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Chapter 7 - Diversity In Living Organisms Page no :-  80

Solution 1

There are large number of organisms and it is very difficult to study them individually, so classification enables us to deal with enormous diversity of life in an arranged manner.

Concept insight: Recall the need for classification.

Solution 2

We can see the following variations in the life forms around us:
i. Size: Organisms vary greatly in size-from microscopic bacteria to elephants, whales and large trees.

ii. Colour: The colour of various animals is quite different. Some worms are even colourless or transparent. Various types of pigments are found in plants.

iii. Life span: Life span of different organisms also varies greatly. Example - a mosquito lives only for a few days while a turtle can live for around 200 years. Some pine trees live for thousands of years.  

                   

Concept insight: Recall the need for classification.

Chapter 7 - Diversity In Living Organisms Page no :-  82

Solution 1

The more basic characteristic for classifying organisms is the kind of cells they are made of. It is because different organisms may share same habitat but may have entirely different form and structure. 

On the other hand, the kind of cells they possess will tell various things about them whether they are eukaryotes or prokaryotes, whether they are unicellular or multicellular organisms, etc.

Concept insight: Students should recall two categories of organisms-unicellular and multicellular organisms.

Solution 2

The primary characteristic on which the first division of organisms is made is the nature of the cell - prokaryotic or eukaryotic cell.

Concept insight: Recall the two types of cells - prokaryotic and eukaryotic cells.

Solution 3

Plants and animals are put into different categories on the following basis:Mode of Nutrition:

Mode of Nutrition:

·         Plants are autotrophs i.e. they are able to make their own food.

·         Animals are hetrotrophs i.e. they cannot make their own food. They depend on plants directly or indirectly for their food.

Concept insight: Recall the difference between plant and animal cell.

Chapter 7 - Diversity In Living Organisms Page no :-  83

Solution 1

Primitive organisms are those which have ancient body designs and have not changed much. They have simpler body design and are also called lower organisms.           

On the other land, the organisms which have acquired more complex structure and body design relatively recently are called advanced organisms. They have complex body design and are called higher organisms.

Concept insight: Difference in the organization of the cell that lead to the hierarchy of organization from cell to tissue to organ to organ system and finally to organism.

Solution 2

Yes.

It is because the 'advanced' organisms also were like the primitive ones once. They have acquired their complexity relatively recently.

There is a possibility that these advanced or 'younger' organisms acquire more complex structures during evolutionary time to compete and survive in the changing environment.

Example: Many advanced organisms are multicellular and have attained division of labour.

Concept insight: Recall the two types of cells - prokaryotic and eukaryotic.

Chapter 7 - Diversity In Living Organisms Page no :-  85

Solution 1

The organisms belonging to Kingdom Monera are unicellular and prokaryotic whereas the organisms belonging to Kingdom Protista are unicellular and eukaryotic.

Concept insight: Recall the basic structure of organisms of kingdom Monera and Protista.         

Solution 2

Kingdom Protista                       

Concept insight: Recall the basic characteristics of kingdom Protista.

Solution 3

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

Concept insight: Recall the hierarchy of classification.

Chapter 7 - Diversity In Living Organisms Page no :-  88

Solution 1

Division Thallophyta

Concept insight: Student should clearly remember the classification chart of Plant kingdom.

Solution 2

Pteridophytes	Phanerogams
(i) They have naked embryos. (ii)Reproductive organs are hidden or inconspicuous. (iii) Pteridophytes have special tissue for conduction of water but it is not much developed.	(i) Embryo is present in seed. Seed also contains stored food. (ii)  Reproductive organs are well developed (in gymnosperms cone and in angiosperms flower bear male and female organs). (iii)Phanerogams have well developed vascular tissue.

Concept insight:

·         Differences should always be written in tabular form.

·         Differences should be written in terms of their significance.

·         Write only those many numbers of differences as asked in the question.

·         Give example wherever possible.

Solution 3

Differences between gymnosperms and angiosperms

Gymnosperms	Angiosperms
1. The plants bear naked seeds. 2. They produce cones formed of sporophytes. The sporophytes carry the male and female sex organs. 3. Ovules are not enclosed in ovary. 4. Plants of this group are usually evergreen, perennial and woody.	1. Seeds are enclosed in fruits. 2. Reproductive organs are flowers. 3. Ovules are enclosed in ovary. 4. Plants of this group may be annual, biennial or perennial. They may be woody or non-woody.

Concept insight:

·         Differences should always be written in tabular form.

·         Differences should be written in terms of their significance.

·         Write only those many numbers of differences as asked in the question.

·         Give example wherever possible.

Chapter 7 – Diversity In Living Organisms Page no :-  94

Solution 1

Poriferan Animals

Coelenterate Animals

1. These organisms have minute pores called ostia all over the body and a large opening called osculum at the top for the exit of water. 2. Body is made up of a single layer of cells. 3. Canal system for circulating water through the body present. 4. External skeleton present. The body design involves very little differentiation and division into tissues. 5. These are non-motile animals and are attached to some solid support. 6. Tentacles are absent.

1. These organisms have a single pore. 2. Body is made of two layers of cells, one making the outer lining and the other the inner lining of the body. 3. No water canal system present in the body. 4. Skeleton absent. More body design differentiation is shown by these animals. 5. They are motile animals. Some species of this group live in colonies while others have a solitary life-span. 6. Tentacles are present.

Concept insight:

·         Differences should always be written in tabular form.

·         Differences should be written in terms of their significance.

·         Write only those many numbers of differences as stated in the question.

·         Give example wherever possible.

Solution 2

Annelids	Arthropods
1. They have true body cavity called 'coelom'. 2. Body bears lateral appendages for locomotion in the form of setae and Parapodia. 3. Organ differentiation occurs in a segmental fashion, with the segments lined up one after the other from head to tail. 4. They breathe through body surface. 5. They do not possess chitinous exoskeleton. 6.They have closed type of circulatory system.	1. The body cavity is blood filled and called "haemocoel". 2. Jointed legs are there for locomotion. 3. These animals are also segmented but lack complete metamaric segmentation. 4. They posses different organs for breathing, like gills, trachea booklungs, etc. 5. Chitinous exoskeleton present. 6. Open type of circulatory system present.

Concept insight:

·         Differences should always be written in tabular form.

·         Differences should be written in terms of their significance.

·         Write only those many numbers of differences as stated in the question.

·         Give example wherever possible.

Solution 3

Amphibians	Reptiles
1. They can live both on land and in water. 2. They breathe either through gills or lungs. 3. Body is not covered with scales. 4. Their eggs don't have any tough and hard covering around them. 5. They lay eggs in water and fertilization takes place in water.	1. They live either on land or in water. 2. They breathe through lungs only. 3. They have scales on their body. 4. The eggs have a hard covering. 5. Water is not necessary for fertilization.

Concept insight:

·         Differences should always be written in tabular form.

·         Differences should be written in terms of their significance.

·         Write only those many numbers of differences as stated in the question.

·         Give example wherever possible.

Solution 4

Aves	Mammalia
1. The body is covered with feathers. 2. Forelimbs are modified into wings. 3. They lay eggs. 4. No mammary glands to feed their young ones. 5. Bones have air cavities.	1. The body is covered with hairs. 2. They don't have wings. 3. Most of them give birth to young ones. 4. They have mammary glands for the production of milk for the nourishment of the young ones. 5. Bones are solid, hard and filled with bone marrow.

Concept insight:

·         Differences should always be written in tabular form.

·         Differences should be written in terms of their significance.

·         Write only those many numbers of differences as stated in the question.

·         Give example wherever possible.

Chapter 7 - Diversity In Living Organisms Page no :-  97 (Ex.)

Solution 1

Following are the advantages of classifying organisms:

i. It makes us aware of and gives us information regarding the diversity of plants and animals.
ii. It makes the study of different kinds of organisms much easier.
iii. It tells us about the inter-relationship among the various organisms.
iv. It helps us understanding the evolution of organisms.
v. It helps in the development of other life sciences easy.
vi. It helps environmentalists to develop new methods of conservation of plants and animals.

Concept insight: Recall the need for classification.

Solution 2

The characteristic which is more basic should be considered first.    

Next, choose those characteristics which are dependent on the previous ones and would decide the variety in the next level for developing a hierarchy in classification.

In case of classification of animals, the characteristics used to classify in a hierarchy are:

i. Prokaryotic or eukaryotic cell.

ii. Unicellular or multicellular cell type.

iii. Autotrophic or heterotrophic.

Concept insight: Classification of organisms starts with basic differences in the characteristics of organisms.

Solution 3

The basis for grouping organisms into five kingdoms is:

i. Complexity of cell structure - There are two broad categories of cell structure: Prokaryotic and Eukaryotic. Thus, two broad groups can be formed, one having prokaryotic cell structure and the other having eukaryotic cell structure. Presence or absence of cell wall is another important characteristic.

ii. Unicellular and multicellular organisms - This characteristic makes a very basic distinction in the body designs of organisms and helps in their broad categorizations. 

iii. Mode of nutrition -Organisms basically have two types of nutritions - autotrophic (they can manufacture their own food) and heterotrophic (they obtain their food from external environment, i.e., from other organisms). Thus, organisms can be broadly classified into different groups on the basis of their mode of nutrition. 

iv. Phylogenetic relationship - Phylogeny is the evolutionary history or ancestry of an organism. It is believed that the simple organisms are primitive and complex organisms are advanced. Thus, primitive and advance nature of organisms also helps in their classification into broad groups. For example, the Monera are believed to have given rise to Protista, from which the remaining three kingdom of multicellular organisms have evolved.

Concept insight: Classification of organisms starts with basic differences in the characteristics of organisms. Recall the main features in which one organism differs from the other.

Solution 4

The major divisions in Kingdom Plantae are:

i. Thallophyta

ii. Bryophyta

iii. Pteridophyta

iv. Gymnosperms

v. Angiosperms

The following points constitute the basis of these divisions:
i. Whether the plant body has well differentiated, distinct components.
ii. whether the differentiated plant body has special tissues for the transport of water and other substances.
iii. The ability to bear seeds.
iv. Whether the seeds are enclosed within fruits.

Concept insight: Recall the classification chart of the Plant Kingdom.

Solution 5

The characteristics used to classify plants is different from animals because the basic design are different, based on the need to make their own food (plants) or acquire food (animals). 

The criteria for dividing the plants include:
i. Differentiation of the plant body.
ii. Distinct vascular (conduction) tissues.
iii. Seed producing ability.
iv. Seeds are enclosed within fruits or not.

But the animals can't be divided into groups on these criteria. It is because the basic designs of animals are very different from plants. They are divided on the basis of their body structure.

Concept insight: Recall the basic differences between the plant and the animal kingdom.

Solution 6

Vertebrates can be further classified into subgroups on the basis of simple to complex body structures and their functions. For example, fishes have two chambered heart, amphibians have three chambered heart while birds and mammals have four chambered heart to keep the oxygenated and deoxygenated blood separate.

The following characteristic features are considered for classifying vertebrata into the further subgroups:

Class	Pisces	Amphibia	Reptilia	Aves	Mammalia
Characteristics	Exoskeleton of scales; endoskeleton of bone/cartilage; breathing through gills.	Gills in larva; lungs in most adults; slimy skin.	Exoskeleton of scales; lays eggs outside water.	Exoskeleton of feathers, lay eggs outside water, flight possible.	Exoskeleton of hair, external ears, mostly giving birth to live young ones.

Concept insight: Students should remember the main characteristics of kingdom Vertebrata.