1. The Living World
CLASS 11 BIOLOGY
UNIT I – DIVERSITY IN THE LIVING WORLD
UNIT II – STRUCTURAL ORGANISATION IN PLANTS AND ANIMALS
UNIT III – CELL : STRUCTURE AND FUNCTIONS
UNIT IV – PLANT PHYSIOLOGY
UNIT V – HUMAN PHYSIOLOGY
CLASS 12 BIOLOGY
Unit-VII Genetics and Evolution
Unit-VIII Biology and Human Welfare
Unit-X Ecology and Environment
Characteristics of Living Beings
Growth is an important feature of living beings. Growth can be seen in some non-living things; like a cloud. But the growth in non-living things happens because of accumulation of matter from outside. On the other hand, the growth in a living being happens because of internal processes, i.e. cell division. Most of the plants show indeterminate growth, while the growth in animals is definite.
All living beings produce their offspring through the process of reproduction. Reproduction is important for continuing the lineage of a species. There are two main types of reproduction, viz. sexual and asexual.
The chemicals within a living organism undergo a continuous change. This process is called metabolism. Metabolism is composed of two processes, viz. anabolism and catabolism.
a. Anabolism: The process of synthesis of any substance is called anabolism, e.g. photosynthesis.
b. Catabolism: The process of breaking up of a substance is called catabolism, e.g. respiration.
Response to External Stimuli:
All living organisms respond to external stimuli. Light, heat, chemicals, other organisms, etc. are examples of external stimuli. Response to external stimuli is important for the survival of an organism.
Diversity in the living world
The number and types of organisms present on earth refer to biodiversity.Number of species described is 1.7-1.8 million.
It is the study of identification, classification, nomenclature & documentation of organisms. Systematics (Latin ‘systema’) means systematic arrangement of organisms.Systema Naturae is the book written by Linnaeus.
Processes of taxonomy
It is the understanding of characters of organisms such as external and internal structure, structure of cell, development process, ecological information etc.
Nomenclature is only possible when the organism is described correctly and we know to what organism the name is attached to. This is identification.
It is the grouping of organisms into convenient categories (taxa) based on characters.
It is the providing of standardized names to the organisms such that a particular organism is known by the same name all over the world.
The system of naming with two components (Binomial nomenclature) is proposed by Carolus Linnaeus.Botanical names are based on the rules provided in International Code for Botanical Nomenclature (ICBN).Zoological names are based on International Code for Zoological Nomenclature (ICZN).
Universal rules of Binomial nomenclature Scientific names are generally in Latin and written in italics.The first word is genus name (Generic name) and second word is the species name (specific epithet).When handwritten, the names are underlined.The names are printed in italics.The first name (Genus) starts with capital letter and the second name (species) starts with small letter.
E.g. Homo sapiens- Homo represents the genus name and sapiens represents the species name.
Name of the author appears after the specific epithet, i.e.,at the end of the biological name and is written in an abbreviated form, e.g., Mangifera indica Linn. It indicates that this species was first described by Linnaeus
Nomenclature and Identification:
An organism is known by different names in different languages. It would be impossible for any person to remember the names of an organism in all the languages. Hence, there is need for a uniform system of nomenclature of organisms. A uniform system of nomenclature and identification helps the scientists in systematic study of living beings. ICBN (International Code for Botanical Nomenclature) applies to the plants and ICZN (International Code for Zoological Nomenclature) applies to the animals.
General Rules for Nomenclature:
Biological names are usually written in Latin. They are written in italics.
A biological name usually contains two terms. The first term shows the genus, while the second term shows the species.
Biological name is underlined, when it is handwritten.
The first term of the biological name begins with a capital letter. The second and the subsequent terms begin with the small letter.
Various steps of the classification hierarchy are called taxonomic categories. Each category represents a particular rank and is usually called the taxon.
A group of individuals in which the individuals can interbreed among themselves is called species. Members of a species have a large number of similar characters. For example; all the tigers are called Panthera tigris. Since all of them can interbreed hence, they are kept under one species.
A group of closely related species is called genus. Example; Lion (Panthera leo), leopard (Panthera pardus) and tiger (Panthera tigris) are members of the genus Panthera. Similarly, potato, tomato and brinjal belong to the genus Solanum.
A group of closely related genera is called a family. For example; potato and chili belong the family Solanaceae. Similarly, the genus Panthera and the genus Felis belong to the family Felidae.
A group of closely related families is called order. For example; Convolvulaceae and Solanaceae are plant families which belong to the order Polymoniales. Similarly, Felidae and Concidae belong the order Carnivora.
The group of closely related orders is called class. For example; orders Primata and Carnivora belong to the class Mammalia.
A group of closely related classes is called phylum. In the Plant Kingdom; the term phylum has been replaced with division. For example; pisces, amphibia, reptilia, aves and mammalia belong to the
The group of all the related phyla is called the Kingdom. For example; all autotrophic organisms which are eukaryotic and contain chloroplast are kept under the Plant Kingdom. Similarly, all heterotrophic organisms which are eukaryotic and lack a cell wall are kept under Animal Kingdom.
-Museum is a collection of preserved plants and animalsfor study and reference. A museum contains Specimens preserved in preservative solutions in containers or jars.Plant and animal specimens preserved as dry specimens.
Insects preserved in insect boxes after collecting, killing and pinning. Stuffed larger animals like birds and mammals. Collections of animal skeletons.
d. Zoological Parks (Zoos)
These are the places where live wild animals are kept in protected environments under human care.
It enables to learn about their food habits and behavior.
It is the device used to identify each species in a group of organisms based on similarities and dissimilarities.
The keys are based on the contrasting characters generally in a pair called couplet. It represents the choice made between two opposite options.Each statement in the key is called a lead.
Flora, manuals, monographs & catalogs
These are some other means of recording descriptions.
They also help in correct identification.
Flora contains the actual account of habitat and distribution of plant species of a given area.
Manuals help in providing information for identification of names of species found in an area.
Monographs contain information on any one taxon