NCERT Solutions for Class 9 Science Chapter 7 Diversity in Living Organisms
Class 9 Science NCERT Textbook Page 80
Question:- 1. Why do we classify organisms?
Answer:- We classify organism to make study about them easier and convenient for us.
Question:- 2. Give three examples of the range of variations that you see in life-forms around you.
Answer:- Three examples of the range of variations that we see in life-forms around us:-
- The size of organisms ranges from microscopic bacteria to blue whales.
- The colour of various organisms varies greatly whereas some worms are even transparent or colourless.
- Various organisms have a wide range of life spans. for example, a crow lives only 15 years, whereas a parrot can live up to 140 years.
Class 9 Science NCERT Textbook Page 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:- Various organisms may share the same habitat but they may have completely distinct forms and structures. As a result, their residence cannot be used to classify them. So the more basic characteristic for defining organisms is the type of cells they are formed of.
Question:- 2. What is the primary characteristic on which the broad division of organisms is made?
Answer:- The nature of cells is the fundamental characteristic that divides organisms. It is divided into two types: prokaryotic and eukaryotic cells, which are further divided into subclasses.
Question:- 3. On what bases are plants and animals put into different categories?
Answer:- Plants and animals are put into different categories on the basis of the presence and absence of a cell wall as well as the mode of nutrition.
Class 9 Science NCERT Textbook Page 83
Question:- 1. Which organisms are called primitive and how are they different from the so-called advanced organisms?
Answer:- In primitive organisms there were a simple cellular structure and there were no division of work. Whereas most advanced organisms have millions of cells and different organs and organ systems for various biological purposes.
Question:- 2. Will advanced organisms be the same as complex organisms? Why?
Answer:- Yes, advanced organisms are the same as comple organisms, Because advanced organisms means greater degree of evolution which leads to more complexity.
Class 9 Science NCERT Textbook Page 85
Question:- 1. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?
Answer:- The presence or absence of a well-defined nucleus determines whether an organism belongs to the kingdom Monera or Protista. The nucleus of Monera has no nuclear membrane, whereas the nucleus of Protista is well definednucleus.
Question:- 2. In which kingdom will you place an organism which is singlecelled, eukaryotic and photosynthetic?
Question:- 3. In the hierarchy of classification, which grouping will have the smallest number of organisms with maximum common characteristics and which will have the largest number of organisms?
Answer:- Answer: Kingdom Monera organisms will have a small number of organisms with the greatest number of features in common. And the kingdom Animalia will have the largest number of organisms.
Class 9 Science NCERT Textbook Page 88
Question:- 1. Which division among plants has the simplest organisms?
Answer:- Thallophyta or algae.
Question:- 2. How are pteridophytes different from the phanerogams?
Question:- 3. How do gymnosperms and angiosperms differ from each other?
Class 9 Science NCERT Textbook Page 94
Question:- 1. How do poriferan animals differ from coelenterate animals?
Division of labour is not noticed
Division of labour is observed
They show cellular level of organisation.
They show Tissue level of organisation.
For example:- Spongilla, Euplectella
For example:- Hydra, sea anemone, corals
Question:- 2. How do annelid animals differ from arthropods?
Question:- 3. What are the differences between amphibians and reptiles?
Question:- 4. What are the differences between animals belonging to the Aves group and those in the mammalian group?
Question:- 1. What are the advantages of classifying organisms?
Answer:- Following are the advantages of classifying organisms:
- It makes the study of various organisms much easier.
- It tells us about the inter-relationship among the different organisms.
- It helps us understanding the evolution of different organisms.
- It helps environmentalists to develop new methods of conservation of various plants and animals.
Question:- 2. How would you choose between two characteristics to be used for developing a hierarchy in classification?
Answer:- The basis of the start of the hierarchy will be formed by the Gross character while the Fine character will build the foundation of later phases.
Question:- 3. Explain the basis for grouping organisms into five kingdoms.
Answer:- The basis for grouping organisms into five kingdoms are following:-
- Number of cells
- Layer of cells
- Presence or absence of cell wall
- Mode of nutrition
- Level Of organization
Question:- 4. What are the major divisions in the Plantae? What is the basis for these divisions?
Answer:- The major divisions in Kingdom Plantae are:
- → Bryophyta
- → Pteridophyta
- → Gymnosperms
- → Angiosperms
These divisions are based on the following criteria:-
Whether the plant body has well-differentiated, distinct components; whether the differentiated plant body has particular tissues for transporting water and other substances; and whether the seeds are encased within fruits.
Question:- 5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?
Answer:- The basic structure of a plant’s body is a major criterion for distinguishing Thallophytes from Bryophytes. Aside from that, the presence or lack of seeds is a significant criterion. Gymnosperms and angiosperms are further divided based on whether or not the seeds are coated. It is self-evident that the morphological trait serves as the foundation for plant classification.
Animal taxonomy is based on smaller structural differences. As a result, cytology takes the role of morphology as the foundation. Animals are classed depending on their cell layers and whether or not they have a coelom. Animals are placed higher in the hierarchy based on the presence or lack of minor traits, such as the presence or absence of four legs.
Question:- 6. Explain how animals in Vertebrata are classified into further subgroups.
Answer:- Pisces and Tetrapoda are the two superclasses of vertebrates. Pisces animals have a streamlined physique with fins and tails to help them swim. Tetrapoda animals have four limbs for locomotion.
Tetrapoda is further divided into the following groups:
(a) Amphibia: These animals have evolved to live both in water and on land. When submerged, it is possible to breathe oxygen through the skin.
(b) Reptilia: Crawling animals that sire offspring. Extreme temperatures are difficult for skin to survive.
(c) Aves: The forelimbs of Aves have been modified into wings to aid in flight. There are beaks present. Feathers cover the entire body.
(d) Mammalia: Mammary glands are present to provide nourishment to the young. Hair grows on the surface of the skin. The majority of the creatures are viviparous.