Characteristics Of Organisms
Published on Dec 07, 2015
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PRESENTATION OUTLINE
DEFINING LIVING
- Is more difficult than you'd think
- Things that are living are called "organisms"
- Scientists have abandoned a definition in favor of a checklist
We all know that we're alive, but when was the last time you considered what that really means? Most of us, if asked, mention things like having a heart beat or breathing as proof that we're living. However, those processes only apply to some organisms. Any definition that we use has to apply to all organisms. Defining "living" is important for our study of agriscience and biotechnology because these sciences deal with the care of organisms. The problem is that if you ask 50 different scientists to define it, you'd get 50 different definitions.
The solution to this dilemma is to come up with a set of characteristics that all living things have in common. If and only if something possesses all of these characteristics can it be called an organism. The characteristics are broad enough to apply to any organism. Let's look at each of the characteristics. . .
The solution to this dilemma is to come up with a set of characteristics that all living things have in common. If and only if something possesses all of these characteristics can it be called an organism. The characteristics are broad enough to apply to any organism. Let's look at each of the characteristics. . .
Photo by Tyler Durdan_
HOMEOSTASIS
- The root word "homo" means "same
- "Stasis" implies that something stays the same.
- The word literally means "same-same"
- It means that organisms maintain an unchanging internal environment
All organisms maintain stable environmental conditions. We keep our body temperatures, blood sugar, and blood volume stable because of our homeostatic mechanism. Examples of this mechanism include shivering when we're cold to generate heat, feeling hungry when our blood sugar drops, and feeling thirsty when our blood volume drops. Even plants and single-cellular organisms maintain water, sugar, and oxygen balance.
Photo by Scott the Hobo
CELLS WITH DNA
- Cells are the building blocks of organisms
- Cells contain DNA
All organisms are composed of one or many cells. Cells are the smallest part of organisms that are still alive themselves. We can take a single cell from an organism and culture it in a lab. The cell will continue to carry out its life processes.
Within each cell is DNA. We typically think of this as the molecule of heredity. While this is true, DNA also carries the instructions for all of the cell's processes. Therefore, the DNA is responsible for the cells life processes.
Within each cell is DNA. We typically think of this as the molecule of heredity. While this is true, DNA also carries the instructions for all of the cell's processes. Therefore, the DNA is responsible for the cells life processes.
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OBTAINING ENERGY
- Organisms need energy to function
- Consumers eat others to get this energy
- Producers do photosynthesis to get energy
Everything that organisms do needs energy. The best source of energy is from carbohydrates. Plants are producers, also called autotrophs, that convert the sun's energy into carbohydrates. Animals are heterotrophs, or producers. They get their carbohydrates by eating plants and other organisms. They can use the carbohydrates stored in other organisms to fuel their bodies.
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ADAPTATION
- Refers to physical and behavioral characteristics
- Adaptations help organisms survive
Environments frequently change. In order to survive these changes, organisms have to be able to adapt. Adaptations are the physical characteristics that make an organism suitable to its environment. They also include the behaviors that organisms exhibit to help them survive.
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EVOLUTION
- This is the result of adaptation
- Produces changes in species
In the long term, adaptation produces changes in species known as evolution. Organisms which exhibit favorable adaptations survive and reproduce more often than others. Since they reproduce more, the genes that produce the favorable adaptations spread through the population, changing the whole species over time.
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REPRODUCTION
- Organisms can make more like themselves
- This can be either sexual or asexual
Most organisms combine their genetic information with the opposite sex during sexual reproduction. This produces a new combination of genes which can produce new adaptations in the resulting offspring.
A few organisms can reproduce without another organism asexually. This produces an offspring that is essentially a clone of the parent.
Reproduction is unique among the characteristics of living things in that it's the only one that isn't required for the individual's survival. However, if the species is to survive, some of the organisms within the species must reproduce.
A few organisms can reproduce without another organism asexually. This produces an offspring that is essentially a clone of the parent.
Reproduction is unique among the characteristics of living things in that it's the only one that isn't required for the individual's survival. However, if the species is to survive, some of the organisms within the species must reproduce.
Photo by VinothChandar
GROWTH AND DEVELOPMENT
- Acquiring adult characteristics
Young organisms are always smaller than the parents. In order to become adults, organisms must grow to adult size. However, getting bigger isn't enough. As young grow, they must also develop. For example, in humans, development involves brain changes as we mature and eventually, the events of puberty. You can think of development as the organism maturing.
Photo by PRAVEEN VENUGOPAL
THAT'S IT!
These are the characteristics that unite all organisms. Remember, in order to be considered living, all of these characteristics must be present. Everything from the smallest bacteria to the largest oak tree, to the family dog has them, and so do you!
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