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

NCERT Solutions for Class 9 Science (biology) Chapter 7 Diversity in Living Organisms are given below. In these solutions, we have answered all the intext and exercise questions provided in NCERT class 9 science textbook. Class 9 NCERT Solutions Science Chapter 7 provided in this article are strictly based on the CBSE syllabus and curriculum. Students can easily download these solutions in PDF format for free from our app.

Class 9 Science Chapter 7 Textbook Questions and Answers

INTEXT QUESTIONS

PAGE NO – 80

Question 1: Why do we classify organisms?

Answer: There are millions of species on this earth. For anybody, it is impossible to study about each of them in his lifetime. Classification makes it easy to study the organisms; on the basis of certain common characters.

Question 2: Give three examples of the range of variations that you see in life forms around you.

Answer: We can see following range of variations in different life forms:

(a) Variation in size: this variation can be observed at microscopic bacteria to the blue whale and red wood trees of California.

(b) Variation in lifespan: The insects like fruit flies live for few hours while some trees-like pine live for several years.

(c) Variations in body colours: Some living things are colourless, such as worms, whereas birds, insects, flowers are colourful.

PAGE NO. 82

Question 1: Which do you think is a more basic characteristic for classifying organisms?
(a) The place where they live.
(b) The kind of cells they are made of. Why?

Answer: The kind of cells an organism is made of is more basic characteristic of classifying organism because it gives a scientific angle to classification. Moreover, a particular dwelling place can be full of organisms of a wide variety.

Question 2: What is the primary characteristic on which the first division of organisms is made?

Answer: Organisation of nucleus is the primary characteristic on which the first division of organisms is made. Based on this, organisms can be either prokaryotic or eukaryotic.

Question 3: On what bases are plants and animals put into different categories?

Answer: The following is the basis for categorization of plants and animals:

(a) The most fundamental consideration of classification is the presence and absence of a cell wall.

(b) The next important criterion is the mode of nutrition. The mechanism through which entities acquire their nutrients is used as the base for classification.

PAGE NO. 83

Question 1: Which organisms are called primitive and how are they different from the so-called advanced organisms?

Answer: An organism which is simple is called primitive. On the other hand, an organism with high level of division of labour, by formation of organs and organ system is called advanced.

Or

A primitive organism or lower organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time. An advanced organism or higher organism has a complex body structure and organization. For example, an Amoeba is more primitive as compared to a starfish. Amoeba has a simple body structure and primitive features as compared to a starfish. Hence, an Amoeba is considered more primitive than a starfish.

Question 2: Will advanced organisms be the same as complex organisms? Why?

Answer: Complexity in body design evolves because of necessity to adapt according to the changing environment. Hence, a complex organism would be an advanced one; in comparison to a simple organism.

PAGE NO- 85

Question 1: What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

Answer: Organisms which are prokaryotes belong to the kingdom Monera. On the other hand, organisms which are eukaryotes and unicellular belong to the kingdom Protista.

Question 2: In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?

Answer: Kingdom Protista includes single celled, eukaryotic, and photosynthetic organisms.

Question 3: In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

Answer: In the hierarchy of classification,a species will have the smallest number of organisms with a maximum of characteristics in common, whereas the kingdom will have the largest number of organisms.

PAGE NO – 88

Question 1: Which division among plants has the simplest organisms?

Answer: Algae or Thallophyta has the simplest organisms among the plants.

Question 2: How are pteridophytes different from the phanerogams?

Answer:

Pteridophyta	Phanerogams
They have inconspicuous or less differentiated reproductive organs.	They have well developed reproductive organs.
They produce naked embryos called spores.	They produce seeds.
Ferns, Marsilea, Equisetum, etc. are examples of pteridophyta.	Pinus, Cycas, fir, etc. are examples of phanerogams.

Question 3: How do gymnosperms and angiosperms differ from each other?

Answer: Seeds are naked in gymnosperms, while they are covered in angiosperms. Gymnosperms do not bear flowers, while angiosperms bear flowers.

PAGE NO – 94

Question 1: How do poriferan animals differ from coelenterate animals?

Answer:

• Animals from Porifera show cellular level of organisation, while those from Coelenterata show tissue level of organisation.
• In Porifera there is no division of labour, while in Coelenterata some division of labour is seen.
• Porifera do not have coelom, while coelenterata have coelom.

Question 2: How do annelid animals differ from arthropods?

Answer: Segmented body in annelids, while true segmentation is absent in arthropods. Arthropods have joined appendages, which are absent in annelids.

Or

Annelids	Arthropods
Metameric segmentation is observed where the body is segmented from head to tail	Incomplete metameric segmentation. The body is not completely segmented
They are referred to as segmented worms	They are termed as animals with jointed legs
The coelom is the true body cavity they possess	Presence of a body cavity containing blood known as ‘haemocoel’
Breathing takes place through the skin	Breathing takes place through the trachea, gill, book lungs etc
Most of the annelids are hermaphrodites	They have separate sexes
Example – Nereis, Earthworm	Example – Housefly, crab

Question 3: What are the differences between amphibians and reptiles?

Answer:

Amphibians	Reptiles
They live on land as well as in water.	They live usually on land.
They are oviparous.	They are oviparous as well as viviparous.
Fertilization is external.	Fertilization is internal.
They can breathe through gills as well as lungs.	They breathe through lungs.
The heart is three-chambered.	The heart is three-chambered but the ventricle is further divided through a septum.
They secrete toxins from their skin to protect themselves from predators.	The skin is protected by hard scales, and they also secrete toxin through teeth and nails.
Skin is smooth and highly porous.	Skin is dry, hard and scaly.
The webbed feet help them to swim.	They have limbs to facilitate running and swimming.
Their eggs are covered with gel.	Their eggs are covered with a hard protective covering.

Question 4: What are the differences between animals belonging to the Aves group and those in the mammalian group?

Answer:

Aves	Mammalia
Body is covered with feathers	Body is covered with hairs
Teeth absent	Teeth present
They possess a beak	Beak absent
Forelimbs are present and modified to take a flight	Forelimbs are present and used for multiple activities
Bones are hollow	Bones are solid
Body is streamlined	Streamlining of body is not observed (except whales)

EXERCISE

Question 1: What are the advantages of classifying organisms?

Answer: There are millions of species on this earth. For anybody, it is impossible to study about each of them in his lifetime. Classification makes it easy to study the organisms; on the basis of certain common characters.

Or

There are a wide range of life forms (about 10 million-13 million species) around us. These life forms have existed and evolved on the Earth over millions of years ago. The huge range of these life forms makes it very difficult to study them one by one. Therefore, we look for similarities among them and classify them into different classes so that we can study these different classes as a whole. This makes our study easier.

Therefore, classification serves the following advantages:

(i) It determines the methods of organising the diversity of life on Earth.

(ii) It helps in understanding millions of life forms in detail.

(iii) It also helps in predicting the line of evolution.

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

 Answer: We need to look at the fact if given character is present in a small number of organisms or a larger number of organisms. In the first case, the commonality of characters would represent a species. In the latter case, the commonality of characters would represent a higher taxa; like genus, family, order or phylum.

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

Answer: The following factors govern the basis of grouping organisms into five kingdoms

• The number of cells present forms the first criteria.
• Next is the arrangement and the number of layers present.
• Another important factor for classification is the existence of cell wall.
• Classification of complex organisms is also based on the mode of intake of nutrition.
• To classify, we consider the organization level too.

Or

R.H. Whittaker proposed a five kingdom classification of living organisms on the basis of Linnaeus’ system of classification. The five kingdoms proposed by Whittaker are Monera, Protista, Fungi, Plantae, and Animalia.

The basis for grouping organisms into five kingdoms is as follows:

(i) On the basis of the presence or absence of membrane-bound organelles, all living organisms are divided into two broad categories of eukaryotes and prokaryotes. This division lead to the formation of kingdom Monera, which includes all prokaryotes.

(ii) Then, eukaryotes are divided as unicellular and multicellular, on the basis of cellularity. Unicellular eukaryotes form kingdom Protista, and multicellular eukaryotes form kingdom Fungi, Plantae, and Animalia.

(iii) Animals are then separated on the basis of the absence of a cell wall.

(iv) Since fungi and plants both contain a cell wall, they are separated into different kingdoms on the basis of their modes of nutrition. Fungi have saprophytic mode of nutrition, whereas plants have autotrophic mode of nutrition. This results in the formation of the five kingdoms.

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

Answer: The major divisions of Plantae and the basis for these divisions are as follows:

• Thallophyta: Simple body design; with no differentiation into root, stem and leaves.
• Bryophyta: Body is differentiated into stem and leaf-like structures. Vascular system is absent.
• Pteridophyta: Body is differentiated into root, stem and leaves. Vascular system is present. Reproductive organs are inconspicuous. Seeds are not produced.
• Gymnosperms: Seeds are naked.
• Angiosperms: Seeds are covered.

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

Answer: In the plant kingdom, morphological characters are taken into consideration while deciding about the divisions. Morphology is the study of shapes and forms of various parts. In the animal kingdom, anatomical characters are taken into consideration while deciding about subgroups. Anatomy is the study of various organs’ design in animals.

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

Answer: Vertebrata has two subclasses namely:

(i) Pisces: The body is streamlined. Muscular tail is present which assists in locomotion. Body is covered with scales. Paired gills are present; which can breathe oxygen dissolved in water. They are cold-blooded animals. The heart has only two chambers. They lay eggs.

(ii) Tetrapoda: Animals have four limbs for locomotion and hence the name tetrapoda.

Furthermore, the tetrapod animals are classified as:

(a) Amphibia: These animals are adapted to live both in water and land. Mucus glands on skin keep the skin moist. The animals breathe through skin when in water and through lungs when on land. The heart has three chambers. These are cold blooded animals. Examples: Frog, toad, salamander, etc.

(b) Reptilia: These animals show crawling movement for locomotion. Skin is hardened to form scales. Most of the reptilians have three chambered heart but crocodile has four-chambered heart. They don’t need water to lay eggs, rather eggs are covered with hard shells and laid on land. Examples: snakes, lizards, crocodile, turtle, etc.

(c) Aves: The body is covered with feathers. Forelimbs are modified into wings. These are warm-blooded animals. The heart has four chambers. Bones are hollow (pneumatic); which assists in flying. All the birds belong to this class.

(d) Mammalia: The body is covered with hairs. Skin has seat glands and sebaceous glands. Mammary glands are present in females and are used for nourishing the young ones. Most of the mammalians give birth to young ones and are called viviparous. Some of the mammals lay eggs and are called oviparous. Examples: human, chimpanzee, lion, platypus, horse, etc.

Class 9 Science NCERT Solutions Chapter Diversity in Living Organisms

CBSE Class 9 Science NCERT Solutions Chapter 7 helps students to clear their doubts and to score good marks in the board exam. All the questions are solved by experts with a detailed explanation that will help students complete their assignments & homework. Having a good grasp over CBSE NCERT Solutions for Class 9 Science will further help the students in their preparation for board exams and other competitive exams such as NTSE, Olympiad, etc.

NCERT Solutions for Class 9 Science Chapter 7 PDF

Below we have listed the topics discussed in NCERT Solutions for Class 9 Science Chapter 7. The list gives you a quick look at the different topics and subtopics of this chapter.

Section in NCERT Book	Topics Discussed
7.1	What is the Basis of Classification?
7.2	Classification and Evolution
7.3	The Hierarchy of Classification Groups
7.4	Plantae
7.5	Animalia
7.6	Nomenclature