________
(2) __________________________________
(3) __________________________________
(3) __________________________________
LIFE AND LIVING
13
11. The following two figures show micrographs that were taken by an electron microscope.
Examine these two micrographs and answer the following questions.
Figure 1
Figure 2
11.1 Indicate which micrograph is an example of plant tissue and which one is an example of animal tissue.
Figure 1 : ________________________________
Figure 2 : ________________________________
11.2 Name TWO reasons why you chose the micrograph as an example of plant cells.
____________________________________________________________________________________
____________________________________________________________________________________
11.3 Do neat sketches of the cells that form each type of tissue and give an appropriate heading as well as the
necessary captions.
12. 12.1 What is a stem cell?
_____________________________________________________________________________________
_____________________________________________________________________________________
12.2 Why is stem cell research being welcomed as a wonder cure by the medical world?
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
• Do further research on stem cell research and discuss your findings in the classroom.
• Also give your opinion regarding stem cell research - i.e. do you agree or not?
14
LIFE AND LIVING
2
SYSTEMS IN THE HUMAN BODY
BODY SYSTEMS
• The human body consists of several integrated systems working together to keep us alive.
• In this section we will study the following seven main body systems in the human anatomy.
Digestive
system
Circulatory
system
Respiratory
system
Musculoskeletal
system
Excretory
system
Nervous
system
Reproductive
system
• When we study each of these body systems, we will pay attention to the following:
- The function (or main purpose) of the system in the body.
- The main processes that occur in the system.
- The main components (organs) that make up the system.
- The main health issues associated with that specific system.
THE DIGESTIVE SYSTEM
Function of the digestive system
• The digestive system breaks down food into dissolved nutrients that are absorbed into the bloodstream and
transported to cells throughout the body.
Main processes of the digestive system
• There are four main processes that occur in the digestive system in different areas along the digestive tract. They
are:
► Ingestion: This occurs when food is taken in through the mouth into your body by eating or drinking.
► Digestion: This is the process where large food molecules are broken into smaller soluble food molecules which
are then transported in the bloodstream.
• There are two types of digestion:
1. Mechanical digestion
- Occurs when food is broken down physically by chewing, churning, or grinding and crushing.
- Mechanical digestion takes place in your mouth and in your stomach.
2. Chemical digestion
- Occurs when different digestive enzymes break down the pieces of food into smaller molecules.
- Enzymes are chemicals that break up large food molecules into smaller molecules.
- Different enzymes work on different food molecules.
- Chemical digestion starts in the mouth where enzymes in the saliva start breaking down starch.
- Chemical digestion also occurs in the stomach and small intestine.
► Absorption: This is the movement of digested, soluble food molecules through the wall of the digestive system
into the bloodstream, from where it is carried to all the cells in the body.
► Egestion (defecation): When any undigested or unwanted particles passing through the digestive tract are
excreted as faeces (excrement) at the end of the digestive tract (through the anus).
Main components in the digestive system
• The human digestive system consists of two main groups, the digestive tract and the supporting organs.
• The digestive tract is a long, hollow duct through which the food moves.
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• It has two openings to the outside, the mouth at the one end and the anus at the other end.
• The following organs form part of the digestive tract:
(1) the mouth; (2) the oesophagus; (3) the stomach; (4) the small intestine; (5) the large intestine.
• The supporting organs help with the process of digestion and includes the teeth, the tongue, the salivary
glands, the liver and the pancreas.
• The teeth and tongue help with mechanical digestion.
• The glands (i.e. the liver, pancreas and salivary glands) produce and store chemicals (enzymes) that breaks down
the food chemically.
• The different components of the human digestive system are indicated in the following figure:
tongue
teeth
salivary glands
mouth
oesophagus
liver
stomach
gallbladder
pancreas
small intestine
colon
caecum
rectum
anus
large intestine
The digestive system.
The mouth
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Food enters the digestive tract through the mouth.
When you put food in your mouth it is called food components.
Ingestion or digestion starts in the mouth.
In the mouth we find the teeth, tongue and special glands called salivary glands.
The teeth play a role in the biting, chewing and grinding of food (pulverising food into smaller pieces) during
mechanical digestion.
The tongue holds the food between the teeth, mixes the food with saliva, rolls the food into a small ball of food
(called a bolus) and helps with the swallowing process.
Taste buds on the tongue allows us to taste our food.
The salivary glands contain enzymes that help with the chemical digestion, secretes saliva, moistens food to
form a bolus and smooths the bolus to make swallowing easier.
Once the food has formed a bolus (round ball) it is swallowed and moves into the oesophagus.
The oesophagus
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The oesophagus (gullet) is a long duct with muscles that help the food (bolus) to move into the stomach.
It’s like squeezing toothpaste from a tube.
The rhythmic contraction (wave motion) of the muscles in the oesophagus is called peristalsis.
Peristalsis assists in pushing the bolus down into the stomach.
It has no digestive function.
The stomach
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The food is mixed in the stomach (a muscular organ) with a liquid that is secreted by the stomach wall.
This liquid is called digestive juices (gastric fluid) and it contains hydrochloric acid and enzymes.
These chemicals help to further break down food molecules (chemical digestion).
The stomach wall has muscles that contract and pulverize the food.
The muscle walls grind the food and mix it with the digestive juices (mechanical digestion).
Food stays in the stomach for about two hours where it is churned and mixed with digestive juices.
A sphincter at the exit of the stomach opens and food moves through the valve into the small intestine.
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The small intestine
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The small intestine is about 6 m long and is specially adapted for the last stages of digestion.
The major part of digestion and the absorption of digested food takes place in the small intestine.
During the last stage of digestion the food is broken down into a simpler form in order to be utilised by cells.
Glands in the wall of the small intestine secrete intestinal juice that contains enzymes.
Food that has not been fully digested is broken down by the action of these enzymes until simple, soluble food
molecules are formed.
• Soluble food molecules move through the small intestine wall where it is absorbed into the blood stream
(absorption).
• The food molecules are transported in this way to the cells where they are used.
The large intestine
• The large intestine is about 1,5 m long and 70 mm in diameter.
• The following parts of the large intestine are distinguished:
- The caecum: Is the widest part where the large intestine joins the small intestine.
- The colon: Makes up the greatest part of the large intestine that first extends upwards, then across and finally
downwards.
- The rectum: Is the last part of the large intestine that ends at the anus.
• No digestion takes place in the large intestine.
• By the time the food reaches the large intestine, most of the nutrients have been absorbed.
• All the undigested food ends up in the large intestine as waste food.
• Here the body absorbs most of the water, mineral salts and certain vitamins from the content.
• The substances remaining in the large intestine are further decomposed by bacteria into faeces (excrement) and
stored in the rectum before excretion.
• Faeces (excrement) leaves the body through the anus – this is called egestion or defecation.
Other parts of the digestive system
• There are several organs that help the digestive system to function.
• These organs include the liver, gallbladder and pancreas.
• They secrete special fluids into the digestive tract that contain different enzymes and chemicals.
• These substances help to digest the food.
► The liver
- The liver is the largest organ in the body and has many functions and plays an important role in digestion.
- It produces a yellow-green liquid called bile.
- Bile contains substances that help digest fatty foods.
► The gallbladder
- The gallbladder temporarily stores bile until it is needed.
► The pancreas
- The pancreas produces gastric juices with digestive enzymes that break down (digest) starch, protein, carbohydrates, fats and oils.
Health issues involving the digestive system
Peptic ulcers
• A peptic ulcer is an open sore that can form in the stomach wall or in the upper part of the intestinal tract.
• Peptic ulcers are caused by certain bacterial infections in the stomach.
• It can also occur as a result of smoking, the use of painkillers and stress.
Anorexia
• Anorexia is a type of eating disorder that affects the mind.
• People suffering from this eating disorder have an abnormal fear of gaining weight and
therefore deliberately do not eat and intentionally go hungry.
• This leads to many health issues such as loss of bone density, kidney damage, heart
problems and even death.
Diarrhoea
• Diarrhoea is the excretion of faeces that is sparse and watery.
• Diarrhoea usually lasts two days only and is generally caused by a virus.
• It is sometimes called gastric flu.
• Diarrhoea is also a symptom of other diseases such as cholera.
• Cholera is caused by a bacterium and can lead to death in young children if not treated.
Cirrhosis of the liver
• Cirrhosis of the liver is when the liver is scarred as a result of continuous damage to the liver cells.
• The scar tissue replaces healthy tissue and prevents the liver from functioning properly.
• The most common causes of cirrhosis is excessive drinking of alcohol or infection from the hepatitis C virus.
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Exercise 1
THE DIGESTIVE SYSTEM
1. 1.1 What is the function of the digestive system?
_____________________________________________________________________________________
_____________________________________________________________________________________
1.2 Name the main processes of the digestive system.
_____________________________________________________________________________________
1.3 Name the main parts of the digestive system.
_____________________________________________________________________________________
1.4 Name health issues involving the digestive system.
_____________________________________________________________________________________
2. Complete the following table so that each of the processes that you mentioned in Question 1.2 above matches
the description best.
Process
Description
Large food molecules are broken down into smaller soluble food molecules
which are then transported in the bloodstream.
When undigested food is excreted in the form of faeces.
The movement of digested, soluble food molecules through the wall of the
digestive system into the blood.
Taking food through the mouth into the body.
3. Distinguish between mechanical digestion and chemical digestion.
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
4. Why should the food we eat be digested?
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_________________________________________________________________________________________
_________________________________________________________________________________________
5. What is the name of the process by which food passes through the oesophagus?
_________________________________________________________________________________________
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6. 6.1 Name the parts numbered (1) to (11) in the following figure.
(1)
(4)
(5)
(9)
(11)
(1) _______________________
(2) _______________________
(2)
(3) _______________________
(4) _______________________
(3)
(5) _______________________
(6) _______________________
(7) _______________________
(8) _______________________
(9) _______________________
(10) _______________________
(6)
(7)
(8)
(11) _______________________
(10)
6.2 Give a title for this figure.
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6.3 Which parts (organs) mentioned in Question 6.1 do not form part of the digestive tract.
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6.4 Name the part of the digestive tract where:
6.4.1 Food enters the digestive tract.
_________________________________
6.4.2 Waste leaves the digestive tract.
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6.4.3 Food enters the bloodstream.
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6.4.4 Digestion is completed.
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6.5 Name the organ in the digestive system that has the following function:
6.5.1 Serves as temporary food store.
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6.5.2 Transports food to the stomach.
_________________________________
6.5.3 Absorbs water and mineral salts.
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6.5.4 Stores undigested food.
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6.5.5 Temporarily stores gall until it is needed.
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7. Study the following sketch of the organs of the digestive system.
7.1 Draw arrows on the diagram to show the path of food through the
digestive tract.
7.2 Explain what happens to a piece of meat when it enters the mouth and
passes through the digestive system.
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
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_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
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8. Do further research and give the basic causes and symptoms of the health issues listed below.
8.1 Anorexia nervosa
Causes
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Symptoms
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8.2 Diarrhoea
Causes
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Symptoms
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8.3 Peptic ulcers
Causes
__________________________________________________________________
__________________________________________________________________
Symptoms
_____________________________________________________________________________________
_____________________________________________________________________________________
8.4 Cirrhosis of the liver
Causes
__________________________________________________________________
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Symptoms
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