CBSE - Diversity in Living Organisms

There are millions of organisms on this earth. So, it is harder to study them one by one. Therefore, we look for similarities among them and classify them into different classes to study these different classes as a whole. Classification makes our study easier.

Examples of range of variations observed in daily life are:
→ Organisms vary greatly in size-from microscopic bacteria to elephants, whales and large trees.
→ The colour of various animals is quite different. Some worms are even colourless or transparent. Various types of pigments are found in plants.
→ The life span of different organisms is also quite varied. For example, a crow lives for only 15 years, whereas a parrot lives for about 140 years.

The more basic characteristic for classifying organisms is the kind of cells they are made of because different organisms may share same habitat but may have entirely different form and structure. So, the place where they live cannot be a basis of classification.

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

Plants and animals are put into different categories on the basis of Mode of nutrition.Plants are autotrophs. They can make their food own while animas are heterotrophs which are dependent on others for food. Also, locomotion, absence of chloroplasts etc. make them different.

A primitive organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time.As per the body design, the primitve organisms which hav simple structures are different from those so-called advanced organisms which have complex body structure and organization.

Yes, because the advanced organisms also were like the primitive ones once. They have acquired their complexity relatively recently. There is a possibility that these advanced or 'younger' organisms acquire more complex structures during evolutionary time to compete and survive in the changing environment.

The criterion for the classification of organisms belonging to kingdom Monera or Protista is the presence or absence of a well-defined nucleus or membrane-bound organelles. Kingdom Monera includes organisms that do not have a well-defined nucleus or membrane-bound organelles and these are known as prokaryotes. Kingdom Protista, on the other hand, includes organisms with a well-defined nucleus and membrane-bound organelles and these organisms are called eukaryotes.

Kingdom Protista

In the hierarchy of classification,a species will have the smallest number of organisms with a maximum of characteristics in common, whereas the kingdom will have the largest number of organisms

Division Thallophyta

Pteridophyta	Phanerogams
They have inconspicuous or less differentiated reproductive organs.	They have well developed reproductive organs.
They produce naked embryos called spores.	They produce seeds.
Ferns, Marsilea, Equisetum, etc. are examples of pteridophyta.	Pinus, Cycas, fir, etc. are examples of phanerogams.

Gymnosperm	Angiosperm
They are non-flowering plants.	They are flowering plants.
Naked seeds not enclosed inside fruits are produced.	Seeds are enclosed inside fruits.
Pinus, Cedar, fir, Cycas, etc. are some examples of gymnosperms.	Coconut, palm, mango, etc. are some examples of angiosperms.

Porifera	Coelenterate
They are mostly marine, non-motile, and found attached to rocks.	They are exclusively marine animals that either live in colonies or have a solitary life-span.
They show cellular level of organisation.	They show tissue level of organisation.
Spongilla, Euplectella, etc. are poriferans.	Hydra, sea anemone, corals, etc. are coelenterates.

Annelids	Arthropods
The circulatory system of annelids is closed.	Arthropods have an open circulatory system.
The body is divided into several identical segments.	The body is divided into few specialized segments.

Amphibian	Reptiles
They have a dual mode of life.	They are completely terrestrial.
Scales are absent.	Skin is covered with scales.
They lay eggs in water.	They lay eggs on land.
It includes frogs, toads, and salamanders.	It includes lizards, snakes, turtles, chameleons, etc.

Aves	Mammals
Most birds have feathers and they possess a beak.	They do not have feathers and the beak is also absent.
They lay eggs. Hence, they are oviparous.	Some of them lay eggs and some give birth to young ones. Hence, they are both oviparous and viviparous.

Following are the advantages of classifying organisms:
→ It makes us aware of and gives us information regarding the diversity of plants and animals.
→ It makes the study of different kinds of organisms much easier.
→ It tells us about the inter-relationship among the various organisms.
→ It helps us understanding the evolution of organisms.
→ It helps in the development of other life sciences easy.

→ It helps environmentalists to develop new methods of conservation of plants and animals.

We choose that characteristics which depends on the first characteristics and determines the rest variety.

The basis for grouping organisms into five kingdoms are:
→ 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.
→ Unicellular and multicellular organisms - This characteristic makes a very basic distinction in the body designs of organisms and helps in their broad categorizations.

→ Cell Wall: Presence and absence of cell wall leads into grouping.

→ Mode of nutrition -Organisms basically have two types of nutritions - autotrophic who can manufacture their own food and heterotrophic who 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.

The major divisions in Kingdom Plantae are:
→Thallophyta
→ Bryophyta
→ Pteridophyta
→ Gymnosperms
→ Angiosperms

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

The characteristics used to classify plants is different from animals because the basic design are different, based on the need to make their own food (plants) or acquire food (animals). 
Criteria for deciding divisions in plants are:
→ Differentiated/ Undifferentiated plant body
→ Presence/ absence of vascular tissues
→With/without seeds
→ Naked seeds/ seeds inside fruits

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

Animals in Vertebrata are classified into five classes:

(i) Class Pisces: This class includes fish such as Scoliodon, tuna, rohu, shark, etc. These animals mostly live in water. Hence, they have special adaptive features such as a streamlined body, presence of a tail for movement, gills, etc. to live in water.

(ii) Class Amphibia: It includes frogs, toads, and salamanders. These animals have a dual mode of life. In the larval stage, the respiratory organs are gills, but in the adult stage, respiration occurs through the lungs or skin. They lay eggs in water.

(iii) Class Reptilia: It includes reptiles such as lizards, snakes, turtles, etc. They usually creep or crawl on land. The body of a reptile is covered with dry and cornified skin to prevent water loss. They lay eggs on land.

(iv) Class Aves: It includes all birds such as sparrow, pigeon, crow, etc. Most of them have feathers. Their forelimbs are modified into wings for flight, while hind limbs are modified for walking and clasping. They lay eggs.

(v) Class Mammalia: It includes a variety of animals which have milk producing glands to nourish their young ones. Some lay eggs and some give birth to young ones. Their skin has hair as well as sweat glands to regulate their body temperature.

1. Find out incorrect sentence
(a) Protista includes unicellular eukaryotic organisms
(b) Whittaker considered cell structure, mode and source of nutrition for classifying the organisms in five kingdoms
(c) Both Monera and Protista may be autotrophic and heterotrophic
(d) Monerans have well defined nucleus
Ans. (d) Monerans have well defined nucleus
Explanation: Monerans are prokaryotes, i.e., they do not have well defined nucleus.

2. Which among the following has specialised tissue for conduction of water?
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta
(iv) Gymnosperms
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Ans. (c) (iii) and (iv)
Explanation: Specialised conductive tissues are not found in thallophyta and bryophyte. They first appear in pteridophyta.

3. Which among the following produce seeds?
(a) Thallophyta
(b) Bryophyta
(c) Pteridophyta
(d) Gymnosperms
Ans. (d) Gymnosperms
Explanation: Gymnosperms and angiosperms are seed bearing plants, but plants of lower groups do not bear seeds.

4. Which one is a true fish?
(a) Jellyfish
(b) Starfish
(c) Dogfish
(d) Silverfish
Ans. (c) Dogfish
Explanation: Dogfish is cartilaginous fish. Jellyfish is a coelenterate, starfish belongs to Echinodermata and silverfish is an insect. 

5. Which among the following is exclusively marine?
(a) Porifera
(b) Echinodermata
(c) Mollusca
(d) Pisces
Ans. (b) Echinodermata
Explanation: Porifera, Mollusca and pisces are found in freshwater also.

6. Which among the following have open circulatory system?
(i) Arthropoda
(ii) Mollusca
(iii) Annelida
(iv) Coelenterata
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) and (iv)
Ans. (a) (i) and (ii)

7. In which group of animals, coelom is filled with blood?
(a) Arthropoda
(b) Annelida
(c) Nematoda
(d) Echinodermata
Ans. (a) Arthropoda
Explanation: Blood is not present in other groups in the options.

8. Elephantiasis is caused by
(a) Wuchereria
(b) Pinworm
(c) Planarians
(d) Liver flukes
Ans. (a) Wuchereria

9. Which one is the most striking or (common) character of the vertebrates?
(a) Presence of notochord
(b) Presence of triploblastic condition
(c) Presence of gill pouches
(d) Presence of coelom
Ans. (a) Presence of notochord
Explanation: Triploblastic condition, gill pouches and coelom are present in many nonvertebrates
as well.

10. Which among the following have scales?
(i) Amphibians
(ii) Pisces 
(iii) Reptiles
(iv) Mammals
(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iii)
(d) (i) and (ii)
Ans. (c) (ii) and (iii)
Explanation: Amphibians and mammals do not have scales on their body.

11. Find out the false statement
(a) Aves are warm blooded, egg laying and have four chambered heart
(b) Aves have feather covered body, fore limbs are modified as wing and breathe through lungs
(c) Most of the mammals are viviparous
(d) Fishes, amphibians and reptiles are oviparous
Ans. (d) Fishes, amphibians and reptiles are oviparous
Explanation: Some fishes and reptiles are viviparous. Amphibians show external fertilization and hence cannot be kept under either oviparous or viviparous animals.

12. Pteridophyta do not have
(a) root
(b) stem
(c) flowers
(d) leaves
Ans. (c) flowers
Explanation: Flower are present only in angiosperms.

13. Identify a member of porifera
(a) Spongilla
(b) Euglena
(c) Penicillium
(d) Hydra
Ans. (a) Spongilla

Explanation: Euglena belongs to protozoa, Penicillium belongs to fungi and Hydra belongs to coelenterata.

14. Which is not an aquatic animal?
(a) Hydra
(b) Jelly fish
(c) Corals
(d) Filaria
Ans. (d) Filaria
Explanation: Filaria is a disease which happens because of Wuchereria.

15. Amphibians do not have the following
(a) Three chambered heart
(b) Gills or lungs
(c) Scales
(d) Mucus glands
Ans. (c) Scales
Explanation: Three chambered heart is found in amphibians. Lungs are present in adults and gills are present in tadpoles. Mucus gland is present on skin of amphibians.

16. Organisms without nucleus and cell organelles belong to
(i) fungi
(ii) protista
(iii) Cyanobacteria
(iv) archaebacteria
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iv)
(d) (ii) and (iii)
Ans. (b) (iii) and (iv)
Explanation: Prokaryotes belong to monera and cyanobacteria and archaebacteria belong to monera. 

17. Which of the following is not a criterion for classification of living organisms?
(a) Body design of the organism
(b) Ability to produce one’s own food
(c) Membrane bound nucleus and cell organelles
(d) Height of the plant
Ans. (d) Height of the plant
Explanation: A small shrub and a large tree; both belong to angiosperms. This shows that heights of a plant cannot be a criterion for classification.

18. The feature that is not a characteristic of protochordata?
(a) Presence of notochord
(b) Bilateral symmetry and coelom
(c) Jointed legs
(d) Presence of circulatory system
Ans. (c) Jointed legs
Explanation: jointed legs are found in arthropoda; which does not belong to chordata.

19. The locomotory organs of Echinodermata are

(a) tube feet
(b) muscular feet
(c) jointed legs
(d) parapodia
Ans. (a) tube feet 

20. Corals are
(a) Poriferans attached to some solid support
(b) Cnidarians, that are solitary living
(c) Poriferans present at the sea bed
(d) Cnidarians that live-in colonies
Ans. (d) Cnidarians that live-in colonies

21. Who introduced the system of scientific nomenclature of organisms
(a) Robert Whittaker
(b) Carolus Linnaeus
(c) Robert Hooke
(d) Ernst Haeckel
Ans. (b) Carolus Linnaeus
Explanation: It was Carolus Linnaeus who proposed binomial nomenclature of organisms.

22. Two chambered heart occurs in
(a) crocodiles
(b) fish
(c) aves
(d) amphibians
Ans. (b) fish
Explanation: Amphibians have three-chambered heart. Crocodiles and aves have fourchambered heart.

23. Skeleton is made entirely of cartilage in
(a) Sharks
(b) Tuna
(c) Rohu
(d) None of these
Ans. (a) Sharks
Explanation: Sharks belong to cartilaginous fish; while others belong to bony fish.

24. One of the following is not an Annelid
(a) Nereis
(b) Earthworm
(c) Leech
(d) Urchins
Ans. (d) Urchins
Explanation: Sea urchins belong to coelenterate.

25. The book Systema Naturae was written by
(a) Linnaeus
(b) Haeckel
(c) Whittaker
(d) Robert Brown
Ans. (a) Linnaeus

26. Karl Von Linne was involved with which branch of science?
(a) Morphology
(b) Taxonomy
(c) Physiology
(d) Medicine
Ans. (b) Taxonomy

27. Real organs are absent in
(a) Mollusca
(b) Coelenterata
(c) Arthropoda
(d) Echinodermata
Ans. (b) Coelenterata
Explanation: Coelenterates show tissue level of organization and hence real organs are absent in them.

28. Hard calcium carbonate structures are used as skeleton by
(a) Echinodermata
(b) Protochordata
(c) Arthropoda
(d) Nematoda
Ans. (a) Echinodermata

29. Differentiation in segmental fashion occurs in
(a) Leech
(b) Starfish
(c) Snails
(d) Ascaris
Ans. (a) Leech
Explanation: Leech belongs to annelida which show segmentation in body.

30. In taxonomic hierarchy family comes between
(a) Class and Order
(b) Order and Genus
(c) Genus and Species
(d) Division and Class
Ans. (b) Order and Genus
Explanation: The sequence is: Division→ Class→ Order→ Family→ Genus→ Species.

31. 5-Kingdom classification has given by
(a) Morgan
(b) R. Whittaker 
(c) Linnaeus
(d) Haeckel
Ans. (b) R. Whittaker

32. Well defined nucleus is absent in
(a) blue green algae
(b) diatoms
(c) algae
(d) yeast
Ans. (a) blue green algae
Explanation: Blue green algae belong to monera which are prokaryotes and hence welldefined nucleus in absent in them.

33. The ‘Origin of Species’ is written by
(a) Linnaeus
(b) Darwin
(c) Hackel
(d) Whittaker
Ans. (b) Darwin
34. Meena and Hari observed an animal in their garden. Hari called it an insect while Meena said it was an earthworm. Choose the character from the following which confirms that it is an insect.
(a) Bilateral symmetrical body
(b) Body with jointed legs
(c) Cylindrical body
(d) Body with little segmentation
Ans. (b) Body with jointed legs
Explanation: Presence of jointed legs is a salient feature of arthropoda and insects belong to arthropoda. 
 

(a) Whittaker proposed five kingdom classification.

(b) Monera is divided into Archaebacteria and Eubacteria.

(c) Starting from Class, Species comes before the Genus.

(d) Anabaena belongs to the kingdom Monera.

(e) Blue green algae belongs to the kingdom Protista.

(f) All prokaryotes are classified under Monera.

Ans. (a) T (b) T (c) F (d) T (e) F (f) T

(a) Fungi shows __________ mode of nutrition.
Ans. saprotrophic
(b) Cell wall of fungi is made up of __________.
Ans. chitin
(c) Association between blue green algae and fungi is called as __________.
Ans. lichens
(d) Chemical nature of chitin is __________.
Ans. carbohydrate
(e) __________ has smallest number of organisms with maximum number of
similar characters.
Ans. species
(f) Plants without well differentiated stem, root and leaf are kept in __________.
Ans. thallophyta
(g) __________ are called as amphibians of the plant kingdom.
Ans. bryophytes

Gram—dicot
Wheat—monocot
Rice—monocot
Pumpkin—dicot
Maize—monocot
Pea—dicot

Ans. (a)�B; (b)�A; (c)�D; (d)�C; (e)�F; (f)�E, (g)�G.

Ans. (a)�C; (b)�B; (c)�F; (d)�A; (e)�E; (f)�D.

Classify the following organisms based on the absence/presence of true coelom (i.e., acoelomate, pseudocoelomate and coelomate) Spongilla, Sea anemone,  Planaria, Liver flukes, Wuchereria, Ascaris, Nereis, Earthworm, Scorpion, Birds,Fishes, Horse. 

Spongilla—Acoelomate
Sea anemone—Acoelomate
Planaria—Acoelomate
Liver fluke—Acoelomate
Wuchereria—Pseudocoelomate
Ascaris—Psudocoelomate
Nereis—Coelomate
Scorpion—Coelomate 
Earthworm—Coelomate
Birds, Fishes and Horse—Coelomate 

Torpedo—Cartilagenous
Sting ray—Cartilagenous
Dog fish—Cartilagenous
Rohu—Bony
Angler fish—Cartilagenous
Exocoetus—bony. 

Rohu, Scoliodon— 2 chambered.
Frog, Salamander, Flying lizard, King Cobra—3 chambered.
Crocodile, Ostrich, Pigeon, Bat, Whale—4 chambered.

Cold blooded—Rohu, Scoliodon,Frog, Salamander, Flying Lizard, King Cobra, Crocodile,
Warm blooded— Ostrich, Pigeon, Bat, Whale. 

(i) Platypus (ii) Echidna

(a) Five kingdom classification of living organisms is given by __________.
Ans. Robert Whittaker
(b) Basic smallest unit of classification is __________.
Ans. Species
(c) Prokaryotes are grouped in Kingdom __________.
Ans. Monera
(d) Paramecium is a protista because of its __________.
Ans. Eukaryotic unicellular organisms
(e) Fungi do not contain __________.
Ans. Chlorophyll
(f) A fungus __________ can be seen without microscope.
Ans. Mushroom
(g) Common fungi used in preparing the bread is __________.
Ans. Yeast
(h) Algae and fungi form symbiotic association called __________.
Ans. Lichens

(a) Gymnosperms differ from Angiosperms in having covered seed.
(b) Non-flowering plants are called Cryptogamae.
(c) Bryophytes have conducting tissue.
(d) Funaria is a moss.
(e) Compound leaves are found in many ferns.
(f) Seeds contain embryo.
Ans. (a) F
(b) T
(c) F
(d) T
(e) T
(f) T

(a) Bilateral, dorsiventral symmetry is found in __________.
Ans. Liver fluke
(b) Worms causing disease elephantiasis is __________.
Ans. Filarial worm
(c) Open circulatory system is found in __________ where coelomic cavity is filled
with blood.
Ans. Arthropods
(d) __________ are known to have pseudocoelom.
Ans. Nematodes

Ans. (a) Dorsal fin
(b) Caudal fin
(c) Pelvic fin
(d) Pectoral fin
Function of Caudal fin�Caudal fin helps in streamlined movement in water.

Ans. (a) Thallophyta
(b) Without specialized vascular tissue
(c) Pteridophyta
(d) Phanerogams
(e) Bear naked seeds
(f) Angiosperms
(g) Have seeds with two cotyledons
(h) Monocots

Ulothrix, Spirogyra, Cladophara, Ulva and Chara,

The Thallophyta, bryophyta and pteridophyta are called as �Cryptogams� because the reproductive organs of these groups are inconspicuous or hidden. Seeds are absent. On the other hand �Phanerogams� include gymnosperms and angiosperms which have well
differentiated reproductive tissue and the embryo with stored food. Embryo develops into seed.

Define the terms and give one example of each
(a) Bilateral symmetry
(b) Coelom 
(c) Triploblastic
Ans. (a) The left and right halves of the body have the same design, eg, liver fluke.
(b) Coelom is the internal body cavity between visceral organs and body wall in which well-developed organs can be accommodated, eg. Butterfly
(c) Animals having three layers of cells from which differentiated tissue can be made are called triploblastic, eg. star fish 

All organisms given in the question do not belong to same group. Leech and Nereis belong to phylum annelida because they have metamerically segmented body i.e., body is divided into many segments internally by septa. Body segments are lined up one after the other from head to tail. But Scolopendra, prawn and scorpion belong to phylum arthropoda as these have jointed legs and open circulating system.

Mango tree is more complex and evolved because, it is eukaryotic, autotrophic, terrestrial sporophyte with covered seed. The bacteria is unicellular prokaryote and fungi are the heterotrophic, simple thallophyte with no tissue systems.

Flying lizard belongs to group reptiles and characterised as cold blooded, body covered with scales and having three chambered heart, while birds belong to group aves and have characteristics of being warm blooded, having feather covered body, forelimbs modified as wings and having four chambered heart.

Bat, rat and cat belong to class mammalia and have following common features
(a) All have notochord at some stage of life cycle.
(b) All are warm blooded.
(c) All have four chambered heart.
(d) All have skin covered with hair and with sweat and oil glands.

Because both are (1) cold blooded (2) have scales (3) breathe through lungs (4) have three chambered heart, and (5) they lay eggs with tough covering.