Table of Contents
Characteristics Of Living Organisms
Following are the main characteristics of living beings that are not present in non-living organisms.
- Viruses are micro-organisms that are strict or obligate parasites of animals or plant cells. Many of the viruses are also parasites on bacteria.
- A large number of viruses cause diseases in plants and animals.
Characteristics Of Virus
- A virus consists of two components, a protein coat and a core of nucleic acid which is either DNA or RNA.
- DNA viruses are called adenoviruses and RNA viruses are called retroviruses.
- The shape of a virus is due to its protein coat.
- Viruses are of many shapes i.e. rods, spherical, hexagonal, or icosahedral.
- Sometimes their shape is complicated.
- Viruses replicate inside a living cell and many viruses are synthesized along with their protein coats and nucleic acid.
- The nucleic acid contains instructions for the shape of the virus.
Diseases Caused By viruses
Characteristics Of Bacteria
- Bacteria are unicellular prokaryotic organisms that generally divide by transverse binary fission.
- They possess rigid cell walls and act as pathogens
- The nucleus is not well organized
- No definite chloroplast, chlorophyll is dissolved in chromoplasm.
There are three forms of bacteria which are:
- Round called Cocci
- Rod-like called Bacilli
- Spiral called Spirrila
Classification Of Bacteria According To Mode Of Nutrition
According to the mode of nutrition, there are three types of Bactria:
- Devoid of chlorophyll
- Are heterotrophic and get food from living animals and plants
- Lack chlorophyll hence cannot prepare their own food.
- Get food from dead organic remains
- Contain chlorophyll
- Can synthesis food by photosynthesis
- Few get their food by chemosynthesis
Reproduction In Bacteria
- Vegetative: By Binary Fission
- Asexual: By Formation of Endospores
- Sexual: By Conjugation
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