Science [5 marks Questions]

Plants need vascular bundles for transport the food, minerals and water. When water and minerals are absorbed by the roots, then this cannot be direct reach to the upper parts of plants. So xylem tissue takes them and transport it to the upper part of plant like shoot, stem and mainly for leaves for preparing food by photosynthesis. If roots do work of absorption of water and minerals then it also needs energy. For example if we do any work then we need energy to do that work. It is same with the roots. They need their food for energy. When leaves do photosynthesis and form food, then this cannot directly get by the roots. So phloem is used for transporting the food from leaves to roots. Hence plants need transporting system. But bryophtes do not need this system because they are thallophytes.

The number of cells in the body varies with different organisms. In some lower forms of life (Example: Euglena, Amoeba) The body is formed of a single cell; these organism are described as unicellular. In a unicellular organism, all life activities are carried out by itself with its internal structures. The intracellular structures are called the organelles
In the vast majority of plants and animals, the body is made up of numerous cells. They are called multicellular organisms. A multicellular organism is actually an aggregation of cells. Here a group of cells functions in a same way to form a tissue or an organ (Example: Xylem vessels, cork cells, cells in the skin). Multicellular organisms have a great capacity to survive than unicellular organisms.

During the process of ‘breathing in’ the air sacs or alveoli of the lungs get filled with air containing oxygen. The alveoli are surrounded by capillaries carrying blood so the oxygen of air diffuses from the alveoli walls into the blood from where it is carried to all the parts of the body.As the blood passes through the tissues of the body, the oxygen present in it diffuses into the cells. This oxygen combines with the digested food to release energy. Carbon-dioxide gas is produced as a waste product during respiration in the cells of the body tissues which diffuses into the blood. Blood carries the carbon-dioxide back to the lungs where it diffuses into the alveoli.

Pancreatic juice contains digestive enzymes? Pancreatic Amylase, trypsin and lipase.Functions:
Pancreatic amylase: The enzyme amylase breaks down the starch. Trypsin: Trypsin digests the proteins. Lipase: Lipase breaks down the emulsified fats.

Digestion of carbohydrates: Digestion of carbohydrates begins from buccal cavity. Salivary amylase converts starch into sugar. Other complex carbohydrates are converted into glucose in the small intestine.
Digestion of Proteins: Protein is partially digested in the stomach. For this, stomach secretes the enzyme pepsin. In small intestine, pancreatic juice provides the enzymes trypsin and chymotrypsin. These enzymes complete the digestion of proteins.
Digestion of Fats: Digestion of fats takes place in small intestine. Bile; from liver; emulsifies the fat. Due to this, fat is broken into small globules. This makes it easier for the enzyme to digest fat. Lipase is the enzyme which converts fat into glycerol and fatty acid.

Yes there will be exchange of respiratory gases. If a person holds his breath for 25 seconds after expiration, It is so because, even after we exhale, some amount of air remains in the lungs. This volume of air is called as residual volume which has a quantity of about 1200ml. So even if a person hasn't inhale the air for 25 seconds, then also this residual volume will continue gaseous exchange in lungs for some time. But if this period last some more longer, then this can be lethal.

Anaerobic respiration is a type of respiration that takes place in the absence of oxygen and aerobic respiration. The steps of anaerobic respiration have some similarities to aerobic respiration. Both forms start their process with glycolysis, which is the beginning of carbohydrate catabolism, or the breakdown of larger molecules into smaller ones.Anaerobic respiration takes place in the fluid portion of the cytoplasm of cells, away from the mitochondria or any other organelles. It begins with glycolysis, which breaks apart glucose and generates energy and a compound known as pyruvate, and also includes fermentation, which breaks down the pyruvate for more energy.

1.  

1. The tissue X is phloem. Phloem is made of living cells and helps in the transport of food from leaves to other parts of the body.
2. A sieve tube, which forms the phloem, has tiny pores in its end walls and contains only cytoplasm. It does not have any nucleus. Hence, component A is a sieve tube.
3. Companion cell is a component of phloem and has cytoplasm as well as nucleus. Hence, component B is a companion cell.

2.  

1. Tissue Y is xylem. It is made of dead cells and helps in the transport of water and minerals from the soil via roots to the rest of the plant body.
2. Xylem vessel is a component of xylem and has open ends. Hence, component C is xylem.
3. Tracheid does not have open ends. Hence, component D is a tracheid.

1.  

1. X is yeast.
2. Y is ethanol.
3. Z is carbon-dioxide.

2. Fermentation is the process of converting sugar into substance Y by the action of X.
3. Anaerobic respiration is exhibited by X in the above process.

1. Animals like X are known as carnivores.
2. Animals like Y are known as herbivores.
3. Animals like X have longer small intestine as they are grass eating animals and they need long intestine to digest the cellulose present in the grass.
4. Lion is a carnivore.
5. Cow is an herbivore.

1.  

1. Gland A is salivary gland.
2. Substance B is saliva.
3. Enzyme C is salivary amylase.

2. Tube D is oesophagus.
3. The movement E is known as peristaltic movement.
4. (i) F is hydrochloric acid, G is mucus and H is pepsin.

The injured cells and the platelets disintegrate at the site of the wound and release thrombokinase or thromboplastin.
Thrombokinase with the help of calcium ions converts prothrombin of the plasma into thrombin.
Thrombin in the presence of calcium ions reacts with the soluble fibrinogen and converts it into insoluble fibrin. Fibrin is a solid substance which forms threads and a meshwork at the site of the wound.
Blood cells are trapped in the network of the fibrin. The blood shrinks and squeezes out the rest of the plasma in the form of a clear liquid. The solid mass which is left behind is called a clot or thrombus.

1.  

1. Organism A is bacteria.
2. Substance B is acid.

2.  

1. Part C is the tooth enamel.
2. part D is the dentine of the tooth.

3. The small holes, E, are known as cavities.
4. F is the pulp of the tooth.
5. When a bacterium (organism A) reaches the pulp (part F) of the tooth, it irritates the nerve endings and causes toothache.

The second stage of urine formation, tubular re-absorption, is called selective re-absorption The filtrate enters the kidney in the proximal tubule. This region of the kidney is special because many things can be removed from the filtrate. These valuable things are recollected, or reabsorbed, by the body.
Glucose, certain salts, vitamins, hormones, and amino acids are restored to the body and will not be included in urine. Sometimes, if the body has too much of something then the extra sugar or salt will stay in the filtrate. For example, diabetics with high levels of blood glucose may have glucose in their urine since it cannot all be reabsorbed. The filtrate after reabsorption is like pre-urine.

The tooth has hard outer covering called enamel. The part of tooth below enamel is called dentine inside which is the pulp cavity. The pulp cavity contains nerves and blood vessels.

Dialysis is the process of removing nitrogenous wastes and excess water from the body by using a clinical device, called as artificial kidney and a dialyzing fluid. When kidney function decreases to a critical level or complications arise, a person may need to start dialysis.
There are two main types of dialysis, hemodialysis and peritoneal dialysis.
Hemodialysis uses a machine and a filter to remove waste products and water from the blood.
Peritoneal dialysis uses a fluid (dialysate) that is placed into the patient's abdominal cavity to remove waste products and fluid from the body.

1. The unicellular animal P is Amoeba.
2. Q is pseudopodia and R is the food vacuole.
3. Chemical S is the digestive enzyme and Process T is diffusion.
4. Organelle U is cell membrane and Process V is egestion.

The raw materials for photosynthesis are carbon-dioxide and water. The green plants take carbon-dioxide from air for photosynthesis. The carbon-dioxide gas enters the leaves of the plants through the stomata present on their surface. The water required by the plants for photosynthesis is absorbed by the roots of the plants from the soil through the process of osmosis. The water absorbed by the roots is transported upwards through the xylem vessels to the leaves where it reaches the photosynthetic cells and utilized in photosynthesis.

The soil is the richest source of raw materials for the plant like nitrogen, phosphorous, water and other minerals. Water is essential for all physiological activities of the plant. The absorption of all these substances occurs through a part of the plant called roots.
Water from the soil first goes to the roots. Plant roots cannot pump water itself but they actively transfer nutrient ions to the low parts of a vascular structure which is continuous with a structure called xylem. Xylem consists of long, dead plant cells that form upright tubes. Water flows after the ions.
The plant transport system moves raw materials from roots and energy from leaves. This is done by two independent conducting tubes called xylem which transports water and minerals from the soil and phloem transports the food from leaves to other parts of plants. vessels tracheids of xylem tissue, stem, leaves, and roots form a continuous water conducting channel reaching to all parts of the plant. The difference of concentration of ions in roots and soil, help water to enter roots from the soil to eliminate this difference(caused by root cells take up ions from soil). This maintains the steady movement of water upwards via roots.
the pressure of the absorbed water from the roots make the water to move upward. but this pressure is still not so affective to move it to the top. to move minerals n water to the top, transpiration is used. during transpiration, water loses from the leaves which creates a low pressure of water. which in turn pulls the water upward.

Principle of Dialysis: The blood from an artery in the patients arm is made to flow into the dialyser of a dialysis machine made of long tubes of selective permeable membrane (like cellulose) which are coiled in a tank containing dialysing Solution. The dialysing Solution contains water, glucose and salts in similar concentrations to those in normal blood. As the patient’s blood passes through the dialysing Solution most of the waste like urea present in it pass through the selectively permeable cellulose tubes into the dialysing Solution. The clean blood is pumped back into a vein of the patients arm.

Lion	Carnivore
Man	Omnivore
Dog	Omnivore
Goat	Herbivore
Crow	Omnivore
Elephant	Herbivore
Snake	Carnivore
Hawk	Carnivore
Rabbit	Herbivore
Deer	Herbivore

1. Heart is the organ in the human body that acts as a double pump. Hence, organ A represents the heart.
2.  

1. The oxygenated blood from the lungs enters the left atrium (chamber C) via the blood vessel called pulmonary vein (B). Hence, B is pulmonary vein.
2. The contraction of left ventricle (chamber D) forces the blood into the blood vessel called aorta (E), which supplies the oxygenated blood to the organs of the body, except the lungs. Hence, E is aorta.
3. From the body tissues, the deoxygenated blood is transported back to the heart into the right upper chamber called right atrium (G), by the vena cava (F). Hence, F is vena cava.
4. Contraction of chamber G (right atrium) forces the deoxygenated blood into the lower right chamber called right ventricle (H). Finally, the contraction of H (right ventricle), sends the deoxygenated blood into the lungs through the blood vessel called pulmonary artery (I). Hence, I represent pulmonary artery.

3.  

1. The chamber C represents left atrium.
2. The chamber D represents left ventricle.

4.  

1. The chamber G represents right atrium.
2. The chamber H represents right ventricle.

1.  

1. Blood is the liquid connective tissue that circulates in our body continuously without stopping. Hence, A is blood.
2. Our blood contains a pigment called haemoglobin, which imparts it a red colour. Hence, pigment B is haemoglobin and colour C is red.
3. Our blood contains a pigment called haemoglobin, which imparts it a red colour. Hence, pigment B is haemoglobin and colour C is red.

2.  

1. White blood cells, fight infection and protect us from diseases. Hence, D refers to white blood cells.
2. Platelets are the component of blood, which help in the clotting of blood (A). Hence, E refers to platelets.
3. Plasma is a liquid, which consists mainly of water with many substances dissolved in it. Hence, F refers to plasma.
4. Red blood cells carry oxygen from the lungs to all the parts of the body. Hence, G refers to red blood cells.

3. Blood also carries the digested food from the small intestine to all other parts of the body.
4. E (platelets) and G (Red blood cells) are the cells without nucleus.
5. Amoeba and grasshopper do not have blood (A) like liquid in their body.

1. Yeast shows anaerobic respiration.
2. Humans show aerobic respiration.
3. In humans beings, during high muscular activity, the respiration represented by equation (iii) occurs. It occurs in the muscle tissue.
4. Equation (ii) represents aerobic respiration.
5. Equation (i) represents anaerobic respiration.
6. Aerobic respiration, i.e. the reaction represented by equation (ii), produces maximum amount of energy.

Difference Between Right And Left Lung:

	Characteristics	Right Lung	Left Lung
1.	Position	Situated on the right side of the respiratory system	Situated on the left side of the respiratory system
2.	Structure	Wider and shorter	Narrow and long
3.	Lobe	Three	Two
4.	Base Shape	Concave	Less concave than the right lung
5.	Bronchus	2 bronchi	Single
6.	Weight	Heavy	Light
7.	Provides space for	Liver	Heart
8.	Number of fissures	Two	One
9.	Type of fissure	One horizontal and one oblique	One oblique
10.	Weight in grams	700	650

1. Ingestion: (L. ingestus - taken in). It is taking in of solid food with the help of temporary or permanent mouth. Amoeba can ingest food particles from any point on its surface. Paramoecium (another unicellular organism) has fixed point for the same. Amoeba captures food with the help of temporary finger-like processes called pseudopodia. Paramoecium has small hair-like processes called cilia. Beating of cilia creates current in water that pushes food particle through cytostome or cell mouth. The process of ingestion of solid food particle by a cell or unicellular organism is called phagocytosis.

As soon as Amoeba comes in contact with a food particle or prey, it throws pseudopodia all around the same. The tips of encircling pseudopodia fuse and the prey comes to lie in a vesicle or phagosome.

2. Digestion: It is conversion of complex insoluble food ingredients into simple absorbable form. Digestion can be intracellular or intercellular. Intercellular digestion occurs in a digestive tract. Intracellular digestion takes place in the cytoplasm of cells. Here, a lysosome fuses with phagosome to produce a food vacuole, also called gastriole or temporary stomach. Reaction of food vacuole is acidic at first and alkaline later on. Digestion of food occurs with the help of digestive enzymes brought by lysosome. It changes complex insoluble substances of food into simpler absorbable substances.
3. Absorption: The digested simple and soluble substances pass out of food vacuole into the surrounding cytoplasm.
4. The absorbed food materials are converted into various constituents of protoplasm including food reserve.
5. (L. egestus - discharge): It is throwing of undigested components of food out of the body. In Amoeba, the old food vacuole with heavier undigested material reaches the rear end, passes to the surface, fuses with surface membrane and throws out the undigested materials. The process is called egestion. Paramoecium has a definite cytopyge or cell anus.

1.  

1. Kidneys are bean shaped organs in the human body, towards the back of the body, just above the waist. Hence, organs P are kidneys.
2. Urea is the waste product that is formed by the decomposition of unused proteins in the liver. Hence, the waste substance Q represents urea.

2.  

1. Urea (substance Q) is brought into kidney (organ P) through blood by an artery called renal artery. Hence, R represents renal artery.
2. The numerous tiny filters called nephrons (S) present in the kidneys (organ P), clean the dirty blood by removing the waste product Q (urea). The clean blood then goes into circulation through T, i.e. renal vein. Hence, vein T represents the renal vein.
3. The tiny filters S are known as nephrons.
4. The waste substance Q (urea), other waste salts and excess water form yellowish liquid called urine (U). Urine goes from organ P (kidney) into a bag-like structure V, i.e. urinary bladder, through two tubes W, called ureters. This urine is then thrown out of the body through tube X, called urethra.
   Hence, (i) the liquid U is urine, (ii) structure V is urinary bladder, (iii) tubes W is ureters, and (iv) tube X is the urethra.

	KIDNEY	ARTIFICIAL KIDNEY
1.	Kidney is the naturally developed excretory organ located in the body of humans.	Artificial kidney is the man-made device.
2.	Excretion of urine by kidneys is done naturally when body fluids are filtered.	Artificial kidneys are use it to dispose urine in patients who is kidneys are completely damaged.
3.	Kidneys have the capacity of reabsorption to maintain iconic balance in the body.	Artificial kidney does not have the reabsorption capacity to maintain iconic balance in the body.
4.	Functioning of kidneys is stimulated by the nervous system and hormones in the body.	The functioning of artificial kidney is done with the help of the machine.
5.	The natural kidney continuously receives the blood and water, filter them and keep the body away from toxic wastes by the process of excretion.	The artificial kidney is the device used in kidney damage persons only from time to time, under supervision of a specialist doctor.
6.	Kidneys are made up of nephrons.	Artificial kidneys are made with cellophane tubes.

The heart features four types of valves which regulate the flow of blood through the heart. These valves permit blood flow only in one direction, and prevent back flow of blood. The four types of valves are:

1. Tricuspid Valve: This valve separates the right atrium from the right ventricle, and regulates the blood flow between them. Tricuspid valves allow blood to flow from the right atrium into the right ventricle, and prevent back flow of the same.
2. Pulmonary Valve: This valve separates the right ventricle from the left pulmonary artery. These valves prevent the control the flow of blood from the right ventricle into the left pulmonary artery.
3. Mitral Valve: Bicuspid valve or Mitral valve separates the left ventricle from the left atrium.
4. Aortic Valve: This valve separates the left ventricle from the aorta, and controls the blood flow from the ventricle into the rest of the body.

The primary organs of therespiratory system are the lungs, which function to take in oxygen and expel carbon dioxide as we breathe. The gas exchangeprocess is performed by the lungs and respiratory system. Air, a mix of oxygen and other gases, is inhaled.

	Artery	Vein
1.	Direction of Flow: It carries blood from heart to an organ.	It brings blood from an organ towards the heart.
2.	Speed: Blood flow is rapid in artery.	Blood flow is slow in vein.
3.	Jerks: Blood flows with jerks.	Blood flows smoothly.
4.	Pressure: Blood flows under pressure.	There is little pressure.
5.	Internal Valves: They are absent.	Internal valves are present to prevent back flow.
6.	Wall: It is thick and elastic.	It is comparatively thinner and little elastic.
7.	Lumen: Narrow.	Wide.
8.	Type of Blood: Artery carries oxygenated blood except pulmonary arteries.	Vein carries deoxygenated blood except pulmonary veins.
9.	Occurrence: It is deep seated.	It is superficial.
10.	Collapsibility: Artery is not collapsible.	Vein is collapsible.
11.	Blood After Death: It does not contain blood after death.	Vein is full of blood even after death.

Breathing or the process of taking in fresh air and releasing foul air can be easily observed because thorax shows alternate expansion and contraction. It is involuntary though it can be prevented for a brief period. Rate of breathing is controlled by respiratory centre of brain. Expansion of thorax causes fresh air to be drawn in. Contraction of thorax causes foul air to be expelled. Therefore, breathing consists of two steps, inspiration and expiration.

1. Inspiration or Inhalation: It is bringing of fresh air into lungs for exchange of gases. During inhalation, thoracic cavity enlarges due to two types of inspiratory muscles, phrenic and external intercostals. Phrenic muscles straighten the diaphragm by moving its curved part downwards. It increases length of thorax. Contraction of external intercostal muscles pushes the rib cage in outward and upward direction. It increases girth of thorax. Being air tight, increase in size of thoracic cavity causes expansion of lungs. It decreases air pressure in the lungs. As a result outside air rushes into lungs through external nostrils, nasal cavities, internal nostrils, pharynx, larynx, trachea, bronchi, bronchioles to alveoli. While passing through respiratory tract, the incoming air is:

• Filtered by hair present in anterior part of nasal cavities.
• Cleansed of dust and microbes throughout respiratory tract by lysozyme, mucus and cilia.
• Air conditioned (bringing temperature of inhaled air to that of body) with the help of blood capillaries present below nasal epithelium.
• Moistened by water vapours from wet epithelium.

2. Exchange of Gases: It occurs in the alveoli. Fresh air has high concentration of oxygen and a very low concentration of carbon dioxide. As a result, oxygen diffuses from alveolar air to blood present in capillaries around the alveoli. Carbon dioxide diffuses from blood into alveolar air.

Respiration is a cellular process which occurs in each and every cell of body. It starts with glycolysis- a reaction in which breakdown of glucose occurs. Glucose gets converted into pyruvic acid. The process of glycolysis takes place in cytoplasm.
Now this pyruvic acid enters into mitochondria via link reaction in which it gets converted into acetyl-CoA. Now this acetyl-CoA enters in the mitochondria where it performs kreb's cycle in mitochindrial matrix. All the ATP and NADH2 and FADH2 produced till now performs ETS cycle (Electron transport chain) which is located in the mitochondrial membranes. Finally it undergoes oxidative phosphorylation and ATPs are released.

GLYCOLYSIS(in cytoplasm) → LINK REACTION(in cytoplasm) → KREB
CYCLE(mitochondrial matrix) → ELECTRON TRANSPORT SYSTEM
(mitochondrial membrane) → OXIDATIVE PHOSPHORYLATION(mitochondrial membrane).

1. During daytime when photosynthesis occurs, oxygen is produced. The leaves use some of this oxygen for respiration and the rest of oxygen diffuses out into the air. Carbon-dioxide produced by respiration is all used up in photosynthesis by leaves during the daytime. Even more carbon-dioxide is taken in from air. Thus, the net gas exchange in leaves during daytime is: Oxygen diffuses out Carbon-dioxide diffuses in.
2. At night time, when no photosynthesis occurs and hence no oxygen is produced, oxygen from air diffuses in leaves to carry out respiration. Carbon dioxide produced by respiration diffuses out into air. So, the net gas exchange in leaves at night is: Oxygen diffuses in Carbon-dioxide diffuses out.

1. The organ A is small intestine.
2. Liquid B is bile and Organ C is gall bladder.
3. The digestive enzymes D, E and F are Amylase, Trypsin and Lipase, respectively.
4. The projections G are villi that are present on the inner wall of organ A.
5. Tube H is the large intestine, Part I is the rectum, Opening J is the anus and The process K is egestion or defecation.

1. T is Amoeba.
2. Q is frog.
3. P is fish.
4. S is grasshopper.
5. R is earthworm.

Double circulation is the circulation of blood through heart twice while supplying the blood to the whole body. In double circulation, there are two loops or circuits where the blood travels to heart.
Systemic circulation: First stage of systemic circulation starts from left atrium to left ventricle. This transfers the oxygen rich blood to aorta for the supply to various parts of the body. Later, the veins and venules collect the blood from various parts of the body. This blood is rich in carbon dioxide than oxygen and is known as deoxygenated blood. Deoxygenated blood is poured into superior vena cava then to right atrium. Right atrium passes the blood to right ventricle for pulmonary circulation.
Pulmonary circulation: The pulmonary artery collects the blood from right ventricle and passes to lungs for oxygenation. Lungs collects the deoxygenated blood supplied to it and purifies. Then the oxygenated blood is pumped back to left atrium of the heart through the pulmonary vein. Left atrium passes the blood to left ventricles where they pump the oxygenated blood to aorta for systemic circulation.
The double circulation maintains a strict separation of oxygenated and deoxygenated blood. Thus it ensures the high supply of oxygen and improves the body efficiency.

The food for plants is prepared by the green leaves by the process of photosynthesis. The leaves are the food production centres. Using the sunlight and Carbon dioxide they synthesize food through photosynthesis in the chloroplasts. Every part of plant body like the roots and stem also require food for its functioning so the food prepared by the leaves must be transported to different parts of the plant. All of this takes place through the vascular tissues of the plants. The process of transportation of carbohydrates (sugar) produced by the leaves to other parts of the plant is known as translocation. It is done through Phloem tissues. The movement of carbohydrates in phloem is bidirectional.

EXTERNAL RESPIRATION:

• It is a physiological process.
• It takes place along the respiratory surface along the lungs.
• also known as breathing.
• It is a process during which oxygen is taken up by capillaries of lung alveoli and carbon dioxide is released from blood.

INTERNAL RESPIRATION:

• It is a biological process.
• takes place within the cells( i.e.., at cellular level).
• It is the process in which oxygen is released to tissues or living cells and carbon dioxide is absorbed by the blood.

1. Organism X could be a human being. The breathing organs A are lungs.
2. Organism Y could be a fish. The breathing organs B are gills.
3. Organism Z could be a frog. The breathing organ C is skin and D are lungs.
4.  

1. Z is an amphibian.
2. Y is an aquatic organism.
3. X is a terrestrial organism.

1.  

1. Organism A is yeast.
2. AmoebaOrganism B is .
3. C is mosquito.Organism.

2.  

1. P is alcohol.
2. breathes through the cell membrane.Amoeba Q is the cell membrane because
3. R is spiracle.
4. S is tracheae.

3.  

1. Organisms B and C undergo aerobic respiration.
2. Organism A, i.e. yeast, undergoes anaerobic respiration.

The conducting tissues in plants are xylem and phloem. 'Xylem' and 'phloem' are vascular tissues which are present in plants for the 'conduction of water and minerals'.
Xylem transports sap or water to the different parts of the plant. Phloem is the tissue that transports food prepared by the leaves to all parts of the plant. The xylem and phloem transport water and food internally within the plants.
These tissues are further made up of cells which may be living as well as dead cells and also other tissues that help these conducting tissues to do their work.

The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual) as well as hundreds of minor salivary glands. Salivary glands can be classified as serous, mucous or seromucous (mixed).
There are 3 major salivary glands:

1. Parotid Gland: Parotid glands are the largest salivary gland. Each gland is approximately 6cm long. They are located within each of our cheeks. In our oral cavity they are responsible for the secretion of about 20% of saliva.
2. Sublingual gland: It is the smallest of the major salivary glands. They are located under the tongue. Approximately 5% of the saliva comes from these glands.
3. Submandibular gland: These glands are located beneath the lower jaw, outside the oral cavity. This is the movable part of our jaw. It is the second largest salivary gland and produces approx. 65-70% of saliva.