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SECTION – A

1. What is meant by Tautonymy ? Give two examples.

Ans. The practice of naming the animals or organisms, in which thegeneric name and species name are the same, is called Tautonymy.

Ex : Axis axis – spotted dear.

Naja naja – The Indian Cobra.

2. What is Enterocoelom ? Name the enteroelomate phyla in theanimal kingdom.

Ans. Animals in which the body cavity is formed from the mesodermalpouches of archenteron are called 'enterocoelomates'.

Echinoderms, hemichordates and chordates are theenterocoelomates.

3. Distinguish between exocrine and endocrine glands withexamples.

Ans. Exocrine glands are provided with ducts. Secrete mucus saliva,earwax, oil, milk, digestive enzymes and other cell products.

Endocrine glands are ductless and their products are hormoneswhich are not sent out via ducts, but are carried to the target organsby blood. Ex : pitutory gland.

4. Mention any two substances secreted by mast cells and theirfunctions.

Ans. Mast cells secrete heparin – an anticogulant – histamin, bradykinin –vasodilators and seroonina – vasocon strictor. Vasodilators cause inflammationin response to injury and infection.

5. What is the function of radula ? Give the name of the group ofmolluscs which do not possess a radula ?

Ans. The buccal cavity contains a file – like rasping organ called radulafor feeding, except the bivalves and tusk of Molluscs.

SOLUTIONS FOR PRACTICE PAPER – 3

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6. Name two poisonous and non – poisonous snakes found insouth India.

Ans. Poisonous Snakes : 1) Naja naja (Cobra),

2) Bungarus (Krait)

3) Vipera russelli (Chain viper)

Non – poisonous Snakes :1) Ptyas (rat snake)

2) Tropidonotus (Pond or grass snake)

7. List any two differences between a flagellum and a cilium.Ans.

8. What is a kinety ?

Ans. In the ciliate protozoans a longitudinal row of kinetosomestogether with kinetodesmata constitute a unit called kinety.

9. What is a hyper parasite ? Mention the name of one hyperparasite.

Ans. A parasite that parasitises another parasite is called Hyper parasite.

Ex : Nosema notabilis (acnidosporan) is a parasite in

Sphaerospora polymorpha (acnidosporan parasite in the urinary bladder

of the toad fish).

10. Mention the advantages of some UV. rays to us.

Ans. 1) UV radiations kills the microorganisms present on the body

surface of animals.

2) UV radiations helps in the conversion of sterols present in the

skin into vitamin D in mammals.

Cilium

1. Cilium helps in locomotion,feeding and acts as sensorystructures.

2. Cilium produce pendularmovement.

3. Cilium small in size 5 – 10 µin length.

Flagellum

1. Flagellum helps inlocomotion only.

2. Flagellum produce undularmovement.

3. Flagellum is about 150µ inlength.

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SECTION – B

11. Define species. Explain the various aspects of 'species'.

Ans. Species : Species is the 'basic unit' of classification. Species is a

Latin word meaning 'kind' or 'appearance'. John Ray in his book 'Historia

Generalis Plantarum', used the term 'species' and described it on the

basis of common descent (origin from common ancestors) as a group

of morphologically similar organisms. Linnaeus considered species, in

his book 'Systema Naturae', as the basic unit of classification. Buffon,

in his book 'Natural History', proposed the idea of evolution of species

which is the foundation for the biological concept of evolution.

This biological concept of species (dynamic nature of species) became

more popular with the publication of the book "The Origin of Species"

by Charles Darwin.

Buffon's biological concept of species explains that species is an

interbreeding group of similar individuals sharing the common 'gene

pool' and producing fertile offspring. Species is considered as a group

of individuals which are :

1) Reproductively isolated from the individuals of other species – a

breeding unit.

2) Sharing the same ecological niche – an ecological unit.

3) Showing similarity in the karyotype – a genetic unit.

4) Having similar structure and functional chracteristics – an

evolutionary unit.

12. Explain Haversian system with a neat labelled diagram.

Ans. The compact bone consists of several structural units called Ostens

or Haversion systems arranged around and parallel to the bone

marrow cavities.

Haversian system : consists of a Haversian canal that runs

parallel to the marrow cavity. It contains an artery, a vein and a lymphatic

vessel. Haversian canal is surrounded by concentric lamellae. Small fluid

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filled spaces called'lacunae' provided withminute canaliculi lie inbetween the lamellae.Canaliculi connect thelacunae with one anotherand with Haversian canal.Each lacuna encloses oneosteocyte (inactive form of

osteoblast). Thecytoplasmic processes ofosteocytes extend throughcanaliculi. A Haversian canaland the surroundinglamellae and lacunae are

collectively called a Haversian system or osteon. The Haversian canalscommunicate with one another, with the periosteum and also withthe marrow cavity by transverse or oblique canals called Volkmannscanals. Nutrients and gases diffuse from the vascular supply of Haversiancanals.

13. Write short notes on the salient features of the anthozoans.

Ans. 1) Anthozoans are commonly referred to as sea anemones.

2) Anthozoa includes sea anemones, corals, sea pens.

3) All are marine forms. These are solitary or colonial.

4) They are sedentary and only polypoid inform.

5) Coelenteron is divided into several compartments by verticalsepta called mesenteries.

6) Mesoglea contains connective tissue.

7) Cnidocytes occur both in the ectoderm and endoderm andis cellular as contains amoebocytes.

8) Germ cells are derived from the endoderm.

Eg: Adamsia (sea anemone), Gorgonia(sea fan), Pennatual(sea pen).

PariosteumOuter circumferentiallamellaeInterstital lamellae

Concentric lamellae

Haversian canal

Volkman's canalInner circumferenitiallamellaeEndosteumBone marrow

T.S. of a compact bone

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1. These are live in all kinds ofaquatic habits.

2. Endoskeleton made by bone.

3. Body covered by cosmoid,ganoid, cycloid or ctenoid scales.

4. Caudal fin is homocercal.5. Operculum present.6. Air baldder present.7. Gills are filamentous and are

four in each side.8. These are mostly ammono- telic.

Ex : Catla, Labeo, Exocetus, Hippocampus.

1. These are marine farms.

2. Endoskeleton made by carti-laginous.

3. Body covered by plocoidscales.

4. Caudal fin is heterocercal.5. Operculum absent.6. Air bladder absent.7. Gills are lamelliform and are

five to seven in each side.8. These are ureotelic.

Ex : Scoliodon, Pristic, Torpedo

Cartilaginous fishes Bony fishes

14. Compare and contrast cartilaginous and bony fishes.

Ans.

15. Describe the process of longitudinal binary fission in Euglena.

Ans. Binary fission is the most common method of asexual reproductionin protozoans.

Longitudinal binary fission is performed by Euglena. In this typeof binary fission, the body divides into two halves longitudinally, hencecalled longitudinal binary fission.

Longitudinal binary fission in Euglena – different stages

Chromatic Duplication ofChrosomes

Longitudinal furrow

Nuclei

Daughterenglenae

Dividingnucleus

Nucleus

A B C D E

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During the process of binary fission, the nucleus, basal granules,chromatophores, cytoplasm undergo division. The nucleus divides bymitosis into two daughter nuclei. Then the kinetosomes and thechromatophores also divide. At first, a longitudinal groove develops inthe middle of the anterior end. This groove extends gradually towardsthe posterior end until the two daughter individuals are separated.One daughter Euglena retains the parental flagella. The other daughterindividual develops new flagella. From the newly formed basal granules.The stigma, paraflagellar body and contractile vacuole of the parentdisappear. They develop afresh in both the daughter euglenae. Thelongitudinal binary fission is known as symmetrogenic division,because the two daughter euglenae resemble each other like 'mirrorimages'.

16. What are the adverse effects of tobacco ?

Ans. Effect : Smoking increases the carbon monoxide (CO) level andreduces the oxygen level in the blood. Nicotine stimulates the adrenalgland to release adrenaline and nor – adrenaline into blood. Thesehormones raise the blood pressure and increase the heart rate. Smokingis associated with bronchitis, emphysema, coronary heart disease, gastriculcer and increases in incidence of cancers of throat, lungs, urinarybladder etc. smoking also paves the way to hard drugs. Yet smoking isvery prevalent in society, both among young and old. Tobacco chewingis associated risk of cancer of the oral cavity.

17. Draw a neat labelled diagram of the salivary apparatus ofcockroach ?

Ans.

Periplaneta : Mouth parts

Hypopharynx

Maxlliary palp

Prementum

Paraglossa Labial palp

Labrum

Mandible

Glossa

Galea

LaciniaPalpifer

StipesCardo

Submentum

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18. Describe 'Green House' Effect.Ans. The term Green House effect' has been derived from aphenomenon that occurs in a green house'. Green house is a smallglass house and is used for growing plants especially during winter. Ina green house the glass panel allows the passage of light into it, putdoes not allow heat to escape (as it is reflected back). Therefore, thegreenhouse warms up, very much like inside a car that has been parkedin the sun for a few hours.

The greenhouse effect is a naturally occurring phenomenon thatis responsible for heating of the Earth's surface and atmosphere. Itwould be surprising to know that without green house effect theaverage temperature of the Earth's surface would have been a chilly –18°C rather than the present average of 15°C.

When sunlight reaches the outer most layer of the atmosphere,clouds and gases reflect about one – fourth of the incoming solarradiation and absorb some of it. Almost half of the incoming solarradiation falls on the Earth's surface and heats it up. While a smallproportion is reflected back.

SECTION – C

19. Describe the life cycle of plasmodium vivax in mosquito withthe help of diagram.

Ans. Life cycle of plasmodium in mosquito (The mosquito phase) Rosscycle.

When a female Anopheles mosquito bites and sucks the bloodof a malaria patient the gametocytes along with the other stages ofthe erythrocytic cycle reach the crop of mosquito. Here all the stagesare digested except the gametocytes. Further part of the life cycleconsists of

i) Gametogony ii) Fertilizationiii) Formation of ookinete & oocystsiv) Sporogonyi) Gametogony : The formation of male and female gametes

from the gametocytes is called gametogony. It occurs in the lumen ofthe crop of mosquito.

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Formation of male gametes : During this process the nucleus ofmicrogametocyte divides into eight daughter nuclei called pronucleiwhich reach the periphery. The cytoplasm is pushed out in the form ofeight flagella like processes. Into each flagellum like process onepronucleas enters and forms a micro gamete or male gamete. Thesemale gametes show lashing movements like flagella and get separatedfrom the cytoplasm of microgametocyte. This process is calledexflagellation.

Formation of female gamete : The female gametocyte undergoesa few changes and transforms into a female gamete. This process iscalled maturation. The nucleus of the female gamete moves towardsthe periphery and the cytoplasm at that point forms a projection. Thisprojected region is called the fertilization cone.

ii) Fertilization : The fusion of male and female gametes iscalled fertilization. It also occurs in the lumen of the crop of themosquito. When an actively moving male gamete comes into contactwith the fertilization cone of the female gamete, it enters it, thepronuclei and cytoplasm of these two gametes fuse with each other,

Sexual life cyle in Mosquito

Oocyst

Nuclei

Fermation ofsporoblasts

Sporocyst

Sporocyst burstliberating sporozoites

Sporozoites insalivary glands Male gametocyte

Female gametocyte

Female gamete

Male gamete

Female gameta withfertilization coneFERTILIZATION

Zygote

Vermicule/CokineteCrop wall

Cyst wall

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resulting in the formation of a synkaryon. Since the two gametes aredissimilar in size. This process is known as anisogomy. The female gametethat bears the synkaryon is called the zygote which is round and non –motile.

iii) Formation of ookinete and oocysts : The zygote remainsinactive for some time and then transforms into along, slender, motile,vermiform ookinete or vermicule with in 18 to 24 hours. It pierces thewall of the crop and settles beneath the basement membrane. Itbecomes round and secretes acyst around its body. This encystedookinete is now called oocyst. About 50 to 500 oocysts are formed onthe wall of the crop and appear in the form of small nodules.

iv) Sporogony : The formation of sporozoites in the oocysts iscalled sporogony. According to Bano, the nucleus of the oocyst firstundergoes reduction division followed by repeated mitotic divisionsresulting in the formation of about 1,000 daughter nuclei. Each bit ofnucleus is surrounded by a little bit of the cytoplasm and transformsinto a sickle shaped sporozoite. Oocyst with such sporozoites is calledsporocyst.

When this sporocyst reptures, the sparozoites are liberatedinto the haemocoel of the mosquite. From there, they travel into thesalivary glands and are ready for infection. The life cycle of plasmodiumin mosquito completed in about 10 to 24 days.

20. Describe the blood circulatory system of periplaneta in detailand draw a neat and labelled diagram of it.

Ans. The circulatory system helps in the transportation of digestedfood, hormones etc., from one part to another in the body. Periplanetahas an open type of circulatory system as the blood or haemolymph,flows freely within the body cavity or haemocoel, Blood vessels arepoorly developed and open into spaces. Visceral organs located in thehaemocoel are bathed in the blood. The three main parts associatedwith the blood circulatory system of periplaneta are the haemocoel,heart and blood.

Haemocoel : The haemocoel of cockroach is divided into threesinuses by two muscular, horizontal membranes called dorsal diaphragm

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or pericardial septum and ventral diaphragm. Both the diaphragmshave pores. There is a series of paired triangular muscles called alarymuscles. Every segment has one pair of these muscles situated on thelateral sides of the body. These are attached to the pericardial septumby their broad bases and to the terga by their broad bases and to theterga by their pointed ends or apices. The three sinuses of the haemocoelare known as pericardial haemocoel or the dorsal sinus, the perivisceralhaemocoel or the middle sinus and sternal haemocoel or ventral sinusor perineural sinus. The middle sinus is very large as it contains most ofthe viscera. The dorsal and ventral sinuscs are small as they have onlyheart and nerve cord, respectively.

Heart : The heart lies in the pericardial haemocoel or dorsal sinus.It is a long muscular, contractile tube found a long the mid dorsal line,beneath the terga of the thorax and abdomen.

It consists of 13 chambers. Every chamber opens into the other

present in front of it. Three of the thirteen chambers are situated in

the thorax and ten in the abdomen. Its posterior end is closed while

the anterior end is continued forward as the anterior aorta. At the

posterior side of each chamber, except the last there is a pair of small

apertures called 'Ostia' one on each side. Ostia have valves which allow

the blood to pass only into the heart from the dorsal sinus.

Anterioraorta

Alarymuscles

Heartchamber

Dorsaldiaphragm

HeartPericardial

sinus

Perineuralsinus

Ventralnervecord

Ventraldiaphragm

Perivisceral sinusGut

Periplaneta : Circulatory system

Circulatory sytemBlood circulation

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Blood : The blood of periplaneta is colourless and is calledhaemolymph. It consists of a fluid called plasma and free blood corpusclesor haemocytes, which are phagocytic. The phagocytic, the phagocytesare large in size and can 'ingest' foreign particles such as bacteria. Thereis no respiratory pigment in the blood and so it plays no major role inrespiration.

21. Describe different types of food chains that exist in anecosystem.

Ans. The food energy passes from one trophic level to another trophiclevel mostly from the lower to higher trophic levels. When the path offood energy is 'linear' the components resemble the 'links' of a chainand it is called 'food chain'. Generally a food chain ends withdecomposers. The three major types of food chains in an ecosystem

are Grazing Food Chain, Parasitic Food Chain and Detritus Food Chain.

i) Grazing food chain : It is also known as predatory food chain,

it begins with the green plants (producers) and the second third andfourth trophic levels are occupied by the herbivores, primary carnivoresand secondary carnivores respectively. In some food chains these is yetanother trophic level the climax carnivores. The number of trophiclevel the climax carnivores. The number of trophic levels in food chainsvaries from 3 to 5 generally. Some examples from grazing food chain

(GFC) are given below.

Grazing food chain

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ii) Parasitic food chain : Some authors included the ParasiticFood Chains as a part of the GFC. As in the case of GFCs, it also beginswith the producers, the plants (directly or indirectly). However, thefood energy passes from large organisms to small organisms in theparasitic chains. For instance, a tree which occupies the 1st trophiclevel provides shelter and food for many birds. These birds host manyecto – parasites and endo parasites. Thus, unlike in the predator foodchain, the path of the flow of energy includes fewer, large sizedorganisms in the lower trophic levels and numerous, small sizedorganisms in the successive higher trophic levels.

iii)Detritus Food Chain : The detritus food chain (DFC) beginswith dead organic matter (such as leaf litter, bodies of dead organisms).It is made up of decomposers which are heterotrophic organisms,mainly the 'fungi' and 'bacteria'. They meet their energy and nutrientrequirements by degrading dead organic matter or detritus. These arealso known as saprotrophs (sapro : to decompose).

Decomposers : Secrete digestive enzymes that breakdown deadand waste materials (such as faeces) intosimple absorbable substances.Some examples of detritus food chains are :

1. Detritus (formed from leaf litter)–Earthworms – Frogs – Snakes2. Dead animals – Flies and maggots – Frogs – Snakes.In an aquatic ecosystem, GFC is the major 'conduit' for the energy

flow. As against this in a terrestrial ecosystem, a much larger fractionof energy flows through the detritus food chain than through theGFC. Detritus food chain may be connected with the grazing foodchain at some levels. Some of the organisms of DFC may form the preyof the GFC animals. For example, in the detritus food chain given above,the earthworms of the DFC may become the food of the birds of theGFC. It is to be understood that food chains are not 'isolated' always.

I trophic II trophic III trophic IV trophic V trophic

Level level level level levelRosebush → Aphids → Spiders → Small birds → Hawk

Grass → Grasshopper → Frog → Snake → Hawk

Plants → Caterpillar → Lizard → Snake

Phytoplankton → Zooplankton → Fish → Bird

Grass → Goat → Man

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