Download Organization of life - PBS Science Grade 7

Organization of life
Aseel Samaro
Cells: Starting out small
Most cells are too small to be seen without a microscope.
Do you know what is the world’s largest cell ?
Cells
 The first cell of a chicken is yellow with a tiny white dot
in it
 It is surrounded by clear, jellylike fluid called egg white
 The white dots divides over and over again to from a
chick.
 The yellow yolk (from the first cell) and the egg white
provides nutrients for the developing chick’s cell
Cells
 Not all your cells look or act the same.
 We have about 200 different kinds of cells
 Each type is specialized to do a particular job
Bone cells
Blood cells
Skin cells
Tissues: Cells working in Teams
 Cells are grouped together to make a tissue that has
function.
 A group of cells of the same type which are performing
the same function is called ________
 An example of tissue is muscle, which contracts to allow
movement of the body
 Different types of tissues work together to form an organ
Tissues: Cells working in Teams
Organs: Teams working together
 When two or more tissues work together to do a specific job, the group of tissues
is called an ________
 Organs are made from different tissues which are coordinated to work together.
 Some examples of organs:
Stomach
Heart
Lung
 A leaf is a plant organ
What is the largest organ in the
human being?
Organ System: a Great combination
 Organs work together as organ systems.
 Each system has a specific job to do in the body
 The digestive system which enables to breakdown food into very small particles is
made up of many different organs such as:
Pancreas
Stomach
Liver
 Each organ in the digestive system has a job to do.
 A particular organ is able to do its job because of the different tissue within it.
Organ System: a Great combination
 The organs in an organ system depend on each other.
 If any part of the system fails, the whole system is affected
 Failure of one organ system can affect other organ systems.
Think of what would happen if your
digestive system stopped
converting food to energy
Organism: Independent Living
 Anything that can live on its own is called an organism.
 All organism are made up of a least one cell.
 If a single cell is living on it own it is called unicellular
YOU ARE A MULTICELLULAR ORGANISM
Time For Some Activities (10 Minutes)
Write the following heading on the top of their notebooks
and list two examples of each heading
Cell
Tissue
Organ
Organ system
Give more examples about organ systems
What are these organ system made of ?
Respiratory system
 It is a biological system consisting of
specific organs and structures used for the
process of respiration in an organism.
 The respiratory system is involved in the
intake and exchange of oxygen and carbon
dioxide between an organism and the
environment.
Digestive system
 It is a group of organs working together to convert food
into energy and basic nutrients to feed the entire body
Nervous system
 It is a complex network of
nerves and cells that carry
messages to and from the
brain and spinal cord to various
parts of the body.
Circulatory system
 The system that moves blood throughout the
body.
 It is responsible for the flow of blood, nutrients,
oxygen and other gases, and hormones to and
from cells
Conclusion
 We can think of a human body as being made up of
different systems.
 Each system has a specific purpose in the body.
E.g: circulatory system that pumps blood around our body