Living Organisms

1
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.
2
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

3
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.
4
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.
5
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.
6
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.
7
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 1600s 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.
8
In the late 1600s, 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.
9
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.
10
German botanist Matthias Schlieden and zoologist
Theodore Schwann made many observations of cells
in every living tissue they studied from plants,
muscles, nerves and many others in the early
1800s.
Schlieden
Schwann

• 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.

11
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.
12
Simple microscopes (with one lens) were the tool
of choice for a long time. Compound microscopes
(using 2 lenses) had been invented in the 1600s.
The images produced by compound microscopes were
blurry due to the relatively poor lens quality.
However, a compound microscope can offer greater
magnification.
13
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.
14
A compound light microscope has these common
parts.
15
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.
16
The revolving nosepiece holds the objective
lenses and allows you to change to different
lenses and higher and lower powers of
magnification.
The arm holds up the revolving nosepiece. It is
also what you hang onto when moving a microscope.
The objective lenses magnify the object. The low
power objective lens is the smallest while the
high power lens is the largest.
17
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 doesnt move around with small bumps
and movements of the microscope.
18
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).
19
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.
20
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.
21
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.
22
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.
Lets 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.
4x

?
5.5 mm
Med f. of v.
15x
1.5 mm
?
Med f. of v.
23
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.
24
When we look at microscopic organisms we dont
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.
25
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.
26
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.
27
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.
28
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).
29
General Animal Cell
30
General Plant Cell
31
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.
32
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.
33
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.
34
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.
35
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.
36
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
lysosomes.
A lysosome needs to be kept separate from the
rest of the cell otherwise the digestive
chemicals would kill the cell.
Vacuoles
The Golgi apparatus is like the post office of
the cell. Vacuoles and lysosomes are like the
cells stomach.
37
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.
38
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.
39
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 doesnt 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.
40
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 didnt let anything into the
cell it would be impermeable. An impermeable
membrane would be fatal to cells since they
couldnt 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.
Salty water
Pure 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
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.
Nerve Cell
Sperm Cell
Onion Skin Cell
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 dont 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
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.
Heart
Arteries
Veins
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 the lungs, it branches down into
bronchi. The bronchi branch into smaller
bronchioles. The bronchioles end at tiny sacs
called alveoli.
bronchioles
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 wouldnt 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.
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 smokers 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.