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K. JaganMohanRao Narayana Educational Institutions

“Busy bee” “Silkworm s” “The wild silk m oth”

“Producer of honey and wax” “Seri culture” “Not feeding, but resting”

Unit-VII – Arthropoda and Unit-III – Animal organization The unit-VII includes biology of cockroach, mouth parts of insects, beneficial and harmful insects. The BIE weightage for this chapter is 10 marks. In recent years, two SAQs out of which one was a diagram and one SAQ on Trachea or economic

importance of honey bees or silkworm or ommatidium was given in the public exams of intermediate. Practice the diagrams of mouthparts of housefly, female mosquito and butterfly along with that of

salivary apparatus of cockroach as there is surety for a SAQ question. Practice all diagrams related to important questions when you are in drowsy / sleepy mood to make

yourself alert and active. The unit-III includes animal cell, symmetry, coelom and all tissues. Its weightage is only 6 marks.

There is scope for one SAQ and one VSQ only. Concentrate on Haversian system, cartilage, multipolar neuron, blood, cardiac muscle, pseudocoelom,

biradial symmetry for SAQs. Focus your utmost attention on the VSAQs given below, when compared to the rest in these units.

UNIT-VII (Arthropoda) Concentrate on these VSAQs :: 1. Which is the largest phylum in the animal kingdom? How was its name derived ? (2010) A. 1. Arthropoda is the largest phylum in the animal kingdom. 2. The name Arthropoda was derived due to the presence of jointed legs. 2. Why male mosquitoes are unable to suck the blood of man. (2010) A. In mouth parts of male mosquito mandibles are absent. The first pair of maxillae is vestigial. The hypopharynx is fused with the proboscis. Hence male mosquitoes are unable to suck blood of man. 3. Write any 4 useful products obtained from honeybees. (2009) A. The useful products that are obtained from honey bees are honey, wax, propolis & venom 4. What do you mean by apodemes & tentorium ? A. Apodemes: The lateral invaginations of sclerotised cuticle at several places are called apodemes.

Tentorium: In the head of cockroach, the endoskeletal parts called apophyses are fused to form tentorium.

5. How does tripod movement occurs in cockroach ? A. 1. Each tripod is formed by fore leg and hind leg of one side and the middle leg of the other side. 2. In the tripod movement the fore leg pulls the body, while the hind leg pushes the body and the middle leg of the opposite side acts as a pivot. 6. How does a cockroach move on a smooth surface ? A. In cockroach Plantulae are useful to move on smooth surface. 7. Why is the head in cockroach called hypognathous A. The orientation of head in cockroach is called hypognathous because it is bent at right anlges to the long axis of the body.

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8. How are corpora adiposa of cockroach functionally similar to the liver of vertabrates. A. Corpora adiposa of cockroach are functionally similar to liver of vertebrates because they possess

trophocytes to store food, Mycetocytes with symbiotic bacteria to synthesize amino acids, oenocytes to secrete lipids, urate cells to store uric acid.

9. How does a cockroach conserve water in its body? A. 1. The body of cockroach is covered by waxy epicuticle which prevents loss of water by

dehydration. 2. The rectal papillae absorb water from undigested food materials and conserve water loss from

the body 10. What is meant by apiculture A. Rearing of honey bees is called apiculture

UNIT-III (Animal organization)

1. What is Schwann sheath? What is its function ? (June 2005, March 2008, 2010) A. The outermost layer of myelin sheath that contains cytoplasm and nucleus is called neurilemma or

schwann sheath. It is present around a neuron. 2. What are microglia? What is their function? (March 2010) A. Microglia are small, mesodermal and elongated cells.

They are derived from precursor cells in the bone marrow. When activated microglia become phagocytic. 3. Which symmetry is known as homaxial apolar symmetry? Give an example A. Spherical symmetry is known homaxial apolar symmetry. Animals that exhibit spherical symmetry can be cut into equal halves by any plane passing

through central point. Eg: Heliozoans and Radiolarians 4. What are retroperitoneal organs? A. Organs that occur outside the coelom and are covered by peritoneum only on the surface facing

the coelom are called retroperitoneal organs Eg : Kidneys 5. What is schizocoelom? Name the phylum in which schizocoelom is the functional body

cavity in adults ? ( March-2009 ) A. The body cavity formed by the splitting of mesoderm is called schizocoelom. Phylum Annelida has schizocoelom as the functional body cavity in adults. 6. Which organelles are called ‘suicidal bags’? Why? A. Lysosomes are called “suicidal bags”, as they play a role in autolysis of injured or diseased cells 7. Write what you know about plasma cells of connective tissue A. Plasma cells are large, ovoid cells with spherical and excentric nucleus These are derived from B-lymphocytes and synthesize antibodies 8. What is haematocrit ? A. The percentage of the total blood volume occupied by RBCs is called Haematocrit 9. What is lymph? How does it differ from plasma ? A. The interstitial fluid which passes through the lymphatic vessels is called lymph

It differs from blood plasma, in the Low concentration of serum proteins. 10. What are intercalated discs of cardiac muscle? What is their significance? A. Intercalated discs are the transverse thickenings of plasma membrane that join cardiac muscle

fibres end to end. They contain, gap junctions by which rapid impulse conduction is possible 11. Distinguish between merocrine, holocrine, and apocrine glands ? A. Merocrine glands release the secretory granules by exocytosis with no loss of cellular material

Eg : pancreas In holocrine glands the entire cell disintegrates to secrete its substance. Eg: Sebaceous glands In apocrine gland, apical portion of the cell is pinched off along with secretory product

Eg: Mammary gland

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12. Distinguish between tendons and ligaments ? A. Tendon Ligament Connects muscle to bone Connects bone to bone Contains only collagen fibres Contains collagen fibres (some with few elastic fibres also) 13. Distinguish between osteoblasts and osteoclasts A. Osteoblasts synthesize the organic components of the matrix Osteoclasts are involved in the resorption and remodeling of bone tissue 14. What are muscle spindles ? A. Muscle spindles of skeletal muscles are encapsulated proprioceptors that detect tensional

differences and monitor muscle contraction 15. Name the glial cells that are associated with blood – brain – barrier ? A. Astrocytes are the glial cells associated with blood – brain barrier These are star shaped cells with many radiating processes 16. Distinguish between (a) ganglion and nucleus (b) tract and nerve? A. An aggregate of cell bodies in peripheral nervous system is called a ganglion An aggregate of cell bodies in central nervous system is called a nucleus A bundle of nerve fibres in the central nervous system is known as a tract A bundle of nerve fibres in the peripheral nervous system is known as a nerve.

UNIT-VII (Arthropoda) Concentrate on these SAQs :: 1. Draw a neat labeled diagram of the mouth parts of cockroach. (2008 & 2009)

2. Draw a neat labelled diagram of the salivary apparatus of cockroach.

(Mar 2003, 2007, 2008 & 2010) Ans.

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3. Describe the physiology of digestion in cockroach. (Mar 2006, 2009) Ans. 1. Cockroach is an omnivorous insect. 2. After swallowing, the food passes through the pharynx and oesophagus and reaches the crop. 3. In the crop the food is mixed with digestive juice and most of the food is digested. 4. In gizzard food is ground and filtered. 5. This partly digested food reaches the mesenteron through gizzard. 6. Complete digestion occur in mesenteron as follows

a) Starch Amylase disaccharides b) Sucrose Sucrase glucose + fructose c) Maltose Maltase glucose . d) Lipids Lipase fatty acids + glycerol e) Proteins Proteases amino acids f) Cellulose Cellulase glucose

7. The digested food is absorbed into haemolymph in the posterior region of the mesenteron. 8. The undigested food is finally passed as dry pellets through anus after reabsorption of water through the rectum.

4. Describe the structure of trachea of cockroach. (2005, 2006 & 2009) Ans.

1. Trachea are the respiratory tubes present in the cockroach 2. The wall of trachea is made up of three layers, namely outer basement membrane, middle epithelium and inner cuticle called intima. 3. The intima is produced into many spiral thickenings called taenidia. 4. The taenidia prevents the collapse of tracheae, when air is not present in them. 5. All tracheal branches entering an organ end in a special cell called tracheole cell. 6. From the atrium of each thoracic spiracle several horizontal trachea enter the head and thorax. 7. From the atrium of each abdominal spiracle three tracheal tubes arise and they open into three separate longitudinal trunks.

8. The three pairs of longitudinal tracheal trunks of both sides are interconnected by many commissural tracheae.

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5. Draw a neat labelled diagram of the mouth parts of housefly. (Mar 2004, 2006, 2007, 2008 & 2010)

Ans.

6. Draw a neat labelled diagram of the mouth parts of a female anopheles mosquito.

(2005, 2006) Ans.

7. Describe the modifications that have taken place in the mouth parts of butterfly to suit its

feeding habits. (2005) Ans . 1. Siphoning type of mouth parts are present in butterfly. 2. These mouth parts are best suited to draw nectar from the flowers. 3. There is a proboscis to suck the nectar from flowers. 4. The proboscis is formed by the fusion of the elongated semitubular galeae of the first maxillae. 5. Labium is reduced as a triangular plate. 6. Mandibles and hypopharynx are absent. 7. Maxillary palps and labial palps are reduced.

8. The proboscis is coiled like a watch spring, when not in use.

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8. Explain the economic importance of silkworm moth. (2010) Ans. * Silk moth produces silk of economic importance. 1. Rearing of silkworm and extraction of silk from the cocoons is called sericulture. 2. In sericulture there are three types of activities, such as (a) Production of high yielding strains of moths. (b) Hatching and rearing the larvae in special trays and feeding them with chopped mulberry leaves. (c) Extraction of silk from cocoons. 3. Unbroken silk thread can be obtained from a cocoon of week days old. 4. The process of killing of pupae by keeping them in hot water is called stiffling. 5. Fresh cocoons are called seed in the industry. 6. The process of extraction of silk thread is called reeling. 7. It is dyed and used in the textile industry. 9. Explain the economic importance of honey bees. (2006, 2007, 2008 & 2010) Ans. The Honey bees produce (a) Honey (b) Bee-wax and (c) Bee venom 1. Honey is a good nourishing food. 2. It contains levulose, dextrose and maltose sugars. 3. It is used in the preparation of jellies, jams and cakes. 4.. Honey acts as a good antiseptic agent. 5.. The wax collected from beehive is used in making polishes and candles. 6. Venom of honeybees is used in the treatment of arthritis. 7. Honeybees are good pollinators 10. Describe the digestive system of cockroach with the help of a neat labelled diagram. (2004)

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1. The digestive system of cockroach consists of an elongated, coiled alimentary canal and associated digestive glands. 2. The alimentary canal extends from mouth to anus. 3. The cavity that is present infront of the mouth between mouth parts is called preoral cavity. I. Alimentary canal :- The alimentary canal is divided into three regions, namely A. Foregut B. Midgut and C. Hindgut. A. Foregut or Stomodaeum :- 1. It includes pharynx, oesophagus, crop and gizzard. 2. The pharynx leads into a tubular oesophagus. 3. The oesophagus opens behind into the sac like crop. 4. Behind the crop there is a thick walled muscular gizzard. 5. The gizzard contains six chitinous denticulated plates. It acts as a grinding mill and sieve. 6. The distal part of gizzard contains a membranous stomodeal valve. B. Midgut or Mesenteron:- 1. It is a small tubular structure. 2. Anterior part of mesenteron contains 6-8 finger shaped diverticula called hepatic caecae. 3. These are helpful in digestion and absorption of digested food material. 4. Functionally mesenteron is divided into anterior secretory part and posterior absorptive part. 5. The gland cells of mesenteron secrete maltase, invertase, proteases and lipase enzymes. 6. The food bolus is surrounded by peritrophic membrane. 7. The peritrophic membrane protects the wall of mesenteron from the hard food particles. C. Hindgut or proctodaeum :- 1. It is a long, coiled tube and is divided into ileum, colon and rectum. 2. Ileum is a short tube and Malpighian tubules open into it. 3. Ileum collects uric acid from the Malpighian tubules and undigested food from mesenteron and opens into colon. 4. Colon is a long, coiled tube, opens into rectum, which opens out through anus. 5. Rectum bears six longitudinal rectal papillae. 6. Rectal papillae are useful in reabsorption of water from the undigested food. II. DIGESTIVE GLANDS The digestive glands of cockroach include (a) Salivary glands (b) Hepatic caecae and (c) Glandular cells of mesenteron. A. Salivary glands : - 1. A pair of salivary glands are present one on either side of the crop. 2. Each salivary gland has two lobes. 3. Each lobe of salivary gland has many lobules called acini. 4. An acinus contains a group of zymogen cells, with ductules. 5. The ductules of both the lobes unite to form common salivary duct on each side. 6. Salivary receptacle is present between the two salivary lobes. 7. The receptacular ducts of the two receptacles unite to form a common receptacular duct. 8. The common salivary duct opens into common receptacular duct. 9. Later these ducts form an efferent salivary duct, which opens at the base of hypopharynx. B. Hepatic caecae :- 1. These are also called midgut caecae. 2. They contain secretory and absorptive cells. C. Glandular cells of mesenteron :- 1. These cells lie in the wall of mesenteron and secrete maltase, invertase, proteases and lipase enzymes. 11. Describe the ommatidium of Cockroach with the help of a diagram. (2008 & 2009) Ans. 1. The structural and functional units of a compound eye of cockroach are called ommatidia 2. Each compound eye contains about 2000 ommatidia.

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3. Each typical ommatidium is elongated and pyramidal in shape and contains cornea, corneagen cells, cone cells, crystalline cone, rhabdome and retinulae. A. Cornea : 1. It is the outermost part of the ommatidium, corresponds to a hexagonal facet of the com pound eye. 2. It is a biconvex, transparent part of the cuticle 3. It allows light rays to pass through it. 4. It serves as a converging lens. 5. It is secreted by specialised cells of epidermis called corneagen cells. 6. Cornea sheds off during ecdysis of nymphs and a new cornea is formed below it. B. Corneagen cells or lenticular cells: 1. These are a pair of transparent, specialised epidermal cells. 2. These secrete a new cornea at each moult of the nymph. C. Vitrillae or cone cells :

1. These are four, transparent more or less conical cells. 2. They lie below the corneagen cells. 3. They are present around the crystalline cone, and secrete it. D. Crystalline cone : 1. It is the transparent conical structure. 2. A light absorbing dark iris pigmented sheath surrounds the vitrillae. 3. The cornea, corneagen cells, the vitrillae and crystalline cone together constitute the dioptrical or focussing region of the ommatidium. E. Rhabdome : 1. Below the crystalline cone there is a long, narrow, cylindrical, refractile, rod like structure called rhabdome. 2. It is secreted and surrounded by retinular cells. 3. The rhabdome is composed of seven units called rhabdomeres. F. Retinulae or Retinular cells : 1. These are innermost and elongated cells of an ommatidium. 2. These are seven in number, and act as photoreceptor cells. 3. They rest on a basement membrane. 4. Rhabdome and retinulae form retinal or receptor region. 5. Images of an object develop on receptor region.

UNIT-III (Animal organization) 1. Explain Haversian system ? (March 2006, 2008, 2010)

Each Haversian system or osteon contains Haversian canal, parallel to marrow cavity Haversian canal is surrounded by concentric lamellae Lacunae are found between lamellae Each lacuna encloses one inactive osteocyte Cytoplasmic processes of osteocytes extend into radial canals called canaliculi Canaliculi connect lacunae with one another and with the Haversian canal Haversian canals are connected to each other by transverse or oblique Volkmann’s canal Through Volkmann’s canal, blood vessels, lymphatic vessels and nerves from the surface of bone

reach Haversian canals 2. Describe briefly any two kinds of granulocytes in the blood of man? (may 2006) A. Granulocytes possess granules in their cytoplasm and nucleus is lobed. Hence they are called

polymorpho nuclear leucocytes. They are 3 types i.e Acidophils, Basophils and Neutrophils

2. Neutrophils · Constitutes 62% of circulating leucocytes · Nucleus is 2-5 lobed, linked by fine threads of chromatin

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· They contain abundant specific granules which are stained by neutral dyes. Hence called neutrophil

· They are active phagocytes (microscopic policemen) 3. Acidophils or eosinophils : - · Constitute about 2.3% of leucocytes · Nucleus is bilobed · They contain many specific granules stained by eosin · They associate with allergic reactions and helminthic infections · They phagocytose antigen – antibody complexes

3. Describe agranulocytes in the blood of man? (2006) A. · Agranulocytes do not have granules but contain azurophilic granules and nucleus is unlobed

· Agranulocytes are 2 types 1. Lymphocytes : · Constitute about 30 % of leucocytes · They have spherical nucleus and scanty peripheral cytoplasm · They play an important role in immune reactions · They are the only leucocytes which return from the tissues into blood after diapedesis 2. Monocytes : - · They constitute about 5.3% of leucocytes · Their nucleus is kidney shaped · They differentiate into macrophages in connective tissues

4. Explain biradial symmetry A. · Biradial symmetry is exhibited by sea anemones

· This type of symmetry seems to have been derived from the radial type by the elongation of mouth and associated parts.

· The body of organisms is heteropolar and has oro – aboral axis · In sea anemone mouth is oval, having long axis and short axis · Both axes are apolar as there is no differentiation of dorsal and ventral surfaces · These animals can be divided into antimeres by two planes · One passing through long axis of mouth and oro – aboral axis · The other passing through short axis of mouth and oro – aboral axis · The antimeres on either side of one plane are different from the antimeres of other plane

Eg. Ctenophores and most anthozoans 5. Explain bilateral symmetry. Add a note on the advantages of bilateral symmetry A. The principal axis is antero-posterior axis which is heteropolar as the anterior and the posterior

ends are differentiated · Sagittal axis is also heteropolar as dorsal and ventral surfaces are differentiated · But transverse axis is apolar · These organisms can be divided into antimeres by only one plane i.e, median sagittal plane

Advantages · In these organisms, the sense organs and nervous tissue are concentrated in the anterior end · The anterior part of the body is differentiated into head i.e cephalization · As a result of cephalization, the animal can sense the new environment and respond efficiently · They can also move from place to place more efficiently · They have more complex organ systems in the body

6. Explain the formation of pseudocoelom ? A · During the development of some triploblastic animals mesoderm occupies only a part of

blastocoel adjoining the ectoderm · The unoccupied portion of blastocoel persists as body cavity in adults called pseudocoelom · Pseudocoelom is filled with pseudo coelomic fluid · As mesoderm is confined to the body wall only and musculature is also confined to the body wall only · Gut wall is entirely non-muscular · Pesudocoelom serves as hydrostatic skeleton. It protects the internal organs from mechanical

shocks and helps in the circulation of nutrients etc,

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· Tube – within – a- tube arrangement is seen for the first time in pseudocoelomates Eg : Phylum Nematoda

7. Give an account of glandular epithelia ? A. · Glandular epithelia are formed by secretory cells

· Unicellular glands contain isolated glandular cells Eg : Goblet cells in the lining of small intestine

· Multicellular glands contain clusters of glandular cells · Endocrine glands lose their connection with the surface, so these glands are ductless · Exocrine glands retain their connection with the surface epithelium from which they are

originated. So these glands possess ducts · Each exocrine gland has a secretory portion and duct · Merocrine glands release the secretory granules by exocytosis with no loss of cellular material

Eg : pancreas · In holocrine glands entire cell disintegrates to secrete its substance

Eg: Sebaceous glands · In apocrine gland, apical portion of cell is pinched off along with secretory product Eg: Mammary gland

8. Explain the type of muscle characterized by the presence of intercalated discs? A. · Cardiac muscle fibre is having intercalated discs. A cardiac muscle fibre is short, cylindrical and contains centrally located nucleus

· Cardiac muscle fibres are branched forming a network. They are striated · Cardiac muscle fibres are joined end to end by transverse thickenings of plasma membrane called

– intercalated discs · Intercalated discs contain gap junctions and desmosomes · Gap junctions provide, ionic continuity between adjacent cells due to which cardiac muscle acts as

functional syncytium · Contraction of cardiac muscle is spontaneous, involuntary and rhythmic · Some cardiac muscle fibres are autorhythmic, act as pace maker · The rhythm is modified by autonomous nervous system and certain harmones like epinephrine

9. Describe a structure of a myelinated multipolar neuron with the help of a neat, labeled

diagram. Describe the formation of myelin sheath. Add a note on synapse. A. Neuron consists of a cell body and two types of cell processes – dendrites & axon

· Cell body : - It is also known as “ Perikaryon” or “ Soma” or “Cyton” · It contains nucleus with a prominent nucleolus · Cytoplasm contains Nissl bodies, golgi complex, mitochondria and microtubules and occasionally

pigments such as lipofuscin. · Dendrites : - They are short and divide into branches · They conduct impulse to the cell body · Axon : - Axon is a single long and cylindrical process · It originates from cone shaped region of cyton called “the Axon Hillock” · The plasma membrane of the axon is called “ Axolemma” and cytoplasm is called “Axoplasm”

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· The axon terminates on other neurons or effectors by small branches called the terminal arborization

· These branches end in small swellings called Terminal boutons · Some axons give rise to collateral branches · Axon terminals always contain synaptic vesicles with neurotransmitters and mitochondria

Myelin sheath : · Specific cells called schwann cells surround the axon · The plasmalemma of schwann cell winds and wraps around the axon · The layers of cell membrane unite and form myelin sheath having lipids

Synapse : - · It is formed by an axon terminal and dendrite of another cell and intercellular space called synaptic cleft · Axon terminals contain synaptic vesicles · They contain, neurotransmitters and mitochondria · Synapses transmit information to the next neuron by neurotransmitters

3. Describe the respiratory system of cockroach.

1. The respiratory system of cockroach is called tracheal system. 2. The respiratory system of cockroach consists of stigmata, tracheae and tracheoles. A. Stigmata or Spiracles :- 1. 10 pairs of stigmata, two pairs in thoracic region and eight pairs in the abdominal region are present. 2. Spiracles are present on the pleura. 3. All the stigmata are functional, so called holopneustic tracheal system. 4. All spiracles are valvular and surrounded by a chitinous ring like structure called peritreme 5. All spiracles bear small hairs to filter out dust particles. 6. Each spiracle leads into a small chamber called atrium. B. Tracheae :- 1. From the atrium of each thoracic spiracle several horizontal tracheae run inside and join to form many tracheal trunks. 2. These branches enter all the organs of head and thorax. 3. Three tracheal tubes arise form each abdominal atrium. 4. All the abdominal tracheal tubes of one side open into lateral, dorsal and ventral longitudinal trunks.

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5. The three pairs of longitudinal tracheal trunks of both sides are inter connected by many commissural tracheae. 6. All tracheal branches entering an organ end in a special cell called tracheole cell. 7. The wall of tracheae is formed by an outer basement membrane, middle one cell thick epithelium and inner layers of cuticle called intima. 8. The intima is produced into spiral thickenings called taenidia. 9. Taenidia prevent the collapse of tracheae, when air is not present in them. C. Tracheoles :- 1. The terminal structure of the tracheal tube ending close to the tissues is called tracheole cell. 2. Each tracheole cell has several intracellular tubular branches called tracheoles. 3. Their inner surface is lined by a protein called trachein. 4. Intima and taenidia are absent in the tracheoles. 5. Tracheoles are filled with tracheolar fluid.