Levels of organization

The order of life becomes complicated and organized as the order goes up the ladder (in other words, increased).

The first step are subatomic particles. These particles include: electrons, protons, etc.


The next step are atoms. Subatomic particles forms and organizes in mass to become atoms.


Next up, we have molecules. Vast amount of numbers of atoms will form to become molecules. Examples of molecules include: DNA, water, carbon dioxide, etc.


Then, we have organelles. Organelles are subunits within a cell (the next level) that has a specific function within the cell. Examples of organelles include: nucleus, ribosome, mitochondria, etc.

Pictured: Chloroplast

This next step is quite a crucial step of life. This step is the cell. This is such an important step because the cell is the functional basic unit of life.


Then, groups of cells form tissues. Tissues are basically a group of cells that serve a similar function.


The next step is organ. Groups of tissues work together to function as an organ.


After organs, the next step is the organ system. Groups of organs work together to perform a certain task, which makes up the organ system.


The next step is organism. This step refers to a single organism, which can include any living organism from a plant to an animal.


The next step is population. This step includes a group of organisms living in an area from the same species. This group of organisms have a similar niche.


Then, the next step is community. This particular step refers to a group of organisms from different species living in the same area. These different species interact with each other and more niches are filled by these different groups of organisms.


Next, we have ecosystem. The ecosystem includes a group of organisms from different species living in the same area interacting with each other as well as the non-living surrounding. The non-living surroundings are called abiotic factors, which can include anything such as: light, temperature, water, etc.


The next step is biome. This step merely refers to the many biomes in the world (e.g. desert, tropical rainforest, tundra, etc.).


Finally, the last step in the level of organization is biosphere.This step is the largest level and includes all the ecosystems of earth.

The levels of organization is important because it is everything that makes up life. Every step is important and without any one of the steps, the organization would simply not function. The level of organization is much like a chain. If there is a missing link in any part of the chain, life as we know it now would not be the same and simply put, would not work. For example, without something as important as cells, the bigger steps above, such as: organs, organisms, etc. would not be made and would not function at all.

Structure is related to function

This means that organisms' physical attributes and developments are actually tied to what they do to survive within their environment. Physical attributes and structure are not there by random chance, serving no purpose. They are there to serve a specific function for the organism for better survival.

The pelvis is shaped this way so that it holds the organ system.

Ostriches have strong legs (structure) used for faster running (function)

This concept is extremely important to understand. There is a need to understand that every structure has a purpose. The idea that everything is made with a specific purpose and not just randomly is crucial to comprehend because it explains that everything is made with a purpose in mind, that everything has been planned out to be made and will assist in survival.

Adaptation and Evolution

The changes in an organism's external (structure), internal (physiological), and behavioral traits is based on their environment. These changes are made so that the organism can survive and evolve (DNA plays a big role here as well). As an organism lives in an environment, it will slowly start to adapt to the environment to better ensure survival. This change does not happen overnight, in a year, or in several years. However, it takes several generations for these changes to occur and changes take place gradually.

Rabbit in the summer (brown fur)
Rabbit in the winter (white fur)

A bear hibernating

Adaptation and evolution is also a crucial process to life. Without adaptation, organisms would never be able to survive in an environment. Humans have adapted to the earth's harsh environments and have evolved to who we are today. Without the concept of adaptation, humans would have not lasted on the earth for this long.

Continuity of life

The products of reproduction from a parent(s) are mostly similar to the original due to hereditary traits (DNA codes copied and passed down to off-springs after mitosis/meiosis). Life is continued through the process of reproduction (an important characteristic of living organisms) either asexually or sexually. In asexual reproduction, the parent makes an exact clone of itself as an offspring. However, in sexual reproduction, the offspring receives traits from both parents and therefore, their genetic information and traits are passed down from generation to generation.

A male and a female bird
The offspring

Without the continuity of life, there would be no future generations. There will be no future for the population of that organism and would therefore result in extinction.


Homeostasis is basically the ability that every organisms have in order to keep their temperature and functions inside their body constant under any kind of environmental or external disturbances.

Goosebumps help keep the internal temperature steady from externally cold temperature
Sweat helps keep the internal temperature cool from the externally hot temperature

Homeostasis is also extremely important to life. Without it, our internal conditions will be affected harshly with any kind of extreme weather (either cold or hot) and we would therefore, not be able to survive.

Life forms are interconnected

Just like life forms have levels of organizations, there are food chains that explain how one organism affects the other and vice-versa.


All life forms are connected. There is a way a life form contributes to its community and environment one way or another. As much as they affect the environment, there are other organisms that they depend on, and those organisms depend on other organisms, and so on. Without an organism, the organism that depends on that specific organism will die out and cause a chain reaction in the food web. If they don't die out, they will seek other organisms to depend on, but will eventually affect other organisms that depend on those organisms as well. Therefore, all life forms are interconnected and in ways, all interdependent on each other.

Unity and diversity

Although many organisms differ from each other in many ways (e.g. appearance), they may actually be very similar to each other. In other words, we should not judge a book by its cover. DNA is a popular example of how all organisms are similar. While different organisms have different roles, live in different areas, look different, they may be quite similar in different ways. For example, eagles and sparrows are completely different in terms of size and what they do in the ecosystem. However, much like all birds, they have wings, can fly, have talons, etc.

It is important to acknowledge that all, or most organisms share a common characteristic, so that we can understand that we are not much different from other animals and though we may be different in numerous ways, we are all connected with similarities that is just not obvious at times.

Terms to define

Evolution: The changes of traits and behaviours of organisms from their ancestors to the present and later on, to their future. This depends on the environment as well.

E.g. If a bird lives: - In a dangerous area = - Still flies
- Have cautious behaviour.
- In a safe area = - May forget how to fly
- Develops strong legs
- Wings become shorter or non-existent.

Community: Groups of organisms that differ from each other living in the same area (see: levels of organization).

Homeostasis: The physiological ability that an organism has to keep its balance and maintain equilibrium so that it can survive in any conditions. Basically just keeping its internal body balanced depending on the environment.

Population: Group of same type of species living together in one area (see: levels of organization).

Ecosystem: Biotic organisms living together in an abiotic environment filled with abiotic factors. (see: levels of organization).