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 Living Things

Classification Needs of Living Things Characteristics of Living Things

Characteristics of Living Things

All living things share six characteristics:

Cell organization

Growth and development

Adapt to environment

Response to environment

Use of Energy 

Reproduction

 

 

 

Cell organization
All organisms are made of one or more  cells. Cells are the basic unit of structure and function. Cells come in different sizes and shapes, yet all cells are microscopic.

This piece of wood is no longer living. How can you tell it was once part of  a living thing?
Answer

Living things are two types: multicellular and unicellular.

Adapt to their environment:
An adaptation : a structure or behavior that allows an organism to live in his environment. e.g. growing claws for protection, teeth for getting food, growing hands and tails for building homes.

Energy
All living things obtain and use energy. Living things get energy from surroundings. Plants get it from sunlight. Animals get it from food they eat.

Reproduction
All organisms reproduce. Reproduction is the production of other organisms like themselves. Reproduction is needed for the survival  necessary for the survival of the group and not for the survival of the individual. It is two types: sexual and asexual.
Sexual reproduction: Two Parents of different sexes: one sperm ( produced by the male) unites with the egg (produced by female) to produce a zygote that develops to adult.


Asexual reproduction: a single parent produces offspring identical to itself. e.g. hydra.

Response to environment
All organisms react to changes in their environment. A change in an organisms surroundings that causes the organism to react is called a stimulus e.g. light, temperature. A response is a change in behavior e.g. a Venus fly trap closing its leaves when a fly sits on it. What is the stimulus in this example? Response? Answer.

Growth and development
Growth is the process of growing larger in size like a small tree turning into a large tree.
Development is the process of changing into a more complex organism
 e.g. a tadpole developing to a frog.

Needs of Living Things

All living things need energy, water, stable internal conditions and a living space.

Energy Stable internal conditions

Water

Living space

 

 

Energy
All living things need energy  to live. Energy is obtained either directly or indirectly. Organisms are two types: 
Autotrophs: are organisms that use the sun's energy to make their food. e.g. plants.
Hetrotrophs: are organisms that can't make the their own food. They get their food from surroundings. e.g. animals, mold..

impalas
                    Autotrophs vs. Heterotrophs.
These impalas get their energy by eating grass.
                    (Plants are  autotrophs). A leopard, in contrast, gets its energy by eating impalas and other animals. Impalas and leopards are both heterotrophs.

Water
Water makes up about 70% (of the body mass) of  most organisms. Organisms need water in metabolic processes like: 
- dissolving  and transporting  substances from one place to another.
- breaking down food
- building body parts
- removing wastes.

Stable internal conditions
External and internal conditions are important to living   things. Most organisms need to live within certain  range of external  conditions (like temperature and pressure). Even though outer conditions might change, living organisms have the ability to maintain stable internal conditions. This is called  homeostasis.

 

Living space
All organisms need a living space, a place to get food, water and shelter. 


    

Classifying Organisms

Taxonomy is the science of classifying living things based on similar characteristics. Scientists use taxonomy to organize living things into groups so that the organisms are easier to study. The modern system of taxonomy has seven major levels of classification:
Kingdom
    Phylum
        Class
            Order
                Family
                    Genus
                        Species
The basis of modern classification was developed by Linnaeus. In this system each organism is given two-part name called the scientific name- its genus and species e.g. Felis domesticus (Felis is the genus and domesticus is the species name)

Accordingly all living things are divided to five kingdoms: Monerans, Protists,  Fungi, Plants and Animals

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