Characteristics of Living Organisms

Living Organism Characteristics

All living organisms share common characteristics, including:

• Organisation

The ordered way in which living things are arranged structurally. Cell theory argues that all living things are made of cells. Some living organisms consist of one cell (unicellular) e.g. bacteria and amoeba, others multicellular e.g. humans. All organisms carry out their activities in cells. This gives a structured plan to improve efficiency and increases the likelihood of survival.

• Nutrition/Energy (feeding):

Nutrition is the way organisms obtain and use food. Food is required as a source of materials and energy.  Plants and some bacteria are autotrophic i.e. they make their own food.  Animals, fungi and most bacteria are heterotophic i.e. they need to consume food which is made by plants.

• Excretion:

Excretion is the removal of waste products of metabolism e.g. urea and carbon dioxide from the body.  These waste products can become toxic to the cell if allowed to accumulate.  The organism tries to maintain a stable internal environment (homeostasis).

Plants excrete less because they make their own food and do not produce or take in as much waste (stomata used for waste gases).

Advanced animals transfer waste internally from cells to blood to excretory organs e.g. lungs, skin, urinary system, whilst the liver breaks down toxic material.

• Reproduction:

The formation of new individuals/organisms. Sexual reproduction involves the fusion of gametes whereas asexual involves cell division e.g. budding, binary fission, vegetative propagation.

• Response:

The reaction of organisms to stimuli in their environment. Animals use their muscles and glands to respond to stimuli such as light, temperature, pressure and sound (5 senses).  Animals tend to move to find food mainly and avoid danger.

Movement in plants is less obvious. Plants show growth tropisms e.g. respond to light (e.g. stem bends towards light), water, gravity, chemicals, temperature and touch.