Characteristics of Living Organism
All living organism, whether they are single-celled, many-celled, plants or animals, do the following things :
All living organism need food. Some of this food is used to make new tissue for growth and replacement but most of it is used to provide energy.
Types of nutrition :
a. Autotrophic organism (Autotrophs)
Build up all the organic molecules they need from simple inorganic substances.
Ex : plants in any ecosystem, it is the autothroph which are the producers.
b. Heterotrophic organism (Heterotrophs)
Use ready make organic compounds as their food source. These organic compounds will have been made, originally by autotrophic organisms (mainly plants)
The heterotrophs digest the organic compounds to simpler substances and absorb the products into their bodies.
Animal, fungi, and some bacteria and protists are heterotrophs.
Animal take in food, in the form of complex organic molecules (carbohydrates, lipid, and protein) and digest them to simpler compounds (glucose and amino acid) which can be absorbed.
Fungi and heterotrophic bacteria also digest their food source but do so by a process of external digestion.
These are organisms which feed on dead and decaying matter. Often they release digestive enzymes into their food and absorb the soluble products back into their bodies. Bacteria and fungi are examples of saprotrophs which digest dead wood, rotting vegetation or the humus in the soil.
A parasite is an organism which derives its food from another organism, called the host, while the host is still alive
a) Ectoparasites live, for most of their life cycle, on the surface of their host.
b) Endoparasites live inside the host
A tapeworm is an endoparasite living in the intestine of a vertebrate host and absorbing the host’s digested food
A flea is an ectoparasite which lives in the fur or feathers or mammals or birds and sucks blood from the skin.
An aphid (greenfly) is a parasite on plants and sucks food from the veins in their leaves or stems.
Breathe >> they take in oxygen and give out carbondioxide. This exchange of gases
takes place between the organism an the air or between the organism and
water. The oxygen is used for respiration.
Respire >> They break down food to obtain energy.
Respiration >>The process by which energy is produced from food
>>The chemical process which takes place in cells
1) Aerobic Respiration
Aerobic means that oxygen is needed for this chemical reaction.
The process is called oxidation and the food is said to be oxidized.
The process is :
C6H1206 + 6O2 à 6CO2 + 6H2O + energy
Aerobic respiration takes place in mitochondria. The mitochondria generate a compound called ATP, which is used by the cell as the source of energy for driving other chemical reactions in the cytoplasm and nucleus.
2) Anaerobic Respiration
Anaerobic means in the absence of oxygen.
In this process, energy is still released from food by breaking it down chemically but the reactions do not use oxygen though they do often produce carbondioxide.
Example : Fermentation
C6H1206 -> 2C2H5OH + 2CO2 + energy
Fermentation is the action of yeast on sugar solution to produce alcohol.
3. Grow and Development
Growth è is the process of biological change happening in organism, which is the increment of size
(volume, mass, and height) that has irreversible properties (cannot go back to the initial
Development è is the specialization of cells to be certain structure and function.
The development cannot be measured, but it can be seen from the change of shape and maturity level.
Every living organism produces other organisms, or offspring, of the same kind. This process is called reproduction. Only living organisms can reproduce. Livingthing reproduce in many different ways. However, there are two basic forms of reproduction. Sexual reproduction usually requires two parents. Asexual reproduction requires only one.
5. Respond to stimuli or irritability
All living things react to stimuli. Stimuli are changes in the environment, or surroundings of living organisms. Some common stimuli that affect plants and animals are light and temperature. The action or movement of the organisms caused by the stimulus is called response. The zbility of an organism to respond to a stimuli is called irritability.
Locomotion refers to the movement of an organism from place to place. Movement refers to a change in position of any part of an organism body, but does not necessarily involve locomotion. Chewing, breathing, the heart beat and blinking are all examples of movement in humans.
Many chemical reaction take place inside the cell of an organism in order to keep it alive. Some products of these reactions are poisonous and must be removed from the body. For example, the break down of glucose during respiration produces carbondioxide. This carried away by the blood and removed in the lungs. Excess amino acids are deaminated in the liver to form glycogen and urea. The urea is removed from the tissues by the blood and expelled by kidneys.
Urea and similar waste products, like uric acid from the breakdown of proteins, contain the element nitrogen. For this reason they are often called nitrogenous waste products.
During feeding, more water and salts are taken in with the food than are needed by the body. So these excess substances need to be removed as fast as they build up.The nitrogenous waste products, excess salts and spent hormones are excreted by the kidneys as a watery solution called urine.