Life Science

1. Levels or Organization

2. Key Concept
 As multicellular organisms develop, their
cells differentiate (change & separate) to
form different levels of organization

3. Key Concept
 Why it Matters: so
organisms like humans
(we are multicellular) can
have different kinds of
cells, tissues, organs, and
organ systems

4. Unicellular Organisms
 “uni-” = one
 Prokaryotes are unicellular organisms
 Some algae, some protists, and some
eukaryotes (yeasts), are unicellular
 Can individually do everything they need to
stay alive

6.  Benefits over multicellular organisms:
 Need fewer resources
 Can live in harsher conditions

7. Multicellular Organisms
 “multi-” = more than one
 Plants, animals, some protists, and most fungi
are multicellular

8. Multicellular Organisms
 Start as a single cell  many cells  cells
differentiate (change) into different types of
cells  cells group together to form tissues

9. Multicellular Benefits
 Larger size = have less predators and have more
options of things to eat

10. Multicellular Benefits
 Longer life – organism will continue to live even if
a single cell dies

11. Multicellular Benefits
 Specialization – each type of cell has a specific
job, making the organism more efficient

12. Levels of Organization
 1st Level: Cells

13. Levels of Organization
 1st Level: Cells
 2nd Level: Tissues
example
muscle tissue

14. Levels of Organization
 1st Level: Cells
 2nd Level: Tissues
 3rd Level: Organs

15. Levels of Organization
 1st Level: Cells
 2nd Level: Tissues
 3rd Level: Organs
 4th Level: Organ Systems
 Cells  Tissues  Organs  Organ Systems

16. Level 1 : Cells
 Cells can be specialized (have
a certain function)
 Function = job
 Function is related to the cell
structure
 Structure = how parts of the
cell are put together
 Shape
 Material it’s made from
 Structure of a brain cell is
different from muscle cell

17. Level 2: Tissues
 Tissue = group of cells that work together to do a
specific job
 Ex: Heart muscle tissue
is made of heart muscle
cells
 Animals have 4 types of
tissue: nerve, muscle,
connective, protective
 Plants have 3 types of
tissue : transport, protective, ground

18. Level 3: Organs
 Organ = structure that is made up of 2 or more
tissues working together to get a specific job done

19. Level 3: Organs
 Ex: Stomach – muscle tissue moves food,
special tissues make chemicals to digest food,
connective tissue holds stomach together,
nervous tissue sends messages back and forth
between the stomach and brain

20. Level 4: Organ Systems
 Organ system = group of organs working
together to perform a specific function
 Each organ system has a specific job
 Ex: Digestive system is made of several organs
including the stomach and intestines

21. Cells
-basic unit of an animal’s structure
-become specialized
Tissues
-made of cells that work together to perform a specific function
Organs
-made of different types of tissues that work together to perform a specific function
Organ Systems
-made of organs that work together to perform a specific function
Organisms