Sunday, October 26, 2014

Environment and Living Planet

Among the nine planets of the solar system, with is the only one where life exists. Plants and animals exist on earth because it has all the favorable conditions required for survival of life.

Even on earth life is not found everywhere because survival requires a particular type of environment. That part of the earth where plants and animals exist is called biosphere. Biosphere is further divided into three parts; lithosphere, hydrosphere and atmosphere. Lithosphere is that part of earth where rocks, sand, soil, plants, animals, etc. are found. That part of the earth where water is present is called hydrosphere. All the animals and plants need water to live. The blanket of air which surrounds the earth up to a height of about 100 km is called atmosphere. Atmosphere is a balanced mixture of several gases like nitrogen, oxygen and carbon dioxide. The major atmosphere extends up to 320 km above lithosphere and hydrosphere. About 10 km below and 10 km above the surface of the earth is biosphere. In reality 90 percent living beings live in the area between 1 km below and 1 km above the earth’s surface.
Biosphere or ecological frame work always remains in a dynamic equilibrium. In this many biological and physical elements are present in a balanced state. Air, water, soil, animal, plants and bacteria are all linked to each other or to their surroundings by some means or the other. This system is called environment. Environment includes all those conditions which affect our life. Plants, animals, water, air, land are important parts of our environment because living being cannot survive without them. Our houses, villages, towns etc. all are included in the environment. Man has created an imbalance in the environment by its haphazard exploitation to fulfill his needs. The trees are being cut mercilessly; water and air are becoming highly polluted. If environmental pollution keeps on increasing with the present rate, the very existence of the life on earth is endangered.

Sunday, May 11, 2014

Oceans and Rivers


Oceans
Oceans cover around 71 percent of the earth’s surface and the remaining 29 percent is the land area. They are estimated to contain 1.3x10 18 tons of water. There are five oceans: the Atlantic, Pacific, Indian, Arctic and Antarctic. There are smaller bodies of water called seas, sounds, bays and gulfs. All of these are connected to each other.
The Pacific Ocean is the largest and the deepest. It covers an area of about 16, 62, 40,000 sq. km. the second largest is the Atlantic ocean which has an area equal to half of the Pacific Ocean. The Indian oceans are the third largest. It extends from Kanyakumari (Cape Comorin) in India to the South Pole, Antarctica. The Arctic Ocean surrounds the North Pole. It is completely frozen and unnavigable. Some people consider Antarctica also to be an ocean.
The ocean water is saline and not if for drinking. The average salinity is 3.5 percent. The main source of salinity of oceans is the water of the rivers that carry with them billions of tons of dissolved minerals every year.
Oceans exercise a great influence on climate. They are the main source of rainfall on the continents. Ocean currents regulate the temperature in the coastal regions. The sea breeze and the land breeze keep moving in their set directions. Due to the heat of the sun, the water in the oceans evaporates into smoke and converts into clouds that cause rainfall to make the soil fertile.




Oceans
Rivers
A river is a large stream of water that flows from high land to low land. The water in rivers comes from rain, snow melt, lakes, springs and water falls. The river water eventually flows into oceans.
There are many kinds of rivers such as- the swift flowing rivers, the slow moving rivers, the straight rivers, the meandering rivers, the large and the small rivers. The speed of flow of water in a river depends on the steepness. The rate of flow at the mountain slopes is higher than that in the plains. The course of river near its source is narrow but it widens as it moves downstream.
Some rivers owe their origin to melted ice in the mountains while others to the glaciers. A river is in youthful stage in mountainous region upper course, in mature stage in flat valleys mid course and in old stage in delta region lower course.
In the upper course the river flows zig-zag through the mountain blocks. Further downwards it develops land forms like gorges and canyons. In mid course, the river slows down but gathers larger volume of water from its tributaries and takes many turns. In the lower course, the river widens its bed and wends its way leisurely. Here, it forms flood plains, ox-bow lakes and deltas. The delta region consists of very fertile soil and silt. Rivers are a very useful means of transport and communication. Ships and boats sail on the rivers. Dams are constructed on big rivers to generate electricity, popularly known as hydroelectric power. Canals are cut from these big rivers to divert the water for irrigation purposes.

Rivers

Sexual Reproduction in Animals


  Animals reproduce to continue their race. Animals reproduce both by asexual and sexual methods. Asexual reproduction occurs in the organisms of lower phyla like protozoa, coelenterate, porifera etc., Majority of the animals adopt sexual reproduction. Male sex organs are called the 'Testes' while the female sex organs are called the 'Ovaries' and they produce cells called 'Gametes' like spermatozoa (or) sperms and ova respectively.
Fertilization:
          Fusion of gametes is called fertilization. Fertilization is of two kinds. When fertilization occurs inside the body of the female animal is called internal fertilization and when fertilization occurs outside the body of the animal, it is called external fertilization. In majority of the animals, sexes are separate and male and female animals are separate. This is called sexual Dimorphism and animals are said to be unisexual.
Conjugation in Paramoecium:
            Paramoecia, after repeated binary fissions, become weak and switch over to sexual reproduction known as conjugation.
The Paramoecia that undergo conjugation are called conjugants. The two conjugants come close and unite. The pellicle that separates them dissolves. The cytoplasm of the two paramecia becomes continuous through this part, where the pellicle is dissolved. This is called as cytoplasmic bridge. At this stage the macronucleus slowly disappears and the micronucleus undergoes meiotic division resulting in four haploid nuclei. Of these four nuclei, three disintegrate and the rest single micronucleus divides into small migratory (male) pronucleus and large stationary (female) pronucleus.
             The male pronucleus of one conjugant fuses with the female pronucleus of another conjugant through cytoplasmic bridge resulting in synkaryon. Then after the conjugants get separated and are called as exconjugants.
In each exconjugant, the synkaryon undergoes 3 mitotic divisions and form 8 nuclei. Of these eight, three disappears. Of the remaining five nuclei, four develop into macro nuclei and one into micronucleus.
              Each exconjugant, with a single micronucleus and four micronuclei divides twice and forms four daughter paramoecium. Each daughter paramoecium receives one macronucleus from the exconjugant.
              The single micronucleus of the exconjugant divides twice along with the exconjugant and each daughter paramoecium receives one micronucleus. Thus each of the daughter paramoecium receive one macro and one micronucleus. Thus, by conjugation a single paramoecium produces four daughter paramoecium
Different stages in the conjugation of Paramoecium



Reproductive System in Earth Worm
Earthworm is hermaphrodite - both male and female sex organs are present in the same individual. But, earth worm shows protandry condition that is the testes matures much earlier than ovaries and this prevents self fertilization. The testes are present one on each side of the body in 10th and 11th segments. They produce sperm mother cells which inturn matures into sperms in seminal vesicles. The sperms passes out through vas deferens and into male genital aperture.
          A pair of ovaries are present, one on each side of the ventral nerve cord. They arepresent in the 13th segment. Each ovary has one oviduct, which opens out through female genital aperture. Ovaries produce ova and the ova are sent out through an aperture.
A thick girdle like clitellum is formed in between 14-17 segments. When the ovaries mature, the clitellum secretes a viscous substance becomes sticky and attaches with the substratum.
This is called cocoon. Earth worm wriggles and retreats back leaving the clitellum. Eggs and sperm cells are released into this cocoon. Both the ends are closed and it gets hardened to form a cocoon. Fertilization occurs inside the cocoon.
Since fertilization is taking place outside the body, it is external fertilization. After about 8 to 10 weeks, young earthworms come out of the cocoon.


Reproductive System in Earth Worm

Cocoon Formation in Earth Worm


Reproduction in House Fly
In male fly, a pair of testes are present one on either side of the ventral cord. Testes produce sperms. Each testes is connected to a tube called vas deferens. The two ducts unite to form a single ejaculatory duct. It opens out through male genital opening. In female fly, a pair of ovaries are present in the abdominal segment. Each ovary is connected to a oviduct. The two ducts unite posteriorly to form uterus.
It opens out through female genital opening, and is located in a special structure called ovi positor which helps in releasing fertilized eggs. A pair of sperm theca are attached to the ovi positor. They store sperms received during copulation.
Fertilization is internal. The eggs are laid by the female from 6-8 weeks after copulation. The eggs are laid in a clustor in decaying organic matter like manure, cow dung, decomposing fruits and grass, human faeces etc.
Reproduction in House Fly
Reproduction in Frog:
Frog is unisexual and shows sexual dimorphism.
Male Reproductive system:
            The male reproductive system consists of a pair of testes, vas efferentia and a pair of urinogenital ducts. Testes is an oval and yellow body which is attached to a kidney. Inside the testes there are a number of coiled tubules called seminiferous tubules. Spermatozoa are produced in the tubules. Each testes opens into a kidney through 10- 12 tubes called vas efferentia. Spermatozoa enter the kidney through these tubes.
From kidney two tube-like structures called ureters enterinto a chamber called cloaca. The ureters in male frog are called urinogenital ducts.
Spermatozoa produced in seminiferous tubules of testis enter into kidney through vas efferentia and from kidney into cloaca through urinogenital ducts. Cloaca opens outside through cloacal aperture. The discharged spermatozoa is called milt.



Male Reproductive System in Frog
Female reproductive system of Frog:
           It consists of pair of ovaries and a pair of oviducts. A pair of lobed ovaries are attached to the kidneys. Ovary is a sac like structure which is greyish or blackish in colour. Inside the ovary, numerous chambers called "Follicles" are present. Each folliclegives a single ovum.
From each ovary long folded, tube like structure called 'oviduct' arises. This opens anteriorly into the body cavity through a ciliated funnel called Ostium.
Female Reproductive System in Frog

The funnel collects ova from the body cavity posteriorly. The oviduct is enlarged into a sac called ovisac or uterus. which stores ova. The oviducts open into cloaca and are discharged out through the cloacal aperture. Frog release a large number of eggs as a mass called Spawn.
The ovum of frog is spherical. In the upper part is the nucleus and this part is black due to pigment present in the cytoplasm. This part is called animal hemisphere. Yolk is concentrated at the other pole, which is whitish. This pole is called vegetal hemisphere.
Frog Ovum

Shock Waves


Shock waves is a wave of high pressure that forms in a gas or liquid as an object moves through it at or above the speed of sound or as the gas or liquid flows around the object. The shock waves are also called pressure waves and they move away from the object at the speed of sound. These waves contain high energy and are very dangerous. They are produced during cloud thunders, eruption of volcanoes and in lightening. Every year shock waves cause a big loss to many live and property.

 Shock Waves in Supersonic airplane
A shock wave is created in air when a super sonic airplane flies overhead at the speed of sound or faster. When the wave reaches the ground, a sonic boom is heard as the waves strikes the ears. A sonic boom can shatter the window panes.


 Shock Waves in Supersonic airplane
Explosions also produce powerful shock waves which can damage constructions up to several kms. Shock waves can also be produced by the high speed of the bullet of a gun. When the speed of a motor boat in water becomes very high, shock waves are created on the surface of water. Earthquakes also cause shock waves. Explosions of atom and hydrogen bombs create very powerful shock waves which can cause deaths to large number of people. Shock waves are also produced due to the explosion of chemical bombs.

Saturday, May 3, 2014

Respiration


All living organisms require energy for various metabolic activities. The energy is released through the process of respiration (where molecules like glucose and fatty acids are oxidised). Let us know how living organisms get energy through respiration by using oxygen.

Oxidation of food materials, especially glucose, fatty acids and proteins to CO2 and water is called Respiration. Energy is produced in this process. As this process occurs at cellular level it is called Cellular Respiration.
Cellular respiration is the process by which food is broken down by the body's cells to produce energy, in the form of ATP molecules.

Cellular respiration is carried out by every cell in both plants and animals and is essential for daily living. Energy is produced only when glucose and fatty acids are oxidised which are transported from the digestive system to all the other cells in the body which are carried by blood.

Respiratory Substrates:
Substances which oxidised in the body during respiration to produce energy are called respiratory substrates. In all organisms from microbes to man the major respiratory substrates are carbohydrates and fats.

Carbohydrates like starch and cellulose are complex molecules. Such complex molecules are not oxidised directly to produce energy. First of all complex molecules (carbohydrates) are broken down into simple molecules and then oxidised. Between these process so many reactions takes place. But energy is not produced in each and every reaction during the oxidation of glucose or fatty acids. Only in some of the reactions small amount of energy is produced. This energy is converted into chemical energy and is stored in ATP (Adenosine Tri Phosphate).

The ultimate goal of cellular respiration is to take carbohydrates, diassemble them into glucose molecules, and then use this glucose to produce energy-rich ATP molecules.
The general equations for cellular respiration is: One glucose molecule + 6 oxygen molecules produces six carbon dioxide molecules, 6 H2O and approximately 36 -38 ATP molecules.

Mitochondria - Sits of Cellular Respiration
Cellular respiration occurs in Mitochondria. Oxidation of food materials takes place in them. The energy released through oxidation is utilised by the mitochondria to synthesis ATP which are energy rich compounds. Therefore mitochondria are called as Power houses of the cell.

O2, ADP + Pi (inorganic phosphate), carbohydrates, fats are required for the respiratory activity in mitochondria.


  • Mitochondria are sac like structures present in the cytoplasm of the cells.
It has two compartments.
1. An inner compartment
2. An outer compartment
  • The substance in the inner compartment is called Matrix.
  • The inner membrane is thrown into several foldings called Cristae.
  • The space between the foldings is continuous with the outer compartment.
  • On the inner membrane large number of elementary particles are seen which have a spherical head and a stalk.
  • Outer compartment is surrounded by outer membrane.
  • Inner membrane, matrix and elementary particles have large number of enzymes which required for the respiration and energy production.
There are three main stages of cellular respiration.
1. Glycolysis
2. Krebs Cycle
3. The electron transport chain

First step in glucose oxidation is called glycolysis. (In the first stage of glycolysis energy is used to phosphorylate the 6-carbon glucose is used to molecule.) This means that a phosphate is taken from ATP (which becomes ADP) and added to the glucose molecule. This addition of phosphate makes the molecule much more energised and converted into glucose-6 phosphate. Later glucose-6 phosphate is converted to fructose-1, 6-Diphosphate. In this process another ATP is used. Fructose-1, 6-Diphosphate is finally converted into two molecules of pyruvic acid.

Result: 4 ATP and 2 NADH are formed. 2ATP molecules are used in this process. So, net gain is 2 ATP molecules.

Krebs Cycle
It takes place in mitochondrial matrix. This cycle involves series of reactions in which pyruvic acid is oxidised. This cycle discovered by Sir Hans Krebs, that's why it is called as Krebs Cycle.

When oxygen is available pyruvic acid molecules (end product of glycolysis) are converted into Acetyl Co-enzyme A with the release of CO2.

Acetyl Co-enzyme A is attached to oxalo acetic acid and formed into citric acid. When the two carbons are removed in the form of CO2 again oxalo acetic acid (4 C) is formed.

This combines with acetyl co- enzyme A and the cycle continues. So, this cycle is also called as citric acid cycle.


In this process small amount of energy is formed when two molecules of pyruvic acid are oxidised. Therefore 2 ATP molecules are gained.
Electron Transport Chain
Very little amount of energy has been produced during glycolysis and the Krebs Cycle. Most of the energy locked in the original glucose molecule will be released by the electron transport chain and oxidative phosphorylation.

NADH and FADH2 are oxidised in the elementary particles of mitochondria, where one proton and two electrons are formed from each molecule of NADH and are ejected into the inner membrane of mitochondria. These electrons are transferred from one acceptor to another which are arranged in a chain (The energy released is used for production of ATP).

These electrons and protons are finally transferred to oxygen to form water.

Know about a Scientist

Sir Hans Krebs previously been known for his excellent work on the urea science cycle in 1920's and 30's. Hans Krebs (1900 - 1981) received the Noble prize for working out the path way for oxidation of the 2 carbon acetyl group on acetyl Co A via a series of tricarboxylic intermediate. A cyclic pathway is now known as the Krebs Cycle, the Citric acid cycle and TCA Cycle.

Environment – Pollution


 The term pollution refers to the contamination of the environment- air, water and land- with harmful wasters resulted from human activities. Environmental pollution has become a major world wide problem. It has badly affected the whole biosphere.

Pollution has been caused by man. Man has been polluting the air with smoke and poisonous gases; rivers, lakes and oceans with sewage and harmful chemicals. During loading and unloading of crude petroleum in huge tankers million of tons of oil spill sin the oceans adversely affecting the aquatic life. You can observe the dead bodies of birds and fishes near sea shores or floating on the water.
Industries cause air pollution
 Increasing human population of the world and industrialization are the major causes of environmental pollution. The jungles have bee shaved off to accommodate the increasing population. This has considerably reduced the vegetation and forest cover over land. During the lost 50 years industries have multiplied manifold. The harmful chemical discharges of factories are polluting the rivers and oceans. The smoke produced by automobiles is increasing the air pollution and the noise produced by the engines of motor vehicles is aggravation the noise pollution. Modern means of agriculture have increased the use of pesticides which have also added to land and water pollution.
Industries cause water pollution
The marine life in the big lakes like Ari has vanished due to pollution. The sewage water, industrial wastes ad the water from agricultural farms containing extensive amount of fertilizes has filled his lake with too much of phosphates and nitrates. These chemicals have permanently distorted the biological balance of the lake. All the fishes of the lake have died. The water of Ganga and Yamuna Rivers is also becoming badly polluted. The Dal lake of Srinagar is in worse condition because of pollution. Pollution has affected mankind adversely. For the improvement of degradation of biosphere only man is responsible. And protection of flora and fauna also depends on the ways and means adopted by the human beings for their livelihood.

Thursday, April 24, 2014

The Plants Kingdom – Fungi

Fungi are considered to be the oldest plants. They do not contain chlorophyll. Like other thallophytes, they do not contain roots, stems, flowers and leaves. These plants cannot manufacture their own food and so for food, they depend on decaying organic matter, plants and animals. Fungi are, therefore, called parasitic or saprophytic. Most fungi reproduce asexually, but a few species have a sexually reproductive stage which alternates with an asexual stage. Their cell wall is made up of cellulose of chitin. They produce enzymes to digest food. Some familiar fungi are: yeast, molds, mushrooms, mildews, rusts and smelts. Fungi can grow in al kind of climates and environments. Some fungi are also found in air and water. Sir P. A. Nichelly is considered to be the father of fungi way back in 1729. He had discovered the fungi.

Fungi can be useful or harmful to human beings and other organisms.
Some fungi, such as Agaricus, morchella, etc. are consumed as food by man. Certain molds, such as camembert and Roquefort are added to cheese to provide a flavor and to help ripen the cheese. Yeast is used to manufacture bread and alcohol. It is a good source of protein and vitamin B. some molds are used to produce antibiotics. The famous antibiotic penicillin was obtained from a mold in 1929. Fungi are also helpful in maintaining soil fertility.

Rust, smut, mold, etc. cause many dreadful diseases in crops. They also cause diseases in man and domestic animals. They spoil our food. Some species of fungi are poisonous and if they are consumed by man, they may prove fatal. Among these, the highly poisonous fungus is toad stool. From ergot fungus, a hallucinating drug L.S.D. is prepared. Ringworm and athlete’s foot are diseases caused by fungus. Many varieties of mushrooms are poisonous and can cause sickness or even death if eaten. Reference: Children’s Science Library by A.H.Hashmi.
Different species of fungi






Wednesday, April 23, 2014

Environment - Noise Pollution


Today, noise pollution has become a serious health hazard in the big cities. Automobiles, trucks, motor, factory machines and even the means of entertainment like rock music, DJs, etc. produced loud, irritating sounds. Man feels disturbed by such sounds. The harmful effects of intense sounds are referred to as noise pollution.

  Noise is a hazard
The intensity of sound is measured in decibels. It is based on a logarithmic scale which means that ten decibels is ten times more powerful than one decibel and 20 decibels are 100 times more powerful, and so on. Man’s ears can tolerate the sound of up to 80 decibels. The sounds of higher intensity than this are harmful for ears. Normal human voice is of about 60 decibels. People living in noisy places become accustomed to high intensity sounds to send ears lose the sensitivity and capacity to send sound waves to the brain. This leads to deafness.
The clamor of motors, trucks and automobiles
          
          Studies reveal that in India ten percent people living in cities and seven percent in the villages are suffering from auditory defects. Abnormally high noise disturbs the sleep and increases heart beat. Noise pollution causes gastric problems, dilation of pupil of eyes, ulcers in stomach, weakening of teeth and defects in kidney. It is also harmful for the nerves of the womb and adversely affects the embryo of a pregnant woman. Noise pollution can only be checked by the people who are aware of its ill effects.
           The music systems producing very loud sounds can be banned to check noise pollution. Reference: Children’s Science Library by A.H.Hashmi.

Lithosphere or Crust



The uppermost layer of the earth is called litho-sphere or the crust. Its average thickness is 30 km to 40 km under the continents, 5 km to 10 km under the ocean the ocean floor and up to 60 km under the mountains. At certain places below the pacific floor, its thickness is very little. The earth’s crust consists of two layers- the upper layer and the lower layer. The upper layer is called SIAL (silicate + aluminum). It is made up of granite-like rocks which mainly consist of silica and alumina. Below the upper layer lies the lower layer called SIMA (silicate + magnesium) consisting of denser rocky material. Higher temperature prevails in this region. It is the same material of which the rocks on the surface of the earth are made.

There are three kinds of rock structure in the upper continents crust of the earth. Of them, the most abundant are the Pre-Cambrian crystalline shields. In the second place are the coastal areas formed of sedimentary rocks. The structure of the third part is folded mountains.

The crust of the earth is made up of a number of plates- large in size and of varied thickness, called the crustal plates. Some of them are in the form of ocean floor while others are in the form of continents. Earthquakes occur due to the upheavals of these plates. Reference: Children’s Science Library by A.H.Hashmi.

Geysers - Hot Springs



Geysers
                                                          The Old Faithful Geyser
A geyser is jet of boiling water and steam issuing from the earth in a few volcanic regions. The jet of water may persist from a few moments to an hour or more. Beneath the geyser, there is some hot rock and a narrow fissure connects the rock to the mouth of the geyser. Water reaches the rock through this fissure where it is heated to about 100 degree Celsius. Now the steam pressure inside, forces the hot water to come out to the surface of the earth. The flow of hot water continues till such time as cold water does not return to the fissure. The cold water is again converted into steam and as the pressure rises, the hot water is thrown out.

The jet of hot water may rise in the air to a height of 100 meters or more. In some cases it rises to only 1 or 1.5 meters. Geysers are known to exist only in Iceland. New Zealand and Yellowstone national park in the USA. Of these three, Yellowstone has by far the most impressive display of geysers. These geysers are a delightful sight for the viewers and are popular tourist spots.

Hot Springs
 A Hot Spring in Iceland
  The temperature of water of a hot spring is higher than that of ordinary springs. According to scientific findings, ground water temperature rises with increasing depth. The rate of increase in generally about 1 degree centigrade for each 25 meter of increase in depth. When underground hot water flows out regularly through some crack or fissure, it is called a hot spring. In some volcanic regions, the steam formed by the heat of the molten rocks is forced out in the form of hot water.
 
Many minerals get dissolved in hot spring water. The hot spring water containing dissolved sulphur is good for skin diseases. The water of some springs is very hot.
The Maoris of New Zealand cook their food in the local hot spring water. In Haryana, a place called Sona has a hot spring which is quite famous and Manali also has a number of hot springs. Among the hot springs in Dehradun, the capital of the newly formed state of Uttaranchal, the Tapt Kund is a hot water sulphur spring which is quite famous throughout India. Reference: Children’s Science Library by A.H.Hashmi.

Saturday, April 19, 2014

How The Body Utilizes the Fat We Eat


 
With this brief background of fats, fatty acids and cholesterol, consideration may be given to what happens to the fats we eat in our ordinary diet. Fats are utilized by the body for quick energy; if excess fats are eaten, the liver stores them temporarily so that the fats may be gradually released over a period of time. The blood stream is the mechanism utilized by the body for distributing this energy throughout the system. Research chemists were puzzled about how the blood conveyed fat, since it was known that fat does not dissolve in watery substances such as blood. Research revealed the secret. The body creates what scientists call lipoproteins—that is, combinations of fats, protein and cholesterol—because lipoproteins can and do dissolve in the blood.



The body creates these lipoproteins—the combinations of fat, protein and cholesterol—primarily to transport the energy foods in solution in the blood stream. After the lipoproteins are formed, they flow out into the blood and are carried through the body. The fats, now in solution in the blood, burn readily and are soon disposed of. The proteins are soluble in the blood and are also easily used up. The remaining constituent of the lipoprotein is the cholesterol. Until very recently, it was assumed that the body could not use up cholesterol, for it was not a type of food, such as fat, protein or carbohydrate. But the last few years of study indicate that the consumption of cholesterol in foods does have an effect on the serum cholesterol level, tending to raise it in most persons. That is true in even comparatively modest amounts of dietary cholesterol; for example, three-quarters of a pound of steak with fatty marbling, containing 1 gram, eaten daily will increase the cholesterol level in the vast majority of individuals. Therefore, it suggested that the daily consumption of cholesterol should be lowered to not more than 300 milligrams per day. Later on, when the cholesterol level is reduced to 210 or less, it should be possible to relax the restriction, if the intake of polyunsaturated to saturates remains proportionately high. Obviously, this discussion is an oversimplification of the problem, with the more technical details being limited or omitted for the sake of clarity.

Other Factors      

Is diet the sole cause of coronary heart disease? It would appear that diet is vitally related to atherosclerosis, but many other factors remain to be resolved. Conclusions regarding certain unsolved factors may require many, many years. Some factors may be given increased importance as investigations and research continue, whereas others may eventually be eliminated from consideration. These factors include other diseases, the sex differential, overweight, heredity and family history, emotions and stress, age, occupation, exercise, salt in the diet, tobacco and alcohol, and starches.

Cellular Respiration


             Energy is not produced directly by the Oxidation of complex molecules. It is produced when glucose or fatty acids are oxidised in the cells in a process called Cellular Respiration. Energy is released in several stages. Mitochondria present inside the cells use the oxygen entering inside for respiration and energy production. First step of the reactions is glycolysis, which after series of reactions under goes Krebs Cycle and then Electron transport resulting in the production of energy. Let's see the process of Cellular Respiration.
The first step of respiration is the conversion of glucose to pyruvic acid (Glycolysis) which is common for all the three types of respiration i.e., Aerobic, Anaerobic respiration and fermentation.
Let's see the fate of pyruvic acid in aerobic respiration.
Food In Intestine (absorbed by) ----> Blood ---> Liver (through blood) -----> tissues ----> Oxidation of food takes place

Mitochondria
Mitochondria are the sites of cellular respiration. Oxidation of food materials takes place in them. The energy released through oxidation is utilised by the mitochondria to synthesis ATP (Adenosine Tri Phosphate) which are energy rich compounds.
ATP provides energy required for various metabolic functions and reactions of the organism.



About Mitochondria
Meaning and Named by
Localization
Structure
Elementary/F1 Particles
Function
Mito = thread Chondrion = granule
Uniformly distributed in cytoplasm
Two membranes outer and inner
These are on the crests
Biological oxidation of food materials like glucose and fatty acids.
granular cytoplasmic organelle named by --> Benda
No. of Mitochondria varies with the type of the cell and its functional state width varies from 0.5 - 2 μ length is variable upto 40 μ shape – mostly granular
outer one is smooth inner one projects into crests inner chamber is filled with matrix
They are round stalked bodies They are molecules of ATP as enzymes They are responsible for oxidative Phosphorylation
Mitochondriaon synthesizes stores and releases the high energy ATP, so referred as power house of the cell


Cellular Respiration
O2, ADP + Pi (inorganic phosphate), Carbohydrates, fats are required for the respiratory activity in mitochondria.
Glycolysis: Conversion of one molecule of glucose into two molecules of pyruvic
acid.
Glucose + Pi
glucose - 6 - Phosphate + Pi Fructose - 1, 6 di phosphate 2 CH3COCOOH (Pyruvic acid)

Result of Glycolysis: 4 ATP and 2 NADH are formed 2 ATP molecules are used in this process. So, net gain is 2 ATP molecules.
 
Kreb's Cycle: Takes place in mitochondrial matrix.

2CH3COCOOH (In presence of O2)---->2Carbon Compounds Acetyl CoA ( CO2 Removed) ----> 4 Carbon Compounds Oxaloacetic acid ---->6 Corbon atoms citric acid

H+ ions of Acetyl Co A are transferred to NAD+ and FAD+ (Forming) ---> NADH and
FADH2 (large amount of energy is released).

Electron Transport
NADH and FADH2 are oxidised in the elementary particles of mitochondria where 1 Proton & 2 electrons are formed from each molecule of NADH and are ejected into the inner membrane of mitochondria. These electrons are transferred from one acceptor to another which are arranged in a chain (The energy released is used for production of ATP). These electrons and protons are finally transferred to oxygen to form water.
Note: ADP + Phosphate ( in presence of O2 Forms ) ---> ATP (Oxidative Phosphorylation)
  • A net gain of 38 ATP molecules are formed from the total oxidation of one glucose molecule through Glycolysis, Krebs Cycle and Electron transport.
  • Each ATP molecule gives 7,600 calories of energy.
  • 40% of the total energy present in the glucose molecule is converted into ATP energy.

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