what is a biology?
characteristics of Living Beings
1.Cellular organisation
- Unicellular organisation
The organisms which have single -cell ,called unicellular organisms ,e.g Amoeba,Paramecium etc.
- Multicellular organisms
the organisms which have multiple cells of various types are called multicellular organisms,e.g. human,etc.
2. Homeostasis
It is the process of regarding body temperature and maintenance of internal environment in order in continue metabolic processes ,e.g. thermoregulation Its failure leads to
- Heat stroke
It indicates the increase in body temperature above normal level.
- Hypothermia
It means decrease in body temperature below normal level.
3. Reproduction
It is the process of producing young ones by living beings. On the basic of involvement of gametes , It is two types:
- Asexual reproduction
the process which do not involve the fusion of gametes or sex cells ,e.g. Amoeba.
- Sexual reproduction
the process which involves the fusion of gametes ,e.g. humans.
- short-term adaptation
- Long-term adaptation
6.Growth
- Catabolism
- Anabolism
- clinical
- Biological
what is the Diversity in the world ?
The planet earth is full of animals and plants. This refers to biodiversity.Each different kind of Plant and animal represents a species.The number of species that are known and described ,range between 1.7-1.8 million The number of known species are increasing day-by-day because of Projects like global biodiversity information facility and species 2000.the estimated number of living organisms on earth now is between 5-30 million ,most occurring in dense tropical rain forests and under water reefs.
Systematics
It is the study of diversity of living organisms and evolutionary relationship between them. lt is the systematic arrangement of organisms on the basis of following four fields viz, identification, classification,nomenclature and taxonomy.
Identification
classification
Nomenclature
It is the science of providing distinct and proper names to organism so that they can be easily recognised and differentiated from others.
Scientific or technical Names
- Binomial system of nomenclature
As per this system name of any organism consists of two parts or ,i.e.generic epithet and specific epithet,e.g. the botanical name of mango is Mangifera indica L, in which Mangifera is generic epithet representing the genus and indica is specific epithet representing its species .L represents the name of the scientist (Linnaeus), who gave the scientific name to mango.
- Trinomial system of nomenclature
Sometimes binomial nomenclature can also be extended to trinomial system of nomenclature where the name of sub-species or varieties can be incorporated,e.g. Brassica oleracea botrytis.Here botrytis is a variety.
- Polynomial system of nomenclature
Prior to 1750, biologists used descriptive names for organisms with each name being made up of several Latin words e.g. Caryophyllum saxatilis, Folis gramineus , Umbellatus corymbia (caryophyllum growing on rocks having grass-like leaves and umbellate corymb flower).
- Polynomial system of nomenclature
Rules for Nomenclature
- Biological names are printed in italics to indicates their latin origin.
- When handwritten, both words are underlined separately.
- The genus starts with the capital letter while , specific epithet is always with small letter.
- Name of the author is pointed in roman bold letter.
- The name of categories higher then the rank of genus are not printed in italics. Bold letters can however be used.
- Sometimes generic and common names can be same e.g. Gorilla gorilla, Rattus rattus. these are called Tautonyms and are valid in zoological names only.
Codes of Biological Nomenclature
Types of Annotations Used in nomenclature
- Holotype lt is a prototype spcimen, from which description of a new species iis established
- Syntype lt refers to any of two or more specimens cited by an author when there is no holotype.
- Lectotype The specimen selected from original material, when there is no holotype available for it.
- Paratype It Indicates the specimens described along with the holotype.
- Neotype It is new nomenclatural type, when the holotype is not available.
- Isotype It works as duplicate of holotype
What is Taxonomy?
Taxonomy
lt deals with the principles and procedures of identification, nomenclature and classification of organisms . lt reflects the natural and phylogenetic among organisms.
It also provides the details of external and internal structures,cellular structure and ecological information of organisms. the term taxonomy was coined by AP de Candolle.
Branches of Taxonomy
The Various branches of taxonomy are:
Artificial taxonomy makes use of habit and habitat of organisms, Pling used this system frist time.
Practical taxonomy is based on the utility of organisms,
Natural taxonomy is based on the natural similarities amongst organism.
Phylogenetic taxonomy is based on phylogeny or evolutionary history of a species.
Experimental taxonomy is based on experimental determination of genetic inter-relationships.
Chemotaxonomy is based on the presence or absence of chemical in cells or tissies, e.g. amino acids, protein, etc.
Numerical taxonomy is based on the number of shared characters of various organisms. It is also called phenetic or Adamsonian classification.
cytotaxonomy is based on cytological studies.
Karyotaxonomy is based on nuclear and chromosomal studies.
Morphotaxonomy is based on morphological studies of organisms.
Type of Taxonomy
Alpha taxonomy considers only morphology, Beta taxonomy considers genetic,anatomy ,physiology ,etc. and the omega taxonomy is based on phylogenetic relationships.
Modern taxonomy/New Systematics
The concept of modern taxonomy was given by Julian Huxley.1940 ( father of neotaxonomy) According to it,the species are dynamic and ever -changing entity. Studies of organisms are done on a huge number of variations .It includes cytotaxonomy ,numerical taxonomy, chemotaxonomy etc.
Taxonomy categories
classification is not single step process. It involves hierarchy of steps in which each step represents a rank of category. Since, the category is a part of overall taxonomic arrangement .It is called the taxonomic category and all categories together consitutes the taxonomic hierarchy. It was frist introduced by Linnaeus (1751) and hence, is also know as Linnaean Hierarchy. It was given in his book systems Naturae.
- Taxon represents the rank, each category and referred to as a unit of classification, The term 'texon' was first introduced by ICBN during 1956. According to Mayr (1964), taxon is a group of any rank that is sufficiently distinct to be worthy of being assigned a definite category, In simple words, taxon refers to a group of similar, genetically related individuals having certain characters distinct from those of other groups.
- The taxonomic categories ,Which are always used in hierarchical classification of organisms are called obligate categories.
- The sub- categories like sub-species ,sub-class, sub- family, etc. Which facilitate more sound and scientific placement of various taxa are called intermediate categories.
- The taxonomic categories for both plants and animals can be demonstrated as follwos -( in descending hierarchy)
For Plants
Kingdom ------- Division ------ Class ------- Order------ Family ------ Genus
------- Species.
For Animals
Kingdom------- Phylum ------ Class ------ Order ------ Family ------- Genus
------- species.
Each taxa can be explained under the following levels:
- KIngdom
It is the highest category is taxonomy. A kingdom includes all the organisms ,which share a set of distinguished characters.
- Phylum or Division
( Cuvier ,Eichler ) is a taxonomic categories higher than class and lower in rank to kingdom, The term phylum is used for animals, while division is commonly employed for plants . It consists of more than one class having some similar correlated characters.
- Class
(Linnaeus) is a major category , which includes related orders.
- Order
An order (Linnaeus) is a group of one or more related families that posses some similar/corelated characters, which are lesser in number as compared to a family or genera.
- Family
Family (John ray ) is a group of related genera with less number of similarities as compared to genus and species. All the genera of a family have some common features. They are separable from genera of a related family by important differences in both vegetative and reproductive features.
- Genus
(john ray) comprises of a group of related species ,which have more characters common in comparison to species of other genera. In other words genera are the aggregates of closely related species.
- Species
(John ray) is group of individuals which resemble one another in all morphological and reproductive characters and interbreed freely to produce fertile offsprings (as defined by Ernst Mayr). It is the lowest or basic taxonomic categories.
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