The Levels of Organization is a term used in basic biology

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, anatomy

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

, and physiology

Physiology

Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

. It is used with five basic concepts, the smallest the cell. Many specialized cells make up a tissue, many tissues an organ, many organs an organ system, and finally, many organ systems an organism. In bizarre cases microorganism

Microorganism

A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

s (unicellular) and superorganism

Superorganism

A superorganism is an organism consisting of many organisms. This is usually meant to be a social unit of eusocial animals, where division of labour is highly specialised and where individuals are not able to survive by themselves for extended periods of time. Ants are the best-known example of...

s, only one cell or many organisms may occur within a single species or organism.

Level I(correction): Chemical

Level I: Cells

Cells

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

 are the basic building blocks(basic unit)of life and performs vital functions in an organism, stated in Cell Theory.

Level II: Tissues

Tissue

Tissue (biology)

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

, the second level of organization. It is created by joining cells that have similar function or structure.

Level III: Organs

An organ

Organ (anatomy)

In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...

 is a group of tissues that perform a specific function or groups of functions. This is the third level of organization.

Level IV: Organ Systems

An organ system is a collection of organs that perform a specific function- the circulatory system or digestive system for example. Several organ systems are present in humans and other creatures have different kinds of systems. Plants have vascular systems and shark

Shark

Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s have a kind of "electromagnetic

Electromagnetism

Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 system". An organ system cannot live by itself and is dependent on other organ systems to form an organism. Here is a list of human organ systems and the organs they are made up of:

• Circulatory system
  Circulatory system
  The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
  
  : the heart, blood, and blood vessels
• Digestive system: the salivary glands, esophagus, stomach, liver, gallbladder, pancreas, intestines, rectum, and anus
• Endocrine system
  Endocrine system
  In physiology, the endocrine system is a system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. It derives from the Greek words "endo"...
  
  : the hypothalamus, pituitary gland, pineal body, thyroid, parathyroids, and adrenals
• Integumentary system
  Integumentary system
  The integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages...
  
  : the skin, hair, and nails
• Lymphatic system
  Lymphatic system
  The lymphoid system is the part of the immune system comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally toward the heart. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated...
  
  : the leukocytes, tonsils, adenoids, thymus, and spleen
• Muscular system
  Muscular system
  The muscular system is the anatomical system of a species that allows it to move. The muscular system in vertebrates is controlled through the nervous system, although some muscles can be completely autonomous.- Muscles :...
  
  : the muscles
• Nervous system
  Nervous system
  The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
  
  : the nerves, brain, spinal cord, and peripheral nerves
• Reproductive system
  Reproductive system
  The reproductive system or genital system is a system of organs within an organism which work together for the purpose of reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. Unlike most organ systems, the sexes...
  
  : the ovaries, fallopian tubes, uterus, vagina, mammary glands, testes, vas deferens, seminal vesicles, prostate, and penis
• Respiratory system
  Respiratory system
  The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...
  
  : the pharynx, larynx, trachea, bronchi, lungs, and diaphragm
• Skeletal system: the bones, cartilage, ligaments, and tendons
• Urinary system
  Urinary system
  The urinary system is the organ system that produces, stores, and eliminates urine. In humans it includes two kidneys, two ureters, the bladder and the urethra.-Kidney:...
  
  : the kidneys, ureters, bladder, and urethra

Organ systems may be closely intertwined and called things like the musculoskeletal system

Musculoskeletal system

A musculoskeletal system is an organ system that gives animals the ability to move using the muscular and skeletal systems...

 or neuroendocrine system.

Level V: Organisms

An organism is a being thats able to perform simple acts of survival. We humans are one for example. This is the fifth and last level of organization.

Level VI: Population

A Population consist of all the organisms that both belong to the same species and live in the same geographical area

Level VII: Community

A Community is a group of interacting living organisms sharing a populated environment.
See also
Cell Theory
Oraganelles
Diffusion/Osmosis
Active transport
DNA/RNA
Selectively Permeable
Basic functions of a organism/organ system/organ/tissues/cells