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NCERT Solutions for Class 9th Science

 

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Chapter 7. Diversity in Living Organisms

Text-book Questions

 

 

 

Text-Book Questions With Solutions:

 

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Q1. Why do we classify organisms?

ans: We classify organism so that 

(i) We could study each of the organisms in our lifetime, as classification enables easy the study of organisms. 

(ii) It is neccessary to classify the organisms into various group to study their diversities and varieties. 

(iii) we could find out the group of organisms on the basis of similarities. 


Q2. Give three examples of the range of variations that you see in lifeforms around you.

Ans: Three examples of the range of variations;

(i) We have microscopic bacteria of a few micrometre in size. While on the other hand we have blue whale and red wood trees of california of approximate sizes of 30 metres and 100 metres repectively.

(ii) Some pine trees live for thousands of years while insects like mosquitoes die within a few days.

(iii) Some organisms like plants make their own food themselves while others like animals obtain from others. 

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Q1. 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?

Ans: The kind of cells they are made of is a more  basic characteristic for classifying organisms. Because,

(i) It open the way for the further division of classification.

(ii) This is the characteristics that decides the broadest divisions among living organisms.

(iii) It decides the variety in the next level. 

Q2. What is the primary characteristic on which the first division of organisms is made?

Ans: The primary characteristic is the cellular variety of organisms such as prokaryotic and eukaryotic cells. This is the basic characteristic of classification of organism.  

Q3. On what bases are plants and animals put into different categories?

Ans: Plants and animals are put into different categories on the following basis:

(i)     Organisms which have cell-wall and they make their own food i.e autotrophs are put into plants kingdom.

(ii)    Organisms which have no cell-wall and they do not make their own food i.e hetrotrophs are put into animals kingdom. 

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Q1. Which organisms are called primitive and how are they different from the so-called advanced organisms?

Ans: Organisms which have ancient body designs that have not change very much. Such organisms are called primitive organisms. On other side advanced organisms which have developed themselves and much differentiated their body design by formation of organs and organ system.  

Q2. Will advanced organisms be the same as complex organisms? Why?

Ans: Yes, advanced organisms have changed themselves in their body design. And they have quite complex body structure. Since there is a possibility that
complexity in design will increase over evolutionary time, therefore advanced organisms also gain complexity and be the same as complex organism. 

Q1. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

Ans: Organims which are completely prokaryotes are kept in the kingdom of Monera, while the  organisms of kingdom Protista are belong to eukaryotic organisms but unicelular. This is the criterion for classification of organisms as belonging to kingdom Monera or Protista.

Q2. In which kingdom will you place an organism which is singlecelled, eukaryotic and photosynthetic?

Ans: Kingdom Protista.

Q3. 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?

Ans: Species will have smallest number of organisms with a maximum of characteristics in common and Kingdom will have largest number of organisms.

Q1. Which division among plants has the simplest organisms?

Ans: Division Thallophyta.

Q2. How are pteridophytes different from the phanerogams?

Ans: 

                Pteridophytes                  Phanerogams

1. They have naked embryos that are called spores.

2. The reproductive organs of
plants in Pteridophytes are very inconspicuous.

 

1. have naked embryos that are
called spores.

2. These are plants with welldifferentiated reproductive tissues. 

3. Reproductive tissues that
ultimately make seeds. 

Q3. How do gymnosperms and angiosperms differ from each other?

Ans: 

              Gymnosperms

            Angiosperms

  1. They bear necked seed.
  2. They are usually perennial, evergreen and woody.
  1. The seeds develop inside fruit.
  2. They are flowering plants.  

 

Q1. How do poriferan animals differ from coelenterate animals?

Q2. How do annelid animals differ from arthropods?

Q3. What are the differences between amphibians and reptiles?

Q4. What are the differences between animals belonging to the Aves group and those in the mammalia group?

 

 

EXERCISE:

Q1. What are the advantages of classifying organisms?

Ans: The advantages of classification of Organisms.

(i)   It tells relations among the various classes of organisms.

(ii)  It describe about the evolution of organisms.

(iii) It makes simple the study of various organisms. 

Q2. How would you choose between two characteristics to be used
for developing a hierarchy in classification?

Ans: 

(i) The characteristics which is more fundamental or basic should be choosen first.

(ii) Choose the characteristics that decide the broadest divisions among living organisms.

(iii) Chose the characteristics that would decide the variety in the next level for forming a hierarchy in a classification.

 

Q3. Explain the basis for grouping organisms into five kingdoms.

Ans: The basis for grouping organisms into five kingdoms: 

(i) On the basis of cellular structure: like prokaryotic or eukaryotic cells.

(ii) On the basis of number of cells: like unicellular or multicellular.

(iii) On the basis of presence and absent of cell wall.

(iv) Mode of nutrition, like Performing photosynthesis or getting food from outside . 

Q4. What are the major divisions in the Plantae? What is the basis
for these divisions?

Ans: The major divisions in kingdom plantae are:

1. Thallophyta 2. Bryophyta 3. Pteridophyta 4. Gymnosperms and 5. Angiosperms

The following points constitute the basis of these divisions.

(i)  The first level of classification among plants depends on whether the plant body has welldifferentiated, distinct components.

(ii) The next level of classification is based on whether the differentiated plant body has special tissues for the transport of water and other substances within it.

(iii) Further classification looks at the ability to bear seeds and whether the seeds are enclosed within fruits.

 

Q5. How are the criteria for deciding divisions in plants different
from the criteria for deciding the subgroups among animals?

Q6. Explain how animals in Vertebrata are classified into further
subgroups.

 

 

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