DIVERSITY
IN LIVING ORGANISMS
NCERT Textbook Questions
Q.1.
Why do we classify organisms?
Answer.
There is vast number of living organisms in this biosphere and
they have a great diversity in shape, size and form. It is practically not
possible to examine and study each and every organism separately at individual
level. It is therefore, advisable to study the diversity of organisms by
classify them in a orderly manner.
Q.2.
Give three examples of the range of variations that you see in life forms
around you.
Answer. 1. The living organisms vary in size from a few micrometers (e.g.,
microscopic bacteria) to more than 30 metres long (e.g., blue whale)
and more than 100 meters tall (e.g., red wood trees of California).
2.
The living organisms vary in longevity from a few days (e.g., mosquitoes)
to several thousand years e.g. pine trees.
3.
The living organisms range from colourless or transparent to brightly coloured
birds and flowers.
Q.3.
Where do you think is more basic characteristic for classifying organism?
(a)
the place where they live
(b)
the kind of cells they are made of, why?
Answer. The more basic characteristic for classifying organisms is – (b)
the kind of cells they are made of. It
is erroneous to classify organisms on the basis of the place where they live
(such as aquatic, terrestrial, aerial, etc.) because many different kinds of
organisms may live in the same habitat but they do not belong to the same
group. For example, sponges, corals, whales, octopuses, starfishes, fishes
(sharks), etc., live in sea but they differ with each other.
Q.4.
What is the primary characteristic on which the first division of organism is
made?
Answer. The primary characteristic used for making the broadest division
of organism is that whether the organisms are prokaryotic or eukaryotic.
Q.5.
On what basis are plants and animals put into different categories?
Answer. Plants and animals are both eukaryotic organisms. Both are put
into different groups on the basis of their mode of nutrition as well as their
body designs. Plants are autotrophic and perform photosynthesis whereas animals
are heterotrophic and get food from the outside. Plant cells have cell wall (of
cellulose) whereas animal cells do not have any cell wall.
Q.6.
Which organisms are called primitive and how are they different form so-called
advanced organisms?
Answer. The organisms having characteristics that came into existence
earlier are referred to as “primitive” and the organisms having characteristic
that have come into existence later on are called, ‘advanced’. For example, unicellular
prokaryotic bacteria are primitive and multicellular eukaryotic Mammalia are
advanced. Likewise, algae are primitive plants and angiosperms are advanced
plants. Fishes are primitive vertebrates and birds are advanced vertebrates.
Q.7.
Will advanced organisms be the same as complex organisms? Why?
Answer. Yes. The complex organisms are comparatively more advanced as
compared to simple organisms. It is because the complexity in organisation of
organisms has increased over evolutionary time.
Q.8.
What is the criterion for classification of organisms as belonging to kingdom
Monera or Protista?
Answer. The organisms which do not possess well defined nucleus,
organelles and multicellular body design are grouped under the kingdom Monera, e.g.,
Archaebacteria and Bacteria organisms of both groups (subkingdoms) have
prokaryotic organisation. The organisms which are unicellular and eukaryotic
are grouped under the kingdom Protista.
Q.9.
In which kingdom will you place an organism which is single-called, eukaryotic
and photosynthetic?
Answer. Kingdom Protista.
Q.10.
In the hierarchy of classification, which grouping will have the smallest
number of organisms with a maximum of characteristics in common and which will
have the largest number of organisms?
Answer. In the hierarchy of classification, species will have the
smallest number of organisms with a maximum number of characteristics in common
and kingdom will have the largest number of organisms.
Q.11.
Which division among plants has the simplest organisms?
Answer. The organisms belonging to division Algae are the simplest among
the plants.
Q.12.
How are pteridophytes different from the phanerogams?
Answer. The plants belonging to pteridophytes do not produce seeds whereas
those belonging to phanerogams produce seeds.
Q.13.
How do gymnosperms and angiosperms differ from each other?
Answer. The gymnosperms have naked seeds (i.e., seeds are not
enclosed within the fruits) whereas the angiosperms have seeds inside the
fruits.
Q.14.
How do poriferan animals differ from coelenterate animals?
Answer. Porifers differ from Coelenterata in following characters:
Q.15.
How do annelid animals differ from arthropod animals?
Answer. Annelid animals differ from Arthropod animals in following
respects:
Q.16.
What are the differences between amphibians and reptiles?
Answer. Amphibians differ from reptiles in the following respects:
Q.17.
What are the differences between animals belonging the Aves group and those in
the Mammalia group.
Answer. Aves includes the birds which have the following differences with
mammals.
NCERT Exercises
Q.1.
What are the advantages of classifying organisms?
Answer. The classification of organisms have the following advantages:
1.
Classification of organisms according to a definite plan facilitates their
identification and makes their study convenient.
2.
There is a vast number of organisms in this world. It is not possible by the
individual human being to know about all individuals. Thus, the study of a few
representatives from each group gives a broad idea of the life as a whole.
3.
Classification gives information about the organisms which do not occur in
one’s locality.
4.
Classification reveals evolution trends by showing gradually increasing
complexity of structure in various groups of organisms.
Q.2.
How would you choose between two characteristics to be used for developing a
hierarchy in classification?
Answer. Before developing a hierarchy in classification, we need to decide
which characteristics should be used as the basis for making the broadest
divisions. Then we should pick up next set of characteristics for making
subgroups. This process must continue and each time new characteristics should
be used. The characteristics that decide the broadest divisions among living
organisms should be independent of any other characteristics. For example,
nature of cell and form of the body is considered to classify organisms into
broad divisions (e.g., Prokaryotes and Eukaryotes). The characteristics
of the next level should be dependent on the previous one that will decide the
subsequent divisions of the groups.
Q.3.
Explain the basis for groupings into five kingdoms.
Answer. Whittaker (1959) has based his scheme of classification of living organisms
into five kingdoms (namely Monera, Protista, Fungi, Plantae and Animalia) on
following four bases:
1.
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.
2.
Unicellular and multicellular organisms. This characteristic
makes a very basic distinction in the body designs of organisms and helps in
their broad categorizations.
3.
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.
4. 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.
Q.4.
What are the major divisions in the Plantae? What is the basis of this
division?
Answer. Kingdom Plantae includes the following five divisions: 1.
Thallophyta (Algae); 2. Bryophyta; 3. Pteridophyta; 4. Gymnospermae; 5.
Angiospermae.
The
first level of classification of plants is based on the presence and absence of
well - differentiated distinct components in the body. Algae are separated from
rest of the plants in having simple and less differentiated thalloid plant
body. The next level of classification is based on the presence and absence of
vascular tissues (i.e., xylem and phloem). This character separates the
bryophyta from the rest of the plants. Further classification is based on the
ability to bear seeds. Pteridophytes do not bear seeds. Finally, the groups are
formed on the basis of seeds naked or enclosed within fruits. The gymnosperms
have naked seeds whereas Angiosperms bear seeds enclosed within the fruits.
Q.5.
How are the criteria for deciding divisions in plants different from the
criteria for deciding the sub-groups among animals?
Answer. The criteria (norms) for deciding divisions in plants are
different from the criteria for deciding the sub-groups among animals because
the basic designs of their body is different. This is mainly due to the fact
that plants are autotrophic and often remain fixed to substratum, while animals
are heterotrophic and they can move. Thus, the body design of the two groups is
based on the need to make their own food in case of plants and to acquire it
from external source in case of animals. The other characteristics such as presence
or absence of skeleton, etc., are used to make subgroups among animals.
Q.6.
Explain how animals in Vertebrata are classified into further subgroups?
Answer. The major characteristics used to classify animals in Vertebrata
are: 1. The kind of exoskeleton or endoskeleton. 2. The kind of respiratory
organs. 3. The method of reproduction and giving birth to young ones. On the
basis of above mentioned characters the vertebrata is divided into following
classes.
1.
Exoskeleton of scales: Endoskeleton of cartilage or bones; breathing through
gills – Pisces (fishes).
2.
Breathing through gills only in larva; skin slimy – Amphibia.
3.
Exoskeleton of scales or scutes; laying eggs outside the water – Reptilia.
4.
Exoskeleton of feathers; lays eggs; flight possible – Aves (birds).
5. Exoskeleton of hair; external ears;
give birth to young ones – Mammalia.
Questions Based on NCERT
Question Bank (Exemplar Problems in Science)
Q.1.
Write (T) or False (F)
(a)
Whittaker proposed five kingdom classification.
(b)
All prokaryotes are classified under Monera.
(c)
Starting from class, species comes before genus.
(d)
Monera is divided into Archaebacteria and Eubacteria.
(e)
Anabaena belongs to kingdom Monera.
(f)
Blue-green algae belong to kingdom protista.
Answer. (a) T; (b) T; (c) F; (d) T; (e)
T; (f) F.
Q.2.
Fill in Blanks:
(a)
.................. has smallest number of organisms with maximum number of
similar characters.
(b)
Fungi show .................. mode of nutrition.
(c)
Cell wall of fungi is made up of ..................
(d)
Chemical nature of chitin is ..................
(e)
.................. are called amphibians of plant kingdom.
(f)
Association between blue-green algae and fungi is called as ..................
Answer. (a) Species; (b) Saprophytic; (c) Chitin; (d)
Carbohydrate; (e) Bryophyta; (f) Lichen.
Q.3.
You are provided with seeds of Gram, Wheat, Rice, Pumpkin, Maize and Pea.
Classify them whether they are monocot or dicot.
Answer. Dicot seeds, e.g., Gram, Pumpkin, Pea Monocot seeds, e.g., Wheat,
Rice, Maize.
Q.4. Match the items of
Column A with items of Column B
Answer. (a) (iii); (b) (vi); (c) (vii);
(d) (ii); (e) (i); (f) (v); (g)
(iv).
Q.5.
Classify the following organisms based on absence or presence of true coelom as
acoelomate, pseudocoelomate, and coelomate: Spongilla, Sea anemone,
Planaria, Liver fluke, Wuchereria, Ascaris, Nereis, Earthworm, Scorpion,
Birds, Fishes and Horse.
Answer. 1. Acoelomata. Spongilla, Sea anemone, Planaria, Liver fluke.
2.
Psudocoelomata. Wuchereria, Ascaris.
3. Coelomata. Nereis, Earthworm, Scorpion, Birds,
Fishes, Horse.
Q.6.
Endoskeleton of fishes are made up of cartilage and bone. Classify the
following fishes as cartilaginous or bony: Torpedo, Sting ray, Dog fish, Rohu,
Angler fish, Exocoetus.
Answer. (i) Cartilaginous endoskeleton, e.g., Torpedo,
Sting ray, Dog fish.
(ii)
Bony endoskeleton, e.g., Rohu, Angler fish,
Exocoetus.
Q.7.
Classify the following based on number of chambers in their heart: Rohu, Scoliodon,
Frog, Salamander, Flying lizard, King cobra, Crocodile, Ostrich, Pigeon,
Bat, Whale.
Answer. 1. Two-chambered heart, e.g., Rohu, Scoliodon.
2.
Three-chambered heart, e.g., Frog, Salamander, Flying
lizard, King cobra.
3.
Four-chambered heart, e.g., Crocodile, Ostrich, Pigeon,
Bat, Whale.
Q.8.
Classify Rohu, Scoliodon, Flying lizard, King cobra, Frog, Salamander,
Ostrich, Pigeon, Bat, Crocodile and Whale into cold blooded and warm blooded
animals.
Answer. 1. Cold Blooded Animals. Rohu, Scoliodon, Frog,
Salamander, Flying lizard, King cobra, Crocodile.
2. Warm Blooded Animals. Ostrich,
Pigeon, Bat, Whale.
Q.9.
Name two egg laying mammals.
Answer. (i) Duck-Bill Platypus; (ii) Echidna.
Q.10.
Fill in the Blanks
(a)
Five kingdom classification of living organisms is given by ..................
(b)
Basic smallest unit of classification is ..................
(c)
Prokaryotes are grouped in kingdom ..................
(d) Paramecium
is a protistan because of its ..................
(e)
Fungi do not contain ..................
(f) A
fungus .................. can be seen without microscope.
(g)
Common fungus used in preparing the bread is ..................
(h)
Algae and fungi form symbiotic association called ..................
Answer. (a) Whittaker; (b) Species; (c) Monera;
(d)
Unicellular eukaryotic nature; (e) Chloroplasts; (f) Mushroom;
(g)
Yeast; (h) Lichen.
Q.11.
Give True (T) and False (F):
(a) Funaria
is a moss.
(b)
Bryophytes have conducting tissue.
(c)
Non-flowering plants are called cryptogamae.
(d)
Compound leaves are found in many ferns.
(e)
Seeds contain embryo.
(f)
Gymnosperms differ from angiosperms in having covered seeds
Answer. (a) T; (b) F; (c) T; (d) T; (e)
T; (f) F.
Q.12.
Give examples for the following:
(a)
.................. are known to have pseudocoelom.
(b)
Worm causing elephantiasis is ..................
(c)
Bilateral, dorsiventral symmetry is found in ..................
(d)
Open circulatory system is found in ..................
Answer. (a) nematodes or roundworms; (b) Wuchereria or
Filaria;
(c) Liver fluke / Frog/Lizard; (d)
Arthropoda.
Q.13. Label A, B, C, and D
in the given figure. Give the function of B.
Answer.
1. A-Dorsal fin; B-Caudal fin; C-Anal fin or Ventral fin, D-Pelvic
fin.
2.
Caudal fins of the bony fishes are chief locomotory organs and are used in
swimming. Muscular tail of fish provides main propulsive force.
Q.14. Fill the boxes with
appropriate characteristics/plant groups.
Answer. A-Thallophyta; B-Without specialised vascular tissue (non
vascular); C-Pteridophyta; D-Phanerogamae E-Bear naked seeds; F-Angiosperms;
G-Have seeds with two cotyledons; H-Monocots.
Q.15.
Write name of a few thallophytes. Draw a labelled diagram of Spirogyra.
Answer. Algae such as blue green algae and Ulothrix, Spirogyra, Fucus; fungi;
bacteria; lichens.
Q.16.
Thallophyta, Bryophyta and Pteridophyta are called “cryptogams”. Gymnosperms
and angiosperms are called “Phanerogams”. Discuss why?
Answer.
(a) Thallophyta, Bryophyta and Pteridophyta are called cryptogams
because they are seedless and possess inconspicuous or hidden reproductive
organs. They reproduce by the spores.
(b) Gymnosperms and angiosperms
are called phanerogams as they have conspicuous reproductive organs with
seeds containing an embryo and reserve food.
Q.17.
Thallophyta, Bryophyta and Pteridophyta are called “cryptogams”. Gymnosperms
and angiosperms are called “Phanerogams”. Discuss why?
Answer.
(a) Thallophyta, Bryophyta and Pteridophyta are called cryptogams
because they are seedless and possess inconspicuous or hidden reproductive
organs. They reproduce by the spores.
(b) Gymnosperms and angiosperms
are called phanerogams as they have conspicuous reproductive organs with
seeds containing an embryo and reserve food.
Q.18.
Define terms and one example of each (a) Bilateral symmetry, (b)
Coelom, (c) Triploblastic.
Answer.
(a) Bilateral symmetry. It is a type of body
symmetry in which appendages and organs of the body are paired with one of each
pair being present in right and left halves of the body. It is an adaptation of
motile life style, e.g., Frog/Lizards/Sparrow/Human being.
(b)
Coelom. It is a mesoderm lined, fluid-filled internal body cavity that
provides a shock proof environment to the contained body organs, e.g., annelids,
chordates.
(c) Triploblastic. They are animals having three germinal layers - outer ectoderm,
middle mesoderm and inner endoderm, e.g., liver fluke/
Ascaris/Pheretima/house fly/star fish/ Amphioxus/ cat.
Q.19.
You are given Leech, Nereis, Scolopendra; Prawn and Scorpion. All have
segmented body organisation. Will you classify them in one group? If not give
the important characters based on which you will separate these into different
groups.
Answer.
No
(i)
Leech and Nereis have metameric segmentation (i.e., external
segmentation of body corresponding to internal segmentation), closed
circulatory system and unjointed appendages. They belong to phylum Annelida.
(ii)
Scolopendra (centipede), Prawn and Scorpion also have segmented body but
they have open circulatory system, jointed appendages and chitinous
exoskeleton. They belong to phylum Arthropoda.
Q.20.
Which organism is more complex and evolved among Bacteria, Mushroom and Mango
tree, Give reason.
Answer.
Mango tree is more complex and evolved among bacteria, mushroom
and mango tree because of the following characters:
1.
Differentiated sporophyte; 2. Vascular tissues (xylem and phloem); 3. Embryo
stage in life cycle; 4. Seeds present inside fruit. Bacteria are prokaryotic.
Mushroom is eukaryotic (fungus) but without any differentiation in body of
stem, leaves, roots, absence of vascular tissues and embryonic stage.
Q.21.
Differentiate between flying lizard and bird. Draw the diagram.
Answer. Draw diagram of flying lizard and of bird according to following
figures:
Q.22.
List out some common features in Cat, Rat and Bat.
Answer.
Cat, Rat and Bat belong to same class Mammalia, phylum Chordata.
The common characters of these animals are (i) Hair; (ii) Mammary
glands; (iii) Integumentary glands, e.g., sweat glands; (iv)
Seven cervical vertebrae; (v) Diaphragm; (vi) Four chambered
heart, (vii) External pinnae; (viii) Vivipary.
Q.23.
Why do we keep both snake and turtle in the same class?
Answer.
Both
snake and turtle have been placed by taxonomists in class Reptilia of phylum
Chordata. This is done because of following features; (i) skin without
glands; (ii) three-chambered (infact incompletely four chambered) heart;
(iii) respiration through lungs; (iv) cold blooded; (v)
hard shelled eggs; (vi) embryo protected by extra embryonic membranes.
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