Living Organisms
Living things exist in a wide range of sizes, types, and
environmental interactions.
Irises, koalas, and
paramecium are all
considered living
creatures but they are
very different in size,
appearance, and in the
way they interact with
the environment.
1
To classify what is living and what is not living is actually
quite difficult. Scientists are still grappling with this
argument trying to decide if viruses are indeed living
creatures. There are 5 basic characteristics that scientists
have agreed on. Living organisms will…
 Need energy
 Respond to their environment.
 Reproduce
 Grow
 Produce wastes
2
Every living organism carries out these functions in different
ways. They need to use specialized structures to fulfill these
functions.
Lions use their teeth, mouths,
digestive tracks to gain energy. They
need to kill another organism to gain
their energy.
The trees leaves on the other hand
collect sunlight and use special
chemicals to synthesize energy.
Just in the way that they gain energy,
lions and trees have very different
interactions with their environment.
3
In our own bodies we have
many organs which are
specialized to carry out the
functions we need to live.
Each organ is made from
special tissues. These muscle
tissues Are made from long
bundles on thin striations.
4
Muscle tissues are common in the
body. The skeletal muscles move
our limbs. As well, muscle tissues
are part of our stomach, heart, and
esophagus.
The muscle tissues are made from
cells. A cell is the basic unit of a
living system. Like organs and
tissues, each cell is specifically
designed to help carry out a function.
The muscle cell uses long fibers that
relax and contract chemically to
complete their function.
5
The stem, leaves, and roots of this
elodea plant are the organs. The
stem, leaf, and roots are made from
different specialized tissues. These
tissues are made from different
specialized cells.
Plants have very different cells that
make up their tissues. The aquatic
plant elodea has cells designed to
help support the plant as well as
make food using sunlight.
6
Microscopes
It is impossible for us to see cells with our eyes. This is why
many of our ideas about cells were not discovered until the
late 1600’s after the invention of the microscope.
A microscope is a device that magnifies objects.
Magnification makes objects appear larger.
A simple magnifying glass is in a way a type
of microscope.
7
In the late 1600’s, Robert
Hooke used a simple one
lens microscope to look
at a thin slice of oak cork.
He saw little rooms that
reminded him of the cells
where monks lived. Cork
cells are dead so he only
saw their cell walls.
8
Around the same time as Hooke, Anton van
Leeuwenhoek used simple microscopes to view
rain water and blood. He saw in rain water
things he called “animalcules” which we now
call bacteria. In blood, saw blood cells of
different varieties and shapes. Van
Leewenhoek made his own simple microscopes
grinding lenses to about the size of the head of
a pin. They could magnify about 300 x.
9
Schlieden
German botanist Matthias
Schlieden and zoologist
Theodore Schwann made many
observations of cells in every
living tissue they studied from
plants, muscles, nerves and
Schwann
many others in the early 1800’s.
Another German scientist, Rudolf Virchow,
proposed a cell theory about living things.
• All living things are made of cells
• Cells are the basic units of structure and
function in living things.
10
All early microscopes used light to
view the microscopic world.
Mirrors would deflect light through
a sample and into the magnifying
lens. Microscopes that use light are
called light microscopes and are
still used today however an electric
light source is place beneath the
object being studied.
11
Simple microscopes (with one lens) were the tool of choice
for a long time. Compound microscopes (using 2 lenses)
had been invented in the 1600’s. The images produced by
compound microscopes were blurry due to the relatively
poor lens quality. However, a compound microscope can
offer greater magnification.
12
The very best light microscopes can
magnify about 2000x. This is not enough
to see some of the smaller parts of cells
but, the images are in color and single
celled organisms can be seen alive.
Electron microscopes can magnify today up to 2
000 000x.
Electrons are passed and scattered off of objects and then
recorded on a photographic plate. The images are black a
white and kill the living objects being observed. The first
electron microscopes were developed in Germany. The first
practical design of an electron microscope was developed in
Canada by James Hillier and Albert Prebus.
13
A compound light
microscope has these
common parts.
14
The eyepiece (ocular lens) is helps
magnify the object being observed. It
is also what you look though to see
your object.
The tube holds the eyepiece and
objective lenses at the correct
distance from each other. As
well, it refracts the light through
the eyepiece.
15
The revolving nosepiece holds the objective lenses and
allows you to change to different lenses and higher and
lower powers of magnification.
The objective lenses
magnify the object. The
low power objective lens is
the smallest while the high
power lens is the largest.
The arm holds
up the revolving
nosepiece. It is
also what you
hang onto when
moving a
microscope.
16
The stage holds the object you are viewing and
moves up and down to focus the object.
The stage clips secures the object to the stage so
that it doesn’t move around with small bumps
and movements of the microscope.
17
The diaphragm controls the amount
of light going through the object and
into the objective lens. More light is
needed at higher magnifications.
The course-adjustment knob quickly moves the
stage to focus the image (usually only used under
low power magnification). The fine-adjustment
knob slowly moves the stage to focus the image
(usually used for higher magnifications).
18
The light source shines light through the
object and into the objective lenses.
The base provides a heavy support
for the microscope so that small
pushes and movements will not
juggle the object being viewed.
Always have one hand on the base
when carrying a microscope.
19
When you look at
an object trough a
microscope you
see only a small
portion of the
entire object.
What you see
through the
eyepiece is called
the field of view.
As the magnification is increased, the amount you see gets
smaller.
20
In order to measure the field of view a ruler needs to be
observed under the microscope. An ordinary clear plastic
ruler will work. Usually under low power, the millimeter
lines on a clear plastic ruler are visible.
In this case the low power magnification was 4x and
we could see 5.5 mm lines. Therefore, the field of
view for the low power is 5.5 mm.
21
If the low power 4x lens, for a microscope, gives a field of view of
5.5 mm then we can calculate the field of view for the other
magnifications. Let’s say the medium power lens has a
magnification of 15x. We can use the proportion of magnification
to field of view with the following formula.
Medium power
field of view
Med f. of v.
Med f. of v.
=
Low power
field of view
=
5.5 mm

1.5 mm


Mag. of low
power lens
Mag. of medium
power lens
4x
15x
22
The accuracy of this calculation methods completely
depends on how accurate the measurement of the low
power field of view. To get more precise calculations of
field of view, special and expensive rulers called
micrometers are viewed at different magnifications. A
micrometer divides a single millimeter into many tiny
divisions so accurate measurements can be made.
23
When we look at microscopic organisms we don’t look at them
directly on the lens. Instead, we make a wet mount.
First, you place a drop of a sample
onto a clear glass slide. The sample
contains the objects you want to
view.
Then you place a clear glass cover
slip over the sample.
The cover slip will stick to the slide
holding down the objects you want
to view.
24
The specimen is sandwiched between the cover slip and the
slide. Air bubbles are commonly seen as small round
shapes. Being careful when making your wet mount can
reduce the appearance of air bubbles. Most cells are
transparent. Stains are added to help highlight certain cells
and cell parts.
This hydra has been stained
purple so that it can be easily
seen with a microscope.
Imperfections in the glass of the
slide and lenses are also seen
under the microscope.
25
The Cell
We have seen the theory that all living tissues are made from
cells. This can help us to categorize living things into two
broad groups. Unicellular organisms are made from only one
cell. There are many different examples that range from
animal like carnivores like paramecium and hydra to single
celled plants like algae. Many fungi are also unicellular like
penicillium.
26
Organisms made from many cells are multicellular. This
group encompasses all other forms of organisms from dust
mites to blue whales. We are much more familiar with
multicellular organisms due to the fact that we can easily see
and interact with them. However, there are far more varieties
of single celled bacteria than all other forms of life combined.
In fact, the estimate of the total living mass of bacteria far
outweigh any other form of life.
27
Just like animals cells contain structures that complete specific
functions. In animals these are called organs. In cells, these
are called organelles. Most organelles are invisible to even the
best light microscopes
Each organelle completes a specific function for the cell. Not
all cells have the same organelles however, there are some
common characteristics of cell organelles. For example, cheek
cells (left) look very different from onion skin cells (right).
28
General Animal Cell
29
General Plant Cell
30
The cell
membrane
separates the
interior of the
cell and its
environment.
It also
controls the
movement of
materials in
and out of the
cell.
The membrane is like the cells “skin.” It is
visible with a light microscope.
31
Cytoplasm
Cell Membrane
Nucleus
The cytoplasm is a fluid inside of the cell. It is constantly
moving and helps distribute disolved nutrients to different
parts of the cell. The cytoplasm is also visible with a light
microscope with the use of a colored stain. The cytoplasm
is like the cells “blood.”
32
The nucleus of the cell is usually found at the center. It
contains the genetic information in chromosomes. The
nuclear membrane is similar to the cellular membrane. Small
holes exist on the membrane called nuclear pores. Inside the
nucleus is the nucleolus. This small ball produces other
organelles called ribosomes.
The nucleus is visible
with a light microscope
and the appropriate
stains. It is like the
“brain” of the cell
because it controls the
cells functions.
33
The endoplasmic rheticulum (ER)
is a folded organelle usually near
the nucleus. It aids in the transport
of materials in the cell.
Ribosomes are small organelles that
produce long strands of protiens
like a teletype.
If the ER has ribosomes attached to it we call it the rough ER
and if there are no ribosomes we call it the smooth ER.
The ER and ribosomes are not usually visible with a light
microscope. The ER is like the cells “veins.”
34
The mitochondrion is a bean shaped organelle with many
folds and ridges called cristae. These produce the energy
for the cell. Muscle cells would have many mitochondria
(plural of mitochondrion) to produce a lot of energy. These
are like the “power plants” of the cell.
35
The Golgi apparatus is a folded
organelle that packages materials
into balls called vacuoles. Vacuoles
can then be transported safely and
efficiently throughout the cell.
Come vacuoles contain digestive
chemicals. These are called
A lysosome needs to be kept
lysosomes.
separate from the rest of the
cell otherwise the digestive
Vacuoles chemicals would kill the
cell.
The Golgi apparatus is like the “post
office” of the cell. Vacuoles and
lysosomes are like the cell’s “stomach.”
36
The cell wall is only found in plant cells. It is made from
cellulose and offers the plant support. It is thick and difficult
to transport materials out of the cell wall. Plant cells therefore
need large vacuoles to store wastes.
37
Chloroplasts are only found in
plant cells. They are green
organelles that convert light
energy to chemical energy. The
chlorophyll in the chloroplasts in
plants is green which is why
plants are green.
38
Cells are cell organelles are very small. Even the largest
animals and plants are made from very tiny cells that are close
to the same size. Having a small size makes cells very
efficient. Firstly, it doesn’t take much energy to transport from
the membrane of the cell to the center. Secondly, the surface
area to volume ratio is very large if the cell is small. Imagine
two cubic cells. One has has a side length of 1mm and the
other 10mm.
SA  6  10  10
SA  6  1  1
SA  600mm2
SA  6mm2
V  10  10  10
V  111
V  1000mm3
V  1mm3
SA
600
SA 6

 0.6
 6
V
1000
V
1
39
Fluids and Movement in Cells
Cells require materials to exist and complete their necessary
functions. They need water, air, food, and a variety of other
nutrients. The cell membrane separates the cell from the
rest of its environment. It is like our skin.
Cell membranes have openings and special passage ways
that let materials in and out of the cells.
This means that the membrane is selectively permeable.
If the membrane didn’t let anything into the cell it would be
impermeable.
40
Fluids and Movement in Cells
• An impermeable membrane would be fatal
to cells since they couldn’t get their
needed nutrients.
• A totally permeable membrane would also
be fatal since even harmful chemicals
could enter and destroy the cell.
41
One way for a cell to gain and remove materials is by using
vacuoles.
A vacuole containing
waste can approach the
plasma membrane and
merge with it. An
opening is created on
the other side and the
waste pushed out.
The reverse process can also occur where the membrane
can grow around and consume some kind of beneficial
material.
42
The process of gradual mixing of particles in fluids is called
diffusion. According to the particle theory, since particles
of a fluid are in constant motion, when a clump of fluid
particles are added to the moving particles of another fluid,
they will tend to spread out and intermix.
Diffusion is a
natural process.
When perfume is
released in air, it
diffuses through the
air to eventually
spread evenly
throughout the
room.
43
The principle of diffusion is that particles will tend to move
from areas of high concentration to areas of low
concentration. Imagine yourself breathing. When you expel
carbon dioxide, the concentration around you is relatively
higher than 2 m away from you. Therefore, the carbon
dioxide tends to diffuse away from you, which is a good
thing otherwise we would simply breath the carbon dioxide
back. A cell “breaths” in a similar way.
When this amoeba creates carbon
dioxide waste the concentration
inside the cell is relatively higher
than outside the cell. By diffusion
the carbon dioxide moves out of
the cell.
44
Cell membranes remain impermeable
to most large particles. Water
particles, however, are able to flow
relatively easily through cell
membranes.
The diffusion of water across a membrane
is called osmosis. When a cell is put into
pure water, there is a great tendency for
water to rush into the cell (since there is
relatively little water inside the cell
compared to outside). If this happens too
quickly the cell can burst in a process
called lysis.
45
Osmosis can have a significant effect. When there is a
relatively large amount of dissolved solute on one side of a
membrane the osmotic pressure will push water to even out
the concentration of the two sides.
46
Plants use osmosis and diffusion to gain the nutrients and
water they need. If celery is placed in pure water, osmosis
pushes water into the stalk. The cell wall prevents lysis and
the celery stands upright. If the stalk is place in a salt water
solution, then there is relatively more water inside the cells
so water rushes out through osmosis. The stalk falls limp.
Pure water
Salty water
47
Water and nutrients move through a plant through special
tissues called vascular tissues. Phloem tissue moves
sugars made by the leaves to the rest of the plant. Xylem
tissues move water and dissolved minerals to parts of the
plant.
48
The roots of a plant absorb the necessary water and minerals
to make its food. Tiny root hairs have semipermiable
membranes that connect to the xylem tissues. Osmotic
pressure pushes the water up the xylem to the leaves where
most of the photosynthesis (food production) occurs.
49
The large flat leaves are packed with
chloroplasts to gather sunlight and
make sugars. Oxygen is allowed to
diffuse into the leaf through
openings called stomata on the
underside of the leaf.
Plants need to breath just like us. They use
the oxygen in exactly the same way we do
to make energy for to do many of the
functions they need. This also means they
need to expel waste gasses. When the
stomata are open, carbon dioxide, oxygen,
and water escape. This “breathing out” is
called transpiration.
50
The transpiration of a rainforest can sometimes display
visible “tree breath.” During the hot day, the stomata stay
closed to limit the loss of water due to transpiration. During
the cooler night, the stomata open to breath in the air and
slowly release wastes. Transpiration also helps to “pull” the
water through the xylem tissues.
51
General Leaf Structure
Waxy Cuticle
Epidermis
Chloroplasts
Vein
(Xylem &
Phloem)
Epidermis
Stomata
52
Nerve
Cell
Sperm
Cell
Onion
Skin
Cell
Cells are speciallized to
complete the functions they
are required to do. Their
structure relates to their
function. A nerve cell has
long ends to communicate
with other nerves. Sperm
cells are small with whip like
tails to propel them to the
egg. Onion skin cells have
thick strong cell walls.
These specialized cells are
good at completing the tasks
they were designed for. 53
This is an advantage of being a multicellular organism. If
you were a single celled organism, the one cell would have
to move about, collect food, expel waste, and reproduce. A
multicellular organism can specialize certain cells to move
limbs, transport oxygen, communicate responses, and
produce offspring.
Yet, we can still see a great variety of single celled
organisms. This is because it is extremely easy,
comparatively, to create a single celled organism. Their
simplicity makes them prolific. Bacteria cells are even more
simple than animal or plant cells. Bacteria don’t have
organelles. They can reproduce very quickly and easily. By
overwhelming numbers, bacteria have been able to be the
most successful life form on Earth.
54
Body Systems and Health
All of the cells in our body
require food, oxygen, water,
and other nutrients. There are
specialized cells organized
into tissues which are further
organized into organs to carry
out these functions. Many
organs are connected together
and work as an organ system
to carry out functions. Many
organ systems can be
interconnected as well.
55
Our digestive system
consists of all of the
organs we use to consume
and breakdown the food
we eat into its basic
chemicals. These include
the mouth, salivary glands,
esophagus, stomach, liver,
pancreas, gallbladder. It
also includes the large and
small intestines, rectum,
and anus which absorbs
nutrients and expels
wastes.
56
The respiratory system
includes all of the
organs needed to
consume oxygen. These
include the mouth, nose,
trachea, and lungs, and
diaphragm. The lungs
have tissues called
bronchi that branch out
into smaller bronchioles.
At the end of the
bronchioles they branch
into even smaller
alveoli.
57
Heart
Arteries
Veins
The circulatory system is the
connection to all of our other
systems. It is the heart,
blood, arteries, and veins that
run throughout our body. All
of the nutrients collected by
the digestive and respiratory
systems are transferred
through the circulatory
system. All of our systems
and directly connected to the
circulatory system so that the
cells and tissues can receive
these needed nutrients.
58
Arteries carry
blood under
pressure from the
heart. They have
a thick muscular
layer to give them
strength and
flexibility.
Veins carry blood back to the heart and are under much less
pressure. Valves in veins stop the blood from flowing
backward.
59
Veins and arteries
branch into smaller
and smaller vessels
until they are very thin
capillaries.
Capillaries are so thin
that usually blood cells
flow single file.
The walls of capillaries are also very thin which allows
dissolved nutrients in the blood to diffuse through the
membranes.
60
When air enters
bronchioles the lungs, it
branches down
into bronchi.
alveoli
The bronchi
branch into
smaller
bronchioles. The
bronchioles end
at tiny sacs called
alveoli.
61
Oxygen diffuses through
the alveoli to the red
blood cells. Carbon
dioxide from the red
blood cells diffuses into
the alveoli.
The circulatory system
then move the oxygen to
the cells of the body
through the blood. The
lungs push out the carbon
dioxide when you breath
out.
62
A similar process occurs in the
small intestine. Instead of
exchanging oxygen and carbon
dioxide, the blood picks up
digested and dissolved nutrients
through villi and microvilli.
63
Inside the kidney a similar
process occurs. Blood from
capillaries is brought to the
kidney. Tiny nephrons filter
excess water and toxic chemicals.
These wastes are made into urine
and sent through the ureter to the
bladder.
64
The nervous system is also
connected to many of the
other systems of the body.
Tiny electrochemical signals
are sent along nerve cells to
the brain. Most of the nerves
go through the spinal chord.
In many cases, signals
received by the brain trigger
automatic responses like
sweating when you get hot
getting a hungry feeling when
your energy supply is lower.
65
The nervous system does not
control all of your bodies
responses. The endocrine
system (gland system) also
sends chemical signals through
the blood. These chemical
signals are called hormones.
The effect of hormones are
very complex and very
powerful.
66
It is impossible to say which body system is the “most
important.” Each system is dependent on the others. All
cells require oxygen from the respiratory system and
nutrients from the digestive system.
Without regulation and control mechanisms of the nervous
and endocrine systems, our organs wouldn’t know what
jobs they had to do. Imagine eating but your stomach not
knowing it had to help in digestion. If the circulatory
system were to stop functioning, the very specialized cells
would not be able to give or receive the needed chemicals.
All of your systems depend on your blood to fullfill these
needs.
67
Your blood is not complete made from blood cells. Plasma is
the fluid that dissolves many of the nutrients and carries them
to other cells. Red blood cells (RBC) are doughnut shaped
cells that contains iron rich hemoglobin. The hemoglobin
binds to the oxygen and carbon dioxide. White blood cells
(WBC) help attack and digest bacteria infecting the blood.
Platelets burst and make a tangled web to clot blood when
there is a wound. This prevents excess blood loss.
Component
Plasma
RBC
WBC
Platelets
% by Volume
55
44
<1
<1
68
One of the main health problems with the circulatory system
in North America is hypertension (high blood pressure).
Hypertension is a “silent killer”
because you may not feel ill if you
have it. A doctor uses a
sphygmomanometer to measure blood
pressure.
An inflatable cuff is put around the arm of the patient and a
stethoscope is put over an artery in the arm. The cuff is
inflated until no blood flow sounds can be heard. Pressure is
slowly let out until blood starts flowing again. This is the
same pressure in the artery. Since the pressure in the artery
fluctuates with the heart beat, a high (systolic) and low
(diastolic) reading is taken.
69
There are 5 main causes of hypertension.
• Blood Volume: Large volume of blood will raise
pressure
• Heart Rate: A fast heart rate will increase the blood
flow and pressure.
• Artery Size: A small sized artery will raise blood
pressure.
• Artery Elasticity: Inflexible arteries cannot easily allow
blood through and thus increase blood pressure.
• Blood Viscosity: Viscous blood does not flow easily and
therefore requires more pressure to move through the body.
70
A diet rich in fatty foods and
cholesterol can cause build ups
of fatty deposits in your arteries.
These fatty deposits narrow the
opening and can lead to
hypertension. These deposits
can also completely block and
cut off blood flow to areas of the
body. If an artery feeding the
heart is blocked a portion of the
hear can die. This is called a
heart attack.
71
Our digestive system handles many harmful waste chemicals.
If our diets lack fiber, it takes the digestive system longer to
process these chemicals. Bacteria can multiply and cause
infections and damage can be caused by not being able to
expel these wastes in a timely fashion. This is why fiber, even
though it offers little nutritional value, is an important part of
our diets.
Stress, smoking, alcohol, or
other drugs can also allow
bacteria to infect the lining of
our stomachs and intestines.
These can lead to damage and
cause ulcers.
72
Healthy lungs are bright pink
and allow gas exchange
between alveoli and capillaries
easily.
A smoker’s lung contains dark
tar deposits that interfere with
the gas exchange. As well,
toxins from tobacco can greatly
increase the risk of cancers
developing in the lungs and
killing their function.
73
Air pollution can also also effect your respiratory system
health. Clean air in major centers is becoming polluted from
industrial wastes as well as vehicle congestion. Hong Kong
can have clear days if the winds are right. On some days
however, the smog is thick and can cause people to feel light
headed and dizzy from a lack of oxygen.
74