Name: _________________________________
The 6 CLTs
Directions – Read, highlight, and answer the questions.
What do living things have in common?
Let us start by considering this drawing of an aquarium.
In the aquarium, what we see is a fish and a rock. There are many things that go
on inside of the fish, that make it move, grow and behave the way it does. The
rock does nothing but stays there. The rock can stay there for thousands of
years, with or without the water, but the fish will not be able to do so. It will die
at some point.
What is the difference between the fish and the rock? The fish is a living
organism but the rock is not. There are five characteristics of life that the fish has, which the rock does not
have.
 it is made up of cells
 It obtains and uses energy
 It grows
 It reproduces
 It responds to changes in its environment
 It adapts
These characteristics are not for a fish alone. It is the same for all living things (plants and animals). It also
includes very tiny organisms that our eyes cannot see. They are known as microorganisms, and include
viruses, bacteria and fungi. Because we do not see microorganisms with our eyes, it is even harder to know
if they have all the characteristics of living things. We will see more examples in the next pages.
It is possible to have a non-life object display one or two of the characteristics of life. For example, a cloud
can grow in size and move from one place, but it is not a living organism.
This means for something to be classified as a living organism, it must display ALL of the characteristics
listed above. Now, let’s take a closer look at each of the characteristics.
1. True or False – It is possible for something not living to have some of the characteristics of life
Living organisms are made up of cells
The first characteristic of a living thing is that, they are made up of cells. A cell is the basic building block of
all organisms. It is the smallest unit of organization in a living thing. They contain the organism’s hereditary
information (DNA) and can make copies of themselves in a process
called mitosis.
Cells are made up of a nucleus and a cytoplasm, enclosed by a thin wall
called a membrane, which separates it from its surrounding. Plant cells
have a nucleus, cytoplasm and a cell membrane too. The main
difference between a plant and an animal cell is that, plant cells have
a vacuole, chloroplast and a cell wall. Here is an illustration of an animal and a plant cell.
Some microorganisms are made up of only one cell, whiles other bigger organisms such as an ant or a lion
are made up of millions of different cells.
Unicellular organism:
An organism with only one cell is called a unicellular organism. They include bacteria, yeast, amoeba and
paramecia.
Multicellular organism:
These are organisms that are made up of more than one cell. These organisms have very clear cell
structures, with many cell types performing different specialized functions. For example, blood cells only
specialize in blood production, and hair cells only specialize in hair growth and repair. The do not mix up.
2. Which of the following is something that describes a plant cell but not an animal cell?
a. Rectangular shape
e. A Large vacuole
b. Chloroplast
f. Small lysosomes
c. Round
g. A nucleus
d. Cytoplasm
h. Golgi body
Living things obtain and use energy
Cells cannot survive on their own. They need power to stay alive. They need energy to perform functions
such as growth, maintaining balance, repair, reproduction, movement and defense. This means all living
organisms must obtain and use energy to live.
Energy is the power to do things. This power comes in many ways and forms, but they can all be linked to
the sun. It is the source of all energy.
A living organism can either make its own food or depend on others to make food for them. For example
green plants produce their own food from a process called photosynthesis. They use the chloroplasts in
their cells to capture energy in sunlight. They combine it with water and carbon dioxide from the air to
produce sugars for themselves.
Other organisms eat green plants (which has a store of the energy they produce) to obtain energy. Rabbits
and sheep are examples of consumers. Herbivores, carnivores and omnivores are all consumers, and they
all have to go find food to give them energy.
3. How do most plants get their food?
a. They absorb it from the water they drink
b. When the chloroplast turns sunlight into energy
c. By breathing through their stomata
d. Capturing birds and insects in their leaves
Living things grow and develop
Every living organism begins life as a single cell. Unicellular organisms may stay as one cell but they grow
too. Multicellular organisms add more and more cells to form more tissues and organs as they grow.
Growth and development of living organisms are not the same things. Growth is the increase in size and
weight of that organism. Development involves transformation of the organism as it goes through the
growth process.
Think of a newly born baby. It has all the features of a fully-grown adult, but they are very tiny. As the
years go by, they become big and become a young person like you, and later on, into a fully grown adult,
maintaining all the features that they are born with. This
is growth.
In some organisms, growing involves drastic
transformation. Think of a butterfly for instance. It starts
off as a cell (egg). Then it transforms into a caterpillar,
then into a pupa (chrysalis), and then pops out as a
beautiful butterfly.
Plants often start from a tiny seed, and grow into a big
tree. One thing common to all organisms is that they grow or develop to look just like their parent species,
even though there may be some slight variations resulting from the mixing of cells by the parents.
Cell growth and development include its repair. As cells grow old, they wear off. Sometimes they suffer
injury and bruises, but they are able to repair themselves by growing new cells in a process called Mitosis.
Living things reproduce
Reproduction is the process where new organisms (offspring) are generated. A living organism does not
need reproduction to survive, but as a species, they need that to ensure that they are not extinct.
There are two main types of reproduction: these include sexual reproduction and asexual reproduction.
Something we will be talking about soon.
4. What are the stages of the cell cycle?
_____________ _____________ _____________ _____________ _____________ ____________
Living things respond to their environment
Response to stimuli is an important characteristic of life. Anything that causes a living organism to react is
called a stimulus (plural is stimuli) Stimuli can be external or internal.
For instance, if you feel like going to the bathroom, it is an internal stimulus that is controlled by the brain.
If the sun comes up on a warm day, it is an external stimulus that can cause a snake to come out and busk.
The ability of the organism to react is called ‘irritability’
It helps the organism to stay in balance. Living organisms have some senses (sight, smell, touch, taste, etc)
that help them to detect changes in their external environment, as well their internal balance and respond
to them. Some organisms (such as herbivores) respond to stimuli much quicker than others (such as
plants).
Living things adapt to their environment
Adaptation is where living things change to survive, This is different than responding but the change
happens over a long time. In many cases, it can take thousands of years before the change takes place.
When living things adapt they do so to improve their chance for survival. The offspring that survive get to
carry on the species providing new young that have the similar traits to their parents. Here are a couple
examples of adaptations.
5. Which of the following letters are adaptations?: __________________________________________
6. Which of the following letters are responses?: __________________________________________
Choices:
a. Bats hear by sound (echolocation). They send out a sound that bounces off an insect and back to their
ears. This change didn’t happen overnight though. It took place a long time ago.
b. The mailman walked by the front door and the dog started barking.
c. Owls have very wide eyes that aid in the search for food at all hours of the day and night. This change
took place over many generations allowing them to more easily find food.
d. A long time ago, frogs developed the ability to breathe through their skin allowing them to stay under
water longer to avoid predators.
e. The house was warm so we turned on the air conditioning.
f. I was hungry so I ate my lunch.
g. The boo jam tree in Mexico doesn’t grow leaves during the dry season. This change took place over a
long period of time as the trees that did grow leaves in the dry summer months died off while those
that didn’t grow leaves lived.
h. Mr. DelliGatti told a joke that made me laugh so hard I snorted milk out of my nose.
i. The katydid from Costa Rica looks just like a leaf to its predators. Over millions of years the color and
shape has changed to look just like a green leaf. This change allowed the katydid to avoid predators.
j. I touched a hot pan that made me jerk my hand away quickly.
Directions: Identify which characteristic of living things is being described in each of the statements below.
Some may be used more than once!
A.
B.
C.
D.
E.
F.
All living things contain cells.
All living things obtain and use energy.
All living things reproduce.
All living things respond.
All living things grow and develop.
All living things adapt.
_____ 1.
_____ 2.
_____ 16.
An amoeba is a unicellular organism.
When a human steps out into the cold air, the body begins to shiver in order to keep its
temperature at 98.6 degrees Fahrenheit.
Green plants produce their own food through the process of photosynthesis.
An adult hydra is producing its offspring through budding.
The roots of a plant grow towards a source of ground water.
Over three years, Tim's height has increased from 5'4" to 5'11".
A pill bug eats a carrot.
A baby songbird hatches from its egg with both parent songbirds watching.
A tulip opens up in the morning at sunrise and closes up in the evening at sunset.
Identical twins have 99.999% of the same genes.
A caterpillar hibernates in a cocoon, and emerges as a butterfly.
It is thought that humans and chimpanzees once shared a common ancestor.
A beaver is an organism composed of many different types of cells.
A sea worm drops its tail and the tail becomes a new worm.
As a sea worm is placed in fresh water, the pulse slows down in order for the worm to
conserve energy.
That boy shot up five inches in only one year.
_____ 17.
Our cat had a litter of kittens yesterday.
_____ 18.
My dog has become much less clumsy now that he is a year old
_____ 19.
Eat a good breakfast and you will be able to run longer.
_____ 20.
When that car pulled in the driveway, my cat ran to hide under the porch.
_____ 3.
_____ 4.
_____ 5.
_____ 6.
_____ 7.
_____ 8.
_____ 9.
_____ 10.
_____ 11.
_____ 12.
_____ 13.
_____ 14.
_____ 15.