BIOLOGY What exactly is biology anyway?
Biology has to do with.. Living things, of course!! Don t forget things that are not alive (nonliving)! What about things too small to see (microscopic)? And how about the major processes that tie all of these things together (biological cycles)?
The word biology comes from two greek words put together. bios meaning life logos meaning thought or study of Biology is the branch of science that deals with the study of living things. This also must include how these living things interact with the non-living world around them.
The age-old question: What is the meaning of life? How do we know if something is alive or not alive? What does it actually do to be alive? Consider the following
Is there a difference between these two pictures in the quality of life?? Obviously!
Take this plant, squirrel and rock for example. Why is the plant and squirrel alive and the rock is not? Specifically what can the plant and squirrel do that the rock cannot?
Characteristics of all living things Each individual living thing is called an organism. All organisms have the following characteristics: The need for energy. Limited life span. Highly organized and contains complex chemical substances. Growth. Reproduction. Will respond to changes in the environment. Ability to change and adapt to surroundings.
1) The need for energy All living things need energy. Anything that is alive requires a continuous supply of energy to support their bodily functions. Almost all the energy used by a living thing comes from the sun.
Plants store the energy from the sun as glucose (sugar) in their leaves in a process called photosynthesis. The plant uses this sugar as food to support the rest of its functions.
Animals receive their energy from the foods they eat. During digestion, the food is broken down into glucose (sugar) which is stored in the cells of the body and is burned when needed to fuel activities.
2) Limited Life Span If something is alive it will eventually die. The life span of organisms can vary greatly. Example: The mayfly lives for only a few hours to a few days, whereas the giant tortoise lives for about 177 years (in captivity)
3) Highly Organized and Contain Complex Chemical Substances All living things are made up of one or more cells. The cell is the smallest, most basic unit in which substances are organized to produce a living thing.
The presence of cells does not guarantee life exists. After the death of an animal, the cells are present but are not functioning so it is not alive. But the presence of cells does show that life did exist at one point in time.
Living cells contain a complex mixture of substances called protoplasm. All of the components that make up protoplasm are not alive by themselves, yet the cell has the ability to organize all parts of the protoplasm to be alive. Since living things have the ability to organize substances they are called organisms.
4) Growth All living things grow at some point in their lifetime but each species grows at different rates. Bacteria have a very small growth in size. Some trees species can grow very large in size.
Non-living things can also appear to grow. Salt or sugar crystals in an evaporating dish Icicles on the roof in winter One important difference between growth of living things from non-living is how the growth happens. Living things grow from the inside out Non-living things grow by adding more to the outside (like snowmen!)
Growth Continued Maintenance and repair is a type of growth where the organism does not necessarily grow any larger but must constantly maintain and repair the materials of which they are made. Shedding of skin cells Cut on finger Salamander s tail
5) Reproduction Living things can produce offspring similar to themselves. (Biogenesis) Since the lifespan of a living thing is short, they go through phases: growth maturity reproduction latency death. They must be able to create new life to replace them when they are gone.
6) Response to stimuli All living things respond to stimuli, or changes in their environment/ surroundings. A stimulus can be sound, touch, heat, light, moisture etc.. Which causes a response from a living thing. A living thing s response to a stimulus is called irritability. Obtain food (animals, carnivorous plants) Avoid predators (animals) Turn towards light (plants) Gravity (plant root growth)
7) Variation and adaptation In addition to irritability (short term response to a stimulus), living things respond to long term changes over many years. Organisms may be poorly suited to surviving changes in soil type, moisture, temperature so they change to become better at surviving in the new conditions. These changes are a result of variation.
The differences between parents and offspring are the result of variation. Some variations do not affect the survival of an organism or species. Where the difference or variation is crucial to the survival of the organism, the change is called an adaptation.