GSEB Solutions for Class 9 Science and Technology – Diversity in Living Organisms-I (English Medium)
In nephrolepis, the spore producing structure called sporangia arises on the foliage leaf; a characteristic of pteridophytes.
Angiosperms are flowering plants where the ovules are converted into seeds and ovary into fruits after fertilisation. The seeds are thus enclosed within the fruit.
C. Carolus Linnaeus
Binomial classification was given by Carolus Linnaeus and is known as the Father of Taxonomy.
Each kingdom is divided into phyla on the basis of dissimilar characters. Each phylum has organisms with common characters.
C. Robert Whittaker
Robert Whittaker in 1969, gave the five kingdom classification system of organisms.
B. Prokaryotic bacteria
Kingdom Monera includes organisms that lack well developed nucleus and membrane bound organalles. Bacteria and blue green algae are included in kingdom Monera.
Kingdom Monera includes organisms that lack well developed nucleus and membrane bound organalles. Bacteria and blue green algae or cyanophyta are included in kingdom Monera.
A. Algae and Fungi
Algae and fungi live in permanent mutually dependent relationship in the form of lichens. Algae provide food and fungi provide protection to the symbiotic life forms.
B. Monocot plants
Monocot plants have single cotyledons in their seed, show parallel venation and an adventitious fibrous root system.
The first word in the scientific name signifies the generic name or the genus of an organism.
The two important features of bryophytes are:
- Bryophytes are called amphibians of plant kingdom.
- In the life cycle, the gametophytic stage is the dominant stage and the sporophytic stage is the subsidiary stage.
In gymnosperms, pollination takes place only by wind as the male and the female gametophytes are present on separate plants.
In thallophyta, plant body is thallus like and not differentiated into root, stem and leaves.
Thallophyta, Bryophyta and Pteridophyta have inconspicuous reproductive organs and are included in cryptogamae.
Plants of bryophyte are referred to as amphibians.
In bryophyte, the gametophytic stage is principal and the sporophytic stage is subsidiary.
Gymnosperms and angiosperms are included in Phanerogams.
The cell wall of fungi is made up of chitin or of cellulose plus chitin.
The branch of biology that deals with the study of classification of organisms is called taxonomy.
|They show autotrophic mode of nutrition.||They show heterotrophic mode of nutrition.|
|The cell wall is made up of cellulose.||The cell wall is made up of chitin or chitin plus cellulose.|
|Example – Diatoms, Spirogyra||Example – Mucor, Rhizopus|
Bryophytes are the simplest land plants that grow in damp shady places. The sporophytic stage of the plants grows on land; however, water is highly essential for fertilisation. Thus, bryophytes are known as amphibians of the plant kingdom.
|The plant body is thallus like heart shaped and shows the presence of leaf-like and root-like structures.||The plant body is well differentiated into root, stem and leaves.|
|The conducting tissues are absent||Tissues for conduction of water and other substances are present.|
|Gametophytic stage is dominant stage and sporophytic stage is subsidiary.||Sporophytic stage is dominant stage and gametophytic stage is subsidiary.|
|Example – Riccia, Marchantia||Example – Nephrolepis, Marsilea|
|Plants have seeds with one cotyledon.||Plants have seeds with two cotyledons.|
|Plants show adventitious fibrous root system.||Plants show tap root system.|
|Stem is normally unbranched.||Stem is normally branched.|
|The leaves show parallel venation.||The leaves show reticulate venation.|
|Flowers show trimerous symmetry.||Flowers show tetramerous or pentamerous symmetry.|
|Example – Sugarcane, Maize||Example – Sunflower, Mango|
Chemotaxonomy is the application of phytochemical data to the problems of systematic botany.
It is based on the presence and distribution of chemical compounds in plants. 33 groups of chemical compounds are found in plants and they serve as the basis of taxonomy.
Advantages of classification of living organisms are:
- It makes the study of various organisms simpler and easier.
- It helps to understand inter-relationships among different groups of organisms.
- It gives a complete picture of all life forms in a single frame.
- It provides fundamental information for development of other biological sciences.
- Several applied biology fields get useful information from classification.
To study the diverse group of living organisms in an effective manner, it is essential to group the organisms in a systematic manner.
It is first necessary to assort the organisms under different species. Next, on the basis of similarities and dissimilarities, the organisms are grouped into higher categories like genus, order, class and phylum in this order.
This manner of arranging organisms in different groups on the basis of similarities and dissimilarities is called classification.
Morphological characters are the external visible characters of an organism. Morphology forms a useful and primary basis of classifying organisms into different groups.
In earlier systems, only one or few morphological characters were considered for classification of plants. For example, plants were classified as herbs, shrubs, trees and climbers on the basis of their habitat. However, this did not provide a complete solution for classifying all plants.
Later, Linnaeus proposed a system for classification based on the morphological characters of stamens and carpels.
Later, a large number of morphological characters were taken into consideration for classification of plants. The plants showing similar characters were grouped together and dissimilar characters were used for placing the plants in separate groups.
For example, plants showing ovules enclosed in the ovary were grouped as angiosperms and the ones showing naked ovules were grouped as gymnosperms.
The important features of binomial nomenclature:
- The scientific name of each organism has two words. First word is the genus and the second word signifies the species of the organism.
- The scientific names of all the organisms are unique and followed all over the world.
- The scientific names of organisms are written in italics if printed and underlined if handwritten.
- The generic name of an organism always begins with a capital letter and the specie name in small letter.
- Binomial nomenclature was given by Carolus Linnaeus and he is called the father of taxonomy.
Grouping the organisms on the basis of similarities and dissimilarities is called classification. The organisms are grouped in different categories from kingdom to species. Kingdom is the highest category of classification and species is the lowest. The categories of classification are described as follows:
- Kingdom: Kingdom includes all organisms that share common characters
- Phylum: Each kingdom is divided into different phyla that have organisms related to each other by some common characters.
- Class: Each phylum is then divided into different classes that again contain organisms related by some common features.
- Order: Each class has a number of different orders, divided on the basis of dissimilar properties. Organisms in same order have similar characters.
- Family: An order is further divided into a number of families. Organisms in the same family have similar characters. A group of closely related genera make a family.
- Genus: Genus is a further division of a family with members showing very little differences and more of common characters.
- Species: A genus comprises of a number of species. Specie forms the basic unit of classification. All members of the same species are capable of interbreeding among themselves and giving rise to fertile offsprings.