NCERT Solved Exercise Questions – Class 11 Biology Chapter 1 The Living World

1. Why are living organisms classified?

Ans – Earth is home to a great variety of flora, fauna, and germs. The size, form, colour, habitat, and many other properties of all these living things vary. It is impossible to examine every living thing on earth since there are so many of them. As a result, scientists have created systems to categorise all living things. These classification techniques are founded on laws and precepts that enable the identification, nomenclature, and ultimately classification of an organism.

2. Why are the classification systems changing every now and then?

Ans – The earth is home to a vast variety of plants, animals, and microorganisms. While several new species are continuously being found throughout the world, many of these have already been identified by scientists. As a result, new classification systems must occasionally be developed in order to categorise these recently discovered species. As a result, it becomes necessary to modify the current classification systems.

3. What different criteria would you choose to classify people that you meet often?

Ans – The organisation of organisms into groups based on their affinities or interactions is known as classification. Taxonomy is the area of biology that focuses on understanding the methods and ideas used in biological classification. Below, a few key taxonomy components are discussed.

Nomenclature: It is the science of giving separate, proper names to various types of living things. The right name is chosen in accordance with accepted customs and guidelines from all cultures.

Classification: is the process of categorising groups of organisms or individual organisms in accordance with a predetermined scheme or sequence. Animals are categorised using the following terms: Class, Order, Family, Genus, and Species. Each classification is a unit referred to as a taxon.

Identification is the process of figuring out an organism’s proper name and placement within a classification scheme. It finds similarities between the specific organism and another known creature. Assigning an organism to a certain taxonomic group is implied by this. Assume there are three plants, let’s say x, y, and z. AH stand for various species. Another plant, w, looks like y. The plant’s identification came from the fact that it was recognised as being exactly like another plant, y.

4. What do we learn from identification of individuals and populations?

Ans – Understanding an individual’s or a population’s characteristics aids in spotting similarities and differences between individuals of the same sort or between various kinds of creatures. We can categorise the organisms into different groups based on their similarities and differences.

5. Given below is the scientific name of Mango. Identify the correctly written name.

Mangifera Indica Mangifera indica

Ans – The particular name of a species always begins with a tiny letter in the binomial system of naming, but the generic name always begins with a capital letter. Mangifera indica is the proper scientific name for mango.

6. Define a taxon. Give some examples of taxa at different hierarchical levels.

Ans – In the biological system of classification of organisms, a taxon is the taxonomic unit. A phylum, order, family, genus, or species, for instance, indicates a taxon. It stands for a rank. For instance, all insects belong to the same taxon. Aves is the taxon for the class category of birds, and Chordata is the taxon for the phylum category of birds.

Kingdom
↑
phylum or Division
Class
↑
Order
↑
Family
↑
Genus
↑
Species

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

Ans – The correct hierarchical arrangement of taxonomic categories in ascending order of taxonomixal categories

Species → Genus → Family → Order → Class → Phylum → Kingdom

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 one hand, and bacteria on the other hand.

Ans – 1. One of the fundamental components of biological taxonomy is the species. A group of creatures that can interbreed and result in the production of fertile offspring is commonly referred to as a species.

When defining the foundation of a species, more specific or unconventional criteria like DNA similarity, morphology, or ecological niche may be applied.

In the case of animals, the particular name or the specific epithet defines the name of the species. For instance, golden Jackals are members of the Cam’s aureus species, as are grey wolves, etc.

Although their species names differ, they are also members of the Canis genus. But a plant’s species name is merely referred to as a species epithet.

In botany, the term “specific name” refers to the combination of a genus name and a species epithet, such as saccharum in the case of Acer saccharum.

However, bacteria are divided into four categories based on their shapes: spherical, rod-shaped, comma-shaped, and spiral-shaped. The shapes are also used to classify the species of bacteria. As a result, the definition of a species in higher organisms and bacteria differs.

9. Define and understand the following terms:

(i) Phylum

(ii) Class

(iii) Family

(iv) Order

(v) Genus

Ans – (i)Phylum: A phylum is a collection of related classes that share characteristics, such as protozoa.

(ii) Class: A class is a collection of related orders, for instance, the orders Rodentia, Lagomorpha, and Carnivora are all included in the class Mammalia since they all have milk glands and hair.

(iii) family :A family is a collection of related genera. The family Felidal includes the cat genus Felis as well as the lion, tiger, and leopard genera Panthera.

(iv)order :An order is a collection of connected families . The order Carnivora is home to the dog and cat families Coridal and Felidae, respectively. Both cats and dogs are carnivores with big canine teeth.

(v) Genus: A genus is a group of species that are similar in their overall organisational structure but distinct in specifics. According to binomial nomenclature rules, a species cannot be given a name without first being placed in a genus.

10. How is a key helpful in the identification and classification of an organism?

Ans – A collection of sentences with a dichotomic table of alternate attributes make up the artificial analytical tool known as “Key.” Taxonomic keys are tools for quickly distinguishing between unidentified plants and animals based on similarities and differences. Characters that are trustworthy and consistent form the foundation of keys. The keys aid in a quicker preliminary identification that can be confirmed by comparison with a thorough description of the taxon being tentatively identified with. For each taxonomic category, such as Family, Genus, and Species, a different taxonomic key is used.

11. illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.

Ans –Taxonomic hierarchy is the classification of different taxa according to a hierarchy. The hierarchy shows the different kinship tiers. From lowest rank to highest rank, there are less characters in each category that are similar to each other. Linnaeus invented the hierarchical system of classification.

The order of the main categories is:

Species —►Genus-►Family —► Order—► Class
Kingdom -4— Phylum or Division
Increasing specificity – ► Decreasing specificity

Classification of a plant (Wheat):
Kingdom – Plantae
Division – Angiospermae
Class – Monocotyledonae
Order – Poales
Family – Poaceae
Genus – Triticum
Species – aestivum