CBSE - The Living World

A large variety of plants, animals, and microbes are found on earth. All these living organisms differ in size, shape, colour, habitat, and many other characteristics. As there are millions of living organisms on earth, studying each of them is impossible. Therefore, scientists have devised mechanisms to classify all living organisms.
These methods of classification are based on rules and principles that allow identification, nomenclature, and finally classification of an organism.

For example, based on certain principles, once an organism is identified as an insect, it will be given a scientific name and then grouped with other similar organisms. Thus, various groups or taxon include organisms based on their similarity and differences.

Therefore, the biological classification helps in revealing the relationship between various organisms. It also helps in making study of organisms easy and organized.

Millions of plants, animals, and microorganisms are found on earth. Many of these have been identified by the scientists while many new species are still being discovered around the world. Therefore, to classify these newly discovered species, new systems of classification have to be devised every now and then.

This creates the requirement to change the existing systems of classification.

To classify a class of forty students, let us start the classification on the basis of sexes of the students. This classification will result in the formation of two major groups- boys and girls.

Each of these two groups can be further classified on the basis of the names of the students falling in these groups.

Since it is possible that more than one student can have a particular name, these names can be further divided based on the surnames.

Since there is still some chance that more than one student can have the same surname, the final level of classification will be based on the roll numbers of each student.

The knowledge of characteristics of an individual or its entire population helps in the identification of similarities and dissimilarities among the individuals of same kind or between different types of organisms.

It helps the scientists to classify organisms in various categories.

In binomial system of nomenclature, the generic name of a species always starts with a capital letter whereas the specific name starts with a small letter. Therefore, the correct scientific name of Mango is Mangifera indica.

Each unit or category of classification is termed as a taxon. It represents a rank. For example, the basic level of classification is species, followed by genus, family, order, class, phylum or division, in ascending order.
The highest level of classification is known as kingdom.

The correct hierarchical arrangement of taxonomic categories in ascending order is

Species → Genus → Family → Order → Class → Phylum → Kingdom

Therefore, both (a) and (c) represent correct sequences of taxonomic categories.

In sequence (b), species should be followed by genus. Therefore, it does not represent the correct sequence.

In biological terms, species is the basic taxonomical rank. It can be defined as a group of similar organisms that are capable of interbreeding under natural conditions to produce fertile offsprings.

Therefore, a group of similar individuals that are respectively isolated form a species.

Species can also be defined as group of individuals that share the same gene pool.

(i) Phylum

Phylum is the primary division of kingdom. It includes one or more related classes of animals. In plants, instead of phylum, the term ‘division’ is used.

(ii) Class

Class is a taxonomic group consisting of one or more related orders. For example, the class, Mammalia, includes many orders.

(iii) Family

Family is a taxonomic group containing one or more related genera. In plants, families are categorized on the basis of vegetative and reproductive features.

(iv) Order

Order is a taxonomic group containing one or more families. For example, the order, carnivore, includes many families.

(v) Genus

Genus is a taxonomic group including closely related species. For example, the genus, Solanum, includes many species such as nigrum, melongena, tuberosum,etc.

Key is another taxonomical aid that helps in identification of plant and animal species. These keys are based on similarities and dissimilarities in characters, generally in a pair called couplet.

Each statement in a taxonomic key is referred to as a lead. For categorizing each taxonomic rank, such as family, genus, species, etc., different keys are used. It is also useful in identification of unknown organisms.

Keys are of two types- indented and bracketed keys. Indented key provides a sequence of choices between two or more statements while in bracketed key, a pair of contrasting characters are used.

(i) Indented key to identify different species of Rhododendron.

1. Leaves evergreen

2. leaves densely hairy below, orange or white hair; flower appears to have separate petals

………………………. Rhododendron groenlandicum

2. hair absent on leaves, flower has five petals fused in a shallow tube

………………………. Rhododendron maximus

1. Leaves deciduous

3. pink flowers with two free petals and three fused petals

………………………. Rhododendron canadense

3. white to pink flowers with all petals fused together

(ii) Bracketed key to identify different species of Rhododendron.

Leaves evergreen-----------------------------------------------2

1. Leaves deciduous-----------------------------------------------3

2. Leaves densely hairy below, orange or white hair; flower

appears to have separate petals

……….………………………. Rhododendron groenlandicum

2. Hair absent on leaves, flower has five petals fused in shallow

tube

………………………………..Rhododendron maximus

3. Pink flowers with two free petals and three fused petals

……………………………… Rhododendron canadense

3. White to pink flowers with all petals fused together-----4

The arrangement of various taxa in a hierarchical order is called taxonomic hierarchy.

In this hierarchy, species is present at the lowest level whereas kingdom is present at the highest level.

Kingdom
↑
Phylum or division
↑
Class
↑
Order
↑
Family
↑
Genus
↑
Species

A Taxonomic hierarchy

Classification of a plant

As an example, let us classify Solanum melongena (Brinjal).

Kingdom – Plantae

Division – Angiospermae

Class – Dicotyledonae

Order – Solanales

Family – Solanaceae

Genus – Solanum

Species – melongena

Classification of an animal

As an example, let us classify Columba livia (Blue rock Dove).

Kingdom – Animalia

Phylum – Chordata

Class – Aves

Order – Columbiformes

Family – Columbidae

Genus – Columba

Species – livia

As we go from species to kingdom in a taxonomic hierarchy, the number of
common characteristics
(a) Will decrease
(b) Will increase
(c) Remain same
(d) May increase or decrease 

ANS(a) Will decrease

Number of common characters is maximum among members of a particular species. On the other hand, number of common characters is minimum among members of a particular kingdom. 

Which of the following ‘suffixes’ used for units of classification in plants indicates
a taxonomic category of ‘family’. 
(a) – Ales 
(b) – Onae
(c) – Aceae
(d) – Ae 

ANS (c) – Aceae
ou can consider the names of families, e.g. Solanaceae, fabaceae, etc. 

The term ‘systematics’ refers to:
(a) Identification and study of organ systems
(b) Identification and preservation of plants and animals
(c) Diversity of kinds of organisms and their relationship
(d) Study of habitats of organisms and their classification

Ans. (c) Diversity of kinds of organisms and their relationship                                                                 

In fact, the need for a proper classification system was felt because of huge diversity of organisms. Based on certain relationships, organisms were classified into different group and sub-groups.

Genus represents

(a) An individual plant or animal
(b) A collection of plants or animals 
(c) Group of closely related species of plants or animals
(d) None of these 

Ans. (c) Group of closely related species of plants or animals

Taxon genus is just above the taxon species. 

The taxonomic unit ‘Phylum’ in the classification of animals is equivalent to which hierarchial level in classification of plants

(a) Class
(b) Order                                                      
(c) Division
(d) Family 

Ans. (c) Division

In animal kingdom, phylum comes just after the kingdom. Similarly, in the plant kingdom, division comes just after the kingdom. 

Botanical gardens and zoological parks have

(a) Collection of endemic living species only
(b) Collection of exotic living species only
(c) Collection of endemic and exotic living species
(d) Collection of only local plants and animals 

Ans. (c) Collection of endemic and exotic living species

To understand this, you can visit the zoo at Delhi or Kolkata. You can also search in Google image and you will find giraffes; along with tigers and lions. Tigers and lions are endemic species while giraffe is an exotic species.
 

Taxonomic key is one of the taxonomic tools in the identification and classification of plants and animals. It is used in the preparation of
(a) Monographs
(b) Flora
(c) Both (a) and (b)
(d) None of these 

ANS (c) Both (a) and (b) 

All living organisms are linked to one another because

(a) They have common genetic material of the same type
(b) They share common genetic material but to varying degrees
(c) All have common cellular organization
(d) All of above

ANS  (b) They share common genetic material but to varying degrees 

In fact, the whole theory of evolution is based on similarity of genetic materials which indicates towards common ancestry for living organisms. Variations in similarity of genetic material give biodiversity which we see all around us.

Which of the following is a defining characteristic of living organisms?

(a) Growth
(b) Ability to make sound
(c) Reproduction
(d) Response to external stimuli

Ans. (d) Response to external stimuli

Rest of the characters may not be apparent at every instance of time. But response to external stimuli can always be confirmed as and when required. So, this is  considered as a defining characteristic of living organisms. 
 

Match the following and choose the correct option:

Options
(a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A
(b) (i)-E, (ii)-D, (iii)-B, (iv)-A, (v)-C
(c) (i)-D, (ii)-E, (iii)-B, (iv)-A, (v)-C
(d) (i)-E, (ii)-C, (iii)-B, (iv)-A, (v)-D

ANS
(a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A 

It is true that a ball of snow increases in mass, volume and size; when it is rolled over. But in this case, the growth in size of the ball happens because of accumulation of material from outside. In case of growth in a living being, the growth happens because of accumulation of material from inside which is brought about by cell division and formation of new protoplasm.
Thus, growth in a snowball is altogether different when compared to the growth in a living being. 

Whenever we talk about biodiversity, we talk about all the life forms on the earth. In other words, the term ‘biodiversity’ is a universal term which encompasses all the organisms on the earth. But when we talk about a smaller geographical area; like an  ecosystem or a particular habitat; then the term ‘diversity’ is used. So, the given example of the habitat shows diversity. 

As per the ICBN, various hierarchies of units for classifying plants and suffixes used for such hierarchies are as follows:

Kingdom  - Plantae 

Division - Phyta 

Class  - Ae 

Order - Ales 

Family - Eae or – Ceae

Genus - Contains first name of organism which usually has Latin origin and written in italics 

Species - Contains second term of the scientific name which usually has Latin origin and written in italics.  

These variants are called biotypes. All biotypes are similar genetically but they are different morphologically. The morphological difference happens because of the differences in abiotic factors like temperature, pH of soil, climate etc. The difference in abiotic factors is the result of different altitudinal gradients.

Following are the various steps of preparing herbarium:
(a) Collection: This step involves collection of a particular species.
(b) Pressing: This step involves spreading the specimen and pressing it between two sheets of paper so as to preserve most of the parts.
(c) Drying: This step usually involves drying under the sun. 
(d) Poisoning: Sometimes, antifungal treatment needs to be given to the specimen to preserve it for longer duration.
(e) Mounting: This step involves mounting the specimen over a herbarium sheet.
(f) Labelling: This step involves writing full information and classification of the specimen.

Different tools which need to be carried while collecting plants for the preparation
of a herbarium are; digger and pruning knife, sickle, vasculum, polythene bags, old
newspaper or magazine, blotting paper, plant press, field notebooks, herbarium
sheets, glue, labels, etc.

The preserved material should have thorough information and classification. This should
include the names of division, order, family, genus and species. 

The sum of plant species in a given geographical area is called flora of that area. The sum of animal species in a given geographical area is called fauna of that area. The term ‘vegetation’ has wider scope than the term ‘flora’. Vegetation is often used for much wider  eographical area than a particular ecosystem. In many cases, the term ‘vegetation’ is used for all the plants on the global scale.

Endemic Species: A species which is found only in a particular geographical area is called the endemic species for that area. For example; Rauvolfia serpentina is found only in India. So, it is an endemic species in India. 

Exotic Species: A species which is not naturally found in a particular area but may be living because of careful selection and breeding or because of being imported is called an exotic species. For example, Eichhornia crassipes is native of other country but it was introduced in India. So, it is an exotic species in India. 

There are many languages and even more dialects being spoken in different parts of the  world. This means a plant may have different names in different regions of the country or world. This compounds the problem for anybody because nobody can remember all those names. To solve this problem, botanists have devised the system of binomial nomenclature so that a particular species can have unique name for the purpose of
scientific study.

A botanical name is usually composed of two terms, viz. genus name and species name. Care is taken to make a unique name for a particular species. 

Brinjal and potato belong to the same genus solanum because of certain common characters in them. Phyllotaxy, venation, inflorescence, etc. are some of the common characters in these plants which make them the member of the same genus. But breeding between a brinjal plant and a potato plant is not possible. Since capability to interbreed is the most defining criterion for members of a particular species; hence brinjal and
potato are kept under separate species although they belong to the same genus. 

No matter what is the function of a particular cell organelle; all the cell organelles are made up of more or less similar molecules. All the molecules come together in a particular fashion to build up a particular cell organelle. It is similar to the same brick making a small house or a big mansion of a factory. The constituents remain the same but the function and purpose of the finished product changes. Hence, properties of cell organelles
are not always found in the molecular constituents of cell organelles.

This question needs to be addressed from two perspectives, viz. number and variety. For any organism; the population cannot remain constant. In some of the generations,  pollution can be more because of favourable condition. In some other generations,  population can be less because of unfavourable conditions. The kinds of organism cannot be constant because evolution is a never ending process. In every era new species come
into origin and some old species become extinct.  

G Bentham and Joseph Dalton Hooker. Both are famous for their work on “classification of plants based on natural characteristics”. 

ICZN stands for International Code for Zoological Nomenclature.

Contrasting characters

A monograph contains information on any one taxon. A monograph provides work on primary research. 

After mitosis in Amoeba there is no growth in size of the organism rather two new organisms are formed. Hence, formation of new cells in Amoeba is reproduction. 

All the biological reactions in a living being are collectively called metabolism. 
Metabolism is of two types, viz, anabolism and catabolism.

All the biological reactions in a living being are collectively called metabolism. 
Metabolism is of two types, viz, anabolism and catabolism.

The Royal Botanical Garden in Kew (London) is the largest botanical garden in the world.
Some of the well known botanical gardens in India are as follows:
(a) Indian Botanical Garden, Sibpur, Kolkata
(b) Lloyad Botanical Garden, Darjeeling
(c) Botanical Garden of FRI, Dehradun
(d) National Botanical Garden, Lucknow

A living organism is self replicating, evolving and self-regulating interactive system capable of responding, to external stimuli. Growth, reproduction, nutrition, excretion, etc. are various characteristics of living beings. But most of these characteristics cannot be termed as defining features of life forms.

Defining features of life form are: Growth is defined as an increase in mass. Plants grow throughout their life, while most of the animals grow up to a certain age only. But some non-living things also grow in mass, e.g. cloud or snowball. So, growth cannot be termed as the defining feature of life.

Reproduction is the process by which a living being produces its own kind. Majority of organisms reproduce sexually, while many others reproduce asexually; by various methods. On the other hand, there are many living beings which do not reproduce at all, e.g. the worker bee in a beehive. But we consider it as a living being, So, reproduction  cannot be termed as an all inclusive defining feature of life. As non-living things cannot  reproduce; so, reproduction can be termed as a defining feature of life (with certain exceptions).

etabolism involves various biochemical processes during which various molecules are formed and many others get broken down. Metabolic  eaction cannot happen in a cellfree system. While some in-vitro reactions have been tried out in laboratories but they  cannot be termed as real metabolisms. So, metabolism is one of the defining features of life. 

Structural organization which begin with cellular organization is another character of living beings. Some molecules come together and work in perfect synchronization to form a cell organelle and various cell organelles come together to form a cell. Eventually, cells end up forming the tissue; which become organs and finally the whole organism is formed. Cells are altogether different than their constituent organelles; in terms of characters and functions. Similarly; a tissue is entirely different than its component cells; in terms of functions. Similar demarcation and hierarchy of organization is not possible in non-living things. Hence, cellular organization is a defining feature of life.
External stimuli can reach in various forms inside a living organism and the living being responds to each stimulus in a different way.

This can be termed as consciousness to the environment. Such a consciousness is not possible in non-living things. Hence, response to external stimuli is a defining feature of life.

 The scientist should look at various morphological features of the plant. He should begin with broad features; such as type of roots and venation. If fibrous roots are present then the plant may belong to monocotyledonous. In case of tap root, the plant may belong to dicotyledonous. This can be further confirmed with the presence of parallel or reticulate venation and number of cotyledons in the seeds. 
 
After that, the scientist should look at the type of phyllotaxy, inflorescence, etc. Which will help in classifying the plant in order and family. If it is a flowering plant, then a detail study of various floral parts can give various clues about a particular family or order. Type of placentation can be studied by looking at the arrangement of seeds inside the fruits.  Finally, arrangement of antheridium and gynoecium can help the scientist to confirm a particular family for the new species. The scientist also needs to rule out exact similarity with any other existing species before arriving at a unique name for the new species found. 

(a) The common name of Brassica compestris linn is mustard.
(b) The first part denotes the genus, while the second part denotes the species.
(c) These names are written in italics to show their Latin origin. Moreover, it is a convention to write scientific name in italics.
(d) The term ‘linn’ means that this species was first discovered and studies by Linnaeus.

 Tools which help the scientists in studying about plants and animal species are called taxonomical aids. Taxonomical aids include either live species of plants or animals or preserved remains. In case of animals; museum specimens are kept under proper preservation. In case of plants, herbariums are used for the keeping preserved specimens. 

Importance of Herbarium: Herbarium works as a repository of specimens for future reference. This also includes detail information about classification of a particular specimen. In many cases, herbarium serves as a quick referral system while studying about a particular species or about a higher taxonomical level. Herbarium is convenient to make and easier to maintain. It is also easy to transport a herbarium. Importance of Museums: Museums have much wider collection of plants and animal specimen. Museums may also have skeletons of many extinct animals. Thus, a museum offers more options of finding rich information while studying about a plant or animal.

Museums are usually maintained by educational institutions and thus they serve as important tool of study for students as well as for the scientists’ community. Role of Botanical and Zoological Parks in Conserving Biodiversity: Botanical and Zoological Parks serve the very important purpose of conserving the biodiversity. A botanical or zoological park is probably the most secure place for plants and animals to  live in their natural habitat. Especially trained personnel take good care of plants and animal species. They also carry out selective breeding of various plants and animals to
maintain the continuity of a particular species. Moreover, proper treatment is available in case some disease afflicts the plants and animals in such parks. Thus, it can be said that botanical and zoological parks play important role in conserving biodiversity. 

Taxon: A level of biological classification is called a taxon, e.g. phylum, order, family, etc. Taxonomic Hierarchy: In taxonomy, different taxa have their own different levels. This means that a particular taxon will come only after another particular taxon. For example; species always comes after the genus and it can never be the other way around. 

Flow Chart of Plant Categories
Kingdom →Division →Order →Family →Genus →Species
Flow Chart of Animal Categories
Kingdom →Phylum →Order →Family →Genus →Species
In Some cases, animals or plants are further classified into sub-groups; like super-class,
class or sub-phylum.
When we go up the taxonomic hierarchy; the number of common characters becomes lesser and lesser. For example; all members of a species will have the maximum number of common characters. On the other hand, all members of a genus will have a lesser number of common characters.
The number of individuals increases as we go up the taxonomical hierarchy.
 

Key is an important tool to study a taxonomic category. A key is composed of two contrasting characters. These characters generally occur in pairs and such a pair is called a couplet.
While studying a key; either of the contrasting characters is rejected or accepted. Thus, a choice is made between the two contrasting characters in a key. Each statement in the key is called a lead. It is important to note that a key is usually analytical in nature. Moreover, separate keys need to be used for different taxonomic categories.
Keys help in step-by-step identification of a particular organism. For example; presence or absence of notochord gives us a clue whether the organism belongs to vertebrate or invertebrate. Similarly, presence of absence of lungs tells us if the organism belongs to tetrapoda or pisces.   

Metabolism involves various biochemical processes during which various molecules are formed and many others get broken down. All organisms exhibit metabolism, e.g. protozoans, algae, fungi, bacteria, etc. Metabolic reactions cannot happen in a cell-free system.

While isolated in-vitro reactions carried out in laboratories cannot be termed as metabolism because they are conducted in controlled environment and are simulated. 
But such reactions can be termed as living reactions because they are the reactions going inside a living system. 

When it comes to human beings, it is very difficult to define the living state. A person may lie in coma for several years. By technical definition, the person is alive because he is not brain-dead. However, most of his vital organs have stopped functioning. Such a person is kept alive with life support system. A heart and lung machine works continuously to perform the function of oxygenation and circulation. A dialysis unit may be in place to perform the function of kidneys. The person gets nutrition through intravenous fluids. Since the person is in comma so he is not exhibiting consciousness to his environment. In other words, he is not exhibiting response to stimuli; which is one of the defining criteria for life.
Since the person is being kept alive because of life support system; metabolic activities are going on. Hence, the person can be considered as dead. 

But we should not forget that once he is put off the life support system; he will become brain-dead immediately and will be dead by technical definition. 
So, this is a difficult question whether a person in comma is dead or alive.  

Ans. 

It is indeed true that some of the properties of tissues are not the constituents of its cells.

Following three examples support this statement:
(a) A muscle tissue is capable of contraction but all its constituent cells may not be capable of doing so.
(b) The skeletal system is composed of bones and cartilage. A bone is hard and lightweight but its constituents may exhibit similar property.
(c) Blood is capable of carrying oxygen but WBCs are not capable of doing in spite of being the constituents of blood.  

A large variety of plants, animals, and microbes are found on earth. All these living organisms differ in size, shape, colour, habitat, and many other characteristics. As there are millions of living organisms on earth, studying each of them is impossible. Therefore, scientists have devised mechanisms to classify all living organisms.
These methods of classification are based on rules and principles that allow identification, nomenclature, and finally classification of an organism.

For example, based on certain principles, once an organism is identified as an insect, it will be given a scientific name and then grouped with other similar organisms. Thus, various groups or taxon include organisms based on their similarity and differences.

Therefore, the biological classification helps in revealing the relationship between various organisms. It also helps in making study of organisms easy and organized.

Millions of plants, animals, and microorganisms are found on earth. Many of these have been identified by the scientists while many new species are still being discovered around the world. Therefore, to classify these newly discovered species, new systems of classification have to be devised every now and then.

This creates the requirement to change the existing systems of classification.

To classify a class of forty students, let us start the classification on the basis of sexes of the students. This classification will result in the formation of two major groups- boys and girls.

Each of these two groups can be further classified on the basis of the names of the students falling in these groups.

Since it is possible that more than one student can have a particular name, these names can be further divided based on the surnames.

Since there is still some chance that more than one student can have the same surname, the final level of classification will be based on the roll numbers of each student.

The knowledge of characteristics of an individual or its entire population helps in the identification of similarities and dissimilarities among the individuals of same kind or between different types of organisms.

It helps the scientists to classify organisms in various categories.

In binomial system of nomenclature, the generic name of a species always starts with a capital letter whereas the specific name starts with a small letter. Therefore, the correct scientific name of Mango is Mangifera indica.

Each unit or category of classification is termed as a taxon. It represents a rank. For example, the basic level of classification is species, followed by genus, family, order, class, phylum or division, in ascending order.
The highest level of classification is known as kingdom.

The correct hierarchical arrangement of taxonomic categories in ascending order is

Species → Genus → Family → Order → Class → Phylum → Kingdom

Therefore, both (a) and (c) represent correct sequences of taxonomic categories.

In sequence (b), species should be followed by genus. Therefore, it does not represent the correct sequence.

In biological terms, species is the basic taxonomical rank. It can be defined as a group of similar organisms that are capable of interbreeding under natural conditions to produce fertile offsprings.

Therefore, a group of similar individuals that are respectively isolated form a species.

Species can also be defined as group of individuals that share the same gene pool.

(i) Phylum

Phylum is the primary division of kingdom. It includes one or more related classes of animals. In plants, instead of phylum, the term ‘division’ is used.

(ii) Class

Class is a taxonomic group consisting of one or more related orders. For example, the class, Mammalia, includes many orders.

(iii) Family

Family is a taxonomic group containing one or more related genera. In plants, families are categorized on the basis of vegetative and reproductive features.

(iv) Order

Order is a taxonomic group containing one or more families. For example, the order, carnivore, includes many families.

(v) Genus

Genus is a taxonomic group including closely related species. For example, the genus, Solanum, includes many species such as nigrum, melongena, tuberosum,etc.

Key is another taxonomical aid that helps in identification of plant and animal species. These keys are based on similarities and dissimilarities in characters, generally in a pair called couplet.

Each statement in a taxonomic key is referred to as a lead. For categorizing each taxonomic rank, such as family, genus, species, etc., different keys are used. It is also useful in identification of unknown organisms.

Keys are of two types- indented and bracketed keys. Indented key provides a sequence of choices between two or more statements while in bracketed key, a pair of contrasting characters are used.

(i) Indented key to identify different species of Rhododendron.

1. Leaves evergreen

2. leaves densely hairy below, orange or white hair; flower appears to have separate petals

………………………. Rhododendron groenlandicum

2. hair absent on leaves, flower has five petals fused in a shallow tube

………………………. Rhododendron maximus

1. Leaves deciduous

3. pink flowers with two free petals and three fused petals

………………………. Rhododendron canadense

3. white to pink flowers with all petals fused together

(ii) Bracketed key to identify different species of Rhododendron.

Leaves evergreen-----------------------------------------------2

1. Leaves deciduous-----------------------------------------------3

2. Leaves densely hairy below, orange or white hair; flower

appears to have separate petals

……….………………………. Rhododendron groenlandicum

2. Hair absent on leaves, flower has five petals fused in shallow

tube

………………………………..Rhododendron maximus

3. Pink flowers with two free petals and three fused petals

……………………………… Rhododendron canadense

3. White to pink flowers with all petals fused together-----4

The arrangement of various taxa in a hierarchical order is called taxonomic hierarchy.

In this hierarchy, species is present at the lowest level whereas kingdom is present at the highest level.

Kingdom
↑
Phylum or division
↑
Class
↑
Order
↑
Family
↑
Genus
↑
Species

A Taxonomic hierarchy

Classification of a plant

As an example, let us classify Solanum melongena (Brinjal).

Kingdom – Plantae

Division – Angiospermae

Class – Dicotyledonae

Order – Solanales

Family – Solanaceae

Genus – Solanum

Species – melongena

Classification of an animal

As an example, let us classify Columba livia (Blue rock Dove).

Kingdom – Animalia

Phylum – Chordata

Class – Aves

Order – Columbiformes

Family – Columbidae

Genus – Columba

Species – livia

As we go from species to kingdom in a taxonomic hierarchy, the number of
common characteristics
(a) Will decrease
(b) Will increase
(c) Remain same
(d) May increase or decrease 

ANS(a) Will decrease

Number of common characters is maximum among members of a particular species. On the other hand, number of common characters is minimum among members of a particular kingdom. 

Which of the following ‘suffixes’ used for units of classification in plants indicates
a taxonomic category of ‘family’. 
(a) – Ales 
(b) – Onae
(c) – Aceae
(d) – Ae 

ANS (c) – Aceae
ou can consider the names of families, e.g. Solanaceae, fabaceae, etc. 

The term ‘systematics’ refers to:
(a) Identification and study of organ systems
(b) Identification and preservation of plants and animals
(c) Diversity of kinds of organisms and their relationship
(d) Study of habitats of organisms and their classification

Ans. (c) Diversity of kinds of organisms and their relationship                                                                 

In fact, the need for a proper classification system was felt because of huge diversity of organisms. Based on certain relationships, organisms were classified into different group and sub-groups.

Genus represents

(a) An individual plant or animal
(b) A collection of plants or animals 
(c) Group of closely related species of plants or animals
(d) None of these 

Ans. (c) Group of closely related species of plants or animals

Taxon genus is just above the taxon species. 

The taxonomic unit ‘Phylum’ in the classification of animals is equivalent to which hierarchial level in classification of plants

(a) Class
(b) Order                                                      
(c) Division
(d) Family 

Ans. (c) Division

In animal kingdom, phylum comes just after the kingdom. Similarly, in the plant kingdom, division comes just after the kingdom. 

Botanical gardens and zoological parks have

(a) Collection of endemic living species only
(b) Collection of exotic living species only
(c) Collection of endemic and exotic living species
(d) Collection of only local plants and animals 

Ans. (c) Collection of endemic and exotic living species

To understand this, you can visit the zoo at Delhi or Kolkata. You can also search in Google image and you will find giraffes; along with tigers and lions. Tigers and lions are endemic species while giraffe is an exotic species.
 

Taxonomic key is one of the taxonomic tools in the identification and classification of plants and animals. It is used in the preparation of
(a) Monographs
(b) Flora
(c) Both (a) and (b)
(d) None of these 

ANS (c) Both (a) and (b) 

All living organisms are linked to one another because

(a) They have common genetic material of the same type
(b) They share common genetic material but to varying degrees
(c) All have common cellular organization
(d) All of above

ANS  (b) They share common genetic material but to varying degrees 

In fact, the whole theory of evolution is based on similarity of genetic materials which indicates towards common ancestry for living organisms. Variations in similarity of genetic material give biodiversity which we see all around us.

Which of the following is a defining characteristic of living organisms?

(a) Growth
(b) Ability to make sound
(c) Reproduction
(d) Response to external stimuli

Ans. (d) Response to external stimuli

Rest of the characters may not be apparent at every instance of time. But response to external stimuli can always be confirmed as and when required. So, this is  considered as a defining characteristic of living organisms. 
 

Match the following and choose the correct option:

Options
(a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A
(b) (i)-E, (ii)-D, (iii)-B, (iv)-A, (v)-C
(c) (i)-D, (ii)-E, (iii)-B, (iv)-A, (v)-C
(d) (i)-E, (ii)-C, (iii)-B, (iv)-A, (v)-D

ANS
(a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A 

It is true that a ball of snow increases in mass, volume and size; when it is rolled over. But in this case, the growth in size of the ball happens because of accumulation of material from outside. In case of growth in a living being, the growth happens because of accumulation of material from inside which is brought about by cell division and formation of new protoplasm.
Thus, growth in a snowball is altogether different when compared to the growth in a living being. 

Whenever we talk about biodiversity, we talk about all the life forms on the earth. In other words, the term ‘biodiversity’ is a universal term which encompasses all the organisms on the earth. But when we talk about a smaller geographical area; like an  ecosystem or a particular habitat; then the term ‘diversity’ is used. So, the given example of the habitat shows diversity. 

As per the ICBN, various hierarchies of units for classifying plants and suffixes used for such hierarchies are as follows:

Kingdom  - Plantae 

Division - Phyta 

Class  - Ae 

Order - Ales 

Family - Eae or – Ceae

Genus - Contains first name of organism which usually has Latin origin and written in italics 

Species - Contains second term of the scientific name which usually has Latin origin and written in italics.  

These variants are called biotypes. All biotypes are similar genetically but they are different morphologically. The morphological difference happens because of the differences in abiotic factors like temperature, pH of soil, climate etc. The difference in abiotic factors is the result of different altitudinal gradients.

Following are the various steps of preparing herbarium:
(a) Collection: This step involves collection of a particular species.
(b) Pressing: This step involves spreading the specimen and pressing it between two sheets of paper so as to preserve most of the parts.
(c) Drying: This step usually involves drying under the sun. 
(d) Poisoning: Sometimes, antifungal treatment needs to be given to the specimen to preserve it for longer duration.
(e) Mounting: This step involves mounting the specimen over a herbarium sheet.
(f) Labelling: This step involves writing full information and classification of the specimen.

Different tools which need to be carried while collecting plants for the preparation
of a herbarium are; digger and pruning knife, sickle, vasculum, polythene bags, old
newspaper or magazine, blotting paper, plant press, field notebooks, herbarium
sheets, glue, labels, etc.

The preserved material should have thorough information and classification. This should
include the names of division, order, family, genus and species. 

The sum of plant species in a given geographical area is called flora of that area. The sum of animal species in a given geographical area is called fauna of that area. The term ‘vegetation’ has wider scope than the term ‘flora’. Vegetation is often used for much wider  eographical area than a particular ecosystem. In many cases, the term ‘vegetation’ is used for all the plants on the global scale.

Endemic Species: A species which is found only in a particular geographical area is called the endemic species for that area. For example; Rauvolfia serpentina is found only in India. So, it is an endemic species in India. 

Exotic Species: A species which is not naturally found in a particular area but may be living because of careful selection and breeding or because of being imported is called an exotic species. For example, Eichhornia crassipes is native of other country but it was introduced in India. So, it is an exotic species in India. 

There are many languages and even more dialects being spoken in different parts of the  world. This means a plant may have different names in different regions of the country or world. This compounds the problem for anybody because nobody can remember all those names. To solve this problem, botanists have devised the system of binomial nomenclature so that a particular species can have unique name for the purpose of
scientific study.

A botanical name is usually composed of two terms, viz. genus name and species name. Care is taken to make a unique name for a particular species. 

Brinjal and potato belong to the same genus solanum because of certain common characters in them. Phyllotaxy, venation, inflorescence, etc. are some of the common characters in these plants which make them the member of the same genus. But breeding between a brinjal plant and a potato plant is not possible. Since capability to interbreed is the most defining criterion for members of a particular species; hence brinjal and
potato are kept under separate species although they belong to the same genus. 

No matter what is the function of a particular cell organelle; all the cell organelles are made up of more or less similar molecules. All the molecules come together in a particular fashion to build up a particular cell organelle. It is similar to the same brick making a small house or a big mansion of a factory. The constituents remain the same but the function and purpose of the finished product changes. Hence, properties of cell organelles
are not always found in the molecular constituents of cell organelles.

This question needs to be addressed from two perspectives, viz. number and variety. For any organism; the population cannot remain constant. In some of the generations,  pollution can be more because of favourable condition. In some other generations,  population can be less because of unfavourable conditions. The kinds of organism cannot be constant because evolution is a never ending process. In every era new species come
into origin and some old species become extinct.  

G Bentham and Joseph Dalton Hooker. Both are famous for their work on “classification of plants based on natural characteristics”. 

ICZN stands for International Code for Zoological Nomenclature.

Contrasting characters

A monograph contains information on any one taxon. A monograph provides work on primary research. 

After mitosis in Amoeba there is no growth in size of the organism rather two new organisms are formed. Hence, formation of new cells in Amoeba is reproduction. 

All the biological reactions in a living being are collectively called metabolism. 
Metabolism is of two types, viz, anabolism and catabolism.

All the biological reactions in a living being are collectively called metabolism. 
Metabolism is of two types, viz, anabolism and catabolism.

The Royal Botanical Garden in Kew (London) is the largest botanical garden in the world.
Some of the well known botanical gardens in India are as follows:
(a) Indian Botanical Garden, Sibpur, Kolkata
(b) Lloyad Botanical Garden, Darjeeling
(c) Botanical Garden of FRI, Dehradun
(d) National Botanical Garden, Lucknow

A living organism is self replicating, evolving and self-regulating interactive system capable of responding, to external stimuli. Growth, reproduction, nutrition, excretion, etc. are various characteristics of living beings. But most of these characteristics cannot be termed as defining features of life forms.

Defining features of life form are: Growth is defined as an increase in mass. Plants grow throughout their life, while most of the animals grow up to a certain age only. But some non-living things also grow in mass, e.g. cloud or snowball. So, growth cannot be termed as the defining feature of life.

Reproduction is the process by which a living being produces its own kind. Majority of organisms reproduce sexually, while many others reproduce asexually; by various methods. On the other hand, there are many living beings which do not reproduce at all, e.g. the worker bee in a beehive. But we consider it as a living being, So, reproduction  cannot be termed as an all inclusive defining feature of life. As non-living things cannot  reproduce; so, reproduction can be termed as a defining feature of life (with certain exceptions).

etabolism involves various biochemical processes during which various molecules are formed and many others get broken down. Metabolic  eaction cannot happen in a cellfree system. While some in-vitro reactions have been tried out in laboratories but they  cannot be termed as real metabolisms. So, metabolism is one of the defining features of life. 

Structural organization which begin with cellular organization is another character of living beings. Some molecules come together and work in perfect synchronization to form a cell organelle and various cell organelles come together to form a cell. Eventually, cells end up forming the tissue; which become organs and finally the whole organism is formed. Cells are altogether different than their constituent organelles; in terms of characters and functions. Similarly; a tissue is entirely different than its component cells; in terms of functions. Similar demarcation and hierarchy of organization is not possible in non-living things. Hence, cellular organization is a defining feature of life.
External stimuli can reach in various forms inside a living organism and the living being responds to each stimulus in a different way.

This can be termed as consciousness to the environment. Such a consciousness is not possible in non-living things. Hence, response to external stimuli is a defining feature of life.

 The scientist should look at various morphological features of the plant. He should begin with broad features; such as type of roots and venation. If fibrous roots are present then the plant may belong to monocotyledonous. In case of tap root, the plant may belong to dicotyledonous. This can be further confirmed with the presence of parallel or reticulate venation and number of cotyledons in the seeds. 
 
After that, the scientist should look at the type of phyllotaxy, inflorescence, etc. Which will help in classifying the plant in order and family. If it is a flowering plant, then a detail study of various floral parts can give various clues about a particular family or order. Type of placentation can be studied by looking at the arrangement of seeds inside the fruits.  Finally, arrangement of antheridium and gynoecium can help the scientist to confirm a particular family for the new species. The scientist also needs to rule out exact similarity with any other existing species before arriving at a unique name for the new species found. 

(a) The common name of Brassica compestris linn is mustard.
(b) The first part denotes the genus, while the second part denotes the species.
(c) These names are written in italics to show their Latin origin. Moreover, it is a convention to write scientific name in italics.
(d) The term ‘linn’ means that this species was first discovered and studies by Linnaeus.

 Tools which help the scientists in studying about plants and animal species are called taxonomical aids. Taxonomical aids include either live species of plants or animals or preserved remains. In case of animals; museum specimens are kept under proper preservation. In case of plants, herbariums are used for the keeping preserved specimens. 

Importance of Herbarium: Herbarium works as a repository of specimens for future reference. This also includes detail information about classification of a particular specimen. In many cases, herbarium serves as a quick referral system while studying about a particular species or about a higher taxonomical level. Herbarium is convenient to make and easier to maintain. It is also easy to transport a herbarium. Importance of Museums: Museums have much wider collection of plants and animal specimen. Museums may also have skeletons of many extinct animals. Thus, a museum offers more options of finding rich information while studying about a plant or animal.

Museums are usually maintained by educational institutions and thus they serve as important tool of study for students as well as for the scientists’ community. Role of Botanical and Zoological Parks in Conserving Biodiversity: Botanical and Zoological Parks serve the very important purpose of conserving the biodiversity. A botanical or zoological park is probably the most secure place for plants and animals to  live in their natural habitat. Especially trained personnel take good care of plants and animal species. They also carry out selective breeding of various plants and animals to
maintain the continuity of a particular species. Moreover, proper treatment is available in case some disease afflicts the plants and animals in such parks. Thus, it can be said that botanical and zoological parks play important role in conserving biodiversity. 

Taxon: A level of biological classification is called a taxon, e.g. phylum, order, family, etc. Taxonomic Hierarchy: In taxonomy, different taxa have their own different levels. This means that a particular taxon will come only after another particular taxon. For example; species always comes after the genus and it can never be the other way around. 

Flow Chart of Plant Categories
Kingdom →Division →Order →Family →Genus →Species
Flow Chart of Animal Categories
Kingdom →Phylum →Order →Family →Genus →Species
In Some cases, animals or plants are further classified into sub-groups; like super-class,
class or sub-phylum.
When we go up the taxonomic hierarchy; the number of common characters becomes lesser and lesser. For example; all members of a species will have the maximum number of common characters. On the other hand, all members of a genus will have a lesser number of common characters.
The number of individuals increases as we go up the taxonomical hierarchy.
 

Key is an important tool to study a taxonomic category. A key is composed of two contrasting characters. These characters generally occur in pairs and such a pair is called a couplet.
While studying a key; either of the contrasting characters is rejected or accepted. Thus, a choice is made between the two contrasting characters in a key. Each statement in the key is called a lead. It is important to note that a key is usually analytical in nature. Moreover, separate keys need to be used for different taxonomic categories.
Keys help in step-by-step identification of a particular organism. For example; presence or absence of notochord gives us a clue whether the organism belongs to vertebrate or invertebrate. Similarly, presence of absence of lungs tells us if the organism belongs to tetrapoda or pisces.   

Metabolism involves various biochemical processes during which various molecules are formed and many others get broken down. All organisms exhibit metabolism, e.g. protozoans, algae, fungi, bacteria, etc. Metabolic reactions cannot happen in a cell-free system.

While isolated in-vitro reactions carried out in laboratories cannot be termed as metabolism because they are conducted in controlled environment and are simulated. 
But such reactions can be termed as living reactions because they are the reactions going inside a living system. 

When it comes to human beings, it is very difficult to define the living state. A person may lie in coma for several years. By technical definition, the person is alive because he is not brain-dead. However, most of his vital organs have stopped functioning. Such a person is kept alive with life support system. A heart and lung machine works continuously to perform the function of oxygenation and circulation. A dialysis unit may be in place to perform the function of kidneys. The person gets nutrition through intravenous fluids. Since the person is in comma so he is not exhibiting consciousness to his environment. In other words, he is not exhibiting response to stimuli; which is one of the defining criteria for life.
Since the person is being kept alive because of life support system; metabolic activities are going on. Hence, the person can be considered as dead. 

But we should not forget that once he is put off the life support system; he will become brain-dead immediately and will be dead by technical definition. 
So, this is a difficult question whether a person in comma is dead or alive.  

Ans. 

It is indeed true that some of the properties of tissues are not the constituents of its cells.

Following three examples support this statement:
(a) A muscle tissue is capable of contraction but all its constituent cells may not be capable of doing so.
(b) The skeletal system is composed of bones and cartilage. A bone is hard and lightweight but its constituents may exhibit similar property.
(c) Blood is capable of carrying oxygen but WBCs are not capable of doing in spite of being the constituents of blood.  

A large variety of plants, animals, and microbes are found on earth. All these living organisms differ in size, shape, colour, habitat, and many other characteristics. As there are millions of living organisms on earth, studying each of them is impossible. Therefore, scientists have devised mechanisms to classify all living organisms.
These methods of classification are based on rules and principles that allow identification, nomenclature, and finally classification of an organism.

For example, based on certain principles, once an organism is identified as an insect, it will be given a scientific name and then grouped with other similar organisms. Thus, various groups or taxon include organisms based on their similarity and differences.

Therefore, the biological classification helps in revealing the relationship between various organisms. It also helps in making study of organisms easy and organized.

Millions of plants, animals, and microorganisms are found on earth. Many of these have been identified by the scientists while many new species are still being discovered around the world. Therefore, to classify these newly discovered species, new systems of classification have to be devised every now and then.

This creates the requirement to change the existing systems of classification.

To classify a class of forty students, let us start the classification on the basis of sexes of the students. This classification will result in the formation of two major groups- boys and girls.

Each of these two groups can be further classified on the basis of the names of the students falling in these groups.

Since it is possible that more than one student can have a particular name, these names can be further divided based on the surnames.

Since there is still some chance that more than one student can have the same surname, the final level of classification will be based on the roll numbers of each student.

The knowledge of characteristics of an individual or its entire population helps in the identification of similarities and dissimilarities among the individuals of same kind or between different types of organisms.

It helps the scientists to classify organisms in various categories.

In binomial system of nomenclature, the generic name of a species always starts with a capital letter whereas the specific name starts with a small letter. Therefore, the correct scientific name of Mango is Mangifera indica.

Each unit or category of classification is termed as a taxon. It represents a rank. For example, the basic level of classification is species, followed by genus, family, order, class, phylum or division, in ascending order.
The highest level of classification is known as kingdom.

The correct hierarchical arrangement of taxonomic categories in ascending order is

Species → Genus → Family → Order → Class → Phylum → Kingdom

Therefore, both (a) and (c) represent correct sequences of taxonomic categories.

In sequence (b), species should be followed by genus. Therefore, it does not represent the correct sequence.

In biological terms, species is the basic taxonomical rank. It can be defined as a group of similar organisms that are capable of interbreeding under natural conditions to produce fertile offsprings.

Therefore, a group of similar individuals that are respectively isolated form a species.

Species can also be defined as group of individuals that share the same gene pool.

(i) Phylum

Phylum is the primary division of kingdom. It includes one or more related classes of animals. In plants, instead of phylum, the term ‘division’ is used.

(ii) Class

Class is a taxonomic group consisting of one or more related orders. For example, the class, Mammalia, includes many orders.

(iii) Family

Family is a taxonomic group containing one or more related genera. In plants, families are categorized on the basis of vegetative and reproductive features.

(iv) Order

Order is a taxonomic group containing one or more families. For example, the order, carnivore, includes many families.

(v) Genus

Genus is a taxonomic group including closely related species. For example, the genus, Solanum, includes many species such as nigrum, melongena, tuberosum,etc.

Key is another taxonomical aid that helps in identification of plant and animal species. These keys are based on similarities and dissimilarities in characters, generally in a pair called couplet.

Each statement in a taxonomic key is referred to as a lead. For categorizing each taxonomic rank, such as family, genus, species, etc., different keys are used. It is also useful in identification of unknown organisms.

Keys are of two types- indented and bracketed keys. Indented key provides a sequence of choices between two or more statements while in bracketed key, a pair of contrasting characters are used.

(i) Indented key to identify different species of Rhododendron.

1. Leaves evergreen

2. leaves densely hairy below, orange or white hair; flower appears to have separate petals

………………………. Rhododendron groenlandicum

2. hair absent on leaves, flower has five petals fused in a shallow tube

………………………. Rhododendron maximus

1. Leaves deciduous

3. pink flowers with two free petals and three fused petals

………………………. Rhododendron canadense

3. white to pink flowers with all petals fused together

(ii) Bracketed key to identify different species of Rhododendron.

Leaves evergreen-----------------------------------------------2

1. Leaves deciduous-----------------------------------------------3

2. Leaves densely hairy below, orange or white hair; flower

appears to have separate petals

……….………………………. Rhododendron groenlandicum

2. Hair absent on leaves, flower has five petals fused in shallow

tube

………………………………..Rhododendron maximus

3. Pink flowers with two free petals and three fused petals

……………………………… Rhododendron canadense

3. White to pink flowers with all petals fused together-----4

The arrangement of various taxa in a hierarchical order is called taxonomic hierarchy.

In this hierarchy, species is present at the lowest level whereas kingdom is present at the highest level.

Kingdom
↑
Phylum or division
↑
Class
↑
Order
↑
Family
↑
Genus
↑
Species

A Taxonomic hierarchy

Classification of a plant

As an example, let us classify Solanum melongena (Brinjal).

Kingdom – Plantae

Division – Angiospermae

Class – Dicotyledonae

Order – Solanales

Family – Solanaceae

Genus – Solanum

Species – melongena

Classification of an animal

As an example, let us classify Columba livia (Blue rock Dove).

Kingdom – Animalia

Phylum – Chordata

Class – Aves

Order – Columbiformes

Family – Columbidae

Genus – Columba

Species – livia

As we go from species to kingdom in a taxonomic hierarchy, the number of
common characteristics
(a) Will decrease
(b) Will increase
(c) Remain same
(d) May increase or decrease 

ANS(a) Will decrease

Number of common characters is maximum among members of a particular species. On the other hand, number of common characters is minimum among members of a particular kingdom. 

Which of the following ‘suffixes’ used for units of classification in plants indicates
a taxonomic category of ‘family’. 
(a) – Ales 
(b) – Onae
(c) – Aceae
(d) – Ae 

ANS (c) – Aceae
ou can consider the names of families, e.g. Solanaceae, fabaceae, etc. 

The term ‘systematics’ refers to:
(a) Identification and study of organ systems
(b) Identification and preservation of plants and animals
(c) Diversity of kinds of organisms and their relationship
(d) Study of habitats of organisms and their classification

Ans. (c) Diversity of kinds of organisms and their relationship                                                                 

In fact, the need for a proper classification system was felt because of huge diversity of organisms. Based on certain relationships, organisms were classified into different group and sub-groups.

Genus represents

(a) An individual plant or animal
(b) A collection of plants or animals 
(c) Group of closely related species of plants or animals
(d) None of these 

Ans. (c) Group of closely related species of plants or animals

Taxon genus is just above the taxon species. 

The taxonomic unit ‘Phylum’ in the classification of animals is equivalent to which hierarchial level in classification of plants

(a) Class
(b) Order                                                      
(c) Division
(d) Family 

Ans. (c) Division

In animal kingdom, phylum comes just after the kingdom. Similarly, in the plant kingdom, division comes just after the kingdom. 

Botanical gardens and zoological parks have

(a) Collection of endemic living species only
(b) Collection of exotic living species only
(c) Collection of endemic and exotic living species
(d) Collection of only local plants and animals 

Ans. (c) Collection of endemic and exotic living species

To understand this, you can visit the zoo at Delhi or Kolkata. You can also search in Google image and you will find giraffes; along with tigers and lions. Tigers and lions are endemic species while giraffe is an exotic species.
 

Taxonomic key is one of the taxonomic tools in the identification and classification of plants and animals. It is used in the preparation of
(a) Monographs
(b) Flora
(c) Both (a) and (b)
(d) None of these 

ANS (c) Both (a) and (b) 

All living organisms are linked to one another because

(a) They have common genetic material of the same type
(b) They share common genetic material but to varying degrees
(c) All have common cellular organization
(d) All of above

ANS  (b) They share common genetic material but to varying degrees 

In fact, the whole theory of evolution is based on similarity of genetic materials which indicates towards common ancestry for living organisms. Variations in similarity of genetic material give biodiversity which we see all around us.

Which of the following is a defining characteristic of living organisms?

(a) Growth
(b) Ability to make sound
(c) Reproduction
(d) Response to external stimuli

Ans. (d) Response to external stimuli

Rest of the characters may not be apparent at every instance of time. But response to external stimuli can always be confirmed as and when required. So, this is  considered as a defining characteristic of living organisms. 
 

Match the following and choose the correct option:

Options
(a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A
(b) (i)-E, (ii)-D, (iii)-B, (iv)-A, (v)-C
(c) (i)-D, (ii)-E, (iii)-B, (iv)-A, (v)-C
(d) (i)-E, (ii)-C, (iii)-B, (iv)-A, (v)-D

ANS
(a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A 

It is true that a ball of snow increases in mass, volume and size; when it is rolled over. But in this case, the growth in size of the ball happens because of accumulation of material from outside. In case of growth in a living being, the growth happens because of accumulation of material from inside which is brought about by cell division and formation of new protoplasm.
Thus, growth in a snowball is altogether different when compared to the growth in a living being. 

Whenever we talk about biodiversity, we talk about all the life forms on the earth. In other words, the term ‘biodiversity’ is a universal term which encompasses all the organisms on the earth. But when we talk about a smaller geographical area; like an  ecosystem or a particular habitat; then the term ‘diversity’ is used. So, the given example of the habitat shows diversity. 

As per the ICBN, various hierarchies of units for classifying plants and suffixes used for such hierarchies are as follows:

Kingdom  - Plantae 

Division - Phyta 

Class  - Ae 

Order - Ales 

Family - Eae or – Ceae

Genus - Contains first name of organism which usually has Latin origin and written in italics 

Species - Contains second term of the scientific name which usually has Latin origin and written in italics.  

These variants are called biotypes. All biotypes are similar genetically but they are different morphologically. The morphological difference happens because of the differences in abiotic factors like temperature, pH of soil, climate etc. The difference in abiotic factors is the result of different altitudinal gradients.

Following are the various steps of preparing herbarium:
(a) Collection: This step involves collection of a particular species.
(b) Pressing: This step involves spreading the specimen and pressing it between two sheets of paper so as to preserve most of the parts.
(c) Drying: This step usually involves drying under the sun. 
(d) Poisoning: Sometimes, antifungal treatment needs to be given to the specimen to preserve it for longer duration.
(e) Mounting: This step involves mounting the specimen over a herbarium sheet.
(f) Labelling: This step involves writing full information and classification of the specimen.

Different tools which need to be carried while collecting plants for the preparation
of a herbarium are; digger and pruning knife, sickle, vasculum, polythene bags, old
newspaper or magazine, blotting paper, plant press, field notebooks, herbarium
sheets, glue, labels, etc.

The preserved material should have thorough information and classification. This should
include the names of division, order, family, genus and species. 

The sum of plant species in a given geographical area is called flora of that area. The sum of animal species in a given geographical area is called fauna of that area. The term ‘vegetation’ has wider scope than the term ‘flora’. Vegetation is often used for much wider  eographical area than a particular ecosystem. In many cases, the term ‘vegetation’ is used for all the plants on the global scale.

Endemic Species: A species which is found only in a particular geographical area is called the endemic species for that area. For example; Rauvolfia serpentina is found only in India. So, it is an endemic species in India. 

Exotic Species: A species which is not naturally found in a particular area but may be living because of careful selection and breeding or because of being imported is called an exotic species. For example, Eichhornia crassipes is native of other country but it was introduced in India. So, it is an exotic species in India. 

There are many languages and even more dialects being spoken in different parts of the  world. This means a plant may have different names in different regions of the country or world. This compounds the problem for anybody because nobody can remember all those names. To solve this problem, botanists have devised the system of binomial nomenclature so that a particular species can have unique name for the purpose of
scientific study.

A botanical name is usually composed of two terms, viz. genus name and species name. Care is taken to make a unique name for a particular species. 

Brinjal and potato belong to the same genus solanum because of certain common characters in them. Phyllotaxy, venation, inflorescence, etc. are some of the common characters in these plants which make them the member of the same genus. But breeding between a brinjal plant and a potato plant is not possible. Since capability to interbreed is the most defining criterion for members of a particular species; hence brinjal and
potato are kept under separate species although they belong to the same genus. 

No matter what is the function of a particular cell organelle; all the cell organelles are made up of more or less similar molecules. All the molecules come together in a particular fashion to build up a particular cell organelle. It is similar to the same brick making a small house or a big mansion of a factory. The constituents remain the same but the function and purpose of the finished product changes. Hence, properties of cell organelles
are not always found in the molecular constituents of cell organelles.

This question needs to be addressed from two perspectives, viz. number and variety. For any organism; the population cannot remain constant. In some of the generations,  pollution can be more because of favourable condition. In some other generations,  population can be less because of unfavourable conditions. The kinds of organism cannot be constant because evolution is a never ending process. In every era new species come
into origin and some old species become extinct.  

G Bentham and Joseph Dalton Hooker. Both are famous for their work on “classification of plants based on natural characteristics”. 

ICZN stands for International Code for Zoological Nomenclature.

Contrasting characters

A monograph contains information on any one taxon. A monograph provides work on primary research. 

After mitosis in Amoeba there is no growth in size of the organism rather two new organisms are formed. Hence, formation of new cells in Amoeba is reproduction. 

All the biological reactions in a living being are collectively called metabolism. 
Metabolism is of two types, viz, anabolism and catabolism.

All the biological reactions in a living being are collectively called metabolism. 
Metabolism is of two types, viz, anabolism and catabolism.

The Royal Botanical Garden in Kew (London) is the largest botanical garden in the world.
Some of the well known botanical gardens in India are as follows:
(a) Indian Botanical Garden, Sibpur, Kolkata
(b) Lloyad Botanical Garden, Darjeeling
(c) Botanical Garden of FRI, Dehradun
(d) National Botanical Garden, Lucknow

A living organism is self replicating, evolving and self-regulating interactive system capable of responding, to external stimuli. Growth, reproduction, nutrition, excretion, etc. are various characteristics of living beings. But most of these characteristics cannot be termed as defining features of life forms.

Defining features of life form are: Growth is defined as an increase in mass. Plants grow throughout their life, while most of the animals grow up to a certain age only. But some non-living things also grow in mass, e.g. cloud or snowball. So, growth cannot be termed as the defining feature of life.

Reproduction is the process by which a living being produces its own kind. Majority of organisms reproduce sexually, while many others reproduce asexually; by various methods. On the other hand, there are many living beings which do not reproduce at all, e.g. the worker bee in a beehive. But we consider it as a living being, So, reproduction  cannot be termed as an all inclusive defining feature of life. As non-living things cannot  reproduce; so, reproduction can be termed as a defining feature of life (with certain exceptions).

etabolism involves various biochemical processes during which various molecules are formed and many others get broken down. Metabolic  eaction cannot happen in a cellfree system. While some in-vitro reactions have been tried out in laboratories but they  cannot be termed as real metabolisms. So, metabolism is one of the defining features of life. 

Structural organization which begin with cellular organization is another character of living beings. Some molecules come together and work in perfect synchronization to form a cell organelle and various cell organelles come together to form a cell. Eventually, cells end up forming the tissue; which become organs and finally the whole organism is formed. Cells are altogether different than their constituent organelles; in terms of characters and functions. Similarly; a tissue is entirely different than its component cells; in terms of functions. Similar demarcation and hierarchy of organization is not possible in non-living things. Hence, cellular organization is a defining feature of life.
External stimuli can reach in various forms inside a living organism and the living being responds to each stimulus in a different way.

This can be termed as consciousness to the environment. Such a consciousness is not possible in non-living things. Hence, response to external stimuli is a defining feature of life.

 The scientist should look at various morphological features of the plant. He should begin with broad features; such as type of roots and venation. If fibrous roots are present then the plant may belong to monocotyledonous. In case of tap root, the plant may belong to dicotyledonous. This can be further confirmed with the presence of parallel or reticulate venation and number of cotyledons in the seeds. 
 
After that, the scientist should look at the type of phyllotaxy, inflorescence, etc. Which will help in classifying the plant in order and family. If it is a flowering plant, then a detail study of various floral parts can give various clues about a particular family or order. Type of placentation can be studied by looking at the arrangement of seeds inside the fruits.  Finally, arrangement of antheridium and gynoecium can help the scientist to confirm a particular family for the new species. The scientist also needs to rule out exact similarity with any other existing species before arriving at a unique name for the new species found. 

(a) The common name of Brassica compestris linn is mustard.
(b) The first part denotes the genus, while the second part denotes the species.
(c) These names are written in italics to show their Latin origin. Moreover, it is a convention to write scientific name in italics.
(d) The term ‘linn’ means that this species was first discovered and studies by Linnaeus.

 Tools which help the scientists in studying about plants and animal species are called taxonomical aids. Taxonomical aids include either live species of plants or animals or preserved remains. In case of animals; museum specimens are kept under proper preservation. In case of plants, herbariums are used for the keeping preserved specimens. 

Importance of Herbarium: Herbarium works as a repository of specimens for future reference. This also includes detail information about classification of a particular specimen. In many cases, herbarium serves as a quick referral system while studying about a particular species or about a higher taxonomical level. Herbarium is convenient to make and easier to maintain. It is also easy to transport a herbarium. Importance of Museums: Museums have much wider collection of plants and animal specimen. Museums may also have skeletons of many extinct animals. Thus, a museum offers more options of finding rich information while studying about a plant or animal.

Museums are usually maintained by educational institutions and thus they serve as important tool of study for students as well as for the scientists’ community. Role of Botanical and Zoological Parks in Conserving Biodiversity: Botanical and Zoological Parks serve the very important purpose of conserving the biodiversity. A botanical or zoological park is probably the most secure place for plants and animals to  live in their natural habitat. Especially trained personnel take good care of plants and animal species. They also carry out selective breeding of various plants and animals to
maintain the continuity of a particular species. Moreover, proper treatment is available in case some disease afflicts the plants and animals in such parks. Thus, it can be said that botanical and zoological parks play important role in conserving biodiversity. 

Taxon: A level of biological classification is called a taxon, e.g. phylum, order, family, etc. Taxonomic Hierarchy: In taxonomy, different taxa have their own different levels. This means that a particular taxon will come only after another particular taxon. For example; species always comes after the genus and it can never be the other way around. 

Flow Chart of Plant Categories
Kingdom →Division →Order →Family →Genus →Species
Flow Chart of Animal Categories
Kingdom →Phylum →Order →Family →Genus →Species
In Some cases, animals or plants are further classified into sub-groups; like super-class,
class or sub-phylum.
When we go up the taxonomic hierarchy; the number of common characters becomes lesser and lesser. For example; all members of a species will have the maximum number of common characters. On the other hand, all members of a genus will have a lesser number of common characters.
The number of individuals increases as we go up the taxonomical hierarchy.
 

Key is an important tool to study a taxonomic category. A key is composed of two contrasting characters. These characters generally occur in pairs and such a pair is called a couplet.
While studying a key; either of the contrasting characters is rejected or accepted. Thus, a choice is made between the two contrasting characters in a key. Each statement in the key is called a lead. It is important to note that a key is usually analytical in nature. Moreover, separate keys need to be used for different taxonomic categories.
Keys help in step-by-step identification of a particular organism. For example; presence or absence of notochord gives us a clue whether the organism belongs to vertebrate or invertebrate. Similarly, presence of absence of lungs tells us if the organism belongs to tetrapoda or pisces.   

Metabolism involves various biochemical processes during which various molecules are formed and many others get broken down. All organisms exhibit metabolism, e.g. protozoans, algae, fungi, bacteria, etc. Metabolic reactions cannot happen in a cell-free system.

While isolated in-vitro reactions carried out in laboratories cannot be termed as metabolism because they are conducted in controlled environment and are simulated. 
But such reactions can be termed as living reactions because they are the reactions going inside a living system. 

When it comes to human beings, it is very difficult to define the living state. A person may lie in coma for several years. By technical definition, the person is alive because he is not brain-dead. However, most of his vital organs have stopped functioning. Such a person is kept alive with life support system. A heart and lung machine works continuously to perform the function of oxygenation and circulation. A dialysis unit may be in place to perform the function of kidneys. The person gets nutrition through intravenous fluids. Since the person is in comma so he is not exhibiting consciousness to his environment. In other words, he is not exhibiting response to stimuli; which is one of the defining criteria for life.
Since the person is being kept alive because of life support system; metabolic activities are going on. Hence, the person can be considered as dead. 

But we should not forget that once he is put off the life support system; he will become brain-dead immediately and will be dead by technical definition. 
So, this is a difficult question whether a person in comma is dead or alive.  

Ans. 

It is indeed true that some of the properties of tissues are not the constituents of its cells.

Following three examples support this statement:
(a) A muscle tissue is capable of contraction but all its constituent cells may not be capable of doing so.
(b) The skeletal system is composed of bones and cartilage. A bone is hard and lightweight but its constituents may exhibit similar property.
(c) Blood is capable of carrying oxygen but WBCs are not capable of doing in spite of being the constituents of blood.