Excretory System
The main excretory organ of human is kidney and skin. Kidney is a bean shaped organ, which lies in the abdominal cavity one on each side of the vertebral column. Each of them is about 10 cm long and 150g in weight. It is enclosed in a thin, fibrous covering called the capsule. A renal artery brings blood into the kidney along with nitrogenous waste materials, which after filtration in the kidney leaves the kidney through a renal vein. The outer region of kidney is called cortex and inner region is called medulla. Each kidney is made up of numerous coiled excretory tubules, called nephrons. A nephron is the structural and functional unit of kidney. It performs three functions, such as, filtration, reabsorption and secretion. A nephron consists of a long tubules and the Malpighian corpuscle. The proximal end of the tubules consists of Bowman's capsule and the glomerulus.
Bowman's capsule is a double walled cup like structure, which surrounds the dense network of blood capillaries called the glomerulus. Some substance in the initial filtrate, such as glucose, amino acids, salts and a major amount of water are selectively reabsorbed as the urine flows along the tube. The amount
of water reabsorbed depends on how much excess water is there in the body and on how much of dissolved waste is there to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through urethra.
Artificial Kidney
Some time it is possible that kidney may be damaged due to infection, injuries and extreme blood pressure. This results in accumulation of toxic substance like urea in the blood, which can even lead to death of the individual. This can be treated by artificial methods using dialysis. It is a artificial kidney which purify the blood. It consists of long tube like structure made of cellophane suspended in a tank. It is partially permeable and therefore allows solutes to diffuse through.
Excrection in Plants
Plants do not have well developed excretory system to throw out the waste material, because of different physiology, as compared to the animals. The gaseous waste materials are excreted out through the small opening in leaves of the plant, called stomata. The other waste material are excreted in the form of fluid, called latex and resins. It is also removed by the methods of periodic shedding of leaves and bark of the stem. The fruits and the seeds, which more... 
Transportation
Transportation in Plants
There are two types of vascular tissues in plants that helps in transportation of materials. These vascular tissues are xylem and phloem. The xylem tissues are present in roots of the plant and the phloem tissues in their shoot system Water and minerals are taken from the soil and transported to the upper part of the plant through xylem tissue. This transport of nutrient from one part of plant to other part is called translocation. The xylem tissue consists of vessels and tracheids, which carries water and minerals to all parts of the plant. This transport of water and dissolved mineral salt from the roots to the leaves is known as ascent of sap. The pressure with which water is pushed into the xylem tubes of the root is called root pressure. This absorption is a continues process and the excessive of water is excreted out through stomata. This loss of water is called transpiration.
The other vascular tissue, phloem transports the prepared food material front leaves to the other parts of the plant. The phloem tissue consists of tsieve tube, companion cells and phloem parenchyma.
Transportation in Animals
In lower animals the transportation takes place through diffusion and in higher animals, there are specialist tissue responsible for the transportation of material from one part to another. The transport system consists of blood vascular system and a lymphatic system. This system is also called the circulatory system. Blood is a connective tissue which consists of blood plasma and blood corpuscles. Blood plasma is made up of water and other substance dissolved in it.
Human circulatory system, consists of heart and blood capillaries. The human heart is divided into four parts, called chambers. The four chambers of heart are left and right auricles and left and right ventricles. It is divided into two parts, by a thick layer of membrane, called septum. The left and right auricles and ventricles are connected with each other by a small opening called valves. The oxygenated blood from lungs enters into the heart through left auricles via pulmonary veins. When the left auricles contracts the blood is transferred to the left ventricles which expands. When the ventricles contracts the blood is pumped into the aorta for circulation to different parts of the body. The back flow of the blood is prevented by the closing of valves. After circulation through the body, the deoxygenated blood returns to the heart via vena cava into right auricles. When the auricles contracted the blood is forced into right ventricles through small opening called valves. This impure blood from right more... 
Respiration
All the living organisms requires energy for their life processes. They derive this energy from the food they eat. The respiration is the process of breaking down of complex food molecules into simpler form with the release of energy. It is of two types, aerobic and anaerobic respiration. The respiration which takes place in presence of oxygen is called aerobic respiration and the respiration which takes place in absence of oxygen is called anaerobic respiration.
Anaerobic Respiration
The respiration, which takes place in absence of oxygen or with limited supply of oxygen is called anaerobic respiration. In this process, the sugar molecule is broken down into simpler form either in absence of oxygen or with the limited supply of oxygen. It takes place in the cell which lacks mitochondria. In absence of oxygen, glucose is converted into lactic acid or ethanol in different condition. Whereas with limited supply of oxygen yeast convert pyruvate into ethanol and carbon dioxide. Thus, different path is followed after glycolysis. In presence of oxygen pyruvate is oxidized into carbon dioxide and water, with the release of energy.
Aerobic Respiration
The respiration, which takes place in presence of oxygen is called aerobic respiration. It takes place in mitochondria. The product of this reaction is ATP. Inside mitochondria, when an inorganic phosphate group gets attached to compound called ADP, a molecule of ATP is formed. There it forms 38 molecules of ATP which is the unit for energy in the cell.
The exchange of gases in human being is called breathing. Breathing takes place through respiratory system. The human respiratory system consists of nostril, larynx, windpipe, trachea, lungs, bronchi, bronchioles and alveoli.
Air enters into our body through nostril. This air is filtered by fine hairs that is present in the inner lining of nostril. From there air passes through the wind pipe into lungs via trachea.
The trachea consists of rings of cartilage muscles, which prevents it from collapsing when we inhale the air. The trachea is further divided into two parts before entering into two lungs called bronchi. The bronchi when enters into the lungs, it gets further subdivided into smaller capillaries called bronchioles, which finally terminates in balloon like structure called alveoli.
The alveoli helps in the exchange of gases between lungs and blood vessels.
The spherical surface of alveoli increases the surface for the exchange of gases.
The blood brings carbon dioxide from the rest of the body and release it into lungs and takes up oxygen from lungs and carries it back to the body. 
Introduction
We see the variety of things around us in which some are living and some are non living. All the living organisms have organized cellular structure with different levels of organization. An organized and ordered structure with cells, tissues, organs, organ system, is an important feature of living organism that distinguishes it from non living organisms. If this organization break down then the organism is no longer living. The maintenance functions of living organisms must go on forever to sustain life. The process which together performs this maintenance job are called life process. The life process needs energy, which mostly comes from the plants and trees. The outside source of energy is varied, as the environment is not in our control. So these sources of energy is needed to be broken down or built up inside our body. The process of taking in oxygen and using it for the purpose of breaking down food molecule inside our body for releasing energy is called respiration. Whether it is a multicellular or unicellular organisms, the energy is required by all.
Nutrition
Nutrition is a process of providing nutrient to the body i.e. to cell and organisms necessary for supporting life process. In other words, we can say that nutrient are the substance which provide energy to the living organisms to remain alive. There are different modes of nutrition, such as autotrophic and heterotrophic. The autotrophic organisms includes the green plants and some of the bacteria, while all the other organisms comes under the category of heterotrophic mode of nutrition.
Autotrophic Nutrition
The organisms, which can manufacture their own food using the natural raw material are called autotrophs. All the green plants can manufacture their own food using natural raw material and hence are autotrophs. The photosynthesis in plants that takes place in presence of sunlight is an autotrophic mode of nutrition. The material is taken in the form of carbondioxide and water, which is then converted into carbohydrates in the presence of sunlight and chlorophyll. Carbohydrate is used by the plants for providing energy to the plants.
\[C{{O}_{2}}+12{{H}_{2}}O\to {{C}_{6}}{{H}_{12}}{{O}_{6}}\,6{{O}_{2}}+6{{H}_{2}}O\]
In plants and algae, photosynthesis takes place in organelles called chloroplasts. A typical plant cell contains about 10 to 100 chloroplasts. The chloroplast is enclosed by a membrane. This membrane is composed of as phospholipid inner membrane, a phospholipid outer membrane, and an intermembrane space between them. Within the membrane is an aqueous fluid called the stroma.
The stroma contains stacks (grana) of thylakoids, which are the site of photosynthesis. The thylakoids are flattened disks, bounded by a membrane with a lumen or thylakoid space within it. The site of photosynthesis is the thylakoid membrane, which contains integral and peripheral membrane protein complexes, including the pigments that absorb light energy, which form the more... 
Modern Periodic Classification
Periodic Law
'Properties of elements are a periodic function of their atomic number Atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements, when arranged in order of increasing atomic number Z, lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number.
Position of Elements in the Modern Periodic Table:
The Modern Periodic Table has 18 vertical columns known as 'groups' and 7 horizontal rows known as 'periods'. Let us see what decides the placing of an element in a certain group and period. All elements of a group contain same number of valence electrons, which justifies similar chemical properties. The atomic radius decreases in moving from left to right along a period. This is due to an increase in nuclear charge, which tends to pull the electrons closer to the nucleus and reduces the size of the atom. Atoms of different elements with the same number of occupied shells are placed in the same period. Na,
Mg, Al, Si, P, S, Cl and Ar belong to the third period of the Modern Periodic
Table, since the electrons in the atoms of these elements are filled in K, L and M shells.
Metallic & Non-metallic Properties
Metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle, we have silicon, which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table, a zig-zag line separates metals from non-metals. The borderline elements - boron, silicon, germanium, arsenic, antimony, tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals. Metals tend to lose electrons while forming bonds, that is, they are electropositive in nature.
As the effective nuclear charge acting on the valence shell electrons increases across a period, the tendency to lose electrons decreases. Down the group, the effective nuclear charge experienced by valence electrons is decreasing because the outermost electrons are farther away from the nucleus. Therefore, these can be lost easily. Hence metallic character decreases across a period
and increases down a group.
As the trends in the electro negativity show, non-metals are found on the right- hand side of the Periodic Table towards the top. These trends also help us to predict the nature of oxides formed by the elements.
It is know that the oxides more... 
Mendeleeu's Classification
In 1869, a Russian chemist, Mendeleev, on the basis of physical and chemical properties discovered a relation known as "PERIODIC LAW". "The properties of element are the periodic function of their atomic masses".
| Group | I | II | III | IV | V | VI | VII | VIII | |||||||||||||||||||||||||||||||
| Oxide Hydride | R2O RH | RO RH2 | R2O3 RH3 | RO2 RH4 | R2O5 RH3 | RO3 RH2 | R2O7 RH | RO4 | |||||||||||||||||||||||||||||||
| Periods ¯ | A B | A B | A B | A B | A B | A B | A B | Transition Series | |||||||||||||||||||||||||||||||
| 1 | H 1.008 | ||||||||||||||||||||||||||||||||||||||
| 2 | Li 6.939 | Be 9.012 | B 10.81 | C 12.011 | N 14.004 | O 15.999 | F 18.998 | ||||||||||||||||||||||||||||||||
| 3 | Na 22.99 | Mg 24.31 | Al 29.98 | Si 28.09 | P 30.974 | S 32.06 | Cl 35.453 | ||||||||||||||||||||||||||||||||
| 4 First Series Second Series | K 39.102 Cu 63.54 | C 40.08 Zn 65.37 | Sc 44.96 Ga 69.72 | Ti 47.90 Ge 72.59 | V 50.94 As 74.92 | Cr 50.20 Se 78.96 | more...
 Newland's Classification
 Newlands' Law of Octaves The attempts of Dobereiner encouraged other chemists to correlate the properties of elements with their atomic masses. In 1866, John Newlands, an English scientist, arranged the then known elements in the order of increasing atomic masses. He started with the element having the lowest atomic mass (hydrogen) and ended at thorium which was the 56th element. He found that every eighth element had properties similar to that of the first. He compared this to the octaves found in music. Therefore, he called it the 'Law of Octaves'. It is known as 'Newlands' Law of Octaves'. In Newlands' Octaves, the properties of lithium and sodium were found to be the same. Sodium is the eighth element after lithium. Similarly, beryllium and magnesium resemble each other. A part of the original form of Newlands' Octaves is given in Table below:
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Dobereiner’s Classification
In the year 1829, Johann Wolfgang Dobereiner, a German scientist, was the first to classify elements into groups based on John Dalton's assertions. He grouped the elements with similar chemical properties into clusters of three, called 'Triads'. The distinctive feature of a triad was the atomic mass of the middle element. When elements were arranged in order of their increasing atomic mass, the atomic mass of the middle element was approximately the arithmetic mean of the other two elements of the triad.
Introduction
So far Scientists have discovered 118 elements. Some of these elements are in free states, while the others in combined state. But all these elements were not discovered in a day. It has taken a long time to do so. When a very few elements were known, study of these elements were easier. But with the increase in the number of elements, it became difficult to study the properties of all of them separately. So an attempt has been made from time to time to classify these elements into groups, depending upon their physical and chemical properties. The study of the properties of element of a particular group helps the scientists to predict the properties of other elements of that group. In this chapter we will discuss about the classification of the elements into various groups on the basis of their properties.
Soaps and Detergents
A soap is a sodium salt of long chain fatty acid. A soap molecule consists of along hydrocarbon chain. It composed of carbons and hydrogens, with a carboxylic acid group on one end which is ionic bonded to a metal ion, usually a sodium or potassium. The hydrocarbon end is nonpolar and is soluble in nonpolar substances, such as fats and oils; and the ionic end, the salt of a carboxylic acid is soluble in water. The structure of a soap molecule is represented below:
Non-polar hydrocarbon chain ionic end (soluble in nonpolar substances) (soluble in water)
Detergents are structurally similar to soaps, but differ in the water-soluble portion. Three examples of detergents are shown below. When a soap or detergent is added to water, a polar solvent, the molecules form clusters, known as micelles, in which the polar ends of the molecules are on the outside of the cluster and the non-polar ends are in the middle. The leaning action of both soaps and detergents results from their ability to emulsify or disperse water-insoluble materials (dirt, oil, grease, etc.) and hold them in suspension in water. This ability comes from the molecular structure of soaps and detergents.
When a soap or detergent is added to water that contains oil or other water-insoluble materials, the soap or detergent molecules surround the oil droplets. The oil or grease is "dissolved" in the alkyl groups of the soap molecules while the ionic end allows the micelle to dissolve in water. As a result, the oil droplets are dispersed throughout the water. This is referred to as emulsification and can be rinsed away. Soaps, will react with metal ions in the water and can form insoluble precipitates. The precipitates can be seen in the soapy water and are referred to as "soap scum". This soap scum can form deposits on clothes causing them to be gray or yellow in color. To eliminate the metal ions in water, washing aids such as washing soda (sodium carbonate) and borax (sodium tetraborate) were added to the wash water. These compounds would precipitate with the metal ions, eliminating most of the soap scum. With the discovery of synthetic detergents, much of the need for washing aids was reduced. A detergent works similar to a soap, but does not form precipitates with metal ions, reducing the discoloration of clothes due to the precipitated soap. Modern laundry detergents are mixtures of detergent, water softeners, optical brighteners, stain removers, and enzymes.
Which one of the following is a functional group of alcohol?
(a) R-OH
(b) R-CHO
(c) R-COOH
(d) R-CO-R
(e) None of these
Answer: (a)
