Edexcel Year 10 Biology
The variety of life
Lesson 2 Levels of Organisation
Levels of organisation
Syllabus extract
Students will be assessed on their ability to:
• 2.1 describe the levels of organisation within
organisms: organelles, cells, tissues, organs
and systems.
Levels of organisation
Learning Objective:
In order to be successful in this lesson you must be able to:
Explain how organisms are
organised giving explanations of
both the nervous system and the
circulatory system.
Levels of organisation in an organism
• Inside of every organism is a precise
arrangement of structures which work
together to facilitate the functioning of
the particular organism.
• These systems begin with the smallest
structures, called cell organelles.
Objective: to order the levels of organisation in an organism
Order the words below. Have the smallest
on the bottom and work up to the largest.
Organelle
Organ system
Organ
Cell
Organism
Tissue
Now draw a pyramid shape in your workbook (with 6
lines ) and write them in order.
Objective: to order the levels of organisation in an organism
Organism
Organ
system
Organ
Tissue
Cell
Organelle
Cell Organelles
These are found within cells and allow cells to
carry out their functions.
• Nucleus: Control centre of the cell, the
genes decide which proteins the cell makes.
• Cell membrane: allows certain substances
to pass through into the cell.
• Mitochondria: carry out respiration and
provide the cell with energy.
• Cell wall: allows the cell to keep its shape
• Vacuole: storage area for sugars and other
minerals.
• Chloroplasts: contain chlorophyll which
converts sunlight into sugars for food.
The levels of organisation within organisms
The basic building blocks of life
Cells
Cells make up the next level of organisation.
The two main types of cell are plant and animal.
Tissues
Cells which all have a similar function
are grouped together to form tissues,
e.g. muscles are made up of a group of
muscle cells, all specialised to work
together to produce a particular
function. This group of cells forms
muscle tissue.
Examples of animal tissues include:
• muscular tissue, which can contract to bring about
movement
• glandular tissue, which can produce substances such
as enzymes and hormones
• epithelial tissue, which covers some parts of the
body.
Examples of plant tissues include:
• epidermal tissues, which cover the plant
• palisade mesophyll, which carries out
photosynthesis
• spongy mesophyll, which has air spaces to
facilitate diffusion of gases
• xylem and phloem, which transport
substances around the plant.
Organs
A group of tissues all working
together form an organ.
An organ is made of a group of
tissues all working together to
perform a specific function.
Examples of organs include:
heart, lungs, liver and brain.
Plant organs include stems,
roots and leaves.
Example of an animal organ
An example of an animal organ is the stomach,
which contains the tissues:
• muscular tissue, to allow contents to move
through the digestive system
• glandular tissue, to produce digestive juices
• epithelial tissue, to cover the outside and the
inside of the stomach.
These tissues all work together to function as
the stomach.
Organ Systems
The final level of organisation is an organ system.
This is a group of organs that work together to perform a job.
For example: the stomach and intestines are part of the digestive
system.
The heart and lungs are part of the cardiovascular system.
We have lots of different Organ
Systems. Can you name these?
These are just examples of a few but together all of
the organ systems make an organism like you!
OR
Use the computers and the guided worksheet to
produce a presentation showing the levels of
organisation in humans.
Use the circulatory system or the nervous
system as your examples.
Objective: To explain the levels of organisation
True or false
Tissues are made from only one type of cell.
Lots of organ systems work together to make an
organism.
An organelle is bigger than an organ
The circulatory system carries electrical messages
around the body
The spinal cord and brain are organs in the Nervous
system
Learning Objective:
In order to be successful in this lesson you must be able to:
Explain how organisms are
organised giving explanations of
both the nervous system and the
circulatory system.