Class 9 Science Chapter 7–Diversity in Living Organisms

Best NCERT Solutions Class 9 Science Chapter 7 Diversity in Living Organisms .”Diversity in Living Organisms,” the seventh chapter of Class 9 Science, focusses on comprehending the wide range of living forms on Earth and how they are categorised. Students are introduced to the ideas of taxonomy, biological variety, and organism classification in this chapter.

 

1. Why do we classify organisms?

Answer: Studying an organism’s properties is made easier and more convenient by its classification. Because distinct things exhibit similarities, we can classify them together and examine the group as a whole.

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

Answer: A few ranges of variances seen in various living forms are listed below:

(a) Tiny frog to massive whale

 

The eucalyptus tree’s creeper

 

(c) A multicoloured peacock to a black cuckoo

 

3. Which of the following 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:  Based on the type of cells that comprise an organism, the most fundamental classification of that organism should be determined. This is so that species with distinct features can coexist peacefully in the habitat while entities with comparable cell layouts will display traits that are equivalent.

4. What is the primary characteristic on which the broad division of organisms is made?

Answer: The nature of cells is the fundamental feature that mostly divides creatures. Prokaryotic and eukaryotic cells, which are further divided into subcategories, make up the broad classification.

5. On what basis are plants and animals put into different categories?

Answer: The following serves as the foundation for classifying both plants and animals:

(a) The existence or lack of a cell wall is the primary criterion for classification.

(b) The mode of nourishment is the following crucial factor. The basis for classification is the process by which an entity obtains nutrition.

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

Answer: Primitive organisms are defined as those that lack a division of labour and have extremely rudimentary mechanisms, structures, and cell arrangements. On the other hand, advanced organisms—like mammals—have millions of cells organised into numerous organs that each carry out a distinct role.

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

Answer: yes, advanced and complicated organisms are the same. The result of progress is the emergence of distinct cell configurations.

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

Answer: The way the nucleus develops is one of the main classification differences. Protista are defined as having clearly identifiable nuclei walls, whilst Monera are defined as having no nuclear membranes.

9. In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?

Answer: The nucleus wall of the cell must be clearly delineated since it is photosynthetic. It must therefore be categorised under the Protista kingdom.

10. 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:

(a) The creatures who make up the Kingdom Monera will be the fewest in number and share the greatest amount of traits.

(b) The greatest number of creatures will be found among those that belong to the Kingdom Animalia.

 

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11. Which division among plants has the simplest organisms?

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

Q12. How are pteridophytes different from phanerogams?

Answer:The following are the differences between pteridophytes and phanerogams:

Pteridophytes	Phanerogams
They possess a naked embryo	They possess a covered embryo
Exhibit unclear reproductive organ	Exhibit well-defined reproductive organ

Q13. How do gymnosperms and angiosperms differ from each other?

Answer: The seeds of angiosperms are coated, whereas the seeds of gymnosperms are bare.

14. How do poriferan animals differ from coelenterate animals?

Ans:

Listed below are the differences between poriferan and coelenterate animals:

Porifera	Coelenterata
Division of labour is not noticed	Division of labour is observed
The cellular level of the organisation exhibited	The tissue level of the organisation exhibited
Coelom absent	Coelom present

Q15. How do annelid animals differ from arthropods?

Answer: Listed below are the differences between annelid and arthropods:

Annelida	Arthropoda
The entire body is segmented into rings	Segmentation of the body into the head, abdomen and the thorax region
Skeleton is absent	Presence of exoskeleton
Hermaphrodites	Presence of different sexes, bisexuals present

Q16. What are the differences between amphibians and reptiles?

Answer:Listed below are the differences between amphibians and reptiles:

Amphibia	Reptilia
Skin is moist and soft	Skin is hardened
In water, they breathe through their skin	They can exist in water. They come to land to intake oxygen
Respire through lungs or gills	Respire through lungs
Capable of jumping	They crawl
Indirect development is noticed	Direct development observed

Q17. What are the differences between animals belonging to the Aves group and those in the mammalian group?

Answer: Listed below are the differences between animals belonging to the Aves group and the mammalian group:

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 the body is not observed (except for whales)

 

Exercise

Q1. What are the advantages of classifying organisms?

Answer:The following are some benefits of classifying organisms:

-It is simple to study an organism’s common traits after it has been classified.

-Scientific experiment analysis is made simpler.

-It is possible to interpret how humans interact with other entities. It is possible to research their relationships and dependencies.

-Commercial applications are made possible by genetically modifying and crossbreeding entities.

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

Answer:The coarse character will serve as the foundation for the first level of the hierarchy, while the fine character will serve as the foundation for subsequent levels.

For example:

-Because they have a spinal column, humans are classified as vertebrates.

-In order to classify tetrapods

-The presence of four limbs is taken into account for tetrapods.

-For mammals, the mammary gland is an essential component.

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

Answer:The following criteria determine how organisms are categorised into five kingdoms.

-The first condition is the quantity of cells.

-The configuration and quantity of layers are next.

-The presence of the cell wall is a crucial component in categorisation.

-The manner in which complex organisms consume their food is another factor in their classification.

-We take into account the organisational level when classifying.

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

Answer: The following table depicts plant division and the basis of classification for each division.

Division	Basis of Classification
Thallophyta or Algae	Like body
Bryophyta	The body is divided into leaf and stem
Pteridophyta	The body is separated into root, stem and leaf
Gymnosperm	Seed-bearing, naked seeds
Angiosperm	Seed bearings covered seeds

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

Answer:The fundamental cell structure is one of the key characteristics used to divide plants into Thallophytes and Bryophytes.
The classification of gymnosperms and angiosperms is based on how visible their seeds are.
Therefore, morphological traits are crucial for classifying plants. Cytology plays a major role in animal taxonomy since it accounts for minute structural changes.

-When classifying animals, morphology, cytology, and cell layers are important factors to take into account.

-The categorisation of higher hierarchies is determined by the presence or absence of different traits.

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

Answer: Vertebrata has two subclasses, namely

• Pisces
• Tetrapod

 

While the Tetrapoda species have four limbs for mobility, organisms in the Pisces subclass have streamlined bodies with tails and fins that aid in swimming.

Moreover, the following categories apply to Tetrapod animals:

 

1. Amphibians: Members of this category of animals are naturally adaptable. They live in the sea as well as on land. They exhibit the presence of specialist organs that enable underwater breathing.

2. Reptilia: Members of this class of animals are crawlers. They can survive very cold temperatures because of their thick skin.

3. Aves: These organisms have modified forelimbs that aid in their ability to fly. Instead of teeth, they are covered with feathers and have a beak.

4. Mammalia: These animals exhibit nurturing traits since they have mammary glands to nourish them. They have hair covering their skin, and the majority of them are naturally viviparous.

 

 

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