What is cartilage?

Cartilage is soft and flexible. It is non porous. In case of cartilage blood vessels are absent. In cartilage matrix is made up of proteins and there is no deposition of calcium phosphate. In cartilage bone marrow is absent.

What is bone?

Bone is hard and flexible. It is pores. In case of bone blood vessels are present. In bone matrix is made up of calcium phosphate. Inside the bone there is a brownish particles called bone marrow.

What are complex tissue?

The complex tissue are made up of more than one type of cells, They work together as a single unit. The main functions is conduction. Xylem and Phloem are the complex tissue and are the component parts of the vascular bundle.

What are epithelial tissue?

Epithelial tissue serves as a protective covering. It covers both external surface of the organs including blood vessels. Epithelial tissue rests on a non cellular basement membrane. This membrane separates the epithelium from underlying connective. Blood vessels are absent on the epithelial tissue. The cells of the epithelial tissues fit tightly without inter cellular space. Injuries are likely to heal rapidly as well as cells divide and produce new cells to replace the lost damaged cells. Functions of epithelial tissues are protection, absorption, secretion, sensory perception. Based on the number of layers the epithelial tissue is classified into simple and stratified epithelium.

What is sclerenchyma?

Sclerenchyma are called dead tissue. Considerably thicken with lignin deposition. Inter cellular space are absent. Based on the shape sclerenchyma are of two types, fibres and schelereids. cells of the fibres are elongate whereas cells of schelerids is irregular in shape. Its main functions are: it gives mechanical support, it gives protection from various adverse conditions, It helps in the conduction of water, hardness of the pulp is due to sclerenchyma, it also has economical importance eg: jute, fibre etc.

What is collenchyma?

Collenchyma resemble more or less parenchyma. This cell also retain the capacity of divisions. The cell walls are unevenly thickened and these thickened are confined to the corner of the cell. Cell wall is composed of cellulose and paction. It is found in stem and petiole. The functions of collenchyma is to give mechanical support, helps in photosynthesis if chloroplast is present, and can resist bending and stretching caused by winds.

What is parenchyma?

Parenchyma is a unspecialised simple tissue. Cells are living with active protoplasm. It present in the soft part of the plants and storage in the main function. The cells shape may be oval, spherical, or polygonal. Cell walls are thin made up of cellulose. Inter cellular space may or may not be presented in parenchyma. The main functions of parenchyma is storage of food materials, It helps in the regeneration and wound healing.

What are permanent tissues? What are the two types of permanent tissue?

It is composed of cells that have lost the power of division and have attained definite shape,form and size. They may have living or dead cell. Cells are thick or thin well some permanent cells retain power of division and helps in the secondary growth in plants. On the basis of its constitution, the permanent tissue is classified into two types simple tissue and complex tissue.

What is a meristematic tissue and what are its charachteristics?

The term Meristem was suggested by 'Nageli'. Meristematic tissue helps in the formation of new cells hence it is also called formative cells. It is capable of divisions and production of new cells.They have large nucleus  They have less number of vacuoles. Cells tightly packed without inter cellular space. They are usually seen at the growing regions. Cell walls are thin. Cells are small and identical. They are usually isodiametric. The plastids are in proplastid state

What are genes in a cell?

Genes are carrier of hereditary materials. It is present in chromosomes which are located inside the cell. Chemically genes are composed of De Oxy Nucleic Acid (DNA).

Why are lysosomes said to be 'suicide bag'?

Lysosomes contains a number of hydrolitic enzymes, these enzymes are capable of destroying the cell and the cell content.For this reason lysosomes are termed as 'suicide bag'

What are plastids? what are the different kinds of plastids and their functions?

Plastids are the cytoplasmic organelles found only in the plant cells and certain micro organisms
Plastids are of following three types based on the pigment present:
i)Chloroplast: These are green plastids containing chloroplast pigment. It captures light energy and carry out photosynthesis.
ii)Chromoplast: These are coloured plastids containing other than green pigment responsible for brightley coloured flowers, fruits etc.
iii)Luecoplast:: These are colourless plastids. They have no pigment, it perform functions of food storage.

What is cell membrane?

i)It is living membrane.
ii)It is thin outer boundary of cytoplasm.
iii)It is composed of proteins and lipids.
iv)It is semi-permeable.
v)Present both in plants and animal cells.

What is cell wall?

i)Cell wall is the non living boundary wall.

ii)It is present outside the cell membrane.

iii)Cell wall is mainly composed of cellulose.

iv)It is Permeable.

v)Cell wall is present only in plant cells

What is cell theory? Name the different scientists who formulated it?

The cell theory states three major points:
i) The cell is the smallest unit of structure of all living things
ii) The cell is the unit of function of all living things.
iii) All cell arise from pre existing cells.
The cell theory was formulated by two scientists- M.J. Schlieden and Theodar Schwann

What is metre?

In SI system the length is measured as metre. A metre was originally defined in 1889 as the distance between two marks drwan on a platinum iridium rod kept at 0°C in the International Bureau of Weights and Measures at Sevres near Paris.

What is intermolecular force or inter particle force?

The force of attraction between the constituent particles in any form of matter is called the inter molecular force or inter particle force. If the force of attraction between the particle is very strong the substance is said to be rigid. A solid is a rigid form of matter. If the force of attraction is weak is said to be fluid. A gas is a fluid.

What is brownian motion?

The scientist Robert Brown suspended the pollen grains and looked into the water through the microscope it was noticed that pollen grains moves on the surface of the water in a very irregular way because they are constantly being hit by the moving particles of the water. The zig zag motion of pollen grains is known as Brownian motion.

What is the chemical formula?what is the rule for writing formula correctly?

A molecular chemical formula employs symbols to denote the molecule of an element or of a compound. The rule for writing chemical formula are Firstly, write the symbols with positive charge valency first. Secondly, write the valency of each atom on the top of its symbol.Thirdly, divide the valency number by their highest common factor ignore the positive or negative radicle. Interchange the valency of the radicle. Lastly, write  the interchanged valency number to the lower right of the radicle.

What is "Newland's law of octaves"?Why was the law discarded?

According to Newland's law of octaves, when elements are arranged in the order of increasing atomic mass, the properties of every eight element are a repetition of the properties of that starting element. Reason's for the discarding of law of octaves are: i)After the discovery of the noble gases, the idea of octaves failed. For example, the inert gases like helium and neon became the eighth element, thus, making the ninth and not the eighth element shown similar properties. ii) The classification failed with regard to the heavier element i.e. these lying beyond calcium. As more and more element were discovered, they could not be fitted into Newland's octaves

What is the extrusive landforms of the volcanic region?

Extrusive landforms are those formed by the solidification of lava on the surface of land. The most typical extrusive landforms found in the volcanic region is called volcanic cone. When a volcano erupts exclusively a portion of land gets depression. This is called as crater. Volcanic cone is also known as cinder cone which has steep slopes because they consists of large size particles. Cinder and ash cones are formed when only gas erupts with great force and there is no lava formed. The large volcanic hills with alternating layers of lava and ash which has been started as a cinder cone are called composite cones.

What is rock cycle?

When the magma found beneath the earth crust originated and flows in the interior and exterior of earth's surface which cools and solidify to form igneous. Igneous rocks are the parent of of other rocks. Due to weathering, erosion and loading the igneous rocks transported and deposited the sediments for the second transformation is known as sedimentary rocks. Again the rocks changes into metamorphic rocks due to the chemical action that occurs in the igneous and sedimentary rocks. Finally the metamorphic rocks changes into magma due to heating, melting and viseversa. 

What is sound and why is sound a form of energy?

To start vibrations in the body producing sound, mechanical energy is required. The vibrations started by the source are transmitted in the medium in the form of waves on reaching our ear, produce vibrations in the ear drum which are perceived as sound by us. Thus, sound is a form of energy.

What is metamorphic rocks?

It is formed by the process of metamorphism of pre existing rocks. Metamorphism means change of forms. During the process the original minerals get altered and new minerals are formed. The minerals arranged in a serious of bank on a metamorphic rock is known as foliation. Example limestone to marble, slate to shale etc.  Metamorphic rocks are divided into three thermal metamorphism, dynamic metamorphism and regional metamorphism.

What is sedimentary rocks?

The word 'sedimentary' is derived from the Latin word 'sedimentum' means settling down. Sedimentary rocks are formed by the process of weathering, erosion, transportation, and deposition of seas, rivers, lakes, glaciers and even wind. The sedimentary rocks are porous and permeable. The cementation, compaction and hardening of sedimentary rocks into sedimentary rocks are called as Lithosphere. It is also known as secondary or derived rocks because they are derived by the denudation of other pre existing rocks. Sedimentary rocks are sub divided into three on the basis of nature of sediments, origin, composition and made of formation.

What is Igneous Rocks?

The Word Igneous Rocks is derived fro Latin word 'Ignis' means fire. It is also known as primary or parent rocks. Igneous rocks are formed due to the process of solidification of molten magma that originate fro the interior layer of the earth at the time of volcanic eruption. Igneous rocks are divide in two on the basis of mode of origin. They are Intrusive Igneous Rocks and Extrusive igneous rocks.On the basis chemical composition. Igneous rocks are again divide into Acidic and Basic Igneous rocks.

What is minerals?

Minerals are naturally occurring solid inorganic substances, having definite chemical composition and physical properties. It is mainly crystalline in appearance and homogeneous in form. Minerals are made up of Chemical element mainly Oxygen and Silicon.

What is continental drift theory?

The theory was put forward by Alfred Wegner in the year 1912. 250 million years ago there was only one continent called Pangea and a single vast sea Panthalassa. About 200 million years ago Pang-ea drifted into two. Laurasia- which consists of North America and most of Eurasia and Gondwanaland- consists of South Aerica, Africa, The Indian Sub Continent Australia and Antarctica. During the last 180 years age that India Sub Continent moves from Gondwanaland and joins Southern side of Asia.In 1968 this theory got more important with the help of another theory known as Theory of Plate Tectonics. This theory was put forward by W.J. Morgan. It advocate the sea floor spreading.

What is standard time?

To make the uniform tie through out the country, it is based on the Central Meridian of the country or the meridian of the country or the meridian at which the most important cities are located. Such Central Meridian is called as Standard Time. The Meridian passes through Allahabad and close to Chennai. The time based on the Indian Standard Time. The I.S.T is ahead GMT.

What is local time?

Local time is calculated with the help of the sun's ray. It is easily identified with the help of the shadow's. The Local Time differs fro place to place because of the variation in longitude. The time difference is 1 degree is equal to 4 minutes.

What are lines of longitudes?

Lines of longitudes are lines which joins all places having the same angular distance. Measured in degrees along the equator east or west of the Prime Meridian. They are called meridians because all places along the same meridian of the longitude has the same time. The zone between the Prime Meridian and 180 degree longitude is called the Eastern Hemisphere. The opposite zone is called Western Hemisphere.

What is torrid zone?

Torrid is a latin word means roast. It is the widest zone and the hottest region. In between 5°N and  5°S of the Equator, lies Doldrums or the equatorial zones, which has high temperatur, because i.e. recieves vertical rays of the screen. The movement of the winds are from high to low pressure region.

What is temperate zone?

The north temperate zone  lies between the tropic of cancer and the artic circle and the south temperate zone lies between tropic of capricon and the antartic circle. The climatic condition is between summer and winter. In summer days are longer towards the pool and winters are shorter. This zone is more comfortable for living and working.

What is frigid zone?

The north frigid zone lies between Artic Circle and South Pole, South Frigid zone lies between Antartic Circle and South Pole. The slanting rays of the sun reach Artic Circles from 23rd september to 21st march and reach the Antartic Circle from 21st march to 23rd september. This are the coldest zone.

What is waste management and why do we need it?

Waste management works towards reduction, reuse and recycling off all resources. Waste management has become increasingly important as increase in population are not accompqnied by a relative reduction in waste generated. The deep blue ocean which is used to be a favorite waste facility is now protected to certain extend foccusing waste disposal inland

What is oil spills and what are the damage caused by them?

Oil spills are another major causes of death of marine life. Oil spills can be caused making mistaking or being careless, equipment breaking down, natural disasters such as hurricane or deliberate acts by terrorists countrie at war or illegal dumpers.

What is bio-accumulation?

Fishes and other aquatic animals are killed due to the various chemicals in the effluents. Many harmful chemicals accumulate in the fishes and other marine food chains. Plastics that are dumped into the seas do not decompose. Fish and turtle suffocate when they swallow plastic. Thousand of sea birds and marine animals die due to plastic related causes.

How do fertilizers and pesticides pollute our environment?

Fertilizers are used to enchase the fertility of the soil. They contain various nutrients like nitrogen, phosphorus, potassium etc. when added to the soil, they increase the quantity of these nutrients in the soil and thus the availability of the same to the plants for better growth. Pesticides are sprayed on plants to prevent pests from attacking them. Most of the pesticides are non-biodegradable in nature. They remains in the soil for a long time and also enter the crops. When the products of such crops are consumed by human beings, the pesticides enter the human system.

What is nuclear waste? How is it harmful?

One more category of waste which should be handled and disposed off in a very careful and effective manner is nuclear waste. We all know that nuclear waste is radioactive and if it is allowed to pollute the environment, The entire mankind and all plants and animals will be exposed to various radiations emitted from this waste which have very disastrous effect on a life forms. We are aware of the chernobyl disaster and damage caused to the life forms due to it.

Why does medicinal waste fall under the hazardous category?

Hazardous wastes are those substances which cause harm to human beings, animals, plants and the environment. These wastes are those generated in hospital's, clinic, laboratories and other such institutes.These have to be handled and disposed of very carefully. As well aware, these places are frequented by sick people whose tissues are loaded with infected germs. Waste coming from material in contact with those infections is also very infectious and can cause many diseases if not handled and and disposed off properly

Why is the scientist looking for a replacement for CFC's?

CFC are not found naturally they are synthetic in nature. When CFC's escape into the atmosphere, they rise up and reach the ozone layer. Here, the CFC's breakdown the ozone. Scientists believe that the damage to the ozone layer will have two effects on  the earth's surface: Firstly the extra radiation will cause the lower atmosphere to warm up and this will add to the green house effect. Second, the increase in UV  radiation would har many of the earth's organisms including humans.

What is desertification and how isit harmful?

Desertification is the process in which productive semi-arid and arid land is degraded into unproductive desert as a result of human activities. It is mainly caused y inappropriate agricultural practices. Overgrazing removes the cover of vegetation and expose the soil to erosion by wind or water. This prevents air and water from penetrating the ground and increase the surface run off, lowers the water table and prevents the re-establishment of vegetation. The crops are not grown on the land

How has man intelligence led to overutilisation of resources?

The ever increasing population is responsible for the overutilisation of resources. To feed the daily growing population, we need more and more food for which we need more land for farming and agricultural. More homes are also required for the increasing population for which, again, forests are cleared. The indiscriminate cutting of forests is called deforestation. Overutilisation of resources lead to many harmful effects like deforestation, desertification, acid rain, green house effect, hole in the ozone layer etc.

What is water cycle?

Water from sea, river, lakes, ponds etc. will go to the atmosphere as in the form of water vapour by the process of evaporation. The water vapour rises normal cool and changes into droplets of water process of condensation. A large number of droplets to combine to form clouds. This clouds further too large droplets and finally fall down on the earth as rain.

How has man harnessed the kinetic energy of water?

Kinetic energy is the energy possessed by an object due to its movement. Moving water has a lot of energy. The energy of moving water is used to generate electricity. This is known as hydrolatic power. Fast flowing water of river has the energy to uproot trees and carry away stones, trees etc with it. Falling water of a waterfall has tremendous energy. Man has put this hydel energy very effectively to his use.

How do solar energy appliance work?

Man has only recently learnt how to harness solar energy. The sun will be there for billions of years to come and therefore this energy cannot be exhausted easily. We can use the sun's energy directly. One way is to concentrate its heat by using mirrors. In so many place, this is used to make furnaces or to generate electricity.

How is nuclear energy obtained and what are its uses?

This form of energy gets its name from the method of it's production. The nucleus of atoms of specific material's undergo fission gives out tremendous amount of energy. Even fusion of nucleus produces tremendous of energy. This energy is converted to electrical energy and hence the name is "Nuclear Energy". The Energy released in this process is so high that devasting bombs are also made on the same principle. We are all aware of the devasting affects of the bombs dropped on Hiroshima and Nagasaki. Thus we see that the same energy can be used by mankind to help itself. The choice lies in the Judicious decision of mankind.