Rajasthan Board RBSE Class 11 Biology Chapter 23 Plant Taxonomy
RBSE Class 11 Biology Chapter 23 Multiple Choice Objective Questions
Question 1.
What is the smallest unit of plant taxonomy?
(a) Intra specific group
(b) Species
(c) Genus
(d) Family
Question 2.
Who is the father of taxonomy?
(a) Takhtajan
(b) Linneus
(c) Bentham and Hooker
(d) Theophrastus
Question 3.
Which is best definition of species?
(a) Group of individual who can live and survive together.
(b) Group of individual who can do interbreeding
(c) Group of individual who cannot do interbreeding
(d) None of these
Question 4.
Who proposed natural system of classification of plants?
(a) Hutchinson
(b) Engler and Prantl
(c) Bentham and Hooker
(d) John Ray
Question 5.
Which botanical name is correct?
(a) Pisum Sativum
(b) Pisum sativum
(c) Pisum sativum
(d) pisum Sativum
Answers.
1.(b)
2.(b)
3.(b)
4.(c)
5.(c)
RBSE Class 11 Biology Chapter 23 Very Short Answer Questions
Question 1.
What do you mean by phylogenetic?
Answer :
It is a system of classification that indicates the evolu-tionary as well as genetic relationships among organ-isms from the time of their origin to present time. Study of a species from their origin to present time is called phylogeny.
Question 2.
Name the book in which Linneus first time used concept of binomial nomenclature?
Answer :
PhilosophiaBotanica
Question 3.
What is full form of ICBN?
Answer :
International Code of Botanical Nomenclature
Question 4.
Define taxonomy?
Answer :
According to G.H.M. Lawrence (1951) plant taxonomy is branch of science which deals with identification, nomenclature and classification of plants.
Question 5.
Which two names are considered for writing botanical name of a plant?
Answer :
First name is generic name while second name is specific name.
Question 6.
Which language is used to write botanical names of plants?
Answer :
Latin
Question 7.
Which word represent genus in Cassia fistula?.
Answer :
Cassia
Question 8.
Who proposed concept of species?
Answer :
John Ray
Question 9.
Which type of classification used in Indian Universities and Herberium to identify and classified plants?
Answer :
Bentham and Hooker’s Natural system of classification.
RBSE Class 11 Biology Chapter 23 Short Answer Questions
Question 1.
Define species.
Answer :
Species is a group of individual plants which are morphologically as well a genetically same and can freely interbreed with each other in nature to maintain the continuity of life.
Question 2.
Explain natural and Phylogenetic Classification.
Answer :
Natural Systems :
- A system of classification based on the comparison of a large number of near permanent characteristics that bring out natural affinities of organisms is called natural system of classification.
- This type of plant classification was based oh natural similarities of structure, i.e., various morphological characteristics of plant.
Phylogenetic Systems :
- It is a system of classification that indicates the evolutionary as well as genetic relationships among organisms from the time of their origin to present time.
Question 3.
Define Binomial Nomenclature.
Answer :
Plant Binomial Nomenclature is a system of providing distinct and proper scientific names to organisms, each scientific name consisting of two words, first generic name and second species name.
Question 4.
What do you understand by Artificial System of Classification?
Answer :
It is a system of classification which is based on comparison of one or a few superficial traits. The traits were selected on the basis of convenience of taxonomist. This type of classification was incomplete and not sufficient to understand classification position of plants.
Question 5.
Explain characteristics of different taxons of Bentham and Hooker’s classification.
Answer :
Class I : Dicotyledonae:
• Main characters of this class are:
- Two cotyledons in seed with embryo.
- Open and ring type of vascular bundles
- Reticulate venation in leaves.
- Pentamerous or tetramerous flower.
Class II : Monocotyledonae:
• This group includes angiosperms in which the seed bears only one cotyledon.
- The leaves are simple and exhibit parallel venation.
- Closed type of vascular bundles because cambium is absent in it. Vascular bundles are scattered in parenchyma.
- Flowers are usually trimerous. Roots are adventitious.
- It is divided into the following seven series:
Class III : Gymnospermae:
• Gymnosperms are kept between Dicotyledons and Monocotyledons class.
- Reproductive structures in this group are in the form of male and female cones.
- Ovule or seed in this group are naked means ovary or fruit absent in it.
Question 6.
Define Systematic.
Answer :
Systematic (Systema-whole made of part) : Systematic is the science that brings out unique properties at each level of grouping or organisms which connected with identification, nomenclature, description and classification of organisms based on unique properties of every species and groups of species at every level of classification.
Question 7.
How Cruciferae family defined and explained in ancient text ‘Vrikshayurveda’?
Answer :
It was explained in trees, shrubs and herbs and their uses.
Question 8.
Which language is used to write botanical name of a plant at international level and why?
Answer :
Scientific name of a plant should be written in Latin language. Latin language is accepted as most evident, pithy and specific language. It is precise and concise in nature. It is helpful to give correct details about plant.
RBSE Class 11 Biology Chapter 23 Essay Type Questions
Question 1.
Explain Bentham and Hooker’s classification up to class level. Write its lay out, important characters. Write its merit and demerits.
Answer :
Bentham and Hooker’s System of Classification :
- George Bentham, a self-trained British Botanist and Sir Joseph Dalton Hooker, Director of the Royal Botanic Gardens, Kew (England), proposed a natural system of classification in their book Genera Plantarum, which includes three volumes containing the description of all known genera of seed plants in Latin.
- First volume of this book was published in 1862 and last volume in 1883.
- This system of classification, which is clearly derived from the systems of de Jussieu and de Candolle, is the best and most accepted natural system and is still used and followed in several herbaria of the world, including India.
- De Candolle kept Gymnosperms with Dicotyledons while Bentham and Hooker system of classification divided all the Phanerograms or seed plants into Dicotyledons, Gymnosperms and Monocotyledons, with Ranales placed in the beginning of the classification and grasses at the end.
- They kept Gymnosperms in between Dicotyledons and Moncotyledons.
- Bentham and Hooker’s classified seeded plants or Phanerogames into three classes on the basis of morphological characters, phyllotaxy, venation, floral whorls-ca-lyx, corolla, androecium, gynoecium, seed coat and number of cotyledons in plants. Dicotyledons, Gymnosperm and Monocotyledons.
Question 2.
Define Binomial Nomenclature and explain rules of Binomial Nomenclature.
Answer :
Binomial Nomenclature System :
- If name of a plant is not same all around the world than it would be difficult to share study and knowledge about plants. To solve this problem nomenclature system adopted.
- Plant nomenclature is a system of providing distinct and proper scientific names to organisms. Each scientific name consisting of two words, first generic name and second species name.
- Binominal nomenclature first time proposed and used by Gaspard Bauhin(1623) in his book ‘Pinax’.
- Binomial nomenclature for scientific naming of plants was developed by Carolus Linnaeus in his book ‘Philosophia Botanica’ (1751).
- All valid names for plant are ones given by Linnaeus in his book Species Plantarum (1753) and for animals in his book Systema Nature (1758).
- International Code of Botanical Nomenclature (ICBN) has framed certain standard norms to give scientific name to any plant.
Scientific Name of a Plant should be Written in Latin Language
- Reasons for binomial nomenclature in Latin language:
- Latin language is accepted as most evident, pithy and specific language.
- It is precise and concise in nature.
- It is helpful to give correct details about plant.
- Each scientific name consisting of two words, first generic name and second specific name. This process of naming is called binomial nomenclature.
Question 3.
Explain concept of Genus and species with examples.
Answer :
Concepts of Species :
- First time Logical and Scientific concept of species was given by Carolus Linnaeus (1753).
Some Popular Definition of Species :
- The word ‘species’ coined by John Ray.
- According to Darlington (1928)- Genetically isolated population of plants which interbreed within them-selves and morphologically similar can be placed in single species.
- According to Durietz (1930)- Species are very small natural unit of populations which are permanently isolated from each other on the basis of bio types.
- According to Clausen et. al (1945)- Species is a group of plants with same characters in which exchange of genes takes place freely without any harmful effect.
- On the basis of above given three definition a final definition have following points:
- All individuals of a plant species are identical morphologically and in other characters.
- All individuals of a plant species freely can interbreed or sexual reproduction is possible among them to give rise new offspring’s to maintain continuity of life.
- Individuals of one species cannot interbreed or do sexual reproduction to give rise new offspring’s because exchange of genetic material is not possible in between them.
- On the basis of above given facts finally we can say “Species is a group of individual plants which are morphologically as well a genetically same and can freely interbreed with each other in nature to maintain the continuity of life”.
- Inter specific categories show uniformity in external and internal characters but it has been observed that Intra specific categories do not show uniformity in external, internal characters even most of the time they differ from each other genetically also.
The Concept of the Genus :
- The word ‘Genus’ coined by John Ray.
- It is the first higher taxonomic category above the level of
species. . - Genus is formed by the group of species which are similar in more than characters.
a. Monotypic genus : A genus having a single species in it is called as monotypic genus. Genus Homo is monotypic geneus with a single species of Homo sapiens.
b. Polytypic genus : A genus having two or more species in it is called as polytypic-genus. The genus Panther a polytypic genus having P.leo, P.tigris. P onca and P pardus
- Concept of genus is very old. Even in hindi and Sanskrit texts genera of different plants are mentioned; e.g., Pine, Basil and Oak etc.
- All species of Pine are included under the genus Pinus, all species of basil are under the genus Ocimum and all species of Oak are included in Quercus.
- Use of Latin names in nomenclature of plants started by Tournefort (1700). He described approximately 700 genus in his book Tnstitutiones rei herbaria.
- According to him characters of fruit and flower should be considered for explanation of plants and for more clarification of plants vegetative characters should also studied.
- Carolus Linnaeus is considered as father of taxonomy. He used only floral characters to explain genus of plants.
- Now to understand the concept of genus we use knowledge of Anatomy, Cell structure, Embryo, structure of ovule and Pollen structure etc.
- One genus further can be divided in subgenera, sections, subsections and series also.
Question 4.
Explain various types of classification and its basis with suitable examples.
Answer :
Types of Plant Classification
- We know about 4 lac species of plants out of which more than half belongs to Angiosperms.
- Angiosperms are found almost in all habitats on earth i.e. dense forest, deserts, hills and mountains and deep in sea and oceans.
- From the time of Theophrastus (370-285 BC) to present time many scientists studied plants with respect to nomenclature, classification and identification.
All type of classifications can be categories in three type
of category as follows:
1. Artificial Systems :
- It is a system of classification which is based on comparison of one or a few superficial traits.
- The traits were selected on the basis of convenience of taxonomist.
- This type of classification was incomplete and insufficient to understand classifications position of plants
- First time artificial classification used by Theophrastus. He classified all plants in 4 categories
(a) Herb
(b) Undershrubs
(c) Shrub
(d) Tree - Carolus Linneus classified Angiosperm plants on the basis of floral characters, number of stamens and number of carpels in his sexual system of classification
- Dioscorides, Bauhin, Andrea Cesalpino, Chamerious and John ray also proposed some artificial type of classification.
Disadvantage of artificial systems :
- It uses only one or few traits for comparison. As a result, different organisms get grouped together
- The criteria chosen for delimitation of groups may be quite insignificant, e.g., annual and biennial plants.
2. Natural Systems :
- o A system of classification based on the comparison of a large number of near permanent characteristics that bring out natural affinities of organisms is called natural system of classification.
- This type of plant classification was based on natural similarities of structure, i.e., various morphological characteristics of plant.
- First natural classification of plants proposed by Schimper (1879) and elaborated by Eichler (1883).
- Bentham and Hooker’s classification is a best example of natural classification of the plants which was worked out by them in a book ‘Genera Plantarum’
- A.P.D. Condolle, John Lindley and de Jussieu are other famous scientist for their natural classification
- Natural system remained dominant before the concept of evolution was accepted in systematic.
3. Phylogenetic Systems :
- This concept of classification came in existence after Charles Darwin’s theory, i.e., Origin of Species by Natural Selection.
- It is a system of classification that indicates the evolutionary as well as genetic relationships among organisms from the time of their origin to present time.
- Study of a species from their origin to present time is called phylogeny.
- In this type of classification Angiospenns are classified in to families on the basis of phylogeny.
- Engler and Prantl (1887-1889), Hutchinson (1926, 1934), Takhtajan (1954), Cronquist (1968), Dahlgren (1975) and Thorne (1981) are famous for their phylogenetic classifications.
RBSE Class 11 Biology Chapter 23 Additional Questions
Question 1.
Who coined the term ‘Genus’?
Answer :
John Ray
Question 2.
What is name of book wrote by A.P. de Candolle?
Answer :
‘Theory of Elementary Botany’.
Question 3.
Who is known as father of botany?
Answer :
Theophrastus.
Question 4.
Name the book in which Bentham and Hooker gave their classification.
Answer :
Genera Plantarum
Question 5.
Define Polypetalae.
Answer :
It is subclass of dicotyledons having calyx and corolla. In the corolla petals are free.
Question 6.
What are the demerits of Bentham and Hooker’s classification?
Answer :
De-Merits of Bentham and Hooker’s System :
- The system does not give any idea as to the evolutionary history of any genus; family or order means it is not phylogenetic.
- In this system grouping of plants is mainly based on single and artificial characters; with the result, that closely allied families are placed widely apart.
- The group “Monochlamydeae” is entirely artificial.
- Gymnospermae is placed between the Dicotyledones and Monocotyledones, which is extremely anomalous.
- The system does not show any phylogenetic relationship. The main demerit is that this system does not give us any idea as to the evolutionary history of any genus, family or order nor does it give any idea of phylogenetic relationship between them.
- Compositae (Asteraceae) is a highly advanced family and placed in Inferae at the beginning of Gamopetalae.
- Advanced families like Orchidaceae and Scitamineae are treated in the beginning of monocots.
- Liliaceae and Amaryllidaceae were kept apart though they are very closely related.
- The Amaryllidaceae is more allied to Liliaceae but is clubbed with Scitamineae in series Epigynae, on account of inferior gynoecium.
- The position of series Apocarpae is unsatisfactory’ due to its free and superior.carpels.