NCERT Solutions for Class 9 Science Chapter 7 Diversity in Living Organisms

1. What are the advantages of classifying organisms?

Answer: To study wide range of life forms present on the earth we, need to classify them. Following are some advantages of classifying organisms.

• Helps in study of common characters in organisms
• Helps in prediction of line of evolution
• Helps in understanding variety of life forms on earth

2. How would you choose between two characteristics to be used for developing a hierarchy in classification?

Answer: Basis of start hierarchy is the fundamental characteristics. Human beings have vertebral column, this brings them under the classification of vertebrates. Presence of mammary glands helps to classify animals into mammals. Difference between plants and animals is found from characteristic of locomotion.

3. Explain the basis for grouping organisms into five kingdoms.

Answer: Organisms are grouped into five kingdoms on the basis of following characteristics –

• Number of cells present in an organisms
• Layers present in an organism
• Presence of cell wall
• Mode of nutrition

4. What are the major divisions in the Plantae? What is the basis for these divisions?

Answer: Kingdom Plantae is further classified into thallophyta, bryophyta, pteridophyta, gymnosperms and angiosperms. This classification is carried out on basis of differentiated or undifferentiated body, presence or absence of vascular tissues, with or without seed, bear seed or covered seeds.

• First level classification is carried out on the basis of differentiation of plant body. Group of plants do not having well differentiated body are thallophytes.
• Further plants having well differentiated body parts are divided on basis of presence or absence of vascular tissues. Plants without vascular tissues are group in bryophyta. Plants with vascular tissues are grouped pteridophyta.
• Further it is divided on the basis of absence seed formation
• Group of plants having reproductive organs are classified into phanerogams. They are further classified if the seed are naked or covered with fruit. Gymnosperms are group of plants with bare seed and absence of flowers (nonflowering plants). Angiosperms are group of plants having seed covered with fruit and has flowers.

5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?

Answer: The basic design of plants are different from animals. This differentiation is done on the basis of their basic characteristics of food intake. Plants prepare their own food by photosynthesis, whereas, animals acquire food from other sources like plants or other animals. Some of the criteria dividing plants are differentiation of plant body, distinct vascular tissues, seed producing ability, whether seeds are covered in with fruits or not. However, animals cannot be divided on basis of these criteria. Animals are divided on the basis of their body structure.

6. Explain how animals in Vertebrata are classified into further subgroups.

Answer: Vertebrates are classified on the basis of their body structure from simple to complex.

Class	Characteristics	Examples
Pisces	Streamlined body Skin is covered with scales Heart has two chambers Gills are used for breathing Are cold blooded Lay eggs Body structure is made of bone or cartilage	Sea horse, Scoliodon, Rohu, etc
Amphibia	Three chambered heart Contains mucus gland inside skin Skin and lungs are responsible for breathing Lays eggs under water Can survive on water and land	Frog, Toad, Salamander, etc
Reptilia	Have scales on skin Breathe through lungs Cold blooded Heart is three chambered [except crocodile] Lay eggs on land	Snakes, Turtles, Lizards, Crocodiles, etc.
Aves	Warm blooded Have feathers and wings Breathing is done through lungs Lay eggs	Parrot, Pigeon, Ostrich, etc.
Mammalia	Have mammary glands Skin have hairs, sweat glands and oil glands Give birth to young one [except platypus]	Humans, Cats, Dogs, Whales, etc

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