1. these are found as outer most layers of an organ or as lining of body invaginations.
2. Their cells are long and flat.
3. These may form one or more layers of epithelial tissues of skin which is called squamous epithelial cells.
4. Squamous Epithelium provides protection to skin.
5. Some cells are cubical in shape and known as cuboidal epithelial cells.
6. Cuboidal epithelial cells from the lining of glandular ducts and help in the production of cell secretions.
7. Some cells are small and elongated which are found at certain places in the inner lining of different organs and secret juice. These are called columnar epithelial cells e.g. cells of gastric glands in stomach which secrete the gastric juice.
8. Some columnar cells have cilia at their free surface. These are called ciliated columnar epithelial cells e.g. cells present in trachea. Due to movement of these cilia, mucous and other materials are expelled.
1. This tissue is made up of semi fluid matrix.
2. These matrixes contain a variety of cells and fibers.
3. These tissues provide support to different body parts and bind them together. These also protect the organs from germs and help in the production of blood cells.
4. These are of two types:
• Soft connective tissues e.g. fatty tissues and tendons.
• Hard connective tissues e.g. cartilage and bone.
5. Blood is also a special connective tissue with cells suspended in the fluid medium. It transports materials in the body.
1. This tissue is made up of special contractile cells or fibers.
2. The cells are elongated and are called muscle fibers.
3. These cells have the ability to contract and relax which results in movements of body and the organs.
4. Following are the three types of muscles in our body.
These are attached to cartilage and bones. These seem to be striped fibers under the microscope. Therefore these are striped or striated muscles. Their movements are under our control so these are voluntary muscles e.g. muscles of arm and legs which move these parts.
These are found around hollow organs such as blood vessels, gut. These produce slow, sustained contractions but do not fatigue. These re composed of spindle shaped unstriated muscles. These are involuntary and are under the control of the autonomic nervous system.
These are found in the heart. These are composed of branched fibers and are capable of sustained contraction but do not not fatigue. These are also involuntary in action.
1. These are composed of nerve cells which are called neurons.
2. Each neuron consists of a cell body, axon and dendrites.
3. These productive nerve impulse to conduct messages.
4. By this tissue, different body parts have coordination with each other.
5. This tissue also forms brain and spinal cord.
Unicellular Organism (Amoeba)
The organisms consisting of only one cell are called unicellular organisms e.g. Amoeba, Paramecium etc.
1. It is mostly found in fresh water pond or pool.
2. In the ponds, it is found moving about around the weeds and stones. Some species are found in the moist soil.
3. Amoeba is a large protist.
4. It does not have the permanent shape.
5. Its size is about the end of pin or it measures about 0.25mm. Therefore it is observed under the microscope.
6. Its structure is very simple.
7. It consists of nucleus and cytoplasm, which are surrounded by a cell membrane.
8. Cell membrane protects it.
9. Cytoplasm is divided into two parts. Outer clear and transparent part is called ectoplasm while the inner, viscous, translucent and granular part is called endplasm.
10.Endoplasm contains food vacuoles of different sizes. These food vacuoles help in the digestion of food.
11. The food of Amoeba consists of microbes present in the water of pond.
12. Contractile vacuole maintains the concentration of water in the body. It removes surplus water out of the cell.
13. In Amoeba, the exchange of gases and removal of waste.
14. In Amoeba, there are also present mitochondria, golgi bodies and ribosomes.
15. Nucleus changes its place with the movement of the organism.
The organisms consisting of many cells are called multicellular organism. e.g. Brassica Plant, frog, man etc. diagram?
Brassica Plant (Mustard Plant)
1. This plant is sown in winter and at the end of season, it produces seeds and then dies.
2. This is an annual plant.
3. An oil is extracted from seeds of this plant which is known as mustard oil.
4. The scientific name of this plant is Brassica Campestris.
Non-Reproductive Parts or Vegetative Parts
These parts do not directly take part in ***ual reproduction e.g. root, stem, branches and leaves.
These parts directly take part in ***ual reproduction e.g. flower, fruit and seed.
Root of Brassica
The root is that part plant which is present inside the soil. It is produced from radical of seed. The first formed root is called Primary root. During its growth, it gives off secondary and tertiary root. Each root has a root cap at its tip or apex. Behind the root cap, root hairs are present which absorbs water and salts from the soil. Roots also anchor the plant firmly in the soil.
Internal Structure of Root of Brassica
When transverse section of root of Brassica is observed under the microscope, the following parts are very prominent.
It is outermost and protective layer. It is single celled. Some cells grow outward to form root hair.
It is present inner to epidermis. It is made up of several layers of thin walled living cells (parenchyma cells). There are present intercellular spaces. These cells store food.
it is the innermost layer of cortex. There are no intercellular spaces. There are thickenings of special materials around the cell which check diffusion of water from xylem to cortex.
The layer present inner to endodermis is called pericycle. There are also no intercellular spaces. All the branches of roots arise from pericycle.
Xylem is present in middle of root which extends to pericycle in the form of four rays and controls one way transport of water and salts. In between the xylem rays, phloem bundles are present which transport food in two directions.
Stem of Brassica
The stem is that part of the plant which grows above ground. It arises from plumule of seed. It is herbaceous and branched. It bears leaves and flowers. The part of stem or its branch from where a leaf arises is called node. The part between two nodes is called internode. the important function of stem is the conduction of prepared food from leaves to other parts and that of water absorbed from roots to leaves. It supports leaves, flowers and fruits like a pillar. It keeps the leaves in such a position that they can get light to prepare food.
Internal Structure of Stem of Brassica
When transverse section of stem of Brassica is observed under the microscope, following parts are visible.
It is the outermost protective layer of stem. Outer to epidermis, there is layer of cutin which reduces loss of water from stem. The cells are compactly arranged and there are no intercellular spaces.
It is inner to epidermis. It is made up of many layers of parenchyma and collenchyma tissues. The main function of cortex is storage of water and food.
It is innermost layer of cortex. It is not prominent in stem. It allows suitable quantity of waer to enter cortex from xylem.
It is in the form of bundles in between the endodermis and vascular bundles. It is composed of sclerenchyma cells. It forms bundle cap.
In stem, vascular bundles are arranged in the form of ring. Vascular bundle consists of phloem and xylem. Phloem is towards outside and xylem is towards inside. Few layers of cambium are present between the xylem and phloem. Cambium causes increase in diameter of the stem with passage of time.
There are present few layers of thin walled living cells between every two layers. These are called medullary rays. The medullary rays connect the cortex with pith for the transport of food.
The central part of stem consists of living, rounded, thin walled parenchyma cells. This part is called pith. Here food is stored.
Leaf of Brassica
1. Leaf is produced on node of stem or its branch.
2. Each leaf consists of two parts. The stalk of leaf is called petiole and upper broad part is called lamina.
3. Young leaves are without petiole and their margins are entire or smooth.
4. Lower leaves are large in size. These are also without petiole but there margins are wavy.
5. In the middle of leaf there is a thick midrib.
6. From midrib, arise veins of different thickness and form a network in leaf. This arrangement of veins is called reticulate venation.
7. Veins are composed of xylem and phloem.
8. The angle formed between stem and leaf is called axil. In this axil, buds are present which gwo and become branches.
9. The dorsal and ventral surfaces of leaves are different from each other. Such leaves are called bifacial leaves.
10. The main function of leaf is the preparation of food by process of photosynthesis.
Internal Structure of Leaf
When transverse section of leaf is observed under the microscope, following structure are visible.
This layer of cells covers both upper and lower surfaces of leaf. Upper layer is called upper epidermis and lower layer is called lower epidermis. There are more number of stomata in lower epidermis than upper epidermis. This results in less transpiration and CO2 enters according to need. Each stomata consists of two guard cells, which are bean shaped, or kidney shaped. There is a pore between guard cells through which exchange of gases takes place and water vapours come out of leaves.
The tissue present between upper and lower epidermis is called mesophyll. It consists of two parts.
Uper part consists of elongated cells which hare lying vertical. These are double layered closely packed cells and are called Palisade Mesophyll.
The lower part is sponge like and has more intercellular spaces. This is called spongy mesophyll.
Both types of cells have chloroplasts containing chlorophyll. So, photosynthesis takes place here. The function of mesophyll is to manufacture food for the plant.
It consists of midrib and veins. The midrib is bundle. Upper part of midrib is xylem and lower part is phloem. Pericycle and endodermis surround this bundle. Besides this Lamina has other bundle which are called veins.
Flower of Brassica
The flower is reproductive part. With the maturation of age, the plant bears yellowish flowers. Many flowers are arranged on a branch in a special way. This branch is called peduncle. This arrangement of flowers on the peduncle is called Inflorescence.
Parts of Flowers
Flower consists of a stalk and floral leaves. The stalk is called Pedicel. The upper part of pedicel is comparatively swollen and flattened. This is called thalamus. On the thalamus, floral leaves are arranged in four whorls.
The details of floral leaves is as follows:
It is the outermost whorl of floral leaves. It consists of four sepals. On maturation, its colour changes to yellow. In young flowers sepals cover the inner parts of the flower. The main function of calyx is to protect inner parts of the flower.
It is the second whorl of floral leaves. It consists of four free petals. Its yellow colour is conspicuous and can attract insects, honey bees and butterflies which help in pollination.
It is the third whorl present inner to petals. It is the male reproductive part. It consists of six free stamens. These are arranged in two whorls, the outer whorl has two small stamens and inner whorl has four long stamens. Each stamen consists of two parts. Lower stalk is called filament. Upper swollen part is called anther, Inside anther, a large number of pollen grains are produced. When anther matures, a longitudinal slit appears in its walls from which pollen grains escape. AT the base of filament, four nectaries are present. These nectaries secrete nectar. To get nectar, insects visit the flowers. In this way, pollen grains get attached to the bodies of insects and are transferred from one flower to the other. This process is called pollination.
It is the inner most part of flower. It is female reproductive part. It consists of two carpels, which are fused. Each carpel has three parts. The basal swollen part is called ovary. The stalk like part above the ovary is called Style. The top of style is somewhat swollen and it is called Stigma. Overy contains many ovules. Ovules are ripened to form seeds while ovary is ripened to form fruit. The fruit of Brassica is called Siliqua.
Frog is found in he water or near the water. It belongs to class Amphibia. it passes a specific part of life in water and remaining life on land. Its bilogical name is Rana Tigrina. It is a cold blooded animal i.e. blood temperature changes with that of the environment. At the start of winter, water is decreased and temperature is lowered, the frog lives buried in the mud to over come winter.
The body cavity of frog is called Coelom. It contains many organs which form different systems.
Digestive System of Frog
This system consists of alimentary canal and accessory glands like liver and Pancreas.
It is a coiled tube through which food passes. It consists of buccal cavity, pharynx, oesophagus, stomach and intestines.
Buccal Cavity and Pharynx
Mouth is present between upper and lower jaws. Upper jaw has a row of pointed maxillary teeth. Lower jaw lacks teeth. There is a pair of set of vomerine teeth on the roof of the buccal cavity. Frog does not chew the food with teeth. But teeth are used only to grasp the food. The old teeth are continuously replaced by the new teeth through its life. Near the vomerine teeth, internal nostrils are present on the roof of the buccal cavity. These open outwards into external nostrils. Behind them, two large bulges indicate the position of eyes. The tongue of frog is sticky. The tongue is attached at anterior end of buccal cavity. The posterior end of tongue is free and bifid. the frog feeds on different insects. To capture its prey, it suddenly throws its tongue on to the prey, which sticks to the tongue and is brought to the buccal cavity, when the tongue is drawn back.
Near the maxillary joints, pair of opening of eustachian tubes are present. In male frog, there is also, present a pair of opening of vocal, sacs on the lateral side of floor of the buccal cavity which help the croaking. Buccal cavity narrows, posteriorly to form pharynx. The digestive system, respiratory system and ears are linked to pharynx. In posterior part of pharynx, there is another opening called Glottis. This leads to lungs through tachea. It closes at the time of digestion of food but remains open when animal is respiring.
Oesophagus, Stomach and Intestine
Pharynx leads into a small but wider tube called oesophagus or gullet. The oesophagus opens into the stomach. The anterior end of stomach is called Cardiac end while the posterior end is called Pyloric end. The walls of stomach are muscular and glandular.
The muscles of walls of stomach contract and relax, by which food is broken down into tiny pieces. The secretions of stomach have different enzymes which help in chemical digestion. In stomach, digestion of protein of food is started. After stomach, first part of intestine begins which is called duodenum. The ducts from liver and pancreas open into the duodenum. These ducts bring juices from these glands. The second part of intestine is Ilium are called Small intestine. The secretion of pancreas is called Pancreatic Juice. Pancreatic juice enters the bile duct by small duct. This juice digests the food and brings in such form which can be absorbed by the blood through intestine. Digested food is absorbed by illium and surplus water is absorbed by recturm. Remaining undigested food is expelled though cloacal aperture. A membrane keeps the intestine intact at a place and prevents strangulation of small intestine. This membrane is called mesentery.
Respiroatory System of Frog
There are three methods of respiration in frog.
The exchange of gases through lungs is called pulmonary respiration. In this process, frog keeps its mouth closed. Air reaches buccal cavity through nostrils. Nostrils are closed floor of buccal cavity is raised; glottis opens, and air is pushed into the lungs. The intake of air is called inspiration. In frog, there is a pair of balloon shaped lungs. Each lung consists of small thin walled chambers called alveoli which greatly increase the surface area of the lungs. On each alveolus, there are many blood capillaries. When lungs are filled with air, then exchange of gases occurs between blood and air in lungs at the site of alveoli. During this, the exchange of gases occurs between blood and air present in buccal cavity. After this air is removed from the lungs. Frog uses its nostrils and floor of buccal cavity for inspiration and expiration.
Oxygen present in the air is dissolved in moisture present on lining of lungs. Then oxygen is diffused into the blood where it combines with hemoglobin to form oxyhaemoglobin. This oxygenated blood goes to all parts of the body by means of capillaries. Where oxygen separates from oxyhaemoglobin molecules and is absorbed by the cells. Carbon dioxide from cells comes out into the blood, which carries it to the lungs, and from here carbon dioxide is expelled.
In frog, exchange of gases occurs through skin during hibernation and swimming. This is called cutaneous respiration. Skin is richly supplied with capillaries. Skin is moist. Oxygen diffuses through skin to capillaries and is carried by blood and CO2 diffuses back to blood from cells and is discharged out.
Circulatory System of Frog
It consists of blood vascular and lymphatic systems.
Blood Vascular System
The blood vascular system of frog consists of following parts:
Structure of Heart
Heart is conical organ. It is muscular. It has three chambers. It is present in the body cavity between the oesophagus and sternum. Like a pump, it contracts and is relaxes. As a result of this, blood continuously circulates in the body. The heart is surrounded by a membrane which is called pericardial which protects the heart.
The three chambers of heart are as follows:
1. Right Atrium
2. Left Atrium
the two atria form the broader interior part of the heart. The right atrium is larger than left atrium. Both atria are thin walled. The posterior conical thick walled part of the heart is called ventricle. A broad vessel, which is called truncus artenosus, arises from dorsal side of the ventricle and then divides into two branches near the atria. A thin walled triangular sinus venosus opens into the right atrium. Some biologists consider truncus arteriosus and sinus venosus as chambers of the heart.
Function of Heart
• The chambers of the heart beat in a rhythmic way.
• First of all sinus venosus contracts. Then, the two atria contract. After this ventricle and finally truncus arteriosus is contracted.
• The deoxygenated blood from the whole body except lungs is carried to sinus venosus by two precavals and one post caval.
• Sinus, venosus opens into the right atrium through an opening.
• Oxygenated blood from the lungs is brought into the the left atrium by two pulmonary veins.
• Both the atria open into the ventricle and push their blood collectively into the ventricle by a common aperture, which is guarded by a valve.
• This valve maintains the unidirectional flow of blood in the heart and prevents the back flow of blood.
• In the middle of ventricle some mixing of oxygenated and deoxygenated blood takes place. On the two sides the blood remains unmixed due to rapid flow of blood.
• When ventricle contracts the blood goes to the truncus arteriosus through an aperture. This aperture controls the speed and direction of the blood by a spiral valve present at the start of truncus arteriosus.
Arterial System of Frog
The blood vessels which carry the blood from heart to different parts of the body are called arteries. The system consisting of arteries is called arterial system.
It starts from truncus arteriosus. It is divided into two main branches each of which further divides to form three small branches.
It supplies blood to lower jaw, tongue, eye and brain.
It carries blood to lungs and skin.
Right and left systemic arches joint posteriorly to form dorsal aorta. But prior to their union, each systemic arch gives out arteries supplying blood to vertebral column, oesophagus and fore limbs.
It runs along the vertebral column towards hind limbs. It gives off following branches.
It supplies blood to digestive system.
These supply blood to kidneys and general organs.
Posterior Mesenteric Artery
It supplies blood to rectum.
These supply blood to hind limbs of their sides.
After reaching their specific organs, all the arteries divide and redivide to form capillaries. The walls of capillaries are very thin. Due to this reason, the exchange of materials take place between blood and tissues. The capillaries join to form venules. These venules join to form veins. Then these veins carry blood back to heart.
The blood vessels which bring the blood from different body parts, back into the heart are called veins. The system containing of veins is called Venous system.
Following are the major veins in frog.
Blood from right and left lungs goes to left atrium through pair of pulmonary veins. These have oxygenated blood.
Right and Left Precavals
Each precaval is formed by union of three veins which bring blood from tongue, lower jaw, head, shoulders, forelimbs and skin. Both veins open in sinus venosus. From here blood goes to right atrium.
It is formed by union of five or six pairs of renal veins from the kidney and the genital veins. While passing through the liver, it receives two hepatic veins. Then it enters the sinus venosus. Therefore, venous blood from different body parts enters the heart.
Renal Portal Vein
The veins which bring blood from the hind limbs and pelvic region combine to form Renal portal vein. The renal portal vein enters the kidney of its side and form capillaries. Blood from kidney goes to the post caval through renal veins. Post caval caries the blood to the heart.
The Pelvic veins of two sides combine to form abdominal vein. Before entering the liver, it divides into branches. In liver, it is further divided to form capillaries. The blood from the liver is drained into post caval by hapatic veins of both sides.
Hepatic Portal Vein
The blood vessels (veins) bringing blood form various organs of digestive system (stomach, duodenum, illiums, rectum, pancreas and spleen etc) combine to form a large vein. This is known as hepatic portal vein. Near the liver a branch of abdominal vein combines with it. Then it enters the liver and divides and redivides to form capillaries. The, blood entering the liver through hepatic portal veins goes to the post caval by means of hepatic veins. The blood from post caval goes to heart through sinus venosus.
The blood coming back into the heart is of two types.
• Oxygenated blood which comes from lungs by pulmonary veins.
• Deoxygenated blood from all parts of the body enters sinus venosus through precavals and post caval and then enters the right atrium.
Lymphatic System of Frog
In circulatory system, due to blood pressure, many components of blood plasma come out of the capillaries and fill the inter cellular spaces. These components are also in the form of fluid and called tissue fluid or interstitial fluid. Much of it reenters the capillaries and some of it enters the lymph vessels where it is known as lymph. The flow of lymph is unindirectional. Through lymph "vessels" lymph goes to big veins. Thus, lymph again enters the blood.
1. The lymph keeps the tissues wet.
2. The lymph helps in transport of various substances from blood to tissues and vice versa.
Excretory System of Frog
In frog, waste materials are removed in different ways e.g. through skin, lungs, liver digestive system etc. But for removal of nitrogenous wastes, there are two kidneys. Kidneys are attached to dorsal wall of body cavity. These are present close to vertebral column in posterior part of body cavity. These are elongated and made up of urinary tubules. Urinary tubules combine to form collecting ducts which open into Ureter. The urine from kidneys comes into ureters after illustration. Both ureters which start from edges of kidneys open into the cloaca. From here, urine is excreted directly or stored in the urinary bladder, which on opening of cloacal aperture is expelled. The carbon dioxide and water are excreted through lungs and skin while through liver and digestive system; undigested food and some wastes are excreted.
Reproductive System of Male Frog
The reproductive system of male frog consists of a pair of testes and reproductive ducts. Each testis is attached to kidney by means of a membrane. At anterior end of testis, there is present fat body. Each testis is composed of small ducts called seminiferous tubules in which sperms are produced. Sperms enter the kidney via vesa efferentia. Sperms reach the cloaca through ureter. From here, these are dischaged in the water through cloacal aperture in this way, ureter in male frog does two jobs, one is removal of urine and other is removal of ***ual material, so it is called urinogenital duct and the urinary system and genital system are collectively call urinogenital system.
Reproductive System of Female Frog
The reproductive system of female frog consists of a pair of ovaries and reproductive ducts. Ovaries are present close to the kidneys. At their anterior ends, there are present fat bodies. Each ovary contains many follicles in which eggs (ova) are produced. During breeding season, ovaries are enlarged. Ova are released into the body cavity through the coelomic fluid, these enter the oviduct. The anterior part of oviduct is funnel like called oviducal funnel and reach the uterus. The uterus opens into the cloaca. At last, ova are discharge in the water through cloacal aperture. In water, union of sperm with egg results in formation of zygote. From zygotes, offsprings are formed and in this way continuity of race is ensured.
Nervous System of Frog
It consists of three parts:
1. Central Nervous System
2. Peripheral Nervous System
3. Sympathetic Nervous System
Central Nervous System
It consists of brain and spinal cord.
Brain is enclosed in protective layers and is located in cranium or brain case, which is major part of skull.
Brain is divided into three parts:
(a) Fore Brain
(b) Mid Brain
(C) Hind Brain
(a) Fore Brain
This is anterior part of brain. This is associated with sense of smell. It controls the secretion of many hormones. It also receives messages from internal and external environment of the body.
(b) Mid Brain
This is central part of brain. This is associated with eyes and vision.
(c) Hind Brain
This is the posterior part of brain. It controls and coordinates body movements and maintains balance of the body. It also controls respiration, circulation, taste and digestion.
The posterior part of the brain is continuous with spinal cord. It runs through the vertebral column. The spinal cord controls the movements of trunk region.
Peripheral Nervous System
It consists of nerves. These nerves connect the central nervous system (CNS) with various parts of the body. Some nerves originate from brain. These are called cranial nerves other nerves originate from spinal cord. These are called spinal nerves. In frog, there are 10 pairs of cranial nerves and 9 or 10 pairs of spinal nerves.
Basically, nerves are of three types:
These take messages from sensory organs to CNS.
These take messages from CNS to glands and muscles.
These do both above mentioned functions.
In these nerves, first, second and eight pairs are sensory nerves which are associated with senses of smell, sight and hearing. Third, fourth and sixth pairs are motor nerves which carry message from brain to the eye. Nine and ten pairs are mixed nerves, which are supplied to jaw, face, tongue and heart.
These are all mixed nerves. These control functions of different organs.
Ear of Frog
The organ of hearing in frog is "Ear" like other vertebrates.
Structure of Ear of Frog
The ear of frog consists of following three parts.
1. External Ear
2. Middle Ear
3. Internal Ear
External ear consists of a bone. The vibration is produced in external ear when sound waves strike with it. (Figure)
Middle Ear consists of a tympanic membrane. On the inner side of the membrane is a cavity known as tympanic cavity. The cavity contains small rod like bones called ossicles. The middle ear is connected to internal ear by a tube which is called Eustachian tube; it transfers the vibrations towards the internal ear.
The internal ear is a very delicate organ. It consist of three semi circular canals. These canals are filled with a fluid and sensory cells are located at special places in these canals.
Function of Ear of Frog
When sound waves strike the tympanic membrane, it is set into vibration, this is in turn vibrates the internal ear and thus sound waves stimulate the hearing receptors in the inner ear. The internal ear, in addition to hearing also keeps the balance of the body.
Eye of Frog
The frog has two eyes one on each side of the head. If we make vertical section of the eye, we find that the innermost layer of the ball is the sensory retina. The retina contains photoreceptor cells. Outside the retina is the choroid, which is richly supplied with blood capillaries supplying nutrients to the retina. The sclerotic is the hard, outer most layer of the eye. It provides shape to the eye ball. The anterior transparent part of the eye is called cornea. Behind the cornea is Iris. The Iris has a window called the pupil. Behind the pupil is the lens of the eye. The cornea, pupil and lens focus light on the retina. A watery fluid is present in between the cornea and lens. Similarly a jelly like fluid is present between the lens and retina, through which light passes before it strikes retina. Optic nerve takes the sensory messages from the eye to the brain