Characteristics of Living and Non-Living Things
When you look around you would see a variety of objects. These objects or things are all quite unique in their own ways. A closer look at each of these things however would show that they can be broadly classified or grouped into two categories — the non- living and living things by their ability to carry out Junctions known as life processes. These functions or
All living things have the ability to change their positions. In most plants, such movement is limited; involving only bending movement as in shoots or opening and closing ‘of petals. In most animals, it involves movement from one position to the other—that is transitional motion requiring locomotory organs like fins, wings, legs or other sinapler appendage like flagella or tentacles.
Living things require energy, which they can only obtain from the food they eat or synthesise. They can only do this by, carrying out respiration, during which the energy fled up in the food/nutrient stored in the cell is oxidised to release energy in the form of Adenosine Triphosphate (ATP).
Organisms that do this using oxygen are said to be aerobic and, have special organs for oxygen uptake, such as gills in fish, trachea in insect, lungs in man and the stomata in plants. Simple organisms obtain oxygen from their environment simply by diffusion of the oxygen into their cells, e.g. Spirogyra, Amoeba, Paramecium etc.
All living things require food. They need food in order to obtain energy and build, up their body parts during growth replace old or damaged ones. Plains generally manufacture their own food through a process known as photosynthesis, which they are able to do because of the pigment chlorophyll which they possess. The energy for this process is derived from sunlight. Lower plants such as cyanobacteria and algae belong to this category
Animals on the other hand, have to take their food in ready-made form from other living things, mainly plants arid other animals. Some bacteria and all fungi also fall into this category.
Irritability: Irritability, which is the ability to respond to external stimulus, is another distinguishing characteristic of living things. In higher animals these occur in the form of sensory responses. For example, the quick removal of the hand on touching a hot object.
Microscopic animals like Amoeba and paramecium also respond similarly. In plants such responses are usually not as rapid or sudden. They respond more slowly to stimuli such as heat, light, and gravity, irritable or favourable chemicals in various ways and touch e.g. Mimosa plant.
Growth: All living things have the ability to increase in size or mass. Such increase in cell material is known as growth. Growth in microscopic or unicellular organism is usually reflected in cell division after attaining a particular size. But in higher such as including plants and animals, it is accompanied by increasing complexity and differentiation of cells and tissues for various functions.
Excretion: living things do not make use of all nutrients they absorb. Also when energy is obtained by break down of the nutrient, waste is generated. Excretion is the means by which such waste product and excess nutrient are removed from the cells or body of the living thing. In higher organisms such lizard, bird, man etc.
There are special excretory organs that are used for this purpose e.g. skin, kidney and anus etc. In lower animals like Paramecium or Amoeba contractile vacuole is used while in even lower forms like the bacteria, excretion occurs by diffusion across the cell envelope surface.
It is in this system carbon dioxide and nitrogenous wastes 1mm protein breakdown are expelled in such organisms.
Reproduction: This is one of the most fundamental characteristics of living things. All living things have the ability to produce offspring or young ones with similar characteristics to the parents. Without reproduction there cannot be continuity of the species. Reproduction is sexual when it involves fusion or interaction between two sexual forms and asexual when only one sexual form is involved.
Method of feeding:
Animals are different from plants nutritionally because animals require their food in ready- made forms. They are said to be hetetroprophic or holozoic. They cannot manufacture their food as they lack the photosynthetic pigment called Chlorophyll for trapping sunlight.
Because they use ready-made food which they have to digest, they have well developed digestive systems where digestion and absorption take place.
Plants on the other hand are able to carry out photosynthesis because they possess the green pigment called chlorophyll. They are said to carry out autotrophic nutrition and are called autotrophs.
The energy trapped from the sun is used to fix or convert carbon dioxide to sugar which can now be further converted to other forms of food and cell materials through enzyme catalysed reactions in the cell (metabolic process).
Higher animals often carry out extensive movement. They do this mainly because they have to move to where they can get food. Thus, they have well developed organs or appendages of locomotion, plants on the other hand are often sedentary, rooted to a spot and carrying out only limited movements, because their nutritional need such as carbon dioxide, minerals and water can be obtained from their immediate environment, in air, soil or water.
In terms of respiration, plants have a very simple mechanism involving exchange of gases (CO2 and O2) though stomata and lenticels all over the whole of their body surface. Apart from expelling carbon dioxide, they also absorb it during photosynthesis.
Animals on the other hand have special respiratory organs (e.g. gills and lungs) for respiration.
The main strengthening component in plants is found in the life unit
– the cell; plant cells have cell walls made of cellulose which is a carbohydrate. Animals do not have cellulose cell walls. They only have the cell membrane. Rigidity and mechanical support is achieved in animals by possession of exoskeletons or endoskeletons.
Growth in plant is limited to mainly the apical regions, the tips of the root and shoots whereas in animals it occurs evenly in all parts of the body. Plants, however, tend to grow endlessly while animals’ growth stops after attaining a particular size. Plants do not grow throughout their life time and have only fixed numbers of organs.
Excess food is stored in plant, mainly in the form of starch and lipids. Animals on the other hand use glycogen as the main storage material.
Animals produce large amount of waste products because of their heterotrophic mode of nutrition and high level of activity. Hence they have complex organs for excretion and excrete on a regular basis. Plants are less active and produce fewer waste products since they manufacture what they need and are able to effectively store the excess.
The little waste they produce is usually stored up in cells and tissue as harmless solid and liquid compound and the gaseous forms are expelled by diffusion.
Animals responds to stimuli almost immediately after the application of even very brief stimulus. Plant responses are very slow and then only if the stimulus persists for a relatively long time.
Scroll Down to Select Page 2 for the next lesson – Lesson Two: Organisation of Life
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