Multicellular Organisms
Key Area 2.1
Cells, tissues and organs
Cell Specialisations
Learning Intention:
• To learn about multicellular organisms by viewing
cells and tissues using a microscope
Success Criteria:
• Be able to define the term “multicellular
organism”
• Describe the organisation of cells, tissues and
organs in a multicellular organism
Starter Activity
• In your pair, discuss the structures
found in a typical animal cell and their
functions
• Discuss the structures found in a
typical plant cell and their functions
• Name three other types of cell that you
have studied so far
Twig: What is a cell?
Think, Pair, Share
• What is a unicellular organism?
• What is a multicellular organism?
• Give two examples of each
Unicellular organisms
Paramecium
Amoeba
Yeast
Euglena
Bacteria
Multicellular organisms
Multicellular organisms
• Multicellular organisms are made up of
more than one cell.
• These cells can be organised into
tissues and organs.
Twig: Tissues
What do all of these cells have in common?
Cell specialisations
The cells on the previous slide all have
typical structures such as:
–
–
–
–
–
cytoplasm
cell membrane
cell wall
nucleus
chloroplasts
However, the structure each type of
cell is different so that it can carry out
a particular function.
What is a specialised cell?
• Plants and animals consist of many cells and
so are known as multicellular.
• They contain many different types of cell.
• Each type of cell is designed to carry out a
particular job or function.
• This is known as cell specialisation.
Twig: Different types of cell
Did You Know?
• There are over 100 different types of cell
in the human body!
• These are just a few examples………..
Sperm cell
Head contains nucleus
and mitochondria
Tail
Sperm cells swim towards the egg to carry out
fertilisation. They have a tail to enable them to swim
and many mitochondia for producing energy.
Twig: Sperm cell
Egg cell (ovum)
Cytoplasm containing
food store
• Made in the ovaries of
mammals.
• An egg cell is large
compared to sperm.
• Contains a food store in
the cytoplasm for
nourishing the embryo.
Nucleus
Twig: Egg cell
Ciliated cell
• Help to prevent dust and
bacteria entering lungs
nucleus
• Line the windpipe (trachea)
• Have tiny hairs called cilia
cilia
• Cilia sweep mucus with
trapped dust and bacteria
up to mouth to be swallowed
Nerve cell (neurone)
extension of the
cytoplasm (axon)
nucleus
• Longest cells in the body
•Transmit electrical nerve impulses in body
Twig: Nerve cell
Red blood cell
• No nucleus
• Contain haemoglobin to carry oxygen
around the body
• “Biconcave” shape for large surface area
Twig: Blood
Palisade mesophyll cell
• Found in leaves of plants
nucleus
• Packed with chloroplasts
to trap light for
photosynthesis
chloroplasts
Root hair cell
• Root hair
increases surface
area for uptake of
water and
minerals from soil
• Thin cell wall so
water can move in
easily
thin cell wall
root hair
cell membrane
vacuole
Cell Specialisations Task
• Your teacher will
provide a worksheet for
this task
• Use your knowledge of
cells to name each cell in
the worksheet
• Write how the
structure of each cell
allows it to carry out a
particular function
Cell Specialisations Task
• Check your work using
the table opposite
• You may have
remembered additional
information!
Tissues
Learning Intention:
To learn about different tissues in animals
and plants
Success Criteria:
View tissues using a light microscope
Be able to identify and name different
types of tissue
Tissues
1. What are tissues?
2. Can you give some examples of tissues
in the human body?
3. Can you give some examples of tissues
in plants?
4. What is the difference between
tissues and organs?
Tissues
• Tissues are groups of cells that perform
the same function.
• Examples of human tissues include
epithelial tissue and muscle tissue.
• The study of tissue is known as
histology or, in connection with disease,
histopathology.
Tissues
Epithelial tissue
• Epithelial tissue covers body surfaces
and lines cavities and tubes.
• These include the airways and digestive
tract.
• Some epithelial tissue is specialised to
form glands like oil and sweat glands in
the skin.
Muscle tissue
• Muscle tissue helps in body movement
because it can contract and relax.
• There are three different types of
muscle tissue:
- cardiac
- skeletal
- smooth
Smooth muscle tissue
• The structure of these cells allows
them to perform a specific function
• Are spindle shaped
• Can contract and relax
• This allows the cells to slide easily
across one another
Smooth muscle tissue
Plant tissues
• Plants also have different types of cells
that are grouped together into tissues.
• In each case, the structure of each cell
is related to its function.
• Plant tissues include epidermal, palisade
mesophyll and spongy mesophyll.
Epidermal tissue
• Epidermal cells fit together like a
jigsaw
• From Greek word meaning “over-skin”
• Create a strong and protective layer on
the outside of leaves, roots and stems
epidermal
Palisade mesophyll tissue
• These cells have many chloroplasts to
trap light for photosynthesis
• Are column shaped so that they can be
densely packed near the surface of the
leaf
palisade mesophyll
Spongy mesophyll tissue
• These cells have a rounded shape
• This allows them to be loosely arranged
so that they can take up carbon dioxide
by diffusion
• Carbon dioxide can then be used for
photosynthesis
spongy mesophyll
Cross section through a leaf
Histology Task
You are a histologist for the day!
You must…
Use a light microscope to view slides of different tissues.
You should…
Use your knowledge of tissues to name each tissue type: can
you name which part of the organism it comes from?
You could…
Make a pencil drawing of what you see and record how the
structure of each cell type allows it to perform a specific
function: do this for at least four different tissues.
Tissue 1:______
Tissue 3:______
Tissue 2:______
Tissue 4:______
Record your
observations on one
full page in your note
book or on one piece
of A4 paper.
Organs
• A group of tissues working together
form an organ.
• Examples of animal organs include the
heart, lungs, brain and kidneys.
• Examples of plant organs include roots,
stems, flowers, seeds and fruits.
Systems
• A group of related tissues and organs
eg. blood, heart, arteries, capillaries and
veins make up a system.
• The tissues an organs above make up
the circulatory system.
Systems
• Examples or organ systems in animals
include:
• skeletal
• muscular
• digestive
• respiratory
• nervous
• circulatory
Systems
• Examples of organ systems in plants
include the vascular system in the roots
and shoots.
• This includes xylem and phloem. You will
learn about these specialised cells later.
Summary
• Cells have different ___________ that allow
them to carry out a particular__________.
• These are known as cell specialisations.
• Many __________ cells working together
form a __________.
• A group of tissues that work together form
an ___________.
• Organs are found in both _______ and
plants. A group of related tissues and organs
form a __________.
animal
specialised
organ
tissue
structures
function
system
Summary
structures that allow
• Cells have different _________
function
them to carry out a particular__________.
• These are known as cell specialisations.
specialised
• Many __________
cells working together
tissue
form a ______.
• A group of tissues that work together form an
organ
_______.
animal
• Organs are found in both _______
and plants.
• A group of related tissues and organs form a
system
__________.
Key Area 2.1 Consolidation Tasks…
You must complete…
In the back of your notebook: Exercise 1 & 2 from the new unit 2
homework booklet.
Review your KA 2.1 cells, tissue & organs key words.
Review your KA 2.1 cells, tissues & organs learning outcomes.
You should complete…
N5 Text book: Read page 114 – 118
In the back of your notebook: complete Activity 2.1.1 (p116) & Activity
2.1.3 (p118)
You could complete…
On plain A4 paper: Activity 2.1.2 (p116) & Activity 2.1.4 (p118)
Collect 4 study cards and create quiz cards (questions & answers) about
cells, tissues & organs.