Cellular process often occur within distinct cellular regions or compartments. However, they do not occur
independently as one process may regulate another, or provide the components or resources for mechanisms
carried out in distant regions of the cell. Each region, compartment and component functions in concert with each
other to produce cellular machines with highly specialized functions.
Growth refers to a positive change in size, often over a period of time. Growth can occur as a stage of maturation or
a process toward fullness or fulfillment. It can also perpetuate endlessly, for example, as detailed by some theories
of the ultimate fate of the universe.
The quantity can be:
-Physical (e.g., growth in height, growth in an amount of money)
-Abtract (e.g., a system becoming more complex, an organism becoming more mature)
It can also refer to the mode of growth, i.e. numeric models for describing how much a particular quantity grows
Levels of Organization
In unicellular (single-celled) organisms, the single cell performs all life functions. It functions independently.
However, multicellular (many celled) organisms have various levels of organization within them. Individual cells may
perform specific functions and also work together for the good of the entire organism. The cells become dependent
on one another.
Multicellular organisms have the following 5 levels of organization ranging from simplest to most complex:
LEVEL 1 - Cells
Are the basic unit of structure and function in living things.
May serve a specific function within the organism
Examples- blood cells, nerve cells, bone cells, etc.
LEVEL 2 - Tissues
Made up of cells that are similar in structure and function and which work together to perform a
Examples - blood, nervous, bone, etc. Humans have 4 basic tissues: connective, epithelial, muscle, and nerve.
LEVEL 3 - Organs
Made up of tissues that work together to perform a specific activity
Examples - heart, brain, skin, etc.
LEVEL4 - Organ Systems
Groups of two or more tissues that work together to perform a specific function for the organism.
Examples - circulatory system, nervous system, skeletal system, etc.
The Human body has 11 organ systems - circulatory, digestive, endocrine, excretory (urinary),
immune(lymphatic), integumentary, muscular, nervous, reproductive, respiratory, and skeletal.
LEVEL 5 - Organisms
Entire living things that can carry out all basic life processes. Meaning they can take in materials,
release energy from food, release wastes, grow, respond to the environment, and reproduce.
Usually made up of organ systems, but an organism may be made up of only one cell such as bacteria
Examples - bacteria, amoeba, mushroom, sunflower, human
also called green plants (Viridiplantae in Latin), are multicellular eukaryotes of thekingdom Plantae.They form
a clade that includes the flowering plants, conifers and
othergymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Plants exclude
the red and brown algae, the fungi, archaea and bacteria.
Green plants have cell walls with cellulose and characteristically obtain most of their energy
fromsunlight via photosynthesis by primary chloroplasts, derived from endosymbiosis with cyanobacteria. Their
chloroplasts contain chlorophylls a and b which gives them their green color. Some plants areparasitic and have lost
the ability to produce normal amounts of chlorophyll or to photosynthesize. Plants are also characterized by sexual
reproduction, modular and indeterminate growth, and analternation of generations, although asexual reproduction
Animals aremulticellular, eukaryotic organisms of the kingdom Animalia (also called Metazoa).Theirbody
plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in
their lives. Most animals are motile, meaning they can move spontaneously and independently. All animals must
ingest other organisms or their products for sustenance (see Heterotroph).
Most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542
million years ago. Animals are divided into various sub-groups, some of which
are: vertebrates(birds, mammals, amphibians, reptiles, fish); molluscs (clams, oysters, octopuses, squid, snails);arthr
opods (millipedes, centipedes, insects, spiders, scorpions, crabs, lobsters, shrimp); annelids(earthworms, leeches); s
ponges; and jellyfish.
Some fungi, such as Honey Fungus, which is a parasite of woodland trees, have hyphae collected together into long
cables, called rhizomorphs.Becausethere are so many hyphae packed together, they are easily seen, forming black
'bootlaces'.These can spread through a woodland infecting neighboring trees.
The main body of most fungi is made up of fine, branching, usually colourless threads called hyphae.Each fungus
will have vast numbers of these hyphae, all intertwining to make up a tangled web called the mycelium.
The mycelium is generally too fine to be seen by the naked eye, except where the hyphae are very closely packed
together. The picture on the left was taken through a microscope. The hyphae are magnified 100 times life s
Prokaryotes (pro-KAR-ee-ot-es) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus,
+ suffix -otos, pl. -otes; also spelled "procaryotes") are organisms without a cell nucleus (= karyon), or any other
membrane-bound organelles. Most are unicellular, but some prokaryotes are multicellular.
Eukaryotes (IPA:[juːˈkæɹɪɒt]) are organisms whose cells are organized into complex structures by internal
membranes and a cytoskeleton. The most characteristic membrane bound structure is the nucleus. This feature
gives them their name, (also spelled "eucaryote,") which comes from the Greek ευ, meaning good/true, and
κάρυον, meaning nut, referring to the nucleus. Animals, plants, fungi, and protists are eukaryotes.
Unicellular and Multicellular Organisms
What is organism? Organism is any living thing (plant or animal) that exist in this world. A living thing which can
only be seen under a microscope is called a microorganism. An organism can be unicellular or multicellular.
Unicellular organism is an organism which only has one cell while a multicellular organism is an organism that
made up of more than one cell. Unicellular organism usually quite active and always moving around. They can be
easily found in water such as ponds, lakes, rivers and any moist area.Organisms such
as amoeba, plasmodium, paramecium are unicellular organisms.
Most animals and plants are multicellular organisms. Multicellular organism have different types of cells. Each
type of the cells contribute different functions. In humans, there are trillions of cells group into specialized tissues
and organs. The examples of multicellular microorganisms such as hydra (animal) and spirogyra (plant) have shown
The 7 Characteristics of Life:
1. Living Things are Composed of Cells:
Single-cell organisms have everything they need to be self-sufficient.
In multicellular organisms, specialization increases until some cells do only certain things.
2. Living Things Have Different Levels of
Both molecular and cellular organization.
Living things must be able to organize simple substances into complex ones.
Living things organize cells at several levels:
Tissue - agroup of cells that perform a common function.
Organ - a group of tissues that perform a common function.
Organ system- a group of organs that perform a common function.
Organism - any complete living thing.
3. Living Things Use Energy:
Living things take in energy and use it for maintenance and growth.
4. Living Things Respond To Their Environment:
Living things will make changes in response to a stimulus in their environment.
A behavior is a complex set of responses.
5. Living Things Grow:
Cell division - the orderly formation of new cells.
Cell enlargement - the increase in size of a cell. Cells grow to a certain size and then divide.
An organism gets larger as the number of its cells increases.
6. Living Things Reproduce:
Reproduction is not essential for the survival of individual organisms, but must occur for a species to
All living things reproduce in one of the following ways:
Asexual repoduction - Producing offspring without the use of gametes.
Sexual reproduction - Producing offspring by the joining of sex cells.
7. Living Things Adapt To Their Environment:
Adaptations are traits giving an organism an advantage in a certain environment.
Variation of individuals is important for a healthy species.