Multicellular Organisms Unit Six – Organizing Cells.
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Transcript of Multicellular Organisms Unit Six – Organizing Cells.
Multicellular OrganismsUnit Six – Organizing Cells
Multicellular Organisms Multicellular organisms have more cells
(working parts) than unicellular organisms
The Douglas fir tree (shown below) is one of the largest organisms on earth It is 76 metres high and 3 metres in
diameter Consists of many cells which form the
trunk, branches and leaves Together these cells help the tree to
survive
Specialization and Differentiation Multicellular organisms start as a single
cell When the cell divides, the new cells stay
close to one another The number of cells formed determine
the size of the organism As the number of cells increase, each
cell becomes able to perform a specific function within the organism
Specialization and Differentiation How does a town represent the concept
of cell specialization? Mechanic, teacher, doctor, police officer…
Multicellular organisms are specialized to do one job very well
Benefits multicellular organisms – greater efficiency Ex. Heart vs. Digestive System
Cell Differentiation Cell specialization takes place early in
the development of a multicellular organism Each cell changes and develops
characteristics making it unique This process is called cell differentiation
Once a cell differentiates, it performs a specific function Ex. Muscle cells vs. nerve cells
Tissues Differentiated cells are organized according to
the function they perform Tissue refers to a group of cells similar in shape
and function In animals, there are four basic types of tissue:
Epithelial – line cavities and structures in the body like mouth, heart and liver
Muscle – composes muscle in the body Connective – connects, supports and binds tissues
or other organs Nervous – composes the nervous system in the
body
Tissues continued In plants, tissues from thin-walled plant
cells are typically found in the parts of the plant that carries water and nutrients
Tissues in thick walled plant cells are found in the parts of the plant that provide structure
Organs Different tissues join together to form larger structures
such as the skin, stomach and heart These structures are called organs Organs are composed of two or more tissues that work
in unison to perform one of more functions within the organism Ex. Skin is the largest organ in the human body and is
composed of all four of the basic tissue types Skin functions as structural support for the body and acts
as a barrier to protect us internally from the external environment
Animal organs – heart, stomach, brain, lungs, eyes… Plant organs – stems, leaves, flowers, roots…
Organ Systems Organs do not work independently, and two or more
organs working together to perform a related function is known as an organ system Digestive system – mouth, esophagus, stomach, liver,
pancreas, intestines and anus https://www.youtube.com/watch?v=_QYwscALNng
Organ systems frequently overlap and share organs Ex. Circulatory system and respiratory system share the
lungs Interdependent – all organ systems need contact with
the brain Animal organ systems also include the circulatory,
respiratory, musculoskeletal and nervous system
Organ Systems continued Plants have two major organ systems:
Root system – network of roots of the plant
Shoot System – stems, leaves, flowers and buds
Check Your Learning 1. Reconstruct Table One (Organ
Systems in the Human Body) in your notebook
2. Complete questions 2 – 6 on page 151