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18451.

Question : Describe internal structure of (sunflower stem) of young stem of dicot plant.

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Solution :Sunflower is an annual plant. It possesses erect stem.
If transverse section of a young stem of sunflower is stained and studied under microscope, following structure is seen.
Endodermis : If is the outermost protective layer of the stem. It is one layered and made up of parenchymatic cell. Outer wall is covered with thin layer of cuticle, It may bear trichomes and a few stomata work for gas exchange.
Cortex: In cortex hypodermis, main cortex and endodermis these 3 parts are included.
(1) Hypodermis: It is located below the epidermis. Hypodermis layer is made up of collenchyma cells. It has 3 to 4 layers. The walls of cells are stained with cellulose and pectin, cells lack intercellular spaces. This tissue provides mechanical support and strength.
(ii) Main Cortex: The part located below hypodermis is called main cortex. It is made up of parenchymatic tissue. If has conspicuous intercellular spaces.
The wall of cells are thin and made up of cellulose.
Resin ducts are located in this region duct eaciresin is small and surrounded by living secretory cells.
Cells of main cortex store water and food.
(iii) Endodermis: The inner most layer of cortex is called endodermis. It is a single layered, cells are parenchymatous cylindrical or barrel shaped.
Cells possess starch grains. So this layer is called starch sheath.
(3) Stele : Pericycle, vascular bundles, rays and piths are included.
(i) Pericycle : The part located inside endodermis is called pericycle. It is multilayered and it is made up of sclerenchyma and parenchymatous cells. Sclerenchyma cells are located above vascular bundle. It is called as bundle cap.
The part consisting of parenchyma cells of pericycle is located above RAY. They are arranged in a ring.
Each vascular bundle is conjoint, open and with endarch protoxylem.
The development of vessels is endarch.
Vascular bundle includes phloem, meristematic tissue, cambium and xylem tissue.
Phloem is towards CIRCUMFERENCE and xylem is towards centre. A strip of lateral meristem called cambium is present between xylem and phloem. This is called fascicular cambium. Secondary growth can be done due to presence of cambium.
Phloem : This tissue is located above vascular bundles. It includes sieve tubes, companion cells and phloem parenchymatic cells.
There are triangular or quadilateral companion cells with sieve tubes. Companion cells fused with protoplasm are distinguished different. Phloem parenchymatous cells being living /active function to store food. Their wall is thin and made up of cellulose.
Cambium: A strip of lateral meristem is located between xylem and phloem. Cells are alive and without intercellular spaces. The wall of cells is thin and possesses the power of DIVISION.
Cells of cambium : In vertical section they appear rectangle and in radial rows. As the cells of this tissue are meristematic, secondary growth is possible.
Xylem : Xylem tissue is located inside vascular bundle.
In xylem tissues vessel cells are arranged in radial rows. Cells located towards circumference are big so they are called melaxylem.
The cells located towards centre has small diameter. They are called protoxylem. This development of vessels are endarch type.
Xylem tissue is arranged in cutter shape.
Phloem sclerenchyma is with metaxylem and phloem parenchymatic cells are located with protoxylem.
In longitudinal section metaxylem shows net like and pitted thickenings white protoxylem shows ring like and helical thickenings.
Medullary Rays : Parenchymatic cells located between two vascular bundles are extended AERIALLY and arranged in radial direction. They are known as medullary rays.
Medullary rays perform lateral transportation of food and water. Moreover during secondary growth the cells of the medullary rays become meristematic and forms a strip of cambium known as interfascicular cambium. This cambium takes part in secondary growth.
Pith: A large number of rounded parenchymatous cells with large intercellular spaces which occupy the central portion of the stem constitute the pith.
Discussion
18452.

Question : Describe internal structure of monocot stem.

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Solution :Maize is a monocot plant. It.s stem is thin stained section when observed under MICROSCOPE, following parts are seen. (1) Epidermis (2) Ground tissue (3) Vascular bundles.
(1) Epidermis : It is the OUTER most layer. It is a single layer made up of parenchymatous cells. Outer WALL of cells are cuticularised.
No stem appendages are produced from this layer so its surface is soft. Stomata can be seen in this layer. This layer functions as protection and gas exchange.
(2) Ground Tissue : Unlike sunflower stem, cortex, endodermis and pericycle like structures are not found in ground tissue.
At the outer most side of ground tissue, hypodermis is located. It is made up of two or three LAYERS of sclerenchyma tissue. These cells are non-living and lignified. They give mechanical support to stem.
Inside hypodermis thin walled parenchyma is located. Vascular bundles are present in this region. In ground tissue cells towards centre are comparatively large and have inter cellular spaces. (3) Vascular bundles : In maize stem numerous vascular bundles are scattered in ground tissue. Peripheral vascular bundles are generally smaller than the centrally located ones and are more in number and arranged quite near to each other. Sclerenchymatous bundle sheath surrounds them.
Centrally located vascular bundles are less in number and far from each other. Each vascular bundle is surrounded by sclerenchymatous bundle sheath. The vascular bundles having sclerenchymatous bundle sheath are called fibro vascular bundle.
Each vascular bundle is conjoint, collateral and closed vessels are developed as endorch.
In vascular bundles phloem tissue lies outside and xylem tissue lies inside vessels are arranged in shape vascular bundle lacks meristematic tissue.
Phloem tissue : Phloem tissue is located outside in .V. shape. There is no phloem parenchyma present in phloem tissue. Xylem tissue : Xylem tissue is arranged in the shape of an English alphabet .V.. Three to four vessels are present in it. Two big vessels are known as metaxylem. They are located on two separating ends of V while protoxylem are located inside based region of .V..
During development of vascular bundles, some cells around protoxylem break and a big cavity is produced. This cavity is known as Lysigenous cavity. This cavity is fulled with WATER.
Discussion
18453.

Question : Decribe the internal structure of a dorsiventral leaf with the help of labelled diagrams.

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Solution :The section of a dorsiventral leaf (sunflower leaf) is stained through safranin and viewed under MICROSCOPE then following structure is seen:
(1) Epidermis, (2) Mesophyll tissue, (3) Vascular bundles.
(1) Epidermis : A leaf being a flat organ, there are TWO epidermis seen in it:
(i) Adaxial epidermis, (ii) Abaxial epidermis.
(i) Adaxial Epidermis: It is a single layer made up of parenchymatous cells. This protective skin is located on outer wall of cells of this layer. It does possess stomata. RESPIRATORY cavity is present inside of stomata.
(ii) Abaxial Epidermis: It forms the lower surface of the leaf. It is a single layer made up of parenchymatous cells.
Thin protective skin is located outside the surface of abaxial epidermis.
This layer has multicellular leaf hairs. The number of stomata are more than adaxial epidermis. This respiratory cavity is associated with other intercellular spaces
Mesophyll Tissue : The tissue between the upper and lower epidermis is called the mesophyll. It contains palisade, spongy tissue and vascular bundles.
Palisade Tissue : The adaxially PLACED palisade parenchyma is made up of elongated cells which are arranged vertically and parallel to each other. Intercellular spaces are negligible between them. Chloroplasts are present in LARGE amount in cells.
The function of this tissue is of photosynthesis.
Spongy Tissue : These calls located on the upper side of abaxial layer are of irregular shape. Large intercellular spaces are located between the cells. So this issue is called spongy tissue. This tissue has less number of chloroplasts.
Vascular Bundles : Vascular bundles located in leaf are conjoints, collateral and closed. The structure of each vascular bundle is like vascular bundle of stem.
Due to reticulate venation present in sunflower leaf. In vascular bundle xylem, tissue is located towards adaxial epidermis and phloem tissue is located toward abaxial epidermis.
In longitudinally and transversely cut vascular bundle different thickenings are seen in the walls of the cells of xylem.
The size of vascular bundles are dependent on the size of veins.
The vascular bundles are surrounded by layer of thick walled bundle sheath cells.
In these leaves, various type of mesophyll tissue is located in adaxial epidermis and abaxial epidermis so leaves of dicotyledonous are called dorsiventral leaves.
Discussion
18454.

Question : Describe internal structure of dicot root. OR Describe internal structure of sunflower root.

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Solution :For a better understanding of tissue organisation of roots, stems and leaves, it is convenient to study the transverse sections of the mature zones of these organs.
Internal structure of mature root of sunflowers : Sunflower is a dicot and an annual PLANT. This transverse section of the sunflower root is taken and it is stained with safranin washed with water, viewed under microscope from outside to inside following three regions are seen clearly. (1) epidermis (2) cortex (3) endodermis.
Epidermis: It is the outermost layer. Many of the epidermal cells protrude in the form of unicellular root hairs. The cells of this layer are thin walled and made up of cellulose. The primary function of this layer to absorb water and mineral salts.
Cortex : The cortex consists of several layers of thin-walled parenchyma cells with intercellular spaces.
Endodermis: It comprises a single layer of barrel-shaped cells without any intercellular spaces. The tangential as well as radial walls of the endodermal cells have a deposition of water impermeable, waxy material-suberin-in the form of casparian strips.
Pericycle : NEXT to endodermis lies a few layers of thick-walled parenchyomatous cells referred to as pericycle. Initiation of lateral roots and vascular cambium during the secondary growth takes place in these cells.
PITH: The pith is small or inconspicuous.
Conjuctive Tissue : The parenchymatous cells which lie between the xylem and the phloem are called conjuctive tissue.
There are usually two to four xylem and phloem PATCHES. Later, a cambium ring develops between the xylem and phloem.
Stele : All tissues on the inner side of the endodermis such as pericycle, vascular bundles and pith constitute the stele.
Discussion
18455.

Question : Describe internal structure of Isobilateral (Monocotyledonous) leaf. OR Describe internal structure of maize leaf.

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Solution :The leaf of maize is flat and long. The cells produced in mid leaf are of same type. So structurally the leaf of maize is called Isobilateral leaf.
The thin section of maize leaf is stained with safranin and viewed under microscope then following layers are seen in it (1) Epidermis (2) Mesophyll tissue (3) Vascular bundles.
Epidermis : In leaf, two epidermis are seen.
Upper Epidermis : It FORMS the upper most layer or adaxial layer. It is a single layered tissue made up of parenchymatous cells. Its outer surface is covered with protective layer of cuetile.
In adaxial layer at some certain distance Bulliform cells are arranged in long ROWS. These cells are in group of 5 to 7 cells.
These cells in group are comparatively larger than other cells of epidermis. They don.t have protective skin on outer wall of them and it is very thin. Generally unicellular slanting small trichomes are LOCATED on both sides of the cells. These trichomes direct moisture in the atmosphere. So they are called moisture showing trichomes.
The presence of bulliform cells SEPARATES adaxial layer from abaxial layer. Bulliform cells in humid atmosphere absorb water and become turgid and leaf surface is exposed. In dry atmosphere when they are flaccid due to water stress they make the leaves curl inwards to minimize water loss. Thus by these cells, the leaf curls from one side to other side these cells are called motor cells. Moisture absorbent or Bulliform cells are round and like a bubble so called bulliform cells.
(2) Mesophyll Tissue : A leaf possesses isobilateral structure so there is no differentiation like palisade and spongy in mesophyll tissue.
All cells are alike and possess equal amount of chloroplasts.
Only palisade tissue is located between both epidermis in the leaf of maize. These cells are round or oval. Cells have inter cellular space. Air filled sacs are seen clearly below stomata. They are called respiratory cavities.
(3) Vascular Bundles : Maize being a monocot plant, parallel venation in its leaf, vascular bundles are cut vertically. They are located at equal distance from each other.
Vascular bundles are conjoint collateral and of closed type.
Vascular bundles are of large and small both types.
Vascular bundle xylem is located towards adaxial layer and phloem tissue is located towards abaxial layer.
Vascular bundle is surrounded by sclerenchymatous bundle sheath. This bundle sheath is developed till adaxial and abaxial layer so vascular bundles provide strength to leaves.
Small vascular bundles are located between large vascular bundles. Parenchymateous bundle sheath surrounds each small vascular bundle.
Abaxial Epidermis : This epidermis forms the LOWER surface of the leaves. There is thin layer of protective skin on outer wall of cell. There are stomata in this layer. But they don.t have bulliform cells.
Midrib: In the section of midrib, in hypodermis located below adaxial epidermis, group of cells of sclerenchyma and parenchyma are found alternatively. Small-big vascular bundles are located towards abaxial epidermis only. The part between adaxial epidermis and abaxial epidermis is called ground tissue. It is made up of parenchymatous cells.
Discussion
18456.

Question : Describe internal struction of artery and vein in short.

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Solution :Blood is circulated in definite pathway by blood VESSELS - Arteries and VEINS.
(1) Tunica Intime : It possesses squamous tissue
(2) Tunica media : It possesses simple muscles and ELASTIC fibres.
(3) Tunica externa : Outer layer of CONNECTIVE tissue is of collagan fibres
Note : In veins, middle layer is comparatively thin.
Discussion
18457.

Question : Describe in short about saliva gland, its location and types.

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Solution :Main salivary glands are of three types : (i) Parotid GLAND, (ii) Submandibular gland, (iii) Sublingual gland
(i) Parotid gland : It is the biggest gland. It is located below ear, every side in the front.
(ii) Submandibular gland : Located every side below jaws.
(iii) Sublingual gland : It is located below tongue. Salivary glands are FORMED by bags LIKE sacs. It forms small chambers.
These glands are located SLIGHTLY OUTSIDE the oral cavity. It secretes saliva in oral cavity.
Discussion
18458.

Question : Describe in detail structure of Eye, various parts and functions of it.

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Solution :
Paired eyes are located in sockets of the skull called orbits.
Parts of an eye : Each eye ball is nearly a spherical in STRUCTURE.
Its diameter is approximately 2.5 cm and weighs around 6 to 8 gm.
The wall of the eyeball is composed of three layers. (see figure)
(a) Sclera (b) Choroid (c) Retina
Sclera : It is fibrous layer, white layer and have transparent membrane post. 5/6 part is white membrane formed of collagen fibres where as anterior 1/6 part formed of fibrous tissue devoid of blood vessel is called cornea.
Conjunctiva : Conjunctiva is thin, transparent, made up of stratified epithelium. It externally surrounds transparent membrane and open part of white layer. It is thinnest epithelium of animal body.
(b) Choroid : It is middle layer, contains blood vessels and looks bluish in colour.
The choroid layer is thin over the posterior two-thirds of the eye ball, but it becomes thick in the anterior part to form the ciliary body.
Ciliary body continues forward to form a pigmented and opaque structure called Iris. Iris is the VISIBLE coloured portion of the eye.
The eye ball contains a transparent crystalline Lens which is held in place by ligaments attached to the ciliary body.
In front of the lens, the aperture surrounded by the iris is called the pupil. The diameter of the pupil is regulated by the muscle fibres of iris.
(c ) Retina : It is the inner most layer and it contains three layers of neural cells from inside to outside - Ganglionated Cells, Bipolar Cells and Photoreceptor Cells.
Photoreceptor cells are of two types rod cells and cone cells.
These cells contain the light-sensitive PROTEINS called the photopigments.
The daylight photopic vision and colour vision are functions of cones and the twilight scotopic vision is the function of the rods.
The rods cell contain purplish-red protein called Rhodopsin, which contains derivative of VITAMIN A.
In the human eye, there are three types of cones which possess their own photopigments that respond to red, green and blue lights.
The sensations of different colours are produced by various combinations of these cones and their photopigments.
When these cones are stimulated equally, a sensation of white light is produced.
The optic nerves leave the eye and the retinal blood vessels enter in it at a point medial to and slightly above the posterior pole of the eye ball.
Photoreceptor cells are not present in that region and HENCE it is called the blind spot.
At the posterior pole of the eye lateral to the blind spot, there is a yellowish pigmented spot called macula lutea with a central pit called the fovea.
The fovea is a thinned-out portion of the retina where only the cones are densely packed. It is the point where the resolution is the greatest.
The space between the cornea and lens is called the aqueous chamber and contains a thin watery fluid called aqueous humor.
The space between the lens and the retina is called the vitreous chamber and is filled with a transparent gel called vitreous humor.
Discussion
18459.

Question : Describe in detail types of movements exhibited by organisms.

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Solution :Cells of living organisms exhibit three main types of movements :
(i) Amoeboid (ii) Ciliary (III) Muscular.
(i)Amoeboid Movement : Such types of movement exhibited by Amoeba.
Some Specialised cells in our body like macrophages and leucocytes in blood exhibit amoeboid movement.
It is effected by pseudopodia formed by the streaming of protoplasm.
Cytoskeletal elements like microfilaments are also involved in amoeboid movement.
In amoeba such type of movement is exhibited for obtaining food or change of place.
(ii)Ciliary Movement : Occurs in most of our internal tubular organs which are LINED by ciliated EPITHELIUM.
The Coordinated movements of cilia in the TRACHEA help us in removing dust particles and some of the foreign substances inhaled along with the atmospheric air.
Paramoecium can perform various functions by the ciliary movement.
(iii) Muscular Movement : Movement of our limbs, jaws, tongue require presene of muscular movement.
Muscles shows contractility such characteristics is helpful for locomotion in human and other organsims effectively.
Lower organisms lack skeleton system but may show muscular system.
It requires perfect coordinated activity of muscular, skeletal and neural systems.
Discussion
18460.

Question : Describe in detail : ECG

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Solution :ECG is a graphical REPRESENTATION of the electrical of the electrical activity of the heart during a cardiac cycle. A patient is connected to the machine with three electrical leads (one to each write and to the left ankle) that continuously monitor the heart activity.
Each peak in the ECG is identified with a LETTER from P to T that corresponds to a specific electrical activity of the heart.
The p - wave represents the electrical exciation of the atria which leads to the contraction of both the atria.
The QRS complex represents the depolaristation of the ventricals. the contraction starts shortly after Q and marks the begining of the systole.
The T-wave represents the return of the ventricles from ventricles from EXCITED to normal state. The end of the T-wave marks the end of systole.

By counting the number QRS complexes that occur in a given time period, one can determine the heart beat rate of an individual.
Any deviation of shape in ECG indicates a possible abnormality or disease. HENCE it is of a great clinical IMPORTANCE.
Discussion
18461.

Question : Give a concise account on virulent cycle (or) Explain Lytic cycle of a phage.

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Solution :Lytic cycle: during lytic cycle of phage, disintegration of host bacterial cell occurs and the progegy virions are released. The Step involved in the lytic cycle are as follows:
(i) Adsorption : Phage T4 particle interacted with cell wall of host.,. The phage tail makes contact between the two, and tail fibres recognise the specific reciptor sites present on bacterial cell surface. The lipopolysaccharides of tail fibres acts as reciptor in PHAGES. The process involving the recognization of phage two bacterium is called landing.once the contact is established between tale fibre of phahe and bacterial cell, tail fibre band to anchor the pins and base plate to the cell surface. This step is called pinning.
(II) Penetration : the penetration process involves mechanical and enzymatic digestion of the cell wall of the host. At the recognization site phase digests certain cell wall structure by viral enzyme (lysozyme). Afterpinning the tail sheath contracts (using ATP) and appear shorter. After contraction of the base plate enlarge through which DNA is injected into the cell wall without using metabolic energy. The step involving injection of DNA particle alone into the bacterial cell is called transfection. The empty protein COAT living outside the cell is known as 'ghost'.
(iii) Synthesis: this step involves the degradation of bacterial chromosome protein synthesis and DNA replication. The phage NUCLEIC acid takes over the host biosynthetic machinery host DNA gets in activated and breaks down. Phage DNA suppresses the synthesis of bacterial protein and direct the metabolism of the cell to synthesis the proteins of the phage particles and simultaneously replication of phage DNA ALSO takes place.
(iv) Assembly and maturation: the DNA of phage and protein coat are synthesized separately and assembled to from phase particles. The process of assembling the phage particles is known as maturation. After 20 minutes of infection about 300 new phages are assembled.
(v) release: the phage particle gets accumulated inside the host cell and are released the lysis of the host cell wall.
Discussion
18462.

Question : Describe in brief about Actinomycetes.

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Solution :ACTINOMYCETES are ALSO called 'Ray fungi' due to their mycelia like GROWTH. They are anaerobic or facultative anaerobic MICROOGANISMS and are Gram positive. They do not produce an aerial mycelium. Their DNA contain high guanine and cytosine content (E.g., Streptomyces).
Discussion
18463.

Question : Describe hormones of adrenal gland, functions and disorders due to its deficiency.

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Solution :Location : Our body has one pair of adrenal glands, one at the anterior part of each kidney. The gland is COMPOSED of two types of tissues. The centrally located tissue is called the adrenal medulla and outside this lies the adrenal cortex.
The adrenal medulla secretes two hormones called adrenaline or epinephrine and nor-adrenaline or norepinephrine.
These are commonly called as catecholamines.
Adrenaline and nor-adrenaline are rapidly secreted in response to stress of any kind and during emergency situations.
They are called emergency hormones or hormones of fight or flight.
These hormones increase alertness, pupillary dilation, piloerection (raising of hairs). sweating etc.
Both the hormones increase the heart beat, the strength of heart contraction and the rate of respiration.
Catecholamines also stimulate the breakdown of glycogen resulting in an increased concentration of glucose in blood.
They also stimulate the breakdown of lipids and proteins.

The adrenal cortex can be divided into 3 layers, called ZONA glomerulose (outer layer), zone fasciculate (middle layer) and zona reticularis (inner layer).
The adrenal cortex secretes many hrmones, commonly called as corticoids.
`alpha` - glucocorticoids - involved in carbohydrate metablism.
`beta` - mineralocorticoids - regulate the balance of water and electrolytes in our boyd.
Aldosterone is the main mineral corticoid in our body.
Glucocorticoids stimulate, gluconeogenesis, lipolysis and proteolysis, and inhibit cellular uptake and utilisation of amino acids.
Cortisol is also involved in maintaining the cordiovasular SYSTEM as well as the kidneyt functions.
Glucocorticoiuds, particularly cortisol, produces anti-inflammatory reactions and suppresses the immune response.
Cortisol stimulates the RBC PRODUCTION.
Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of `"Na"^(+) H_(2)O` and water and excretion of `K^(+)` and phosphate ions.
Thus, aldosterone helps in the mintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure.
Small amunts of androgenic steroids are also secreted by the adrenal cortex which play a role in the growth of axial hair, pubic hair and facial hair during puberty.
Less production of hormones by adrenal cortex changes carbohydrate metabolism due to which weakness and fatigueness is observed.
It leads to adison.s disease.
Discussion
18464.

Question : Describe hierarchy of organisation in living organisms?

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Solution :There is a physical (non-living) hierarchy and biological hierarchy in the organisation of living body
In physical hierarchy various non-living COMPONENTS aggregate to FORM compounds which finally enter the living world in the form of cells.
These cells organise to form tissues, that form organs and several organs combine to form organ system.
Finally many organ system organise and form a living ORGANISM.
The properties of tissues are not present in the constituent cells but arise as a result of interations among the constituent cells.
For example, Bone is a hard tissue which provide FROME work to the body.
But the cells present inside it do not have this property.
This phenomenon of interactions between various components of the body results in the hierarchy of organisation.
The various life PROCESSES are the result of this interaction and coordination.
Discussion
18465.

Question : Describe hierarchical classification.

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Solution :HIERARCHICAL classification is a system of arrangement for classification in which categories or RANKS are placed in other of logical SEQUENCE. There are seven categories or ranks in the hierarchy. Any given SPECIES can be traced in descending order Kingdom, Phylum, Class, Order, Family, Genus and Species. HIGHER the category, the lesser will be the number of common characteristics of the organisms belonging to that category.
Discussion
18466.

Question : Describe 'Growth' as an characteristic of living organism.

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Solution :All living organisms grow.
Increase in mass and increase in number of individuals are twin characteristics of growth.
A multicellular organism grows by cell division.
In plants, this growth by cell division occurs continuously throughout their life span In Animals, this growth is seen only upto a certain age.
Cell division occurs in certain TISSUES to replace lost cells.
Unicellular organisms also grow by cell division.
Cell division can be easily observ in vitro cultures by simply counting the number of cells under the microscope.
In majority of higher animals and plants, growth and REPRODUCTION are mutually exclusive events.
Increase in body mass is considered as growth.
Non-living objects also grow if we take increase in body mass as a criterion for growth.
Mountains, boulders and sand mounds do grow.
This kind of growth EXHIBITED by non-living objects is by accumulation of material on the surface.
In living organisms, growth is from inside.
Growth therefore cannot be taken as a defining property of living organisms.
Conditions under which it can be observed in all living organisms have to be explained and then we UNDERSTAND that it is a characteristic of living systems.
A DEAD organism does not grow.
Discussion
18467.

Question : Describe first tetrapoda.

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Solution :As the name indicates (Gr., AMPHI : dual, bios : life), amphibians can live in aquatic as well as terrestrial habitats.
Most of them have two pairs of limbs.
Body is divisible into head and trunk.
Tail may be present in some.
The amphibian skin is moist (without scales).
The eyes have eyelids.
A tympanum represents the EAR.
Alimentary canal, urinary and reproductive tracts open into a COMMON chamber called CLOACA which opens to the exterior.
Respiration is by GILLS, lungs and through skin.
The heart is three-chambered (two auricles and one ventricle).
These are cold blooded animals.
Sexes are separate.
Fertilisation is external.
They are oviparous and development is direct or indirect.
Examples : Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander). Ichthyophis (Limbless amphibia).
Discussion
18468.

Question : Describe first stage of respiration.

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Solution : Definition : Glycolysis MEANS the phase till formation of two molecules of pyruvic acid from one molecule of glucose takes place.
Origin : The term glycolysishas originated form the Greek words glucose form sugar and lysis for splitting.

The scheme of glycolysis was given by Gustav Embden, OttoMeyercdofand J. Parnas and is often referred to as the EMP pathway.
In anaerobic organisms, only glycolysisoccurs. Glycolysisoccurs in the cytoplasm of the cell and in thisprocess undergoes partial oxidation toform two molecules of pyruvic acid .
In PLANTS, this glucose is derived from sucrose .
whichis theend productof photosynthesis or from storagecarbohydrates. Both these monosaccharidesreadilyenter the glycolytic pathway.
Glucose and fructose are phosphorylated to give rise to Glucose-6- phosphateby theactivity of the enzyme hexokinase.
Glucose + ATP `overset("Hexokinase")to ` Glucose-6-Phosphate
Thisphosphorylated form of glucose then isomerises toproduce fructose-6- phosphate.
Glucose-6- Phosphate `to` Fructose-6- Phosphate
Subsequentsteps of metabolism of glucoseand fructose are same.
Inglycolysis, a chain of ten reactions, under the control of differentenzymes, takesplace toproducepyruvate from glucose.
Nowfructose-6- phosphate is converted into fructose-1, 6 -biphosphate in presence of ATP.
ATP is utilised at two steps. First in the conversion of glucose into glucose 6-phosphate an in second stepthe conversion of fructose 6-phosphate to fructose 1, e-biphosphate.
Now the fructose 1,6-biphosphate is split into dihydroxyacetone phosphate and3-phosphoglyceraldehyde (PGAL).
Fructose 1, 6-Biphosphate `to ` DHAP(3G) + PGAL (3G)
There isone step where NADH + `H^(+)`is formed from `NAD^(+)`,this is when 3-phosphoglyceraldehyde is converted to 1,3-biphosphoglycerate (BPGA).
3-phosphoglyceraldehyde `to` 1,3-biphosphoglycerate + NADH `+ H^(+)`
Two redox-equivalents are removed (in the form of hydrogen atoms) from PGAL, and transferred to a molecule of `NAD^(+)`
PGAL is oxidisedand with inorganic phosphate to get converted intoBPGA.
Theconversion of BPGA to 3-phosphoglyceric acid (PGA) ,is also an energy yielding process. This energy is trapped by the formation of ATP
Another ATP is SYNTHESISED during the conversion of PEP to pyruvic acid .
(Formationof ATP = 4ATP mode)
Pyruvicacid is then the key productof glycolysis. Whatis he metabolic fate of pyruvate ? depends on the cellular need.
There are THREE major ways in which differentcells handle pyruvic acid produced by glycolysis
(1) Lactic acid fermentation.
(2) Alcoholic fermentation.
(3) Aerobic respiration.
fermentation takes place under anaerobic conditions in many prokaryotes and unicellular eukaryotes.
For the complete oxidation of glucose to `CO_(2)and H_(2)O`, however, organisms adopt Kreb, cycle which is also calledas aerobic respiration. This requires `O_(2)`supply.
Discussion
18469.

Question : Describe external structure of small intestine and large intestine.

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Solution :(a) Small Intestine : It is 6.25 m long tube, small intestine starts with stomach. It is surrounded by large intestine in belly button REGION of abdomen. It is divided into three parts.
(i) Duodenum : Starting PART is of .U. shaped. It POSSESSES 25 cm length.
(ii) Jejunum : It is a long coiled middle portion. It is 1 METRE long
(iii) Ileum : It is the last part of small intestine and coiled part.
The opening of stomach into the duodenum is guarded by the pyloric sphincter.
Function : Digestion of food and Absorption.
(b) Colon : It is approximately 1.5 metre long. Colon opens into large intestine. It consists of caecum, colon and rectum.
Caecum is a small blind sac which hosts some symbiotic micro-organisms.
A narrow finger like tubular projection, the vermiform appendix which is a vestigial organ, arises from the caecum. The caecum opens into colon. It has three main parts.
(a) ASCENDING (b) Transverse (c) Descending
The descending part opens into the rectum which opens out through the anus.
Function : Absorption of water, salts and glucose.
Discussion
18470.

Question : Describe external Morphology of frog.

Answer»

SOLUTION :Skin of frog : The skin of frog is smooth and slippery due to the presence of mucus.The skin is without exoskeleton. The skin is always maintained in a moist condition.The colour of dorsal side of body of frog is GENERALLY olive green with dark irregular spots. On the ventral side the skin is uniformly pale yellow.frog never drinks water but absorb it by skin.The body of a frog is divisible into head and TRUNK. A neck and tail are absent. Above the mouth, a pair of nostrils is present.Eyes are bulged and covered by a nictitating membrane that protects them while in water. On either side of eyes a membranous tympanum (ear) receives sound signals.The forelimbs and hind limbs help in swimming, walking, leaping and burrowing.Feet have webbed digits that help in swimming.Sexual dimorphism in frog : Frogs exhibit sexual dimorphism. MALE frogs can be distinguished by the presence of sound producing vocal sacs and also a copulatory pad on the first digit of the fore limbs which are absent in female frogs.During mating period the colour of skin of male frog because dark yellow. No change of colour occurs in females In male frog, abdomen region is narrow and flat while during REPRODUCTION season, the abdomen of female becomes broad and inflatted due to development of numerous egg cells in ovary.
Discussion
18471.

Question : Describe essential minerals on the basis of their diverse functions.

Answer»

Solution :Essential elements can also be generated into FOUR broad categories in the basis of their diverse functions. These categories are:
(A) Essential elements as components of biomolecules and hence structural elements of cells eg. Carbon,hydrogen, OXYGEN and nitrogen.
(B) Essential elements that are components of energy related chemical compounds in plants eg. magnesium in chlorophyll and phosphorous in ATP.
(C) Essential elements that activate or inhibit enzymes.
For eg.`Mg^(+2)` is an activator for both ribulose biophosphate carboxylase oxygenase and PHOSPHOENOL pyruvate carboxylase.
`Zn^(+2)` activates alcohol dehydrogenase.
Mo, activating nitrogenase during nitrogen metabolism.
(D) Some essential elements can after the osmotic potential of a cell.
e.g potassium plays an IMPORTANT role in the opening and closing of stomata.
Discussion
18472.

Question : Describe external body structure of cockroach.

Answer»

Solution :The adults of the common species of cockroach are Periplaneta Americana. The body of cockroach is long, flat from dorsi-ventral side and of brownish red colour. Adult cockroach has 25 mm to 45 mm length and breadth of 8 to 12 mm. The size of male is little long. The body of this animal is hard and protected by exoskeleton made of CHITIN. In each segment, exoskeleton has hardened plates called tergites and sternites that are joined to each other by a thin and flexible articular membrane called arthrodial membrane. Cockroach possesses bilateral structure.The body of the cockroach is segmented and divisible into three distinct regions - head, thorax and abdomen. There is no internal segmentation. Head : Head is triangular in shape and lies anteriorly at right angles to the longitudinal body axis. It is connected with thin neck to thorax. Head is formed by the fusion of six segments. The head capsule bears a pair of compound eyes. It is bean shaped. A pair of thread like antennae arise from membranous sockets. It can move in all directions. Anterior end of the head bears appendages forming biting and chewing type of mouth parts. The mouth parts are sensitive.

Mouth parts : The mouth parts consisting of a labrum (upper lip), a pair of mandibles, a pair of maxillae and a labium (LOWER lip). A MEDIAN flexible lobe acting as tongue lies within the cavity enclosed by the mouth parts.

Thorax : Thorax consists of three parts - prothorax, mesothorax and metathorax. The head is connected with thorax by a short extension of the prothorax known as the neck. Each thoracic segment bears a pair of walking legs. The first pair of wings arises from mesothorax and the second pair from metathorax.Forewings called tegmina are opaque dark and leathery and cover the hind wings when at rest. The hind wings are transparent, membranous and are used in flight. Abdomen : The abdomen in both males and females consists of 10 segments. Each segment has tergites and sternum and lateral membrane. Eight and ninth tergite are covered with seventh tergite. Tenth tergite has GROOVE in the middle and anus is followed by it. In male and female cockroach both along with tenth tergite. A pair of segmented Anal cerci is associated which is a sound receptor organ. Anal style comes out from the ninth strength of male cockroach. It leads in females.In females the 7th sternum is boat shaped and together with the 8th and 9th sterna forms a brood or genital pouch whose anterior part contains female gonopore, spermathecal pores and collateral glands. In males, genital pouch or chamber lies at the hind end of abdomen bounded dorsally by 9th and 10th terga and ventrally by the 9th sternum. It contains dorsal anus, ventral male genital pore and gena apophysis.
Discussion
18473.

Question : Describe excretory system of frog.

Answer»

Solution :The elimination of nitrogenous wastes is called excretion. These wastes are removed by well developed excretory system. The excretory system consists of a pair of kidneys, ureters, cloaca and URINARY bladder.Kidney : These are compact, dark red and BEAN like structures situated a little posteriorly in the body cavity on both sides of vertebral column.Each kidney is COMPOSED of several structural and functional units called uriniferous tubules or nephrons.Two ureters emerge from the kidneys in the male frogs. The ureters act as urinogenital duct which opens into the cloaca.Urinary bladder : The thin-walled urinary bladder is present ventral to the rectum which also opens in the cloaca. The frog excretes urea and thus is a ureotelic ANIMAL. Excretory wastes are carried by blood into the kidney where it is separated and excreted.
Discussion
18474.

Question : Describe endocytosis.

Answer»

Solution :Cell surface membrane are able to TRANSPORT individual molecules and ions. There are processes in which a cell can transport a large quantity of solids and liquids into cell endocytosis or out of cell exocytosis.
Endocytosis: During endocytosis the cell wraps the cell surface membrrane around the MATERIAL and brings it into cytoplasm INSIDE a VESICLE. there are two types of endocytosis:
1. Phagocytosis- Particle is ingulfed by membrane, which folds around it and forms a vesicle. the enzymes digest the material and products are absorbed by ctyoplasm.
2. Pinocytosis-Fluid droplets are engulfed by membrane, which forms vesicles around them.
Exocytosis: Vesicles fusse with plasma membrane and eject contents. this passage of material out the cell is known as exocytosis. this material may bea secretion in the case of digestive enzymes, hormones or mucus.
Discussion
18475.

Question : What is oxidativephosphorylation ?

Answer»

Solution :The following STEPS in the respiratory process are to releaseand utilisethe energy stored in `NADH + H^(+) and FADH_(2)`
Thisis accomplished when they are oxidised through the electron transport system and theelectrons are passed on to `O_(2)`resulting in the formation of `H_(2)O`
The metabolic pathwaythrough whichthe electron passes form ONE carrier to another is called the electron transportsystem .(ETS)
It is present in the inner mitochondrialmembrane .
Electronsfrom NADH produced in the mitochondrial matrix during citric acid cycleare oxidised by an NADHdehydrogenase (Complex-I).
Electronsare then transferred to ubiquinonc location within theinner membrane.
Ubiquinone also receives reducing equivalents via `FADH_(2)` (Complex -II)
That is generated during oxidation of succinate in the citric acidcycle.
The reduced ubiquinone is then oxidised with the transfer of electronsto cytochrome c via cytochrome `bc_(1)` complex (Complex - III)
Cytochrome c is small protein attached to the other surface to the inner membrane and acts as a mobile carrierfor transfer of electrons between complexIII and IV .
Complex IV refers to cytochrome c oxidase complex containing cytochromes a and `a_(3)` and two copper centers.

ATP formation in ETS :
When the electrons pass form one carrier to another via complex I to IV in the electron transport chain, they are coupledto ATP synthase (complex V)for the production of ATP from ADP and inorganic phosphate.
The NUMBER of ATP molecules synthesised depends on thenature of the electron donor.
Oxidation of one molecule of NADH gives rise to 3 molecules of ATP, while that of one molecule of `FADH_(2)`produces 2 molecules of ATP.
Although the aerobic of respiration takes place only in the presences of oxygen .
The role of oxygen is limited tot he terminal stage of the process. Yet the PRESENCE of oxygen is VITAL, since it drives the whole process byremoving hydrogen form the system .
Oxygen acts as the final hydrogen accepter . (For production of` H_(2)` O)
In respirationit is the energy of oxidation-reduction utilised for the same process . it isfor this reason that theprocess is called oxidative phosphorylation .
Discussion
18476.

Question : Describe Diploblastic and Triploblastic organisation in animals.

Answer»

Solution :Germ layers are group of cells BEHAVING as a unit during early stage of embryonic development
It differentiate to give rise to all the tissues/organs of the fully formed individuals.
On the basis of germ layers animals are classified as follows.
(1) Diploblastic :
Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an INTERNAL endoderm are called diploblastic animals.
In addition an undifferentiated layer mesoglea is present in between the ectoderm and the endoderm e.g. coelenterates.
(2) Triploblastic :
The animals in which the DEVELOPING embryo has a third germinal layer MESODERM, in between the ectoderm and endoderm are called triploblastic animals (e.g. All animals from phylum Platyhelminthes to phylum chordates.
Discussion
18477.

Question : Describe digestive tract or alimentary canal of cockroach with diagram.

Answer»

Solution :The alimentary canal of COCKROACH is complex. It is divided into three regions - Foregut, Midgut and Hindgut. Mouth : The mouth opens into a short tubular pharynx. There are mouth organs present in mouth. Pharynx, lead to a NARROW tubular passage called oesophagus. This in turn opens into a sac like structure called CROP used for storing of food. The crop is followed by gizzard or proventriculus. It has an outer layer of THICK circular muscles and thick inner cuticle forming six highly chitinous plate called teeth. The part fill gizzard forms foregut. Gizzard open in midgut. Gizzard helps in grinding the food particles by teeth present in it. The lumen of foregut and midgut is covered by cuticle. A ring of 6-8 blind tubules called hepatic or gastric caecae is present at the junction of foregut and midgut, which secrete digestive juice. Midgut opens into hindgut. At the junction of foregut and midgut is present another ring of 100-150 yellow coloured thin filamentous Malpighian tubules. They help in removal of excretory products from haemolymph. The hindgut is broader than midgut and is differentiated into ileum, COLON and rectum.The rectum opens out through anus.
Discussion
18478.

Question : Describe digestive system of frog with diagram.

Answer»

Solution :The digestive system of frog consists of alimentary canal and digestive glands. The alimentary canal is short because frogs are carnivores and hence the length of intestine is reduced. The mouth opens into the buccal cavity that leads to the oesophagus through pharynx.Oesophagus is a short tube due to absence of neck. Oesophagus opens into stomach.Stomach : It is located on the left side in the body cavity. It is long, broad and slightly curved as cavity. It is made up of two parts. The anterior larger part is called cardiac stomach and the posterior narrow part is called pyloric stomach.The pyloric END of stomach is constricted and its opening into SMALL intestine is guarded by a sphincters, (a circular RING like muscule) Small intestine is divided into duodenum and illeum.Duodenum curves upwards to form a ‘U’ with the stomach.Liver and Pancreas are accessory digestive glands. Liver produces bile juice. It is stored in gallbladder. Pancreas is a digestive gland. It secretes PANCREATIC juice that possesses digestive enzymes. Liver and Pancreas : Bile juice and pancreatic juice. The hepatic duct and cystic ducts join to form a common bile duct which runs through pancreas and opens into the duodenum.Ileum : It is the longest and coiled part of alimentary canal. Digestion and absorption of digested food occurs in small intestine. Large Intestine : Ileum opens into large intestine. Anterior rectum is a short broad tube. It goes further and opens into cloaca. Cloaca : It is a small saclike structure and receives the openings of anus and urine genital apertures.Cloaca opens towards the exterior through ventor cloacal opening situated at the posterior end of the body.Digestion process in frog : Food is captured by the bilobed tongue. Digestion of food takes place by the action of HC1 and gastric juices secreted from the walls of the stomach. Partially digested food is called chyme. Chyme is passed from stomach to the first part of the intestine, the duodenum.The duodenum receives the bile from gall bladder and pancreatic juices from the pancreas through a common bile duct.Bile emulsifies fat and panecreatic juices digest carbohydrates and proteins. Final digestion takes place in intestine. Absorption : Digested food is absorbed by the numerous finger like folds in the inner wall of intestine called villi and micro villi.The undigested solid waste MOVES into the rectum and passes out through cloaca.
Discussion
18479.

Question : Describe different types of Symmetry.

Answer»

Solution :Animals can be categorised on the basis of their symmetry:
(1) Asymmetrical, (2) Radial symmetry, (3) BILATERAL symmetry
(1) Asymmetrical : Sponges are mostly asymmetrical, i.e., any plane that passes through the centre does not divide them into EQUAL HALVES.
(2) Radial Symmetry: When any plane passing through the central axis of the body divides the organism into two identical halves, it is called radial symmetry. Example : Coelenterates, ctenophores and echinoderms have this kind of body PLAN.
(3) Bilateral Symmetry : Animals like annelids, arthropods, etc., where the body can be divided into identical left and right halves in only one plane exhibit bilateral symmetry.
Discussion
18480.

Question : Describe different types of growth rates.

Answer»

Solution :The increased growth per unit time is termed as growth rate.
Thus, rate of growth can be expressed mathematically.
An organism or a part of the organism can produce more cells in a variety of ways.
Types : The growth rate shows an increase that may be arithmetic or geometrical.
Arithmetic growth : In arithmetic growth, following mitotic cell division, only one daughter cell continues to divide while the other differentiates and matures.
The simplest expression of arithmetic growth is exemplified by a root elongating at a constant rate.
Refer the above graph.
On plotting the length of the organ against time a linear curve is obtained.
Mathematically, it is expressed as.
`L_(t)=L_(o)+rt`
`L_(t)="length at time t"`
`L_(o)=` length at time zero
R = growth rate/elongation per unit time.

Geometrical Growth : In living organisms during geometric type of growth rate pattern follows three important phases.
(a) Lag phase (Initial or the BEGINNING phase) : It is mainly characterized by very slow growth.
(b) Log phase (exponential phase) : It is the middle phase of the system and is characterized by very fast and rapid growth of the plant body.
After initiation of growth, it increases rapidly at an exponential rate.
During this phase, both progeny cells undergoing mitotic cell division retain the ability to divide and CONTINUE dividing till the next phase appears till the time nutrient supply is appropriate.

Diagrammatic representation of: (a) Arithmetic (b) Geometric growth and (c) Stages during embryo development showing geometric and arithematic phases
Under favourable conditions the characteristic course of growth is observed. Thus, if we plot the parameter of growth rate against time the typical shaped, a sigmoid curve is seen.
It shows a characteristic feature of all living organism growing in a natural environment.
This curve is typeical for all cells, TISSUES and organs of a plant.

The exponential growth can be expressed as :
`W = W_(0)E^(rt)`
Where `W_(1)=` Final size (weight, height, number etc.)
`W_(0) =` Initial size at the beginning of the period
t = Time of growth
e = Base of natural logarithms

r = Relative growth rate that measures the ability of the plant to produce new plant material, known as efficiency index.
The final size `[W_(1)]` depends on the initial size `[W_(0)]`
Discussion
18481.

Question : Describe Datura metel in botanical terms.

Answer»

Solution :Datura metel in botanical terms:
1. Habit: Large, erect and stout herb.
2. Root: Branched tap root system.
3. Stem: Stem is hollow, green and herbaceouswith strong odour.
4. Leaf: Simple, ALTERNATE, petiolate, entire or deeply lobed, glabrous exstipulate showingunicostate reticulate venation.
5. Inflorescence: Solitary and axillary cyme.
6. Flower: Flowers are large, greenish white , bracteate, bracteolate, pedicellate, complete, heterochlamydeous, pentamerous, regular actinomorphic, bisexual and ypogynous.
7. Calyx: Sepals 5, green synsepalous showing valvate aestivation. Calyx is mostly persistant, odd sepal is posterior in position.
8. Corolla: Petals 5, greenish white, SYMPETALOUS, plicate (folded like a fan) showing TWISTED aestivation, funnel haped with wide mouth and 10 lobed.
9. Androecium: Stamens 5, free from one another, EPIPETALOUS, altemipetalous and are inserted in the middle of the corolla tube. Anthers are basifixed, dithecous, with long filament, introse and longitudinally dehiscent.
10. Gynoecium: Ovary bicarpellary, syncarpous superior ovary, basically bilocular but tetralocular due to the formation of false septum. Carpels are obliquely placed and ovules on swollen axile placentation.
11. Fruit : Spinescent capsule opening by four apical valves with persistent calyx.
12. Seed : Endospermous.
13. Floral Formula :
Discussion
18482.

Question : Describe Crassulacean Acid Metabolism (CAM Cycle).

Answer»

Solution :
1. It is one of the carbon pathways identified in succulent plants growing in semi-arid or xerophytic condition.
2. First observed in Crassulaceae family plants like Bryophyllum, Sedum, Kalanchoe and is the reason behind the name of this cycle .
3 . Also noticed in plants from other families Eg.., Agave , Opuntia , Pineapple , Orchids , etc.
4 . The stomata are closed during day and are open during night ( Scotoactive) . This reverse stomatal rhythmhelps to CONSERVE water loss through transpiration and will stop the fixation of `CO_(2)` during the day time .
5. At night time CAM plants fix `CO_(2)` with the help of Phospho Enol Pyruvic acid (PEP) and produce OxaloAcetic Acid (OAA) .
5. Subsequently OAAis converted into Malic acid like `C_(4)` Cycle and gets accumulated in vacuole increasing the acidity .
6. During the day time stomata are closed and Malic acid is decarboxylated into Pyruvic acid resulting in the DECREASE of acidity . `CO_(2)` thus formed enters into Calvin Cycle and produces carbohydrates .
Significance of CAM Cycle .
1It is advantageous for succulent plants to obtain `CO_(2)` from malic acid when stomata are closed.
2 During day time stomata are closed and `CO_(2)` is not taken but CONTINUE their photosynthesis .
3. Stomata closed during the day time and help the plants to avoid transpiration and water loss .
Discussion
18483.

Question : Describe compositional elements present in bile juice.

Answer»

Solution :Semi digested food chyme comes to intestine by pyrrolic stomach. Chyme comes into contact of three different secretions in small intestine.
Pancreatic juice, bile juice and intestinal juice.
Various types of movements are generated by the muscularis layer of the small intestine. These movements help in a THOROUGH mixing up of the food with various secretions in the intestine and there by FACILITATE digestion.
Pancreatic juice possesses inactive enzymes trypsinogen, chymotrypsinogen and procarboxypeptidases and amylase, lipase and nuclease.
Trypsinogen is activated by an enterokinase, secreted by the intestinal mucosa into active trypsin which in turn activates the other enzymes in the pancreatic juice.
Proteases + peptones `overset"Trypsin"to` polypeptide + Amino Acid
Trypsin convents chymotrypsinogen into chyme trypsin and procarboxy peptidases in to carboxyl peptidase.
proteoses + polypeptides + peptones `to`Chymotrypsin small polypeptide + Amino Acid.
Polypeptide `overset"Carboxypoptidose"to` Peptide, Amino acid
Amylase present in pancreatic, juice hydrolyses carbohydrates and disaccharide is formed. Polysaccharide (starch `overset"Amylase"to`Disaccharide Maltese).
The bile released into the duodenum contains bile pigments (bilirubin and biliverdin), bile salts, cholesterol and phospholipids but no enzymes.
Bile helps in emulsification of fats i.e. breaking down of the fats into very small micelles.
Fats `overset"Lipases"to` Diglycerides `to` Monoglycerides
Nucleases of pancreatic juice reacts on nucleic acid and forms nucleotides and nucleosides.
Nucleic acids `overset"Nucleases"to` Nucleotides `to` Nucleosides
Digestion by intestinal juice in JEJUNUM and ILEUM: The enzymes of intestinal juice react on enzymes, final products react on them and convert into absorbable simple FORM.
Dipeptide `underset"(Erepsin)"overset"Dipeptidases"to` Amino Acids
Maltose `overset"Maltase"to` Glucose + Glucose
Lactose `overset"Lactose"to` Glucose + Galactose
Sucrose `overset"Sucrose"to` Glucose + Fructose
Nucleotides `overset"Nucleotidases"to` Nucleosides `overset"Nucleosidases"to` Sugars+ `N_2` Bases
Di and Monoglycerides `overset"Lipases"to` Fatty acid+Glycerol
Simple components produced from bio mega molecules are absorbed into jejunum and ileum of small intestine.
Undigested and unabsorbed components are passed into large intestine.
Discussion
18484.

Question : Describe contribution of cork cambium in secondary growth.

Answer»

Solution :As the stem continues to increase the girth due to the activity of vascular cambium, the outer cortical and epidermis layers get broken and need to be replaced to provide new protective cells layers. Hence sooner or later another meristematic tissue called cork cambium or phellogen develops in the cortex REGION.
Phellogen is a couple of layers thick, it is made of narrow, thin WALLED and nearly rectangular cells. Phellogen cuts off cells on both sides.
The outer cells differentiate into cork or phellem while the inner cells differentiate into secondary cortex or phelloderm.
The cork is impervious to water due to suberin deposition in the cells wall.
The cells of secondary cortex are parenchymatous.
Phellogen, phellem and phelloderm are collectively known as periderm.
Due to the activity of the cork cambium. Pressure BUILDS up on the remaining layer PERIPHERAL to phellogen and ultimately these layer die and slough off.
Bark : Bark is a non-technical term that refers to all tissues exterior to the vascular cambium, therefore including secondary phloem.
Early barks : Bark refers to a number of tissue types viz periderm and secondary phloem. Bark that is formed early in the season is called early or soft bark. Towards the end of the season, late or hard bark is formed.
Lenticels : At CERTAIN regions, the phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming a lens shaped opening called lenticels.
Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem. These occur in most woody trees.
Discussion
18485.

Question : Describe common characteristics of Bryophytic plants.

Answer»

Solution :• Habitat: They are commonly growing in moist shaded areas in the hills.
• Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction
• They play an important role in plant succession on bare rocks / soil.
• Body structure : The plant body of bryophytes is more differentiated than that of algae. It is thallus-like and prostrate or erect.
• They are attached to the SUBSTRATUM by unicellular or multicellular rhizoids. They lack true roots, stem or leaves.
• They may possess root-like, leaf-like or stem-like structures.
• The main plant of the body is haploid. It is called a gametophyte. Reproductive organs : The sex organs in bryophytes are multicellular.
• The male sex organ is called antheridium. They produces biflagellate antherozoids.
• The female sex organ is called archegonium. It is flask-shaped and produces a single egg
• Fertilization :
• antheroizoids are RELEASED into water where they can come in contact with archegonium.
• An antherozoid fuses with the egg to produce zygote.
• Zygotes do not undergo reduction division (Meiosis) immediately, They produce a multicellular body called a sporophyte.
• The sporophyte is not free-living but attached to the photosynthetic gametophyte and derives nourishment from it.
• cells of the sporophyte undergo reduction division to produce haploid spores.
• Economic Importance of Bryophytes : • Bryophytes in general are of little economic importance but some Mosses provide food for herbaceous mammals, birds and other animals.
• Species of Sphagnum, a moss, provide peat that have long been used as fuel and as packing material for trans-shipment of living material because of their CAPACITY to hold water.
• Mosses along with lichens are the first organisms to colonise rocks and hence are of great economical importance.
• They decompose rocks making the substrate suitable for the GROWTH of higher plants.
• Since Mosses form dense mats on the soil, they reduce the impact of falling rain and prevent soil erosion.
• Types of Bryophytes : The bryophytes are divided into liverworts and mosses.
Discussion
18486.

Question : Describe Coenanthium inflorescence. Give an example.

Answer»

Solution :It is a special INFLORESCENCE. A circular disc LIKE fleshy open RECEPTACLE bears pistillate flowers at the CENTRE and staminate flowers at the periphery. Eg: Dorstenia.
Discussion
18487.

Question : Describe class - Mammalia.

Answer»

Solution :Mammalia are found in a variety of habitats - polar ice caps, deserts, mountains, forests, GRASSLANDS and dark caves.
Some of them have adapted to fly or live in water.
The most unique mammalian characteristic is the presence of milk producing glands (mammary glands) by which the young ones are nourished.
They have two pairs of limbs, adapted for walking, running, climbing, burrowing, swimming or flying
The skin of mammals is unique in possessing hair.
External EARS or PINNAE are present.
Different types of teeth are present in the jaw.
Heart is four-chambered. 
They are homoiothermous.
Respiration is by lungs.
Sexes are separate and fertilisation is internal.
They are viviparous with few exceptions and development is direct.
Examples : Oviparous - Ornithorhynchus (Platypus),
Viviparous - Macropus (Kangaroo), Pteropus (Flying FOX), Camelus (Camel), Macaca (Monkey), Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (ELEPHANT), Equus (Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), Panthera leo (Lion).
Discussion
18488.

Question : Class Mammalia:

Answer»

Solution :(L. Mamma - Breast)
They are found in a variety of habitals. Their body is covered by hair, a unique feature of mammals. Some of them are adapted to fly or live in water. Presence of mammary glands is the most unique feature of mammals. They have two pairs of limbs adapted for walking, running , climbing, burrowing, swimming and flying. Their skin is glandular in nature, consisting of sweat glands. scent glands and sebaceous glands. Exoskeleton INCLUDES hrony epidermal horns, spines, scales , claws, nails , hooves and bony dermal plates. Teeth are thecodont, heterodont and diphyodont. External cars or pinnae are present. The heart is four chambered and pssess a left systematic arch . Mature RBCs are circular, biconcave and non nucleated. Mammals have a large brain when compared to other animals They show greatest intelligence among all animals. Theri kidneys are metanephric and are ureotelic. All are HOMEOTHERMIC, sexes are separate and fertilization in internal.
Examples : Oviparous - Ornithorhynchus (Platypus), Viviparous - Macropus (Kangaroo), Pteropus (flying fox), Macaca (Monkey), Canis(DOG) , Felis(Cat), Elephas (Elephant) , EQUUS(Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (TIGER), Panther leo (Lion), Homo sapiens (Human), Bos (Cattle).
Discussion
18489.

Question : Give difference : Chondrichthyes and Osteichthyes

Answer»

Solution :Chondrichthyes are marine animals with streamlined body and have cartilaginous endoskeleton.
Mouth is located ventrally.
Notochord is persistent throughout life.
Gill slits are separate and WITHOUT operculum (gill cover).
The skin is tough, containing minute placoid SCALES.
Teeth are modified placoid scales which are backwardly directed.
Their jaws are very powerful.
These animals are predaceous.
Due to the absence of air bladder, they have to swim constantly to avoid sinking.
Heart is two-chambered (one auricle and one ventricle).
Some of them have electric organs (e.g., Torpedo) and some possess poison sting (e.g.. Trygon).
They are COLD blooded (poikilothermous) animals, i.e., they lack the capacity to regulate their body temperature.
Sexes are separate.
In males pelvic fins bear claspers.
They have internal fertilisation and MANY of them are viviparous.
Examples : Scoliodon (Dog fish), PRISTIS (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray).
Discussion
18490.

Question : Describe circulatory system of frog

Answer»

Solution :The vascular system of frog is well-developed closed type. It has lymphatic system also.The blood vascular system involves heart, blood vessels and blood. The lymphatic system consists of lymph, lymph channels and lymph nodes.Heart of Frog : Heart is a muscular structure situated in the upper part of the body cavity. It has three chambers, two atria and one ventricle and is covered by a membrane called pericardium A triangular structure called sinus venosus joins the right atrium. It receives blood through the MAJOR veins called vena cava. The ventricle opens into a sac-like conus arteriosus on the ventral side of the heart.The blood from the heart is carried to all parts of the body by the arteries. The veins collect blood from different parts of body to the heart and form the venous system.Portal system : Special venous connection between liver and intestine as well as the KIDNEY and lower parts of the body are present in frogs. The former is called hepatic portal system and the later is called renal portal system.Blood : Blood has blood plasma and blood cells. RBC (red blood cells) or Erythrocytes, WBC (white blood cells) or Leucocytes and blood platelets. The circulation of blood is DONE by pumping of muscular heart. Red coloured pigment namely Haemoglobin is present in red blood cells. These cells are nucleated.Lymph : Lymph is different from blood because it lacks protein and red blood cells, During circulation the blood carries nutrients, gases and water to the respective SITES.
Discussion
18491.

Question : Describe circulatory system of cockroach.

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Solution :The blood vascular system of COCKROACH is of open type. Means during circulation blood instead of passing from capillaries enters into space called hemocoel. So body organs and tissues have direct contact with blood. Blood is mainly MADE up of blood plasma and irregularly shaped cells. Blood has no respiratory pigment so it is colourless. It is called hemolymphs. The HEMOLYMPH is COMPOSED of blood plasma and hemocytes. The heart of cockroach consists of elongated muscular tube lying along mid dorsal line of thorax and abdomen. It is differentiated into funnel shaped chambers with ostia on either side. The first 3 segments are LOCATED in thorax region and remaining are located in abdomen region. Blood cells are of two types. Small sized proleucocytes and large sized phagocytes.Blood enters into heart from sinuses through ostia and is pumped anteriorly to sinuses again.
Discussion
18492.

Question : Mention briefly about the circulatory system of earthworm.

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Solution :The circulatory system of earthworm is of closed type consisting of blood vessels, capillaries and heart.Blood is RED, haemoglobin is dissolved in blood plasma. Blood glands are present on the 4th , 5TH and 6th segments. They produce blood cells and haemoglobin which is dissolved in blood plasma. Blood cells are PHAGOCYTIC in nature. Due to closed circulatory system the blood circulates only into, blood capillaries, blood vessels and hearts.Due to contraction, blood circulates only in one direction. Smaller blood vessels supply the gut, nerve cord and the body wall.

Respiretory system : Earthworms lack specialised breathing devices. Respiratory exchange OCCURS through body surface into their blood stream. For this the body walls NEEDS to be wet. Blood flow mixes in `O_(2)` from there.
Discussion
18493.

Question : Describe Calvin cycle. OR C_(3) pathway.

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Solution :Calvin and his co-workes worked out the whole pathway and showed that the pathway operated in a cyclic manner, the RuBP was regenerated.
Calvin pathway occurs in all photosynthetic plants, it does not matter whether they have `C_(3) or C_(4)` (or any other) pathways.
Calvin cycle can be described under three stages : (1) carboxylation (2) reduction (3) regeneration.
(1) Carboxylation : Carboxylation is the fixation of `CO_(2)` into a stable ORGANIC intermediate.
Carboxylation is the most crucial STEP of the Calvin cycle where `CO_(2)` is utillsed for the carboxylation of RuBP.
This reaction is catalysed by the enzyme RuBP carboxylase which results in the formation of two molecules of 3 - PGA.
Since this enzyme also has an oxygenation activity it would be more correct to call it RuBP carboxylase - oxygenase or RuBisCO.
(2) REDUTION : These are a SERIES of reactions tha lead to the formation of glucose.
The steps invole utilisation of 2 molecules of ATP for phosphorylation and two of NADPH for reduction per `CO_(2)` molecule fixed.
`2PGA + 2ATP + 2NADPH rarr 2` Triose phosphate (2 PGAC)
The fixation of six molecules of`CO_(2)` and 6 turns of the cycle are required for the REMOVAL of one molecule of glucose from the pathway.

Regeneration : Regeneration of the `CO_(2)` acceptor molecule RuBP is crucial if the cycle is to continue uninterrupted. The regeneration steps require one ATP for `PGAL overset(ATP) rarr RuBP`
Hence for every `CO_(2)` molecule entering the Calvin , 3 molecules of ATP and 2 of NADPH are required.
It is probably to meet this difference in number of ATP and NADPH used in the dark reaction that the cyclic phosphorylation takes place.
To make one molecule of glucose 6 truns of the cycle are required.
Discussion
18494.

Question : Describe characteristics and types of connective tissue.

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Solution :They perform special function of linking and supporting other tissues/organs of thebody. Structure : This tissue has less number of cells.It has more amount of intercellular fluid. This fluid is created by cells of tissue. New cells are formed from pre-existing cells. Cells of this tissue secrete structural protein fibres (EXCEPT blood tissue). It is called collagen or Elastin. These fibres provides strength, flexibility and elasticity. These cells also secrete polysaccharide which gets deposited between cells and fibres and acts as matrix. Types of connective tissue : Connective tissue is classified into three types : (i) Loose connective tissue (ii) Dense connective tissue (iii) Specialised connective tissue. (i) Loose connective tissue : Loose connective tissue has cells and fibres loosely arranged in a semi-fluid ground substance. There are two type of loose connective tissue. (a) Areolar connective tissue, (b) ADIPOSE tissue (a) Areolar connective tissue :Location : This tissue is found in the gastrovascular cavity, peritoneum and in mesentery which is surrounding the intestines and in walls of arteries and at many other PLACES. Structure : The matrix fluid of this tissue is comparatively thick. In matrix network of fibres, they are collagenous and are of protein. Fibres are of two types : White fibres and yellow fibres.White fibres : They are made up of collagen and elastic. They can toilerate stretch and pressure. White fibres are wavy and new branched and are arranged in groups. Yellow Fibres : They are nonbranched, single and made up of elastin material and elastic. They can not bear stretch and pressure. There are three types of cells in it : fibroblasts, macrophages and mast cells. Fibroblasts : They are irregular in shape, flat and possess processes. They form protein fibres like collagen and elastin. Macrophages : They are large irregular shaped cells. They perform phagocytosis of bacteria, large particles and decomposed material. Mast cells : They store inflammatory materials. They secrete three type of active materials : Heparin, Histamine and Serotonin.

(b) Adipose tissue : Adipose tissue is another type of loose connective tissue located mainly beneath the skin. The cells of this tissue are specialised to store fats. The excess of nutrients which are not used immediately are converted into fats and are stored in this tissue.

(ii)Give . information about tendons and ligaments.Dense connective tissues : Fibres and fibroblasts are compactly packed in the dense connective tissues or irregular pattern and are called dense regular and dense irregular tissues. In the dense regular connective tissues, the collagen fibres are present in rows between many parallel bundles of fibres. Tendons : That attach skeletal muscles to bones. Ligaments : That attach one bone to another. Dense irregular connective tissue : This tissue has fibroblasts and many fibres (mostly collagen) that are oriented differently.

(iii) Specialised connective tissue : (a) Cartilage (b) Bones and (c) Blood are various types of specialised connective tissue. (a) Cartilage tissue : The intercellular material of cartilage is solid and pliable and resists compression. Cells of this tissue (chondrocytes) are enclosed in small cavities within the matrix secreted by them. Most of the cartilages in VERTEBRATE embryos are replaced by bones in adults. Location : Cartilage is present in the tip of nose, outer ear joints, between adjacent bones of the vertebral column, limbs and hands in adults. "* There are four types of cartilage tissue, (i) Hyaline cartilage (ii) White fibrous cartilage (iii) Yellow elastic cartilage (iv) Cartilage fused with calcium. (b) Bones tissue : Bones tissue is also a skeletal tissue. It is solid, brittle and in-elastic. It has ossein fluid and different salts in its matrix. Its cells are called osteocytes. The structure of bone is very complex. It gives strength to bones. It is a main tissue of the body. It gives structural frame to the body. Bones support and protect softer tissues and organs. The bone cells are present in the spaces called lacunae limb bones such as the long bones of legs, serve weight bearing function. They also interact with skeletal muscles attached to them to bring about movements.The bone marrow in some bones is the site of production of blood cells. In bones of mammals, many structure like pillars are seen. It is called as Haversian system. In each Haversian system many Lamellae of bone material form CONCENTRIC rings around large longitudinal canals within the bone tissue. These canals are called Haversian canals.

(c )Blood tissue : Blood is a fluid connective tissue containing plasma, red blood cells, white blood cells and platelets. It is the main circulating fluid that helps in the transport of various substances
Discussion
18495.

Question : Describe C_(4) pathway.

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Solution :Plants that are adapted to dry tropical regions have the `C_(4)` pathway.
These plants have the `C_(4)` oxaloacetic acid as the first `CO_(2)` fixation product. They use the `C_(3)` pathway or the Calvin cycle as the main biosynthetic pathway.
Internal specially of `C_(4)` plants leaves :
(1) `C_(4)` plants are special. They have a SPECIA type of leaf anatomy, they tolerate higher temperatures.
They show a response to high light intensities.
They lack a process called photorespirations.
They have greater productivity of biomass.
(5) Invertical sectio of leaves, one of a `C_(4)` plant cells of mesophyll are seen.
(6) The particularly larage cells around the vascular bundles of the `C_(4)` pathway plants are called bundle sheath cells, and the leaves which have such anatomy are said to have .Kranz. anatomy.
(7) Here "Kranz" means "WREATH" and is a REFLECTION of the arrangement of cells.
(8) The bundle sheath may have SEVERA layers around the vascular bundles.
(9) They are characterised by having a large number of chloroplasts, thick walls impervious to gaseous exchange and no intercellular spaces.
(10) There are no inter - cellular spaces around cells. If we cut a section of the leaves of `C_(4)` plants - maize or sorghum - to observe the Kranz anatomy and the distribution of mesophyll cells.

The pathway shown in given figure is called Hatch and slack pathway. This is also a cyclic process.
Stages or steps of `C_(4)` pathway : Steps of `C_(4)` pathway are as follows :
Step 1 : Atomspheric `CO_(2)` enters into the cells of mesophyll where the primary `CO_(2)` acceptor is a 3-carbon molecule phosphenonlpyruvate (PEP)
The enzyme responsible for this `CO_(2)` fixation is PEP carboxylase or PEPCASE.
The mesophyll cells lack RuBisCO enzyme.
The `C_(4)` acid OAA in the mesophyll cells
`CO_(2)+PEP overset("PEPcase")rarrOA A`
Step 2 : It then forms other 4-carbon compounds like malic acid or aspartic acid in the mesophyll calls itself. which are transported to the bundle sheath cells. In the bundle sheath cells these `C_(4)` acids are broken down to release `CO_(2)` and a 3-carbon molecule.

Step 3 : The 3 carbon molecul is tranported back to the mesophyll where it is converted to PEP again, thus completing the cycle
Pyuruic acid `rarr` Inmesophylll (in presence of ATP)
Pyruvic acid + ATP `rarr` (PEP)
Step 4 : The `CO_(2)` relased in the bundle sheath cells enteres the `C_(3)` or the Calvin pathway, a pathway common to all plants.
The bundle sheath cells arerich in an enzyme Ribulose, biophosphate carboxylase-oxygenase (RuBisCO), but lack PEPcase.
Thus, the basic pathway that result in the formation of the sugars, the calvin pathway is common to the `C_(3) and C_(4)` plants.
Discussion
18496.

Question : Describe briefly types of neural system in human.

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Solution :The human neural system is divided into TWO parts:
(i) The Central Neural System (CNS)
(ii) The Peripheral Neural System (PNS)
The CNS includes the brain and the spinal cord. It is the site of information processing and control.
The PNS comprises of all the nerves of the body associated with the CNS (brain and spinal cord)
The nerve fibres of the PNS are of two TYPES :
(a) Afferent Nerve Fibres (b) Efferent Nerve Fibres
The afferent nerve fibres transmit impulses from tissues/organs `rarr` CNS
The efferent never fibres transmit the regulatory impulses from CNS involuntary organs/tissues.
The PNS is divided into two subdivisions :
(i) Somatic Neural System (ii) Autonomic Neural System
The somatic neural system relays impulses from the CNS to skeletal muscles.
The autonomic neural system transmits impulses from CNS `rarr` involuntary organs and smooth muscles to the body.
The autonomic neural system is again divided into Sympathetic Neural System and Parasympathetic Neural System.
VISCERAL Nervous : System is part of peripheral nervous system which allows travelling conduction nerve impulses of nerves, GANGLIONS plexuses (nerve network) from central nervous system to internal organs and from internal organs to CNS. It is formed of whole complex.
Discussion
18497.

Question : Describe briefly what was demonstrated in the reaction named after its discoverer Robin Hill?

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SOLUTION : R. Hill (1937) found that when isolated CHLOROPLASTS from ground up leaves of Stellaria media placed in cell extracts, produced oxygen from `H_2 O` in illuminated stage. He also noticed that cell extracts can be replaced by SALTS of IRON like ferric oxalate. The substances when added to illuminated isolated chloroplasts in the absence of `CO_2` acted as hydrogen acceptors i.e. oxidants. These substances are called Hill oxidants or Hill REAGENTS.
Discussion
18498.

Question : Describe briefly the various stages of cell cycle during the interphase preceding mitosis.

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SOLUTION :`G_1` phase - CELL METABOLICALLY active and GROWS
S phase (synthesis phase) - DNA replication
` G_2` phase - proteins synthesize, cell grows.
Discussion
18499.

Question : Describe briefly the structure of human brain.

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Solution :HUMAN brain is a soft nervous structure , weighing about 1280 to 1380 gms. It is protected by cranium of the skull and meninges . Meninges are the three membrances covering central nervous system (brain and spinal cord).
Human brain comprises of about 100 billion neurons and is divisible into,
1. Fore brain (Prosencephalon).
2. Mid barin (Mesencephalon).
3. Hind brain (Rhombenceohalon).
Sagittal section of brain reveals the following details.
FORE BRAIN : Fore brain comprises of cerbrum , diencephalon , (thalamus and hypothalamus) and olfactory lobes.
Cerebrum :
It is the largest part of the brain It consists of two hemisperes. Cerebral of two hemispheres . Cerebral cortex is chiefly composed of cell bodies (cyton) of the neurons and is called grey matter , whereas cerebral medulla is chiefly composed of nerve fibres and is the seat of intelligence. Surface of the cerebral cortex shows number of folds and deep groves . Folds of the cerebral cortex are called 'gyri' and the deep grooves are called 'fissures' . Cerebrum also shows shallow furrows termed as 'sulci' . These fissures divide each cerebral hemisphere into five lobes , namely,
(i) Frontal lobe : It is the largest of the four lobes making up the anterior one third of each hemisphere.
(ii) Praietal lobe: It lies behind the frontal lobe and is separated from it, by a fissure of Rolando or central fissure.
(iii) TEMPORAL lobe : It lies below and behind the frontal lobe and is seperated from it by a lateral sulcus.
(iv) Occipital lobe : It lies behind the parieto - occipital sulcus.
(v) Insula (Island of Reil) : It is not visible because it is located deep with in the lateral sulcus. It is covered by parts of frontal , parietal and temporal lobes.
Corpus callosum : It is the network of nerve fibres connecting two hemispheres of cerebrum .
Diencephalon : Diencephalon is the part of a fore brain which CONNECTS the cerebrum with mid brain . Diencephalon comprises of thalamus and hypothanlamus.
(i) Thalamus : It isthe sensory stimuli and relays them to different aeas of the cerebral cortex.
(ii) Hypothalamus : It is the REGIONS of the diencephalon found below the thalamus . It is associated with pituitary and pineal glands (pineal gland secretes the hormone melatonin) . A stalk like infundibulum connects it with the pituitary gland. it controls various metabolic activities like regulation of the heart beat, regulation of body temperature , regulation of sleep, B.P , water electropyte balance , etc.
Optic chiasma : Just below the hypothalamus there is a region at which the optic nerves cross each other. This region is called optic chiasma.
Olfactroy lobes : These are extended part of the frontal lobes . They are olfaction in function and are poorly developed in human BEINGS.
MID BRAIN : It comperises of crebral peduncles and corpora quadrigemina . Cerebral peduncles connect brain stem (midbrain , pons and medulla oblogata) with the cerebrum. where as corpora quadrigemina extend as optic lobes . These are centres for visual and auditory reflexes.
HIND BRAIN: Hindi barin comprises of cerebellum, pons varoli and medulla oblongate.
Cerebellum : It is the first part of hindi brain, and also the second largest part of the brain. It has two lobes. Cerebellum is connected with co - ordination and smoothness of movement. It help to maintain body balance and co - ordinated speech.
Medulla oblongate : It is the last part of the hind brain which posteriorly continues as spinal cord. It controls respiratory activities, dilation of blood vessels ( It initates impulses that causes construction anddilation of the blood vessels ) , reflexes such as sneezing. Coughing, vomiting and winking. Medulla oblongate also has control over heart beat and secretary activities of the alimentary canal.
Pons varoli : It is the bundle of nerve fibres situated between midbrain and medulla oblongate. It alsobridges two lobes of the cerebellum. It regulates respiration.
Different parts of the brain contain inner spaces . These inner spaces of a the brain are called ventricles. They are filled with cerebro spinal Fluid (CSF ). The first and second ventricles are in the hemispheres of the cerebellum. Third one in the diencephalon and fourth in the medulla oblongate.
Discussion
18500.

Question : Describe briefly the four major groups of Protozoa.

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Solution :The four major GROUPS of Protozoa are : zooflagellates, rhizopods, SPOROZOANS and CILIATES.
Discussion