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Diversity In Living Organisms

Class 9th Science Bihar Board Solution
In Text Questions-pg-80
  1. Why do we classifyof organisms
  2. Give three examples of the range of variations that you see in life forms around you.…
In Text Questions-pg-82
  1. Where do you think is more basic characteristic for classifying organism? (a) the place…
  2. What is the primary characteristic on which the first division of organism is made?…
  3. On what basis are plants and animals put into different categories?…
In Text Questions-pg-83
  1. Which organisms are called primitive and how are they different form so-called advanced…
  2. Will advanced organisms be the same as complex organisms? Why?
In Text Questions-pg-85
  1. In which kingdom will you place an organism which is single-called, eukaryotic and…
  2. In the hierarchy of classification, which grouping will have the smallest number of…
In Text Questions-pg-88
  1. Which division among plants has the simplest organisms?
  2. How are pteridophytes different from the phanerogams?
  3. How do gymnosperms and angiosperms differ from each other?
In Text Questions-pg-94
  1. How do poriferan animals differ from coelenterate animals?
  2. How do annelid animals differ from arthropod animals?
  3. What are the differences between amphibians and reptiles?
  4. What are the differences between animals belonging the Aves group and those in the…
Exercise-pg-97
  1. What are the advantages of classifying organisms?
  2. 'How would you choose between two characteristics to be used for developing a hierarchy in…
  3. Explain the basis for groupings into five kingdoms.
  4. What are the major divisions in the Plantae? What is the basis of this division?…
  5. How are the criteria for deciding divisions in plants different from the criteria for…
  6. Explain how animals in Vertebrata are classified into further subgroups?…

In Text Questions-pg-80
Question 1.

Why do we need to classify organisms?


Answer:

We classify an organism because of the following reason:-

▪ There are a wide variety of living organisms on this earth, and they have great diversity in their physical appearance.

▪ The vast number of living organisms makes it very difficult to study them one by one.

Therefore, we look for similarities among the organisms, which will allow us to put them into different classes and then study different classes or groups as a whole. Thus, classification makes the study of an organism very easy.


Question 2.

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


Answer:

Various kinds of variations in life forms such as:

1) Variation in terms of size: microscopic bacteria are few micrometre in size while, on the other hand blue whale and red wood trees of california are approximate 30 metres and 100 metres in size repectively.


2) Variation in terms of age: Pine trees live for thousands of years while insects like mosquitoes die within a few days.


3) Variation in terms of colours: Worm are colourless or even transparent, on the other hand birds and flowers are brightly coloured.




In Text Questions-pg-82
Question 1.

Which do you think is more basic characteristic for classifying organism?
(a) the place where they live

(b) the kind of cells they are made of, why?


Answer: The correct answer is option b.
The better basis of classifying organisms is on the basis of their cellular make up i.e., the kind of cells they are made of.

Reason:

If we talk about where they live, then it won't be a very accurate way of classification because all different kinds of animals can stay at the same place. For example, in a forest we can find all kinds of organisms, mammals (lions, deer, rabbits), reptiles (lizards, snakes) insects and even single celled organisms like amoeba and paramecium. But these organisms are all very different from each other and we cannot use it classify organisms properly.

The most basis characteristic for classification is the cell type. This is because the very first basis of classification is to see whether an organism is a prokaryote or eukaryote. Once we know this, we are able to further classify an organism and gain better knowledge about them.

Question 2.

What is the primary characteristic on which the first division of organism is made?


Answer:

The primary characteristic on which the first division of organism is made is the nature of cell. It is a fundamental characteristic of classification. On the basis of nature of cell, all living organisms are classified into two categories- eukaryotic and prokaryotic. Eukaryotic cell has membrane-bound organelles and defined nucleus while prokaryotic cell does not have membrane-bound organelles and have primitive type of nucleus called nucleoid.



Question 3.

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


Answer:

Plants and animals put into different categories on the basis of:

(i) Mode of nutrition: Plants can synthesise their own food, i.e., they are autotrophic while animals are heterotropic.


(ii) Movement: Plants are static, i.e., they can not move while animals can move.


(iii) Cell wall: Plants have cell wall made up of cellulose while animals do not have cell wall.




In Text Questions-pg-83
Question 1.

Which organisms are called primitive and how are they different form so-called advanced organism?


Answer:

Primitive organism is one which has primitive or ancient body designs that have not changed very much over period of time. Whereas advanced organism has complex body structure and organisation. For example, Unicellular bacteria are primitive while multicellular eukaryotic mammalia are advanced organisms.



Question 2.

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


Answer:
  • There is a high possibility that advanced organisms would be similar to complex organisms.
  • The reason for this is that with time, as the organism evolves, the internal cellular machinery may gradually become more complex.
  • With evoltuion, beneficial traits get preserved in organisms, thus further increasing the complexity.


In Text Questions-pg-85
Question 1.

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


Answer:

Kingdom Protista have unicellular, eukaryotic and photosynthetic organisms.



Question 2.

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:
  • The taxon "species" has the smallest number of organisms having maximum of characteristics in common.
  • While taxon "kingdom" has the largest number of organisms with a maximum number of differences among its members.


In Text Questions-pg-88
Question 1.

Which division among plants has the simplest organisms?


Answer:

Thallophyta is the division of plants that has the simplest organisms. The organisms of this division are commonly called algae.



Question 2.

How are pteridophytes different from the phanerogams?


Answer:

Pteridohyta have naked embryo called spores and inconspicuous reproductive organs whereas phanerogams have well differentiated reproductive organs and covered embryo.



Question 3.

How do gymnosperms and angiosperms differ from each other?


Answer:

In Text Questions-pg-94
Question 1.

How do poriferan animals differ from coelenterate animals?


Answer:

Differences between Porifera and Coelenterata:



Question 2.

How do annelid animals differ from arthropod animals?


Answer:

Differences between Annelida and Arthropoda are:



Question 3.

What are the differences between amphibians and reptiles?


Answer:

Differences between amphibians and reptiles:



Question 4.

What are the differences between animals belonging the Aves group and those in the Mammalia group.


Answer:

Differences between Aves and Mammalia:




Exercise-pg-97
Question 1.

What are the advantages of classifying organisms?


Answer:

The classification of organisms have the following advantages:

•Classification makes the study of wide variety of organisms easier and systematic.


•It reveals relationship among the various groups of organisms.


•Classification gives information about the organisms which do not occur in one's locality.


•It helps to establish a hierarchy of groups of organisms.


•It provides a base for the study of other branches of biology.


•Classification reveals evolution trends by showing gradually increasing complexity of structure in various groups of organisms.



Question 2.

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


Answer:

To develop a hierarchy in classification, we choose the fundamental characteristics among several other characteristics are as follow:-

(1) This fundamental or basic characteristic helps to make the broad division.

(2) Then we should pick up next set of characteristics for making subgroups.For example, nature of cell and form of the body is considered to classify organisms into broad divisions (e.g., Prokaryotes and Eukaryotes).

(3)The characteristics of the next level should be dependent on the previous one that will decide the subsequent divisions of the groups.

(4) This process must continue and each time new characteristics should be used.


Question 3.

Explain the basis for groupings into five kingdoms.


Answer:

The basis for grouping of organisms into five kingdoms are:

1) The complexity of cell structure: It has two major cellular divisions within living things: Prokaryotic and Eukaryotic. Thus, two broad groups can be formed- one having prokaryotic cell structure and the other having eukaryotic cell structure.

2) Some cells: It divides living organisms into unicellular and multicellular.

3) Mode of nutrition: Organisms have two types of nutrition- autotrophic and heterotrophic

4) Based on the organisms that perform photosynthesis (plants), what is the level of organization of their body, that is unicellular and multicellular

5) the animals, how does the individual’s body develop and organize its different parts, and what are the specialized organs found for different functions


Question 4.

What are the major divisions in the Plantae? What is the basis of this division?


Answer:

The major division in the Kingdom Plantae are-

1. Thallophyta (Algae); 2. Bryophyta; 3. Pteridophyta; 4. Gymnospermae; 5. Angiospermae.


The division is based on the following features:


(a) Well-differentiated plant body: The first level of classification of plants is based on the presence and absence of well-differentiated plant body. Algae (Thallophyta) have simple and less differentiated plant body. Hence, they are separated from rest of the plants.


(b) Vascular tissue: The next level of classification is based on the presence and absence of vascular tissues (i.e., xylem and phloem). Bryophtes do not have vascular tissue, hence they are separated from the rest of the plants.


(c) Ability to bear seeds: The further classification is based on the ability to bear seeds. Pteridophytes do not bear seeds.


(d) Seeds naked or enclosed: Further it is classified whether seeds are naked or enclosed within fruits. The gymnosperms have naked seeds whereas Angiosperms bear seeds enclosed within the fruits.



Question 5.

How are the criteria for deciding divisions in plants different from the criteria for deciding the sub-groups among animals?


Answer: The criteria for classifying Kngdom Plantae into groups are different from the criteria for classifying Kingdom Animlia.

The main criteria for classifying Kingdom Plantae are:
1. Differentiation of body into different structures
2. Ability or inability to produce seeds
3. Seed structure: naked or enclosed
4. Presence or absence of tissues of transport

The main criteria for classifying Kingdom Animalia into sub-groups are elucidated.
1. Type of body organization
2. Body symmetry (radial, symmetrical, asymmetrical)
3. Presenveor absence of coelom
4. Presence or absence of segmentation.
5. Presence or absence of a backbone. (notochord)

Question 6.

Explain how animals in Vertebrata are classified into further subgroups?


Answer:

The vertebrates are further classified into subgroups on the basis of server characters such as:

•The kind of exoskeleton or endoskeleton.


•Number of chambers in heart.


•The kind of respiratory organs.


•The method of reproduction and giving birth to young ones.


On the basis of above mentioned characters the vertebrate is divided into following classes.


1) Pisces (fishes)- Exoskeleton of scales; two-chambered heart; breathing through gills.


2) Amphibia – Three chambered heart; breathing through gills only in larva; skin slimy.


3) Reptilia- Exoskeleton of scales or scutes; three chambered heart; laying eggs outside the water.


4) Aves (birds)- Exoskeleton of feathers; four chambered heart; lays eggs.


5) Mammalia- Exoskeleton of hair; four chambered heart; external ears; give birth to young ones.