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What are the advantages of classifying organisms?

Classification is an important branch of science due to the following reasons:

(i) Classification makes the study of huge varieties of organisms easy.

(ii) It reveals before us a picture of all forms of organisms at a glance.

(iii) It helps us to understand the relationship among different groups of organisms.

(iv) It serves as a base for the development of other pure biological science e.g., biogeography, i.e. geographical distribution of plants and animals.

(v) It also helps in the understanding and the development of other applied branches of science such as agriculture, public health and environment biology.


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

The characteristic, which is dependent on the previous one and would decide the variety in the next level, should be chosen for developing a hierarchy in classification.


Explain the basis for grouping organisms into five kingdoms.

The basis for grouping organisms into five kingdom are,

(i) Whether the organisms are made of prokaryotic or eukaryotic cells.

(ii) Whether the organism is unicellular, i.e., a cell living singly or organized into multicellular and thus complex organisms.

(iii) Whether the cells have a cell wall.

(iv) Whether they prepare their own food or get their food from outside.


What is the major division in the plantae? What is the basis for these divisions?

Major divisions in kingdom plantae are,

(i) Thallophyta

(ii) Bryophyta   
(iii) Pteridophyta

(iv) Gymnosperms

(v) Angiosperms

Basis for classification plantae division are,

(i) Whether the plant body has well differentiated, distinct components.

(ii) Whether the differentiated plant body has special tissues for the transportation of water and other substances within it.

(iii) Whether the plants bear the seeds.

(iv) Whether the seeds are enclosed within the fruits.


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

The criteria for classification of plant kingdom into divisions depend upon:

(a) Differentiation of plant body components.

(b) Presence of transport tissues,

(c) Ability to produce seeds and

(d) Enclosure of seeds in fruits.

On these basis animals cannot be classified because animals do not exhibit these characteristics. Animals are classified based on the extent and the type of the body design differentiation found.


Explain how animals in vertebrata are classified into further subgroups.

Vertebrates are classified into further subgroups on the basis of simple to complex form and functions of the organisms.
For example, fishes have two chambered heart, amphibians and reptiles have three chambered heart whereas aves and mammals have four chambered heart to keep oxygenated and deoxygenated blood separately.


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

Range of variations:

(i) Life span – mosquitoes live for a few days whereas cows, dogs, etc. live for many years.

(ii) Colour    – Some organisms, and certain cows, horses, dogs are white but some birds and  flowers are brightly coloured.

(iii) Size      – Some organisms are so small that we cannot see them with naked eyes. On the other hand, the eucalyptus tree is several metre tall.


Which do you think is a more basic characteristic for classifying organisms?

(a) the place where they live.

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

Ans: (b) the kind of cells they are made of.

Reasons – In every place, different types of organisms may live. They may not have similarities except common habitat. Thus, habitat cannot be a basic characteristic for the classification of organisms into groups.


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

The first division of organism is made by identifying whether the organism has Eukaryotic cell, i.e., membrane- bound organelle, including nucleus or has prokaryotic cell, i.e., has no clearly demarketed nucleus and membrane bound organelles.


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

Plants and animals are put into different categories by identifying whether the organisms produce their own food through the process of photosynthesis (plants) or organisms get food from outside (animals).


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

The organisms which have ancient body design, that have not changed very much are called primitive or lower organism.
Advanced organisms are those who have acquired their particular body designs relatively, recently.
Primitive organisms have simpler body design, where as advanced or younger organisms have comparatively more complex body design.


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

Advanced organisms will be the same as complex organisms. This is because the groups of organisms have acquired their particular body designs relatively, recently. There is a possibility that advanced or younger organisms undergo increasing complexity in body design during evolutionary time, to compete and survive.


What is the criterion for classification of organism as belonging to kingdom Monera or Protista?

Kingdom Monera: The organisms which are unicellular and do not have a membrane bound nucleus and organelles are put under Monera.
Kingdom Protista: The unicellular organisms which are membrane bound with definite nucleus and organelles are classified as Protista.


In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

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


Which division among plants has the simplest organisms?



How are Pteridophytes different from the Phanerogams?

Difference between Pteridophytes and Phanerogams are,



Pteridophytes have naked embryos that are called spores.

Phanerogams produce seeds, which consist of embryo and stored food.

The reproductive organs are inconspicuous, therefore called cryptogamae (those with hidden reproductive organs).

They have well differentiated reproductive tissues, which after reproductive process produce seeds.



How do gymnosperms and angiosperms differ from each other?




They produce cones formed of sporophylls.
The sporophylls carry male and female sex organs.

They produce flowers which carry male and female sex organs.

The plants bear naked seeds.

The seeds develop in an organ which modifies into the fruit, i.e., seeds are found covered within a fruit.



How do poriferan animals differ from coelenterate?




There are pores called ostia all over the body and a large opening at the top.

There is only one opening.

There is canal system for circulating of water throughout the body.

There is no water canal system in the body.

External skeleton is present.

Skeleton is absent.

The body design shows minimal differentiation.

They show more body design differentiation.

Tentacles are absent.

Tentacles are present.



How do annelid animals differ from arthropods?


            Annelid animals


They have a true body cavity. The coelomic cavity is not filled with blood .

The coelomic cavity is blood filled.

Body bears lateral appendages for locomotion in the form of chitinous setae or parapodia.

They have jointed legs for locomotion.



What are the differences between amphibians and reptiles?




Animals of this group can live both on land and in water.

Animals can live either on land or in water.

They lack scales on the body.

They have scales.

Their eggs do not have tough covering.

Their eggs have a tough covering.

They lay their eggs in water.

They do not need to lay their eggs in water.

Water is necessary for fertilization.

Water is not required for fertilization.



What are the differences between animals belonging to the aves group and those in the mammalia group?




They have a beak.

They do have a beak.

Their body is covered with feathers.

Their body is covered with hair. Feathers are absent.

Forelimbs are modified into wings for flight.

Forelimbs are not modified into wings as in birds. However, forelimbs may be modified for various purposes.

They lay eggs.

Most of the mammals produce live young ones.

They do not have mammary glands to produce milk for young ones.

They have mammary glands to produce milk for young ones.


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