BIOLOGY
Biology is a fascinating subject. Learning about life on Earth is
fun. Biology is the study of life, what life needs to survive, what
makes life possible, how life evolves and changes, and how life forms
interact with one another.
The Origin of Life
How did we all get here? It is the job of a biologist, or someone
who studies life, to learn where life came from, how it developed, and
to try and determine how life will continue to develop.
Biologists today are not completely sure how life began on
Earth, but after many years of studying life forms, they have come up
with guesses. We call these guesses Theories. The most commonly
accepted theory is the theory of evolution.
About 4.6 billion years ago our Earth looked very different than
it does today. . The surface of our planet was covered in oceans of
hot lava. Instead of breathable oxygen, the atmosphere was made of
a mix of deadly poisons. There was no life. No fishes to fill these
oceans, no plants to cover the rocky surface, no animals to graze the
wilderness. Just a barren wet rock, orbiting the Sun. The Earth's
atmosphere now contained a mix of very poisonous gases, including
carbon
monoxide,
carbon
dioxide,
nitrogen,
hydrogen
sulfide,
methane, and cyanide. Breathing this air would cause death to most
life forms as we know them.
So how did life arrive on Earth?
What came first? The chicken, or the egg? This riddle seems
silly, but think about it. Without chickens, there could be no one to
lay eggs. Yet, without eggs, there could be no chickens, because they
could not have hatched. So which came first? A complicated question,
and not just about chickens, but about all life forms.
What forces changed this barren waist land into the beautiful
garden that it is today? Biologists believe that the process that
created life is something called evolution. Earth's ancient oceans,
while lifeless, but were filled with the chemicals needed for life. These
chemicals were not alive, but they were there, sloshing around. They
call these chemicals “Primordial soup”. This soup was filled with
amino acids, proteins, lipids, and other basic components that are
commonly found in life forms today.
It is believed that life began on the
shores of these ancient oceans, in pools of
water called tidal pools. These shallow pools
would have been full of this “life soup”. Over
many millions of years, as the ingredients of
life splashed around in these pools, possibly
helped by lightning strikes, they formed the
first cells.
What is a cell?
A cell is a basic unit of life. They are tiny packets, or bags of
organelles or tools needed for the cell to survive. A cell can eat, move
around, and reproduce. these cells took the chemicals of life, found in
the soup, and put them together inside protective sacks. These first
cells were very simple, and because there was little or no oxygen
available probably did not need it to survive.
What did these first cells eat?
As strange as it may seam, the first cellular life forms on earth
probably ate soup. Not Chicken Noodle Soup, but the same soup that
they formed in. At that time, there were plenty of proteins, amino
acids, and lipids to go around. The first cells were probably all
consumers. The ancestors of animals.
Over millions of years time, had to form. These cells were called
producers. Producers evolved the ability to actually create their own
food, using the chemicals around them, and the energy from the Sun,
or from heat found in the Earth. These producers would be ancestors
to the plants
From very simple cells, to multi-cellular human beings, life had
a long way to go. A number of very important advances in evolution
allowed life to become what it is today. The first important
advancement was the development of cells that use oxygen.
Remember, the first cells could not use oxygen, because there was
not enough of it in the air. However, as these first cells carried out
the business of living, they released oxygen into the atmosphere.
Over a very long period of time, our atmosphere changed from a
poisonous and deadly mix of gases, to the atmosphere we know
today .
As the atmosphere changed, so did life. Cells evolved that could
use oxygen to carry out their bodily functions. Because oxygen is a
much more efficient gas, this opened the door to larger, faster, and
more complex cellular life forms.
The next major evolutionary advance, was the development of
multi-cellular life forms. No longer was life limited to just one cell.
Creatures began to arise that were made up of two cells, ten cells, or
even thousands, or billions of cells. These cells began to specialize in
different jobs. Some acting as hearts, others as eyes, others as
brains, allowing life to become very complex.
Over millions of years, plants and animals have evolved into many
different forms. Some with big mouths, some with small mouths,
some with sharp teeth, some with no teeth, eyes in the front, eyes on
the side, two eyes, eight eyes, and everything in between. All of this
evolution guided by the simple law of survival of the fittest.
Lets consider another example. Instead of hippopotamuses, this
time we will examine birds. Birds have a very big advantage over
other life forms. They can fly. This ability allows them to move
around quickly, as well as the ability to easily escape from predators.
What is Life?
Look around you. What do you see? A classmate, a brother or sister?
Look out the window, or go for a walk. You will see trees, grass,
plants, dogs, cats, bugs, and many other forms of life.
Now, think about this. Life extends much further than what you can
see. Everywhere around you, all over your keyboard, the computer
monitor, your desk, the walls, the floor, the ceiling, your clothes, and
even your skin, you can find billions and billions of tiny microscopic
life forms.
Life is all around us. From many kilometers (miles) into the
atmosphere, to many meters (feet) beneath the surface of the Earth,
life is everywhere. What is this stuff we call life? What are some
things that all life forms have in common?
Living Things Are Made of Cells
All living things are made up of cells. These cells are the basic
building blocks of life. As an example, have you ever seen a sand
castle? At a distance, the sand castle looks like a smooth brown
building. As you get closer to the sand castle, you can begin to see
that it is not one smooth building, but instead that it is made up of
millions of tiny grains of sand.
Looking at an elephant, you might see what looks like a smooth
gray animal. And it is true that this is what you are seeing. However,
just like the sand castle, if you could get close enough, and if your
eyes were powerful enough, you would realize that what looks like a
smooth gray surface, is really made up of many billions of smaller
objects called cells.
Cells are tiny units of living materials separated by a cellular
wall, or barrier. These cells are so small, that they can only be seen
with a powerful tool known as a microscope. Cells make up every part
of a living thing. Your skin, your hair, fingernails, blood, bones,
nerves, and muscles are all made up of cells. These cells work
together to keep the life form alive.
Many life forms can move. Just like you, they might move to
find food, to find shelter, to avoid danger, or in response to their
environment. Animals move in many different ways. They might use
fins to push them through the water, wings to help them fly, feet,
tails, hands,
Plants also move. They of course can not move as well as
animals, but many plants move their stems to face the Sun, open and
close flowers, and more. Some carnivorous plants even move to trap
prey.
Living Things Perform Chemical Reactions
Inside
complex
taking
take
living
chemical
place.
place
organisms
as
things,
reactions
Chemical
outside
well,
very
are
reactions
of
but
living
not
on
anywhere near the same level. A
living organism is a mini-chemistry
lab. These chemical reactions are
carrying out the functions necessary
for life, including breaking down food
so that it can be used for energy,
creating food, building new cells,
repairing body parts and more.
Living Things Respond To The Environment Around Them
One of the most important characteristics of living things, is
that they respond to the environment around them. This one single
characteristic makes them very different from non-living things,
which do not respond to the environment, but instead just let what
ever happens to them happen.
Your own body responds to its environment in order to keep you
healthy. You might sneeze, to keep dust and germs from entering
through your nose, your immune system responds to invaders by
producing anti-bodies, etc.
Living Things Reproduce
A very important part of the life of living things is the ability
and opportunity to reproduce, to create
offspring. Reproduction is the process of
one or more living things creating another
living thing. Your parents created you. A
mother and father dog reproduce, creating
puppies. By reproducing, living things are
able to pass on their characteristics to
another generation.
Living Things Die
Something that is definitely unique to
living things is that they die.
Anything that is alive will eventually
die. The period of time that something is
expected to live is called the living thing‘s
“life span”. The life span of living things
can vary significantly.
Some things have a life span of only a few hours, or a couple of days.
Some bacteria, and insects, for example, begin their lives, mature,
reproduce, and then die, all within a couple hours. Other living things
can live for many years, such as an elephant, who might live for 70
years, and a human, which can live for 100 years. Then there are the
living things which seem to live forever. A bristle cone pine tree they
can live 5,500 years. That means that today there are bristle cone
pine trees alive, that began their lives before ancient Rome, and even
before many of the ancient Egyptian pharos. Even these long lived
organisms will all eventually die.
Needs of Living Things
What do you need to live comfortably? The list probably includes
food, a home, clothes, and water. Other needs might include love, an
education, friends, enough space to play, and many other things. If
you have pets, what do they need to live a comfortable life style?
Probably many of the same things, food, water, exercise, and more.
Living things have many different needs. Fish need water to survive,
your pet hamster needs a clean cage, and plants need sunlight to
make food. All around us, living things are using their environment to
fill these needs.
Living things often use other living things to satisfy needs, such as in
the example of a lion, who uses his prey as food, or the bacteria in
your body, which uses you as shelter. Other times, living things use
non-living things to fulfill their needs. This might be the lizard who
uses a crack in a cliff side to hide, or plants who use minerals from
the soil to create food.
All life forms have different needs. For example, most fish do not fly,
and most birds do not swim, while most plants don't do either.
However, all life forms do have a few of the same basic needs in
common. Almost all living things need energy, food, water, oxygen,
space, and the ability to maintain homeostasis.
All life forms need energy to survive. Energy is the resource that
allows organisms to do things. What kinds of things might an
organism do with energy? This answer to this question is as varied as
the life forms that use energy. Some, like the African Lion, use
energy to chase after prey. Other life forms, like many creatures we
find in the depths of the Earth's oceans use energy to create their
own light. Living things use energy to grow, to defend themselves,
and to move around.
Energy
With so many living things around us using
energy every day, you might ask where all
this energy comes from. The main source
of energy on the Earth today is the Sun.
The energy found in your body, that you
use to run, jump, and play sports, was
originally produced by the Sun.
Plants use sunlight to create their own food. Many animals then eat
the plants, taking this energy into their own bodies. Other animals
then eat these plant eaters, passing the Sun's energy from one
organism to another.
Food
All living things need a source of food. The food organisms take in
provides them with energy, and also provides them with the
resources, and raw materials they need to build up their bodies,
grow, and repair damage.
The foods that living things consume are very different depending on
the life form. A cow eats a very different diet then a tiger. Even
among humans, there is a lot of difference in what people eat around
the world.
Plants use sunlight to create their own food.
Water
How long can you go without water. After
only a few hours, you will begin to get
thirsty. Within a couple days you without
water, you would get very sick. Without
water, your body would die within about a
week, possibly even sooner.
Living things need water to survive. But
why is water so important? All life forms on
Earth are comprised almost entirely of
water. Your own body is about 66% water.
Water in your blood helps transport food,
and chemicals to your cells. It helps remove
waste products from your body. Water is
used to cool you down, to warm you up, and to carry out the
chemical reactions that allow you to move and grow. Another
important use of water, is to keep your body clean.
Plants use water to grow, to transport
food,
and
to
carry
out
chemical
reactions. In addition, plants use water
as part of photosynthesis, to create
their own food.
Oxygen
Without food, your body would die in a matter of weeks. Without
water, you would day in days. How long do
you think you would live without oxygen? As
an experiment, see how long you can hold
your breath. How quickly does your body let
you know it needs more air?
Most life forms use oxygen as the main ingredient in many of the
chemical reactions needed for life. This is because oxygen is a very
efficient element. The availability of oxygen in the Earth's atmosphere
is believed by biologists to be a
major reason for the advancement
of life on Earth. Without it, life
would probably still be very small,
and very slow.
Organisms get oxygen from their
environment in a variety of ways. Many land animals breath oxygen
directly from the air, while ocean bearing animals often use the
oxygen dissolved in the water to survive. No matter how they get it,
oxygen is an important need for almost all life forms.
Homeostasis
Homeostasis is a big word that biologists use to indicate that an
organism needs to keep conditions inside of itself the same, even
though conditions outside are always changing. One very important
part of homeostasis is body temperature.
On any particular day, the temperature
might change by as much as 50º. In order
for an organism's chemical reactions to
continue as they should, the temperature
on the inside of the organism needs to
remain the same.
How do living things maintain homeostasis? When your body
temperature begins to rise, what happens? You begin to sweat.
Sweating is your bodies way of cooling down, and thus maintaining
homeostasis. What do dogs do to cool down? Living things have many
unique tricks that help them maintain the same conditions inside
themselves.
The 5 Kingdoms. Classification.
Biologist today have classified and divided all living things into five
groups they call Kingdoms.
These kingdoms are based on how living things are the same, and
how they are different. It is important that you understand, that
biologist are still learning about our world, and are making new
discoveries every single day. As our knowledge about the world
around us improves, scientists might find a better way to organize
and classify life. As a result, these five kingdoms may someday
change.
The five kingdoms currently accepted by most (but not all) scientists
are The Moneran Kingdom, The Protist Kingdom, The Fungi Kingdom,
The Plant Kingdom, and The Animal Kingdom.
Moneran
The Moneran Kingdom consists of unicellular life forms. Unicellular
means that they only have one cell. Moneran cells are far simpler and
more basic than the cells of other life forms. These cells have no
nucleus, and are also missing many of the organelles, or parts,
commonly found in other cells. For this
reason, Monerans are thought to be very
distantly related to other life forms.
Monerans are classified into two phyla, or groups, autotrophs, and
heterotrophs. Autotrophs are able to create their own food, similar to
plants. Heterotrophs can not create their own food, and so must rely
on autotrophs as their food source.
Bacteria are commonly placed in The
Moneran Kingdom. Monerans are considered
by many scientists to be the oldest life
forms on Earth, and the ancestors of all the
other types of life that have since evolved.
Protists
The Protista Kingdom consists of unicellular life forms (life forms with
only one cell) who have a nucleus. The primary difference between
protists and monerans is that protists are more complex, having a
nucleus.
Fungi
The Fungi Kingdom is made up of a variety of different funguses. For
many years, it was believed that fungi were plants. Today we know
that fungi are different from plants in some very important ways.
Firstly, unlike plants, fungi cannot make their own food. They must
rely on other food sources to support them. There are also
differences in the basic make up and chemistry of their cells.
One common type of fungi are the mushrooms you find on your
pizza. Other fungi include microscopic fungus, truffles, and more.
Plants
The Plantae Kingdom is made up of all the plants
that you see each day. Most plants are multicellular, meaning that they consist of many cells.
Different types of plants include trees, grass,
Plants use the light from the Sun to produce their
own food. This allows them to
grow
almost
anywhere, as long as there is enough water.
Plants get their green color from the chlorophyll
which is found inside of their cells. Plants use
chlorophyll to collect energy from the light of the Sun. They then use
this energy to create food. In this process, they create the food we
eat, and the oxygen we need to breath. Plants are very important to
the life of almost every other living thing.
Animals
Like many other life forms, animals are multi-cellular. These cells
come together, forming tissues, organs, and organ systems, that help
sustain the life of the animal. From elephants to snails, animals come
in many shapes and sizes, and can be found all over the world.
Animals cannot make their own food. They must rely on other living
things, such as plants, fungi, and other animals to sustain them.
Without other food sources, animals could not survive.
There are more species of animals, then in all the other kingdoms
combined. From worms, to blue whales, to bald eagles, animals have
evolved to fit a wide variety of niches.
Biology Quiz
Enjoy our fun biology quiz. Answer questions about evolution, cells,
microbiology and more. Find out just how much you've been paying
attention during biology lessons at school.
1. Which famous scientist introduced the idea of natural selection?
2. A person who studies biology is known as a?
3. Botany is the study of?
4. Can frogs live in salt water?
5. True or false? The common cold is caused by a virus.
6. Animals which eat both plants and other animals are known as what?
7. Bacterial infections in humans can be treated with what?
8. A single piece of coiled DNA is known as a?
9. A group of dog offspring is known as a?
10. The area of biology devoted to the study of fungi is known as?
11. What is the name of the process used by plants to convert sunlight into
food?
12. The death of every member of a particular species is known as what?
13. The process of pasteurization is named after which famous French
microbiologist?
14. True or false? A salamander is a warm blooded animal?
15. A change of the DNA in an organism that results in a new trait is known
as a?
Biology Quiz Answers
1. Charles Darwin
2. Biologist
3. Plants
4. No
5. True
6. Omnivores
7. Antibiotics
8. Chromosome
9. Litter
10. Mycology
11. Photosynthesis
12. Extinction
13. Louis Pasteur
14. False
15. Mutation