RBSE Solutions for Class 11 Biology Chapter 1 The Living World

Rajasthan Board RBSE Solutions for Class 11 Biology Chapter 1 The Living World Textbook Exercise Questions and Answers.

RBSE Class 11 Biology Solutions Chapter 1 The Living World

RBSE Class 11 Biology The Living World Textbook Questions and Answers

Question 1. 
Why are living organisms classified?
Answer:
There is a vast variety of organisms which differ very greatly in their form, structure and mode of life. To find out a desired organism of known characters from vast array of plants and animals, the organisms must be classified.

Question 2. 
Why are the classification systems changing every now and then?
Answer:
Millions of plants, animals and organisms are found on earth. Many of these have been identified by the scientists while many new species are still being discovered around the world. Therefore, to classify these newly discovered species new systems of classification have to be divised every now and then. This creates the requirement to change the existing systems of classification.

Question 3. 
What different criteria would you choose to classify people that you meet often?
Answer:
The various criteria that may be chosen to classify people include 

• Morphotaxonomy 
• Numerical taxonomy 
• Behaviour and 
• Geographical distribution.

Question 4. 
What do we learn from identification of individuals and populations?
Answer:
The knowledge of characteristics of an individual or entire population helps in the identification of similarities and dissimilarities among the individuals of same kind or between different types of organisms. It helps the scientists to classify organisms in various categories.

Question 5. 
Given below is the scientific name of mango. Identify the correctly written name:
Mangifera Indica    Mangifera indica.
Answer:
In bionomial system of nomenclature, the generic name of a species always starts with a capital letter whereas the specific name starts witty a small letter. Therefore, the correct scientific name of Mango is Mangifera indica.

Question 6. 
Define a taxon. Give some examples of taxa at different hierarchical levels.
Answer:
Each unit of category of classification is termed as a taxon. It represents a rank. For example, the basic level of classification is species followed by genus, family, class, phylum or division in ascending order. The highest level of classification is called kingdom.

Question 7. 
Can you identify the correct sequence of taxonomical categories?
(a) Species → Order → Phylum → Kingdom.
(b) Genus → Species → Order Kingdom.
(c) Species → Genus → Order → Phylum.
Answer:
Species → Genus → Order → Phylum.

Question 8. 
Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meaning of species in case of higher plants and animals on ope hand, and bacteria on the other hand.
Answer:
In biological terms species is the basic taxonomical rank. It can be defined as a group of similar organisms that are capable to interbreeding under natural conditions to produce fertile organisms. Therefore, a group of similar individuals that are respectively isolated from a species. Species can also be defined as a group of individuals that share the same gene pool.

Question 9. 
Define and understand the following terms:
(i) Phylum 
(ii) Class 
(iii) Family 
(iv) Order 
(v) Genus
Answer:
(i) Phylum: Phylum is the primary division of kingdom. It includes one or more related classes of animals. In plants instead of phylum, the term division is used.

(ii) Class: Class is a taxonomic group consisting one or more related orders. For example, the class mammalia includes many orders.

(iii) Family: Family is a taxonomic group containing one or more related genera. In plants families are categorised on the basis of vegitative and reproductive features.

(iv) Order: Order is a taxonomic group containing one or more families. For example, the order, carnivore includes many families.

(v) Genus: Genus is a taxonomic group including closely related species. For example the genus, Solarium include many species such as nigrum, melongena, tuberosum etc.

Question 10. 
How is a key helpful in the identification and classification of an organism?
Answer:
Key is another taxonomical aid that helps in identification of plant and animal species. These keys are based on similarities and disimilarities in characters generally in a pair called couplet. Each statement in a taxonomic key is reffered to as a lead. For categorizing each taxonomic rank such as family, genus, species etc., different keys are used. It is also useful in identification of unknown organisms.
Keys are of two types: indented and bracketed keys. Indented key provides a sequence of choices between two or more statements while in bracketed key is a pair of contrasting characters are used.
Identification of different genera of family Ranunculaceae with indented key.

Identification of different genera of family Ranunculaceae with bracketed key.

Question 11. 
Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.
Answer:
The arrangement of various taxa in a hierarchial order is called taxonomic hierarchy. In this species is present at the lowest level whereas, kingdom is present at the highest level. The hierarchy of major categories is given below:

1. Kingdom
2. Phylum (Plural: phyla)
3. Class 
4. Order 
5. Family
6. Genus (Plural: genera)
7. Species (Plural is also species)

Classification of a Plant:
As an example, let us classify Solanum melongena (Brinjal)

1. Kingdom: Plantae 
2. Division: Angiospermae 
3. Class: Dicotyledonae
4. Family: Solanaceo
5. Order: Solonales 
6. Genus: Solanum 
7. Species: melongena

Classification of an animal:
As an example, let us classify Columba livia (Blue rock Dove)

1. Kingdom: Animalia 
2. Phylum: Chordata 
3. Class: Aves 
4. Family: Columbidae 
5. Genus: Columba 
6. Species:  livia