Define order.

Define order.

Source: NCERT Class 11 Biology Chapter 1 – The Living World Question 9 (iv)

An order is a level of classification in the Linnaean system of taxonomy. It is used to group organisms that are even more closely related than those in different families, but less specific than those in different classes. The order level is one step below the class level and above the family level in the classification hierarchy.

For example, within the animal kingdom, the order Carnivora includes cats, dogs, bears, and other mammals that are characterized by having sharp teeth and claws for hunting and eating other animals. Similarly, within the plant kingdom, the order Rosales includes roses, apples, raspberries, and other plants that share certain characteristics such as being typically angiosperms that have spiral-arranged leaves and stipules.

It's important to note that, like other levels of classification, the characteristics used to group organisms into orders can vary widely depending on the group of organisms, and the definition and content of an order can change as new information becomes available. Also different classification systems may use different criteria for grouping organisms into orders, but the goal is to group organisms that are even more closely related than those in different families, but less specific than those in different classes.

In summary, an order is a level of classification in the Linnaean system of taxonomy, used to group organisms that are even more closely related than those in different families, but less specific than those in different classes. This level of classification is widely used across different branches of the tree of life, like animals, plants, fungi, algae, and microorganisms, and the characteristics used to classify can vary widely depending on the group of organisms. It is an important part of the classification hierarchy that allows us to organize and communicate information about different groups of organisms, and make predictions about their characteristics and behavior.

It's also worth noting that the concept of order is not only used in the animal and plant kingdoms, but also in other branches of the tree of life such as fungi and algae. In the fungi kingdom, for example, the order Agaricales includes gilled mushrooms, while the order Boletales includes bolete mushrooms. In the algae kingdom, the order Cladophorales includes green algae that form long filaments and the order Ulvales includes green algae that form flat blades.

Also, as in other levels of classification, the number and content of orders can change as new discoveries and research updates the classification system. For example, new molecular and genetic techniques are providing new information about the relationships between different groups of organisms, leading to changes in the classification of many orders. Also, sometimes taxonomist may split or join orders based on new data.

As with the other levels of classification, the classification of organisms into different orders is based on a combination of various characteristics, not only morphological but also molecular and genetic characteristics, that help to infer evolutionary relationships between different groups of organisms. The classification of organisms into different orders is an ongoing process, and new information and techniques can lead to changes in classification, new discoveries can lead to new orders being described or the redefining of existing orders.

Other questions from NCERT Class 11 Biology Chapter 1 The Living World Solutions:

Question 1: Why are living organisms classified?

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

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

Question 4: What do we learn from the identification of individuals and populations?

Question 5: Given below is the scientific name of Mango. Identify the correctly written name. Mangifera Indica or Mangifera indica

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

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

Question 8: Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meaning of species in the case of higher plants and animals on the one hand and bacteria on the other hand.

Question 9:  Define and understand the following terms. (i) Phylum (ii) Class (iii) Family (iv) Order (v) Genus

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

Question 11: Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.

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