Chapter 14
Organization of Multicellular Organisms
Organization of Multicellular Organisms
• All organisms are systems, with parts that work
together to help them live, grow, and reproduce.
• The parts of a multicellular organism can be
examined at different levels.
Cells and Tissues
• The basic unit of life
is the cell.
• Cells are tiny
structures
composed of
organelles and
membranes that
carry out life
processes.
Cells and Tissues
• In multicellular
organisms,
different cells
perform different
functions.
• Examples:
• Red Blood Cells: deliver oxygen
• Nerve Cells: send electrical
impulses
Cells and Tissues
• Cells form tissues – a group of similar cells that share
structure and function.
• For example: heart cells make up heart tissues.
Organs
• Within a multicellular organism,
different types of tissues can form an
organ.
• Example: stomach
• Function: digest or breaks down food
• Tissues:
• Muscle – Mix food
• Epithelial – Secrete gastric juices
• Nervous – Communicates to rest of body
• Circulatory – brings oxygen and carries
away waste
• Connective – hold other tissues together.
Organs Systems
• Organs for organ
systems.
• Organ systems – group
of related organs that
work together to do a
particular function.
• In complex, multicellular
organisms, organ
systems function to meet
the needs of cells
throughout the body.
Structure and Function in Plants
• The structures of plant
cells, tissues, and organs
help them to carry out
their specific functions.
• Plant vascular tissues are
made of differentiated
cells that stack together
to form tube-like
structures.
• Vascular tissues allows
plants to transport food,
water, and minerals through
out the plant body.
• Without vascular systems to
transport material, plants
would grow no taller than
mosses.
Structure and
Function in Plants
Structure and Function in Plants
• In a plant leaf, the inner
mesophyll cells carry out
photosynthesis.
• Photosynthesis is the process
of using the energy from
sunlight to convert water and
carbon dioxide to glucose and
oxygen.
Structure and Function in Plants
• The upper layer of the leaf is
transparent, so light can pass
through them to the cells
beneath.
• The wax cuticle keeps water
in the leaf.
Structure and Function in Plants
• The underside of a leaf
contains stomata, openings
that allow water vapor and
other gases in and out of the
plant.
• Guard cells on either side of
the stomata regulate the size
of the opening.
Guard Cells