JKBOSE 9th Class Science Solutions Chapter 13 Diversity In The Living Organisms

◆ Science of classification is called taxonomy.

◆ Each organism is different from all others to a lesser or greater extent.

◆ Bacteria are microscopic of a few micrometre in size whereas blue whale and red wood trees of California are of size 30 metres and 100 metres respectively.

◆ Present day diversity in living beings is the product of 3.5 billion years of organic evolution.

◆ The classification of organisms is arranging organisms into groups or sets on the basis of similarities and differences which also exhibit their relationships.

◆ Carolus Linnaeus is the Father of Taxonomy.

Classification makes the study of a wide variety of organisms easy.

Classification helps us exploring the diversity of life forms.

◆ In two kingdom systems of classification, kingdom plantae and kingdom animalia were classified.

◆ Plants are autotrophic, prepare their own food and plant cells have cell wall of cellulose.

◆ Animals lack chlorophyll and are heterotrophic in nutrition.

◆ R. H. Whittaker (1969) proposed five kingdom systems of classification.

● Nature of cell Prokaryotic or eukaryotic cell.

● Number of cells Single cell or multicellular.

Plants carry out photosynthesis thus autotrophs.

Fungi absorb food, thus absorptive.

Animals have ingestive (holozoic) mode of feeding.

● Evolution of organisms greatly determines their classification.

● Organisms that evolved earlier have simple and ancient body designs whereas the recently evolved younger organisms have complex body designs. .

● Older organisms are also referred to as primitive or lower organisms whereas the younger organisms are referred to as advanced or higher organisms.

◆ The five kingdoms are Monera, Protista, Fungi, Plantae and Animalia.

◆ Advantages of five kingdom system.

1. The subdivisions of two kingdoms have been redistributed among additional kingdoms. Such an arrangement reflects the phylogeny evolutionary history of different life styles in a better way.

2. This system allows us to visualize the increase of complexity with evolutionary time.

3. Five kingdom arrangement allows us to visualize the divergence of their modes of nutrition in the multicellular organisms.

4. An added advantage of Whittaker’s system lies in the coherence and definable estet to characters of a kingdom as a unit of classification.

◆ Monerans lack well defined nucleus and membrane bound cell organelles. This group include bacteria, blue green algae (cyanobacteria) and Mycoplasma.

◆ Protists include unicellular eukaryotic organism. Some may have specialised structures for moving such as cilia, flagella or pseudopodia. Agar, diatoms and protozoans are example.

◆ Plantae and Animalia are further divided into subdivision on the basis of increasing complexity.

◆ Charles Darwin described the idea of evolution in his book, “The Origin of Species (1959)

◆ Primitive’ or ‘lower’ organisms have ancient body designs.

◆ Advanced or higher organisms acquired their particular designs relatively recently.

◆ Complexity in design increases over evolutionary time.

◆ Biodiversity refers to variety of life forms found in particular region.

◆ The warm and humid tropical regions of earth are rich in diversity of plant and animal life. The region is called region of megadiversity.

◆ Fungi are non-green, heterotrophic (parasitic and saprophytic) thallophytes (cell wall chitin). They include moulds, yeast, mushrooms.

◆ Lichens are symbiotic association of algae and fungi.

◆ Plantae are divided into five sub divisions i.e. Thallophyta, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms. 

◆ Members of kingdom animalia includes multicellular eukaryotes without cell walls.

They are heterotrophic in their mode of nutrition.

◆ Animal kingdom is divided into ten groups.

◆ Protozoa are included in protista includes single celled, aquatic, free living or parasitic organisms.

◆ Phylum Porifera include pore-bearing organisms called sponges which are the simplest multicellular animals.

◆ Sponges are vase-like, rounded, sac-like or branched. Euplectella, Sycon, Spongilla, Bath sponge are examples.

◆ Phylum Cnidaria are diploblastic radially symmetrical animals with two layered body wall. They include Hydra, Jelly fish, Sea anemone and Corals.

◆ In Phylum Platyhelminthes, flat-worms have been included which are mostly parasitic.

◆ This group include liver fluke, tapeworm.

◆ Round or thread worms are included in Phylum Aschelminthes which are triploblastic, unsegmented and of bilateral symmetry.

◆ Annelids are triploblastic, bilaterally symmetrically elongated with segmented body.

◆ Animals with jointed legs have been placed in Phylum Arthropoda. In these animals body is covered with chitinous cuticle. It is the largest phylum and includes prawns, insects, spiders, scorpions etc.

◆ In Phylum Mollusca body is divided into three regions i.e. head, dorsal visceral mass and ventral foot. These are soft bodied animals.

◆ In Phylum Echinodermata group includes star fishes, brittle star and sea urchin. These are spiny-skinned.

◆ Protochordata group includes Herdmania and Amphioxus.

◆ In Phylum Hemichordata, body is divided into three parts i.e. proboscis, collar and trunk.

◆ Phylum Chordata represents the most advanced group of kingdom Animalia.

◆ Chordates bear (i) solid rod-like structure called notochord, on dorsal side above the gut, (ii) dorsal hollow nervous system. (iii) pharynx perforated by gill slits.

◆ Pisces includes cartilaginous fishes and bony fishes. These are aquatic in habitat,  gill – breathing and swimming vertebrates. They swim by fins.

◆ Class amphibia includes Amphibious animals that can live both in water and moist places on land. Heart is 3-chambered in amphibians. Examples: Frog, Toad and Salamander.

◆ In Class Reptilia, creeping vertebrates have been included. Few examples of class Reptilia are lizards, snakes, crocodiles and tortoises.

◆ In Class Aves, body is externally covered by feathery exoskeleton which insulates the body. Sound is produced by syrinx. Example: Birds.

◆ In mammals, body has hairy exoskeleton and bears two pairs of pentadactyl limbs modified for various purposes.

◆ The scientific names are unique, understood and followed throughout the world.

◆ Binomial system means that the name of each organism consists of two words, a generic name and a specific name.

⇒ Classification. The method of placing organisms into groups or sub-groups depending upon extent of similarities and differences is called classification.

⇒ Ernst Hacckel (1894), Robert Whittaker (1959) and Carl Woese (1977) have tried to classify all living organisms into broad categories, called Kingdoms.

⇒ Aristotle classified animals according to their habitat (land or water).

⇒ Charles Darwin first described the idea of evolution in his book ‘Origin of Species’.

⇒ Carl Linnaeus is the ‘Father of taxonomy’.

⇒ Aerobe. An organism which can grow and live in the presence of oxygen.

⇒ Anaerobe. An organism which can grow and live in the absence of oxygen.

⇒ Nocturnal. Active during night e.g. cockroach.

⇒ Diurnal. Active during day e.g., Humans.

⇒ Polygamy. When one male lives in the company of many females e.g. Struthio.

⇒ Producers. The first trophic level in a food chain. Producers are those organisms Hats that can prepare food from inorganic materials i.e. green plants.

⇒ Taxonomy. It deals with identification, nomenclature and classification of different types of organisms.

⇒ Genus. Group of related species.

⇒ Species. Basic unit or classification.

⇒ Coelom. Body cavity bounded by visceral and parietal layer of peritoneum.

⇒ Phylogeny. Evolutionary history of an organism is term phoylogeny.

⇒ Biodiversity. Variety of life forms found in a particular area.

Ans.— Classification helps in the study of broad groups of organism of wide variety of organisms in a simple way.

1. Size. Microscopic bacteria a few micrometres in size at one end of the size-scale and 30 metre long blue whale and ~ 100 metre tall red wood trees of California.

2. Life Span. Pine trees live for thousands of years while insects such as mosquitoes die within few days.

3. Colour. Colourless or transparent worms to brightly coloured birds and flowers.

Ans.— The kind of cells is more basic characteristic for classification of organisms. The cells may be Prokaryotic or Eukaryotic. The presence or absence of nucleus, or membrane bound organelles would reflect on every aspect of cell design and capacity to make a multicellular body.

Ans.— Nature of Cell. Prokaryotic cell or eukaryotic cell.

Ans.— 1. Mode of nutrition. Plants prepare their own food by photosynthesis in the presence of sunlight and chlorophyll in chloroplasts and animals acquire ready made food.

2. Plants are fixed whereas animals are motile.

3. Plants show limited growth whereas animals stop growing after attaining a certain size.

4. Plant cells are surrounded by cell wall and animal cells lack cell wall.

Ans.— Primitive organisms. The organisms which have ancient body designs that have not changed very much. They are also called ‘lower’ organisms.

Advanced organisms. The group of organisms that have acquired their particular body design relatively recently. They are also called ‘higher’ organisms.

Ans.— Yes, complexity in design will increase over evolutionary time, hence older (primitive) organisms are simple while younger organisms are more complex.

Ans.— The criterion for classification of monera and protista. Nature and number of cell.

Prokaryotes belong to kingdom monera and single celled eukaryotes belong to kingdom protista.

Ans.— Protista

Ans.— (i) Species will have smallest number of organisms.

(ii) Kingdom will have largest number.

Ans.— Algae (Thallophytes).

Ans.— 1. Phanerogams produce seeds while pteridophytes do not.

2. Reproductive organs are hidden in pteridophytes and well developed in phanerogams.

3. Pteridophytes have specialised tissue for the conduction of water and proper vascular tissues are present in phanerogams.

Ans.— Differences between gymnosperms and angiosperms

Gymnosperms	Angiosperms
1. Seeds are naked.	1. Seeds are enclosed in fruits.
2. Reproductive organs sporophylls form cones.	2. Reproductive organs are flowers.
3. Ovules not enclosed in ovary.	3. Ovules are enclosed in ovary.
4. Xylem lacks vessel.	4. Xylem contains vessels.
5. Companion cells are absent in phloem.	5. Companion cells are present.

Ans.— Differences between poriferan animals and coelenterate animals.

Poriferan animals	Coelenterate animals
1. Numerous minute pores ostia for entry of water and single osculum for exit of water present.	1. The body bears a single pore.
2. Appendages absent.	2. Tentacles as appendages present.
3. Intercellular digestion.	3. Digestion is intracellular as well as intercellular.
4. Spicules or spongin fibres present.	4. Stinging cells called cnidoblasts present.

Ans.— Differences between annelids and arthropods

Annelids	Arthropods
1. Jointed appendages absent.	1. Body bears jointed appendages.
2. Body covered with cuticle.	2. Body covered with chitinous cuticle forming exoskeleton.
3. True coelom as body cavity present.	3. Haemocoel present.
4. Closed type of circulatory system present.	4. Open type of circulatory system present.

Ans.— Differences between amphibia and reptilia

Amphibia	Reptilia
1. Body wall not covered with any kind of exoskeleton.	1. Scales or dermal plates present.
2. Body divided into head and trunk.	2.Body divided into head, neck, trunk and tail.
3. Fertilization is external.	3. Fertilization is internal.

Ans.— Differences between aves and mammals

Aves	Mammals
1. Body covered with feathers.	1. Body covered with hair.
2. Wings present.	2. Wings absent.
3. Pinna absent.	3. Pinna present.
4. Diaphragm absent.	4. Diaphragm present.
5. RBCs nucleated.	5. RBCs without nucleus.
6. Bones spongy and light.	6. Bones solid and heavy.
7. Excretory product is uric acid.	7. Excretory product is urea.
8. Oviparous (egg laying.)	8. Viviparous (give birth to youngones.)

Ans.— Advantages of classification :

(i) Classification makes the study of wide variety of organisms easy.

(ii) Classification of organisms is responsible for description of species.

(iii) It helps in understanding the interrelation among different groups of organisms.

(iv) Classification of living beings recognises the basic taxonomic units of species.

(v) It helps in understanding the evolution of organisms.

(vi) Exact identification of insects helps in controlling epidemic diseases like malaria, filariasis, dengue fever, kala azar etc.

Ans.— Major division of plant kingdom (Plantae)

Ans.— Characteristic is a particular form or function. Many inter-related characteristics are used in order to classify all living organisms.

1. Nature of cell is basic characteristic of classification.

2. Number of cells.

Ans.— 1. Nature of cell. Prokaryotic or eukaryotic.

2. Number of cells. Unicellular or multicellular.

3. Mode of nutrition. Absorptive or autotrophic or holozoic.

Ans.— Criteria for dividing plants. The eukaryotic multicellular organisms with cell wall and carry out photosynthesis and placed under kingdom plantae. The first level of classification among plants depends on whether the plant body has well-differentiated, distinct components. The next level of classification is based on whether the differentiated plant body has special tissues for the transport of water and other substances within it. Further classification looks at the ability to bear seeds and whether the seeds are enclosed within fruits.

Criteria for dividing animals into sub-groups. The eukaryotic multicellular heterotrophic and lacking cell wall are placed in an animal kingdom. They are further classified on the basis of extent and type of body design and differentiation present.

Ans.— Classification of vertebrata

1. Kingdom Monera. Monerans are prokaryotes. e.g. Bacteria, Blue green algae.

2. Kingdom Protista. Protists are unicellular eukaryotes, having widely diverse life styles, e.g. Amoeba, Paramecium, etc.

3. Kingdom Fungi. Fungi are eukaryotic, heterotrophic organisms with assimilative nutrition, e.g. Rhizopus, Agaricus.

4. Kingdom Plantae. Plantae includes eukaryotic multicellular, photosynthetic organisms, e.g. Green multicellular plants.

5. Kingdom Animalia. Animals are eukaryotic, multicellular consumer characterised by ingestive nutrition. This kingdom includes Non-chordates and chordates.

Ans.— Differences between plants and animals

Plants	Animals
1. Autotrophs, prepare food from inorganic substances.	1. Heterotrophs, Feed on complex organic compounds.
2. Carry out Photosynthesis.	2. Do not photosynthesize.
3. Possess chlorophyll.	3. Chlorophyll absent.
4. They are fixed but move parts of the body.	4. They move the whole body.
5. Branching body.	5. Compact body.
6. They are less sensitive and respond slowly.	6. They are highly sensitive and respond quickly.
7. Cellulose in cell walls usually present.	7. Cell wall absent in cells.

Ans.— Apart from the number of cotyledons, the monocots and dicots show several other differences in their morphology and anatomy. These differences are tabulated below.

Monocot plants	Dicot plants
1. Roots are generally adventitious.	1. They usually possess tap root.
2. Venation in leaves is parallel.	2. Venation is reticulate.
3. Flowers of monocots are trimerous i.e. floral leaves in each whorl are either three or a multiple of three.	3. Flowers in dicots are either tetramerous or pentamerous.
4. The calyx and corolla are not differentiated and the outer two whorls are exactly alike to form perianth.	4. The flower has distinct calyx and corolla.
5. Vascular bundles in stem are scattered and closed.	5. The vascular bundles in dicot stem are arranged in ring and are open.

Ans.— 1. These have organ-system organisation and bilateral symmetry.

2. These are triploblastic and haemocoelomates (have haemocoel-a body cavity with blood).

3. Their body is externally covered by a sclerotized chitinous exoskeleton formed of plates, called sclerites, and are formed of chitin.

4. Body is divided into two (Cephalothorax and abdomen) or three parts (Head, thorax and abdomen).

5. Mouth is surrounded by mouth parts which are of different types in different arthropods.

6. These have jointed appendages which are of different types to perform different functions.

7. These have complete (Mouth and anus both present) and coiled alimentary canal.

8. Respiration occurs by gills or book lungs or tracheae (air tubes).

9. Blood is colourless and is called haemolymph

Examples : Periplaneta (cockroach-insect); Butterfly, Dragon fly, House fly, Palaemon (Prawn Crustacean); Crab, Centipede; Millipede and Scorpion (Arachnid).

Ans.— Arthropods are most successful and most adapted to varied environmental conditions due to presence of a hard exoskeleton formed of cutin organised as scleretes and jointed appendages which helps in following functions :

1. Protection from the water loss (as forms a water proof coat).

2. Provides a definite shape to the animals.

3. It is modified to form the wings so helps in flight.

4. It forms the mouth parts with mandibles so helps in biting and chewing.

5. It provides surface for the attachment of muscles.

6. Jointed appendages are modified to perform different types of functions.

Ans.— 1. Spiny skin of these animals contain dermal calcareous plates. Spines may be movable (e.g. sea urchin).

2. Pentaradial symmetry in adult but larva is bilaterally symmetrical.

3. Head absent. But divisible into central disc and arms.

4. Water vascular system (Ambulacral system) is present. It consists of an array of radiating and tube-like appendages called tube feet. Locomotory organs are tubular tube feet or podia and also aid in capturing prey.

5. Body has oral surface bearing mouth and aboral surface bears anus.

6. Tube feet and dermal branchiae aid in gaseous exchange.

7. All are marine, mostly gregarious and free living, creep slowly on the sea bottom. Examples. Star fish, Sea urchin, Sea cake, Sea lily and Sea cucumber.

Ans.— Diagnostic characters of phylum chordata.

1. Presence of notochord, at any stage of life history. Notochord is stiff rod-like structure which is retained throughout life in lower chordates. It is replaced by vertebral column in higher chordates.

2. Presence of dorsal, hollow nervous system.

3. Pharynx is perforated by gill slits at any stage of life history.

4. Tail is present at any stage of life history.

5. Respiratory pigment haemoglobin is present in the R.B.C.

Ans.— Protochordates. Includes two groups called urochordates and cephalochordates. They have string like notohord.

1. The body is not divided region-wise and the coelom is absent.

2. Notochord is present in larval forms and is confined to tail region.

3. There is an atrium which surrounds the pharynx and the pharyngeal clefts open into it.

4. The body of the adult is enclosed in a test. The test is composed of tunicine.

Example. Herdmania.

Ans.— Characters of Cephalochordata.

1. Body is laterally compressed, elongated and pointed at both ends. No distinct head.

2. Only median fins present. Paired fins absent.

3. The notochord is the chief support of body.

4. The mouth is ventral at the anterior end, the anus is on the left side near the base of tail fin and atriopore is an additional ventral opening.

Example : Branchiostoma (Amphioxus)

Cartilaginous Fish	Bony Fish
1. Always marine.	1. May be marine or fresh water.
2. Skin covered by small placoid scales.	2. Scales are large; Scales either cycloid or ganoid.
3. Mouth is subterminal or ventral.	3. Mouth terminal.
4. Gill slits not covered by operculum.	4. Gills covered by operculum.
5. Swim bladder absent.	5. Presence of swim bladder.
6. Endoskeleton entirely cartilaginous.	6. Endoskeleton bony.
7. Tail fin asymmetrical. Examples— Sharks, Rays, Sea horse.	7. Tail fin symmetrical. Examples— Labeo, Catfish, Flat fish.

Flying lizard	Birds
1. Cold blooded.	1. Warm blooded.
2. Body covered with scales	2. Body covered with feathers.
3. Membrananous.	3. Forelimbs are modified into wings for flight.
4. Heart incomplete four chambered.	4. Complete four chambered heart present.

Ans.— Diversity of life. It is also called biological diversity or Biodiversity. It is variety of living system on earth. It may refer to extinct organisms, and also to their diversity in the past. About 2 million species have been described so far and about 17000-19000 new entries are added every year to this list. These organisms include plants, animals, etc. Insects represent more than one half of the total species. The source of such a vast diversity organism is evolution.

Ans.— Objectives of Biological Classification.

1. To recognise and precisely describe the basic units of classification, i.e., species.

2. To devise an appropriate method of assigning the basic units (species) into an ascending series of groups on the basis of their similarities and relationships.

Ans.— Difference between Taxonomy and Systematics.

Taxonomy	Systematics
1. It is the science of identification, nomenclature and classification.	1. Systematics is the science of identification, nomenclature, description and classification.
2. It deals with rules and principles of classification.	2. It brings out unique properties at every level of classification.

Ans.—  Hierarchy of classification. It is a system of arrangement of a framework for classification in which taxonomic categories are placed in the order of logical sequence. Linnaeus was the first to establish and define hierarchy of taxonomic categories. They are classes, order, genus, species and varieties. They are arranged in following order :

Kingdom

       Phylum/Division

               Class

                          Order

                                     Family

                                                   Genus

                                                                 Species

Ans.— (a) Species. It is defined as a dynamic group of organisms, which :

(i) resemble each other in all essential respects, i.e. structure and function.

(ii) differ visibly from all other groups.

(iii) interbreed freely under natural conditions to produce fertile young ones of their own kind.

(iv) are reproductively isolated from other groups.

(v) have descended from a common ancestor in a not too distant past, and

(vi) have similar genetic material.

Species	Taxon
1. It represents the basic taxonomic category.	1. Taxon represents any level of taxonomic category.
2. Species is a rank and therefore represents an abstract ter1m.	2. It is a group of concrete biological objects.
3. It is always monophyletic.	3. Taxon may be monophyletic or polyphyletic.

Ans.— Species change slowly over generations. With time these changes lead to the formation of new species. Evolution thus explains why there are resemblances between species and group of species. It is because they are related by descent, i.e., have a common ancestry. There is enough fossil evidence to show that complex organisms came after simple ones during geologic time.

1. The prokaryotic versus eukaryotic structure of cell.

2. The unicellular versus multicellular organization.

3. The three different modes of nutrition i.e. autotrophic, absorptive and holozoic (ingestive).

Ans.— Refer to Basis & Basics.

3. Monerans have various forms of nutrition : some are autotrophs capable of photosynthesis, others are capable of deriving energy from inorganic chemical reaction (chemosynthetic) : most species absorb organic nutrients from their environment.

4. Reproduction is asexual.

5. Some organisms may have cell wall.

6. Monerans are the important decomposers in the biosphere.

Examples are Bacteria, Blue-Green algae (Cyanobacteria), Mycoplasma.

1. This kingdom includes diverse kinds of mostly unicellular and primarily aquatic eukaryotes.

2. They are eukaryotic organisms having typical eukaryotic cell organelles such as nucleus, mitochondria, ER, Golgi bodies, plastids etc.

3. Mode of nutrition absorptive, ingestive or photo-autotrophic.

4. Mostly bear eukaryotic whip – like flagella or hair – like cilia.

5. Reproduction asexual as well as sexual.

Examples. Protozoan (Amoeba), Euglena, Diatoms.

Ans.— (a) The kingdom of multicellular decomposers is Fungi. This kingdom includes diverse kinds of eukaryotic, predominantly multicellular, heterotrophic organisms.

1. Body organization mycelial or secondarily unicellular, composed of hyphae, coenocytic or septate.

2. They are non-green as chlorophyll is absent.

3. They are heterotrophic in nutrition and obtain food from dead, decaying organic matter by absorption.

4. Cell wall is chitinous cellulose.

5. Asexual reproduction by spore formation.

6. Sexual reproduction also occurs.

Examples. Bread moulds, mushrooms, puff balls and bracket fungi, Penicillium, yeast and certain parasitic fungi.

Some fungal species live in permanent mutually dependent relationship with blue green algae. Such relationship is called symbiotic e.g. Lichens (slow-growing, large, coloured patches on the bark of tree).

Ans.— Kingdom Plantae. This kingdom includes multicellular producers. The characteristics are :

1. Complex multicellular plants adapted for photosynthesis.

2. The plant cells are rigid because of cellulose cell wall.

3. Mostly the cells are rigid and cannot contract and relax like animal cells do. Plants are immobile and do not exhibit the phenomenon of locomotion.

4. Plant synthesize all organic constituents from water, CO₂ and inorganic forms of essential elements using light energy trapped by chlorophyll and accessory pigments.

5. They have unlimited growth.

Ans.— Characters of Kingdom Animalia.

1. Members of the group are multicellular eukaryotes with tissue differentiation.

2. Nutrition heterotrophic, ingestive mode of intake of food.

3. Muscle cells well developed which provide mobility. Howe

4. Nervous system well developed.

5. Ecologically animals are consumers.

6. Sexual reproduction occurs.

Examples. Sponges, insects, molluscs, fishes, birds, reptiles and mammals.

Ans.— In binomial nomenclature, name of every organism is composed of two components-first one is genus (generic) and second species name (specific).

Example. Scientific name of human is Homo sapiens where Homo is generic name and sapiens is specific name.

Ans.— Scientific name of potato is Solanum tuberosum Linn. Where Solanum is genus, is species and Linn is author.

Man is scientifically called as Homo sapiens Mill. Here Homo is a generic name and sapiens is specific name. Mill is author. Sometimes specific names can be given after a country or locality e.g. Rosa indica, Rumex nepalensis.

Ans.— (a) The biological names are same all over the world.

(b) They are uniformly binomial.

(c) They are definite and accepted universally.

(d) They are descriptive.

(e) They indicate general relationship.

(f) All newly discovered plants and animals can be named and described easily.

Ans.— (a) Plants belonging to this group are the simplest and primitive.

(b) Here, the plants are made up of single cell or group of cells.

(c) The plant body is thallus i.e. it is not differentiated into stem, root and leaves.

(d) The zygote formed after fertilization, gives rise to either plant body directly or produces spores.

(f) Vascular tissue absent.

Ans.— Characters of Algae.

1. Green in colour due to chlorophyll.

2. They are photoautotrophs.

3. Reserve food material is starch.

Example : Chlamydomonas, Volvox, Ulothrix, Spirogyra.

Ans.— Green algae

Ans.— (a) The plant body is not differentiated into root, stem and leaves.

(b) Absorbing and anchoring organs are rhizoids.

(c) Vascular tissue and mechanical tissue absent.

(d) Vegetative reproduction is very common.

(e) Sexual reproduction is by gamete formation.

(f) Sex organs are multicellular.

(g) Formation of sporogonium takes place.

Examples : Riccia, Porella, Funaria (Moss), Marchantia (Liverwort) and Anthoceros.

Ans.— Mosses mostly occur in cool, moist places. They form a sort of mat on rock. The presence of water is necessary in their life functions. Mosses are found in humid and moist area because :

1. In mosses sperms are flagellated. They can reach the archegonia only in presence of

2. Mosses have no xylem tissue for conduction of water. So entire body of moss in damp humid places can absorb water.

So water is indispensable in their life cycle for reproduction as well as for other physiological functions.

Ans.— 1. The dominant plant body in ferns is sporophyte. It is differentiated into root, stem and leaves.

2. The leaves are large (megaphyllous), variously-shaped and look like the branches. They are called as fronds. The stem may be an underground rhizome or a trunk as in tree ferns while the roots are adventitious.

3. Ferns bear special spore-bearing leaves called the sporophylls. The spores are produced in sporangia.

4. Spores in ferns, germinate each forming an independent, small gametophyte, the prothallus. The latter bear the sex organs, antheridia (male) and archegonia (female).

Ans.— Common Pteridophytes.

1. They bear naked seeds i.e seeds are not enclosed within a fruit.

2. The plants are usually perennial, evergreen and woody.

3. Flowers are represented by unisexual cones, both being present on the same plant.

Examples : Cycas, Pinus, Cedar etc.

Ans.— Phanerogamae. These are seed bearing plants. Vascular tissue is present. They are found on land. This division is composed of two main sub-divisions i.e. Gymnosperms and Angiosperms.

Ans.— Characters of Angiosperms. (angio means covered and sperma means seed).

1. They are flowering plants with seeds develop inside fruit.

2. Cotyledons are the plant embryos present inside the seed.

3. Plant body is divided into root system and shoot system.

Examples : Mango, Rose, Wheat, Grasses.

Ans.— Classification according to cotyledons.

The number of cotyledons in seed of a flowering plant is either one or two. The angiosperms are divided into two groups-(i) Monocotyledons and (ii) Dicotyledons.

(i) Monocotyledons are the plants in which the seed contains a single cotyledon; e.g. boy Wheat, Rice, Maize, Sugarcane, Grasses. There are about 50,000 species of them.

(ii) Dicotyledons are those flowering plants in which the seed contains two cotyledons. e.g. Solanum, Mango, Beans, Castor, Gram, Sunflower.

Gymnosperms	Angiosperms
1. The seeds are naked.	1. The seeds are present within fruits.
2. These are cone bearing plants.	2. They bear flowers.

Ans.— Chinar. It is pride of Kashmir, locally called ‘Bouine’ (Plantus orrentalis kashmeriana). It belong to family Plantancea. Chinar is a large-sized tree. It grows upto a height of 100 ft and a girth exceeding 70 ft in certain cases. It is native of temperate region. Chinar, a deciduous tree, have palmate leaves and pendulous burr-like fruit. The tree is at its best elegance during autumn.

Ans.— Characters of seed plants which make them specially adapted to life on land are :

1. Presence of vascular tissue.

2. The development of seed habit removed the liquid medium as an essential feature for fertilization.

3. Presence of cuticle in the leaves.

Ans.— 1. Eukaryotic cells lack cell wall.

2. They do not perform photosynthesis instead take readymade food, thus heterotrophs.

3. They have power of locomotion thus they are mobile.

1. Very minute, one celled microscopic organisms. Cell itself is an organism therefore, they are also called acellular organisms.

2. Structure is very simple. The body consists merely of a mass of protoplasm. There is no tissue or organ formation.

3. Generally, there is no skeleton. However, locomotory and feeding organelles such as pseudopodia, flagella or cilia may be present.

Example. Amoeba, Entamoeba, Paramecium, Plasmodium.

Ans.— Porifera (Sponges). 1. They are primitive, sessile animals with specialized cells but no tissues or organs.

2. Pores all over the body, no digestive tract.

3. Collar cells filter out food particles from water current flowing through canal system.

4. Mostly marine.

5. They are called sponges.

Examples : Sponges, Euplectella, Sycon, Spongilla.

Ans.— Unique features of Coelenterates (cnidarians)

1. Tissue level of organisation of the body

2. Special stinging cells, the cnidoblasts, for defence and offence.

3 Incomplete digestive tract bounded by gastrodermis of body wall.

4 Simple gonads without gonoducts.

5. Show polymorphism.

Examples : Hydra, Jelly fish and Sea Anemone.

Ans.— Characters of Flatworms.

1. Dorsoventrally flattened triplo – blastic, bilaterally symmetrical animals.

2. They are acoelomate.

3. Mostly parasite, a few are free living.

4. Incomplete branched or unbranched alimentary canal.

5. Bisexual or hermaphrodite. Life history is complicated.

Examples— Planaria, Fasciola and Taenia.

Ans.— 1. Unsegmented, bilaterally symmetrical cylindrical worms also called as roundworms.

2. They are triploblastic and pseudocoelomate.

3. Mostly free living.

4. Complete alimentary canal present.

5. Sexes are separate and show sexual dimorphism. Fertilized egg has a thick wall and survive adverse condition.

Examples— Ascaris (Roundworm), Ancylostoma (Hookworm), Dracunculus (Guinea worm), Rhabditis.

Filarial worm causes elephantiasis.

Ans.— Distinguishing characters of Arthropods

1. Body covered with chitinous exoskeleton.

2. Body bears jointed appendages.

3. One or two pairs of jointed antennae present.

4. There is an open circulatory system, and so the blood does not flow in well defined blood vessels.

5. The coelomic cavity is blood-filled called haemocoel.

1. Three body regions; head, visceral mass and foot.

2. A glandular fold, the mantle, over the body.

3. Mantle cavity with anal, excretory and genital apertures in it.

4. Calcareous shell around the body in most cases.

5. A rasping organ, the radula in the buccal cavity.

Examples : Pila, Sepia, Octopus.

Ans.— 1. Phylum Echinodermata includes starfish, sea cucumbers, sea urchins, sea

lilies etc.

2. The animals show pentaradial symmetry.

3. There is an exoskeleton of calcareous plates and spines.

4. Locomotion is by tube feet.

5. There occurs a peculiar water vascular system. Echinoderms are confined to sea.

Ans.— Examples of Echinoderms

1. Asterias (Star fish)

2. Sea urchin

3. Antedon (Sea lily)

4. Sea Cucumber

5. Sea cake.

1. Body divided into proboscis, collar and trunk.

2. Respiration through gills.

3. Bilateral symmetry.

Example. Balanoglossus (Tongue worm).

1. The body is divided into three regions a head with an internal cranium, trunk and postanal tail.

2. The notochord is replaced by vertebral column during life history.

3. Body contains cartilaginous or bony endoskeleton.

4. The post-anal part called tail is usually present.

5. There is a complex brain with special sense organs.

6. There is well developed ventral heart with two, three or four chambers.

7. Two pairs of lateral appendages, fins or limbs present.

8. The excretory organs are kidneys.

9. Respiration occurs through gills or lungs.

10. The sexes are separate.

Exoskeleton	Endoskeleton
1. It is present outside the body.	1. It is present inside the body.
2. Examples: chitinuous cuticle of insects, calcareous shell of mollusc, hard plates of echinoderm, scales, feathers, hair, nails, horns of vertebrates.	2. Bones and cartilages constitute the endoskeleton.

Ans.— CLASS PISCES

1. All fish varieties belong to this class which are exclusively water living animals.

2. Their skin is covered with scales/plates.

3. They obtain oxygen dissolved in water by using gills.

4. The body is streamlined and a muscular tail is used for movement.

5. They are cold-blooded and their hearts have only two chambers.

6. Some fish varieties have their skeletons made entirely of cartilage, such as Sharks and some with a skeleton made of both bone and cartilage, such as Tuna or Rohu.

Ans.— Chondrichthyes. (Cartilaginous fishes) : 1. Skeleton cartilaginous. 2. Mouth and nares ventral. 3. Gill slits uncovered. 4. Tail fin asymmetrical. 5. No swim bladder. 6. Intestine with scroll valve. 7. Males with claspers.

Examples : Scoliodon, Narcine, Torpedo, Trygon, Angle, fish, Lion fish.

Ans.— Microscopic bacteria a few micrometres in size, the ~30 metre long blue whale and 100 metre tall redwood trees of California.

Ans.— Pine trees.

Ans.— Taxonomy.

Ans.— Aristotle.

Ans.— The group of animals which have ancient body divisions and have not changed very much. They are also called lower organisms.

Ans.— The group of organisms that have acquired their particular body design relatively recently, also called ‘higher’ organisms.

Ans.— Biodiversity. Variety of life forms found in a particular region.

Ans.— Diverse life form share the environment and all affected by each other result in establishment of a stable community.

Ans.— Well defined true body cavity is absent and the spaces present contain colourless blood (Haemolymph).

Ans.— Arthropods and molluscs.

Ans.— Oviparous animals lay eggs e.g. birds, while viviparous animals give birth to young ones e.g. most of mammals.

Ans.— Animals which have both male and female reproductive organs e.g. earthworm, leech, etc.

Ans.— Spicules (needles) or spongin fibres or both.

Ans.— These are stinging cells present on the tentacles of coelenterates like Hydra. These inject the hypnotoxin and paralyze the prey.

Ans.— Coelenteron.

Ans.— Presence of sclerotized exoskeleton and jointed appendages.

Ans.— Presence of more than two types of individuals in the colony which differ in their structure as well as function e.g. honey bees.

(A) climbers

(B) lianas

(C) runners

(D) herbs.

Ans.— (D) herbs.

(A) short trees

(B) shrubs

(C) bushes

(D) sporophytes.

Ans.— (B) shrubs

(A) trees

(B) creepers

(C) lianas

(D) mesophytes.

Ans.— (A) trees

(A) Marine habitats

(B) Fresh water habitats

(C) Rivers

(D) Terrestrial habitats.

Ans.— (B) Fresh water habitats

(A) Independent gametophyte

(B) Dependent gametophyte

(C) Independent and dominant sporophyte

(D) Flagellate antherozoids.

Ans.— (C) Independent and dominant sporophyte

(A) Angiosperms

(B) Gymnosperms

(C) Monocots

(D) Dicots.

Ans.— (B) Gymnosperms

(A) Rectum

(B) Oral cavity

(C) Stomach

(D) Intestine.

Ans.— (D) Intestine.

(A) Coelenterates

(B) Sponges

(C) Vertebrate

(A) Planaria

(B) Rotifers

(C) Ascaris

(D) Sea anemone.

Ans.— (D) Sea anemone.

(C) absence of pharyngeal gill slits.

(D) dorsally or laterally placed heart.

Ans.— (C) absence of pharyngeal gill slits.