Sunday, August 12, 2012

In general, why are men taller than women?

Height is determined by genetic and environmental factors. And some of the genes determining height, like the aromatase gene, are located on the Y chromosome, which is available only in the males. Therefore, the increased height. 

What is bone made of?

A typical bone has an outer layer of hard or compact bone, which is very strong, dense and tough. Inside this is a layer of spongy bone, which is like honeycomb, lighter and slightly flexible. In the middle of some bones is jelly-like bone marrow, where new cells are constantly being produced for the blood. Calcium is an important mineral that bone cells need to stay strong. 

Wednesday, August 8, 2012

How do pain killers work?


Your body is full of nerve endings in your skin and tissues. Some of these nerve endings can sense pain, like from a burn or a blow to a body part. When cells in your body are injured or damaged, they release a chemical called prostaglandin.
When you take a pain killer medicine, it keeps injured or damaged cells from making and releasing prostaglandin. When the cells don't release this chemical, it means that the brain won't get the pain message as quickly or clearly. So your pain goes away or becomes less severe for as long as the cells aren't releasing the chemical. The pain killers you take will either disrupt the signal heading from the injured area to the brain, or it will change the way your brain interprets that signal. 

What makes popcorn pop?


A popcorn kernel is actually a seed. At its center is a tiny plant embryo, a life form in its earliest phase. The embryo is surrounded by soft, starchy material that contains water. Surrounding the embryo is a hard shell. When the kernel is heated to about 400 degrees Fahrenheit, the water turns to steam. The pressure from the steam causes the kernel’s shell to explode and the starch to spill out.

Monday, July 30, 2012

Why is the black box on an airplane called so, when it is actually painted orange?


Black boxes which usually hold the clues to a plane's crash, are built strong enough to survive bomb blasts, violent impacts and intense fires.  The black box records voice and flight data. The cockpit voice recorder continuously collects data. They are actually orange in color and a very high quality heat resistant paint is used, so that they can be spotted easily even at dimly lit crash sites. They are always placed in the tail end of the flight.
The term 'black box' is generally used to describe a thing/process which is not well understood by most people, but which produces something useful or well known. The term black box is used for the data recorder on airplane, in this context for similar reaso: the crash is the mystery process recorded by the black box - once you open up the black box, the process can be understood.

Why do bulls charge at red cloth?

Bulls are colour blind, so it's not the colour that attracts them, it is the swirling motion of the cape that agitates them. Bullfighters always use a red cape, but it is probably so the crowd can see it better. The color red really has no effect on a bull.

What is the use of gravel on railway tracks?


Gravel used on railway tracks is known as ballast. As rail tracks heats and cools, there is a lot of expansion and contraction, the ballast is there to hold the track from moving. Crushed rock works best as it has countless sharp edges form the broken rocks that actually dig into the sides and bottom of the ties and hold it in place. 
It is also used to dissipate the vibration produced by trains traveling at high speeds. In effect, the gravel layer acts as a cushion and damps the vibrations so that they do not travel long distances. If the rails are laid on a solid base, these vibrations can travel long distances and lead to cracks on the base as well as on nearby buildings.

Monday, July 23, 2012

Why do cut apples turn brown?

Apple is rich in iron. When an apple is uncut, the cells of apple are not exposed to the atmospheric oxygen and remain white. However, when it is cut, the iron particles in apple is oxidized by the oxygen in the atmosphere and hence turn brown.

Why are insects attracted towards lights?

Insect's attraction to artificial light is a cruel trick caused by our innovation moving faster than their evolution. Night flying insects evolved to navigate by the light of the moon. By keeping the moon's reflected light at a constant angle, the insects can maintain a steady flight path and a straight course. Artificial lights interfere with an insect's ability to detect the moonlight. They appear brighter, and radiate their light in multiple directions. The insect simply cannot keep the light source at a constant angle, as it does with the moon. It attempts to navigate a straight path, but ends up caught in an endless spiral dance around the bulb.

Why baldness pattern more common in men than women?


Baldness is related to the testosterone level which is naturally higher in males than in females. Baldness is caused by DHT, a testosterone derivative produced in the skin, and the degree of baldness depends on the hormon receptors present at the hair follicles. DHT tends to have a harmful impact on the hair follicles tending to slow down the hair regrowth process causing balding at a much earlier age in men than for women. 
Women do go bald, but that is more due to aging and or medical conditions.

Why do chefs wear tall hats?

The chef's hat is called a "toque blanche" (French for "white hat"). It is usually shortened to just "toque" . They are worn because the health department requires restaurant employees to wear a hat or hair restraint of some sort. This prevents hair from falling into the food. A hat also can absorb perspiration from the head before it reaches the plate. The tall hat allows room for air to circulate above the chef's head as well. he white hat has come to serve as a marker of a trained professional chef. The height of the hat represents the rank of the chef.

Why do the heels of feet crack?


The skin is normally dry and may have a thick callus which appears as yellow or dark brown discolored area of skin, especially along the inside border of the heel. The thickened dry skin around the heel that is more likely to crack is often due to mechanical factors that increase pressures in that area. 
Other factors that can be involved in the cause of cracked heels include:
 - prolonged standing
 - being overweight (this increases the pressure on the normal fat pad under the heel, causing it to expand sideways - if the skin is not supple and flexible, the pressures to 'crack' are high)
 - open back on the shoes (this allows the fat under the heel to expand sideways and increases the pressure to 'crack')
 - some medical conditions or skin conditions (eg psoriasis and eczema)

Sunday, July 22, 2012

Why coastal areas are so humid?

Humidity is the presence of water vapor in the atmosphere. Due to day time heat in the sea, a lot of evaporation occurs on the surface of the water body. As humid air is heavier, it remains on the surface of the sea. During the day time, the land is warmer than the sea because of which the air is less dense in the land than at sea. Air moves from the region of higher density to a region of lower density and this causes the sea air to be blown towards the adjoining coastal regions thus bringing in a lot of water vapor and thereby increasing humidity.

Thursday, July 19, 2012

Why does reading make some people sleepy?


It really depends on where your reading and what your reading.
Reading is action characterized by rhythmic eye movement, a relaxed physical position and a focused attention. When you’re in this state, your body becomes passive and your alertness decreases unless the topic that you’re reading requires you to use your mind like mathematical calculations, deductive thinking, reasoning etc. Reading is tiresome. When reading continuously, your body exerts a lot of energy from your eyes as magnetic waves. Mental work is three times more demanding than physical work.

Wednesday, July 18, 2012

Why do people have different blood groups?


Human blood types most likely came to exist to fend off infectious diseases. The reason individual humans have different blood types is that they inherit the trait of their blood having certain antigens on the outside of the blood cells from their parents. Antigens are molecules that trigger an immune response. 
Not all human blood types have always existed. In fact, they developed over time because of genetic changes and mutations. It's thought that type A is the oldest type of blood, which then mutated into type B about 3.5 million years ago. About a million years later, type O developed. Some people also have type AB blood, which has both A and B antigens. 
Red blood cells can have A or B antigens, or both A and B antigens, or neither. Blood with A antigens alone is classified as type A, while blood with only B antigens is type B. Blood with both A and B antigens is classified as type AB, and blood with neither antigen is type O. Type O blood is known as the "universal donor" and Type AB blood is likewise called the "universal recipient". 

Monday, July 16, 2012

What Do Astronauts Eat in Space?


The main challenge with eating and drinking in space is that there is no gravity. If you let go of a piece of food in a space craft, it will drift around, not falling to the floor. Water will not stay in a cup, it will float out and hang in the air. Food crumbs may float around the spacecraft causing harm to astronauts or the equipments.
Many types of space food are dehydrated, or freeze-dried, and sealed. When the astronaut is ready to eat the space food, he can add water to rehydrate the meal so that it will be edible. Space food is provided in disposable containers that can be attached to the astronaut's meal tray, which is strapped to his lap, so that the containers do not float freely through space. 
Astronauts expend a lot of energy and endure extreme stresses on their bodies. Their dietary requirements are therefore different from those of their gravity-bound counterparts on Earth. For example, they need extra calcium to compensate for bone loss.

Why do airplane seats have to be in an upright position during takeoff or landing?

Safety is the reason airplane seats must be upright for takeoff and landing. There are two main reasons why flight attendants pester people to keep those seats up—to keep injuries to a minimum during a crash and to clear the maximum amount of space for a quick exit. Since most aircraft emergencies occur during takeoff or landing, having the airplane seats up at this time is crucial. 

Sunday, July 15, 2012

Why do some countries drive on the right and others on the left?


Which side of the road to drive on was decided long before the automobile. In the past, almost everybody traveled on the left side of the road because that was the most sensible option for feudal, violent societies. Since most people are right-handed, swordsmen preferred to keep to the left in order to have their right arm nearer to an opponent. Before automobiles, roads were meant for horse-drawn carriages. The coaches of these carriages have doors on the left side so they were driven on the left side so that alighting and embarking would be safer. During the time when the Horses were used to pull the Carriages the driver had to be situated on the right side of the carriage so that they won't hit their passengers on the rear when they use their whips. This technique was widely used in North America, and people may have started to naturally keep right because this was where the large carriages and wagons were, making riding on the opposite side rather dangerous. As postillion driving spread, more countries may have adopted the habit of keeping right for safety. No matter what side of the road one drives on, in most countries, cars are specifically engineered to drive on a specific side of the road. In countries with right side driving, the driver's seat is on the left, while left hand countries have drivers' seats on the right. In both cases, the seat positions the driver close to the middle of the road for better visibility. 

How many time-zones China has?


China is a vast country encompassing a geographic expanse of the equivalent of five time zones, yet it maintains only one time zone. This single time zone is China Standard Time, or Beijing Time, which is Greenwich Mean Time, plus 8 hours (GMT+8). China covers a range of 60 degrees longitude. It is traditional for every 15 degrees to be considered one time zone, with one-hour differentials. Northern China has an additional 15 degrees longitude, which accounts for the fifth time zone. 
The Chinese government promotes consistency, so the entire country has only one time zone. China does not observe daylight savings time. This can be inconvenient for the people living in the far eastern and western portions of the country as the sun rises and sets too early or too late.

Thursday, July 12, 2012

Why does scratching gives releif to an itch?

Itching is an unpleasant sensation of damage to cells in our skin. As a result of the damage, substances like histamine are set free and irritate the nerve fibres in the skin. These send signals to the central nervous system which provokes an itch. Itch signals are received by the same part of the brain that receives pain signals. Scratching provides a "counterirritation" that distracts the brain from the original itch. Scratching interferes with the pain signals of itch by activating pain receptors in the same area where the itch occurred. However, the relief is usually temporary. Scratching sometimes releases pain-reducing endorphins. The pain neurons become temporarily overwhelmed, which masks the itching sensation and gives releif.

Monday, July 9, 2012

Why is the Hard Drive called "C" by default?


Originally, PCs had no hard drives.  Before bootable CD drives came along, floppy drives were provided with letters A and B. Now, either the bootable CD or floppy may take A. When The hard drive came along, and logically, its partition took the letter C. Hence default drive is called "C" by default.

Sunday, July 8, 2012

Is Arithmetic and Mathematics different?

The most obvious difference is that arithmetic is all about numbers and mathematics is all about theory. Arithmetic is defined as the most basic and fundamental category of mathematics. It includes computations that involve adding, subtracting, dividing, and multiplying numbers that are real, rational, and complex. Mathematics involves studying numbers, shape, and quantity relationships. Mathematics also includes the use of not only signs and symbols, but also proofs.

Thursday, July 5, 2012

How are seedless fruits and vegetables grown?


Seedless fruits and vegetables have been developed by scientists to improve existing varieties, to create new varieties and to meet consumer demands. 
Many plants put out what are known as runners or offsets. These shoots emerge from fully mature plants, and they are designed to spread the plant across a wider area. When a plant produces particularly tasty fruits and vegetables, these offsets can be encouraged to create a plantation which is actually just a series of clones from a single plant. It is also possible to grow seedless fruits through the use of cuttings, which produce clones of the parent tree. Cuttings are produced by snipping off sections of the plant and encouraging them to grow independently. Grafting can also be used to cultivate seedless crops. Grafting is a technique most notably used with fruit trees, in which a branch from one tree is cut and attached to another fruit tree. 

Why is 'money tree' plant called so?

The plant species that is employed for the money tree plant is the Pachira aquatica. It is a plant that is native in South America’s swamp lands. The concept of calling this plant a money tree caught on in Taiwan and  other Asian countries in 1980s.  The popularity of the money tree plant can be attributed to the belief that it brings good luck and fortune.

Tuesday, July 3, 2012

Do animals cry and shed tears?


All animals with mobile eyes are equipped with a tears system that keeps their eyes lubricated and protect their eyes. Tears serve to clean the cornea and keep it moist.
While animals do not cry in the way that humans do, they do produce tears. In animals, it is virtually impossible to tell if their tears are the result of emotions or merely caused by eye irritation. Most scientists agree, however, that humans are the only animals who produce emotional tears. Animals can suffer sadness etc., but most of them aren't capable of crying out of sadness like humans do.

How do pencil erasers work?


An eraser, called a rubber in some places, is an item used to remove the marks left by pencils and some types of pens.
A pencil mark consists of graphite particles that have peeled off from the pencil point onto the paper. Erasers pick up graphite particles, thus removing them from the surface of the paper. Basically, the molecules in erasers are 'stickier' than the paper, so when the eraser is rubbed onto the pencil mark, the graphite sticks to the eraser preferentially over the paper. A single rub using an eraser sufficiently soft to reach between the fibers will pick up most of the graphite particles. Looking at the eraser you can see undamaged graphite pieces sticking to the surface.

Monday, July 2, 2012

Where does magnetic compass point at north pole?


Magnetic compass is an instrument that uses a magnetic needle that points to the magnetic north. This instrument is used for navigation.
There are actually TWO North Poles - the one at the top of the earth (Physical North) and the other which is known as Magnetic North. Magnetic North is actually in northern Canada, and that is where compasses point to. If you were standing exactly on top of the magnetic north pole, your compass would point nowhere. The magnetic needle would spin or point in random direction because its natural inclination would be to move straight down.

Thursday, June 28, 2012

Why do leaves change color, especially in autumn?


Three factors influence autumn leaf color
  - leaf pigments, length of night, and weather.
In leaf pigments, Chlorophyll gives leaves their basic green color, Carotenoids produce yellow, orange, and brown colors  and Anthocyanins gives reddish color. Both chlorophyll and carotenoids are present in the chloroplasts of leaf cells throughout the growing season. Most anthocyanins are produced in the autumn, in response to bright light and excess plant sugars within leaf cells. As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed. The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors. So the leaves look colorful in autumn.  Temperature and moisture also influence the leaf color. During sunny days, lots of sugars are produced in the leaf, which tapers off as colder days start. This in turn spur production of the brilliant colors in leaves.

Wednesday, June 27, 2012

How is sugar and jaggery different?


Both  sugar and jaggery (gur) are made from the same sources, generally sugarcane. But there is a lot of difference in their properties and benefits.
- Color :  Sugar is bright white color, whereas the color of jaggery can range from golden-yellow to golden brown, brown, dark brown like dark chocolate.
- Texture : While sugar crystals are solid and hard, jaggery is semi solid, softer than sugar and also amorphous.
- Processing : To make sugar, the syrup is treated to remove the unwanted particles, so that after condensation and crystallization, the product is white color. On the other hand, in case of jaggery, there is no treatment given to the juice and it also does not undergo the crystallization process. The sugarcane juice is boiled continuously, until thick paste is formed, after which the paste is poured into molds and blocks of desired size.
- Composition : While sugar is made only of sucrose, jaggery is made up of predominantly sucrose, mineral salts, iron and some fiber. Hence, consumption of jaggery is recommended in case of iron deficiency anemia.
- Sugar is instantly absorbed in the blood while jaggery is digested slowly. Jaggerry is also rich source of iron. It acts as a cleansing agent and cleans the lungs, stomach, intestines, esophagus and respiratory tracts.

Sunday, June 24, 2012

Why do we sneeze?


A sneeze begins with a tickling sensation in the nerve endings that sends a message to your brain that it needs to rid itself of something irritating the lining of your nose. Sneezing is a procedure of expelling the harmful bacteria and virus which has entered the body and multiply themselves during cold, allergic reactions or when dust blows on our face.The high velocity of the airflow is achieved by the buildup of pressure inside the chest with the vocal chords closed. Sudden opening of the cords allows the pressurized air to flow back up the respiratory tract to expel the irritants. This helps to remove offending particles in the nose. It is an important reflex action to remove an irritant and to keep our air passages open and free of obstructions.
People don’t sneeze when they are asleep because the nerves involved in nerve reflex are also resting.

Thursday, June 21, 2012

Is there a difference between words - smart, clever and intelligent?


Clever, Smart and Intelligent are attributes which are used interchangeably and synonymously. They express different levels of formality but essentially they may mean the same.
Smart is being quick-witted or "bright". A smart person is usually someone who is quick in thinking though not necessarily having high level knowledge in a broad base of subjects. 
Intelligence is the ability to learn, understand and make judgments or have opinions that are based on reason, and is something which you are born with i.e genetic. A person's intelligence level has to do with how well informed they are, how educated and knowledgeable they have become.
Clever people are born with above-average mental ability using their knowledge creatively. Cleverness is having or showing the ability to learn and understand things quickly and easily. 

Clever person know what works, smart person know when it works, and intelligent person knows why it works :)

Wednesday, June 20, 2012

Why does a liquid remain hot or cold for a long time inside a thermos flask?


Thermos flask consists of double walled glass bottle. The inner side of outer wall and the outer side of inner wall are silvered. The air is pumped out between the two walls of bottle to create a vacuum.
Generally, a hot substance gets cold by releasing its heat to the surroundings. Likewise a cold substance gets hot by absorbing the heat from the surroundings. The most important function of the thermos flask is to prevent the flow of heat to and from the bottle. Conduction, convection and radiation are the three processes by which heat can flow from one place to another. Thermos flask doesn’t allow heat exchange to take place. Glass is used to make up a thermos flask which is a bad conductor of heat; hence heat is prevented from escaping out by conduction. Due to the presence of vacuum within the walls, heat loss due to convection is also ruled out. Since the walls are also silvered heat is also not lost due to radiation. Due to all these reasons mentioned above, a hot thing remains hot and a cold thing remains cold for many hours.

Tuesday, June 19, 2012

Why do doctors examine the pulse of a patient?

The pulse can be felt by placing fingers on the inside of the wrist over the radical artery. When a doctor checks the pulse, heart beats are counted for a minute. Since the rate of contractions felt at the wrist would be same as the heart rate, the pulse tells us about the health of the heart. This tells the doctor about the health of the patient’s heart. The pulse rate depends on the blood requirement of the body and this indicates the pressure on the circulatory system. An irregular pulse rate indicates a fault in the normal functioning of the heart. A good practitioner of Ayurveda can simply measure the pulse of a person and understand all about the ailments in the body.

Monday, June 18, 2012

Which time zone applies to Antarctica where all time zones meet?


Since Antarctica is at the South Pole, and all of the time zones have a common point there, logically, there would be a part of Antarctica that would occupy each of the time zones simultaneously. Antarctica has no official time zones .
There is no specific time zone for Antarctica and neither could there be any. Therefore , researchers in the Antarctic regions of the earth usually use the time zone associated with their research stations. For example , since nearly all flights to Antarctica and the South Pole are from New Zealand , New Zealand time is the most commonly used time zone in Antarctica .
Some prefer to follow the time zone of their nation’s capital.

Why do ants walk in a line?


Ants are social insects. They live in big colonies and have a very organised social life. Red ants make their nests inside the walls of our houses. They generally travel large distances in search for food. In absence of any maps or navigation aids, they have to rely on other mechanisms to find their way around. 
As they walk the ants leave behind a scent that they use to trace their way to a food source or back to their home. The scent that the ants leave behind is called pheromone. The ants walk in a line because they follow the scent left behind by the leader. They are following a trail laid out by another ant that will take them to food, water or their home. As more ants travel the trail the scent gets stronger (easier to follow) and the random bumps are smoothed out making the trail straighter.
Once the food source is depleted,the returning ant will not leave any trail pheromone and hence the concentration of trail pheromone in that particular path gets faded. Thus the other worker ants stop following that path and look for a new source.

Sunday, June 17, 2012

How does soap work to clean body or clothes?


Most of the time, dirt comes in the form of grease or oil which sticks itself onto surfaces and will not come off if only water is just used. This is because oil and grease are non-polar, which means that the oil molecules are not charged and therefore are not attracted to polar substances such as water. Because of this, oil tends to stick with its own molecules or other non-polar substances. Oil and grease will stick onto plates and cutlery during cleaning, and no amount of water can completely remove it.
In order to remove oil from clothes or from your dishes with water, the oils must be made soluble by the process of emulsification. Soap is an excellent cleanser because of its ability to act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another immiscible liquid. This means that while oil (which attracts dirt) doesn't naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed. 

Thursday, June 14, 2012

Why does mosquito bite itch and produces red bump?

Most people experience some kind of skin reaction after being bitten by a mosquito. Only the female mosquito feeds on blood. When the female mosquito stabs her needle-like proboscis (a straw-like mouthpart) into our skin to suck out our blood, she injects us with her saliva. This is filled with digestive enzymes and anticoagulants, and it keeps blood flowing until she is finished with her meal. Our body reacts to the saliva by producing histamine. This makes the blood vessels near the bite enlarge, and so a pink, swollen, and itchy bump appears. When the blood vessels expand, nerves in the area become irritated by the swelling. We feel this irritation as an itchy sensation.

Wednesday, June 13, 2012

Why can't we remember most of our dreams?


Throughout our sleep we are thinking or dreaming and yet upon awakening we tend to forget most of it. Something about the way the brain/mind functions during sleep makes recall difficult. 
Dreams are basically your brain thinking while your body sleeps (subconscious). It's usually a mix up of all your thoughts, concerns, and late experiences- which is why a dream sometimes reminds you of something you forgot - like a review of a movie you saw. You can't remember your dreams because they are less of an experience than they are a thought. You only dream at a certain level of sleep, but your dreams can still last several hours. You forget your thoughts when you sleep just as fast as you do when you're awake. Most remembered dreaming occurs during a phase of sleep called Rapid Eye Movement (REM) sleep, which occurs about every hour-and-a-half. 

Tuesday, June 12, 2012

Why do we have lines on the palms of our hands?


Our hands can bend, they can stretch, they can wiggle, and they can wave! To be able to do that, the skin that covers our hands needs to be able to adjust to the changing shapes. The lines are just folds of skin that allow the hand to bend. Observe that all the lines appear at locations where our skin folds over. They are technically called 'flexion creases', and many of them are on our hands from before we are born. When our hands bend, the creases help fold the skin. A baby will have fewer, softer, lines, since it has not moved its hand as much. 
Feet are very similar in structure to hands but do not bend as much. The lines on the bottom of our feet are not as severe, because sole of feet does not have so much flexibility as hand.

Monday, June 11, 2012

Is the ice in the polar ice cap, fresh or of saltwater?

Even though the glacier ice comes from salty ocean water, the sea ice that forms in the Arctic and Antarctic is fresh water. The presence of salt lowers the freezing point of ocean water and it does freeze. However, the salt molecules are rejected back into the liquid as the ice forms, resulting in freshwater ice floating. The land ice over Greenland and Antarctica is also fresh water, and results from the accumulation of snowfall over long time periods.

Sunday, June 10, 2012

Why do we rub our eyes when we are tired?


When we are tired, our tear ducts produce less fluid, which dries out our eyes. If we are really tired, we may drift off mentally, causing us to stare. Having our eyes open for prolonged periods of time increases dryness.
When we rub our eyes, we stimulate the tear ducts, which spreads moisture over our eyes. This pressure also triggers a reduction in blood pressure, which helps us relax and get ready for sleep. 
This is the same reason we rub our eyes when we're under a lot of stress.

Why do bananas turn black when put in a refrigerator?


Green banana peels contain a plant hormone called ethylene. This is a gaseous chemical that is responsible for helping ripen the banana to yellow. At the same time, a few different natural acids are also being produced that add balance to the ripening process and make the banana sweet.
When you put a banana in the fridge, the acid production slows down because of the cold temperature and, as a result, the ripening process slows down. Yet ethylene production continues to escape, eventually breaking down the cell walls of the peel until it becomes black.

Thursday, June 7, 2012

Why does sunflower always face towards the Sun?

Facing of sunflower towards the sun is known as phototropic movement. Sunflower plant contains a growth hormone named Auxin which is sensitive to the sun-rays. This chemical accumulates on the shaded part of stem and boosts the growth of cells on the shaded part of stem. So the sunflower automatically leans in the opposite direction i.e. towards the Sun. As the direction of shade changes with the direction of the Sun, Auxin hormones also shift their own position on the stem to remain away from the sun-rays. This keeps sunflower always facing the Sun.

Wednesday, June 6, 2012

Why do we stop growing after certain age?


Our body grows with the help of proteins. The proteins get converted into amino acids during the process of digestion. The cells and tissues are produced by these amino acids. Proteins along with minerals produce and repair muscles, tissues and bones. 
Growth of our body is controlled by the endocrine glands that we have. After a certain age, the body gets the full maturity. It takes too much food and energy to keep on growing after we have hit maturity. So after maturity, the body stops growing up, because after this age the glands which are responsible for growth become less active. But there is very slow continuous growth.

Tuesday, June 5, 2012

Why are the two sides of a coin known as heads and tails?


Generally, one side has the imprint or embossing of the official head of state or an insignia or emblem and hence it is called the head side. It is the main side of a coin carrying the portrait head of the ruler or a Symbol and name of the country. Since the opposite of the head is the tail, the reverse side is naturally called 'tails'. It depicts the denomination or issue price of the coin with year and mint mark underneath. 
Technically, the heads and tails sides are known as the obverse and reverse, respectively. The tail side name possibly originated from the British ten pence coin, the reverse of which shows a heraldic lion with its tail raised.

Why does sugar dissolve faster in hot water than cold water?


Sugar dissolves by water molecules surrounding sugar molecules and separting in from the rest of the solid. When sugar is added to water, energy is used up to break apart the molecules in the sugar. The water molecules then begin to spread out to make room for the sugar. This way the sugar gets dissolved in the water.
When the water is hot, the sugar molecules break apart faster, and the water molecules move around the sugar faster. With increased temperature, the water molecules are moving more rapidly, increasing the speed at which hydrated sugar molecules are transported away from the solid, increasing the rate at which the solid dissolves. In cold water, this process is slow, hence the sugar does not get dissolved faster.

Monday, June 4, 2012

Why do we sweat on a hot day?


When the body temperature rises, the sweat glands are stimulated to secrete perspiration. It is nature's way to keep the body cool. During the process of evaporation of sweat, body heat is taken away, thus giving a sense of coolness.
Sweating is therefore the human body's primary cooling mechanism. Because this mechanism uses water, we need to replace lost fluids by drinking more fluids in hot weather. This is especially true after exercising or working in hot weather.  When we sweat, our skin and clothing become covered with water. If the atmospheric humidity is low, this water evaporates easily. The heat energy needed to evaporate the water comes from our bodies. So this evaporation cools our bodies.

Why do owls have three eyelids?

Owls are equipped with 3 eyelids. They have a normal upper and lower eyelid, the upper closing when the owl blinks, and the lower closing up when the Owl is asleep. The third eyelid is called a nictitating membrane, and is a thin layer of tissue that closes diagonally across the eye, from the inside to the outside. This cleans and protects the surface of the eye.

Sunday, June 3, 2012

Why does a wet cloth appear darker than when dry?


We see a cloth's colour by the light which hits it. For example, when white light (containing all colours) hits a green shirt, all the colours in the light are absorbed by the shirt,except green, which gets emitted. This emitted green light is why the shirt looks green to our eyes.
When the shirt becomes wet, water is absorbed in the fabric, including the outer layer of the material. When white light hits the surface of the material where it is wet, some of the light will scatter (refract) from the water. This light doesn't make it back to our eye. Less light coming from the wet region means it will look darker. Not all of the light that is emitted by the green fabricreaches your eyes now. Because there is less light coming from the wet area (some was refracted in a different direction), that area will look darker than the material around it.

Why water droplets are formed outside a glass containing cold water?

The cold water reduces the temperature of the glass. The cold glass reduces the temperature of the air around the glass. The moisture in this surrounding air gets condensed into liquid droplets. Hence we see a layer of water droplets on the outer surface of the glass.

Thursday, May 24, 2012

Why does a flame always point upwards?


Hot gas is generally less dense than cool gas. A flame is very hot gas. Gravity pulls less on less-dense gas, so hot, less-dense wants to rise above cooler, denser gas. As the flame burns on earth, it takes the oxygen from the atmospheric air and and heats the surrounding atmospheric gases. So the hot air around the flame is pushed up as it is less dense And as the air around the flame is pushed up , the air around the flame is drawn towards the flame to take the space of the lighter gases that is pushed up. The colder air surrounding is pulled down by gravity. The flame is being pressurised all around by the atmospheric gases. This results in the flame being elongated upwards. 
In space, where there is no gravity, a flame does not point upwards but will expand spherically around the source.

Why do we sometimes see double rainbow?


Rainbows are a bright spectrum of light that appears in the sky when light reflects off moisture in the air. Double rainbows are less frequent, less bright and usually sit outside the first rainbow. They occur because of a double reflection of sunlight off moisture and appear at an angle of only 50 to 53 degrees.
When refraction occurs to cause single rainbows, the light strikes and goes through moisture. Double rainbows are created in the same way except the sunlight bounces twice off the moisture before re-entering the sky.  The second rainbows are fainter than single rainbows. This is because the light has been reflected twice and had two chances to be transmitted out the back of moisture in the air. 
This second reflection inverts the colors when dispersion occurs. The region between a double rainbow is dark.

Wednesday, May 23, 2012

What is dry ice?


Dry ice is pure, solid carbon dioxide (CO2). As a gas, CO2 exists naturally in our environment.  It's called "dry ice" because it does not melt.  Dry ice goes directly from a solid to a gas in a process called sublimation.
Dry ice keeps items colder for much longer than traditional 'wet ice' because dry ice is extremely cold, -109 degrees F (-78.5° C).  Dry ice sublimates into carbon dioxide gas instead of melting, leaving no liquid mess to clean up. Dry ice is made from pure carbon dioxide that is a (recycled) byproduct of other industrial processes such as the manufacture of ethanol.
Dry ice is much colder than regular ice, and can burn the skin similar to frostbite.

Friday, May 18, 2012

Why is Pluto no longer a planet?


American astronomer Clyde Tombaugh discovered Pluto in 1930. However in 2006, the definition of a planet was changed. 
According to new rules adopted by the International Astronomical Union, a celestial body must meet the following criteria in order to qualify as a planet:
1. A planet must be round.
2. A planet must orbit the sun.
3. A planet must have "cleared the neighborhood" of its orbit. This means that as a planet travels, its gravity sweeps and clears the space around it of other objects. Some of the objects may crash into the planet, others may become moons.

Pluto follows the first two rules: It is round, and it orbits the sun. It does not, however, follow the third rule. It has not yet cleared the neighborhood of its orbit in space. Because it does not follow this third rule, Pluto is no longer considered a planet. It is called a dwarf planet.

Thursday, May 17, 2012

Why are coin banks shaped like pigs (piggy bank) ?

In earlier times, metal was expensive and seldom used for household wares. Instead, dishes and pots were made of an economical clay called pygg. Whenever housewives could save an extra coin, they dropped it into one of their clay jars.They called this their pygg bank or their piggy bank. When an English potter misunderstood the word, he made a bank that resembled a pig, and it caught on. This name caught on because the pig banks were mostly used by children, and a pig is a child-friendly shape that is easy to make out of clay. Once the meaning had transferred from the substance to the shape, piggy banks began to be made from other substances, including glass, plaster, and plastic.

Tuesday, May 15, 2012

Why do some animals eyes glow at night?


Animals, especially ones who are active at night, have a reflective surface behind their retinas.  That surface is called a tapetum lucidum and it helps them see in the dark.  Basically its job is to reflect light, like a mirror, in the eye to allow what little light there is at night to hit photoreceptors in the eye. Light passing into thetheir eyeballs bounces off from the tapetum lucidum, giving the animal the ability to reflect what little light is incoming, thus allowing it see in near darkness. Due to the reflection, their eye glow. Human eyes don't shine/glow because they don't have this layer of tapetum lucidum. 

Why wool keeps us warm than cotton?

Wool is a bad conductor of heat and its fibers can trap air in between themselves. Air is also bad conductor of heat. So, woolen clothes do not allow the heat in our body to escape, i.e, they trap the heat inside our body to keep us warm. That is why we feel warm when we wear woolen clothes. Cotton clothes allow more of this warmed air to "leak out" through the thinner fabric.

Why cannot a petrol fire be extinguished by water?

Petrol as a liquid is less dense than water. As water is thrown onto the petrol, the petrol floats on top of the water and continues to vapourise. It is the vapour which burns, slightly above the surface of the petrol. Also, if small quantity of water is poured over burning petrol, the existing temperature is so high, that the water poured on the fire evaporates even before it can extinguish the fire. 

Monday, May 14, 2012

Why spiders do not stick in their own webs?

The spiders that make webs and use their silk to capture their prey. If a fly or other insect moves into the web, it becomes entangled. There are a couple of reasons why spiders manage to stay clear of entanglement in their own web. A spider actually has very minimal body contact with its web. Its legs are covered with hundreds of little hairs that serve to decrease the total surface area the web can stick to. Spiders use a very careful walking technique with movements that let the strands of web slip off very easily. They are good groomers. Careful cleaning ensures that its legs and body are less prone to sticking, should they suffer a misstep in the web. And additionally, the hair on the legs are covered with a special chemical that prevents the web's sticky coating from adhering.

Sunday, May 13, 2012

Why does water remain cold in an earthen pot?

An earthen pot is made of mud and becomes porous with a very fine holes all over. When water is poured in the pot,  it first spreads itself on to the walls of the pot.This water percolates in the pores to the outer surface. Here evaporation of water takes place thereby producing a cooling effect. The pot becomes cool and also makes the eater inside cool. If you observe, the cool water level is lesser than the intial water level when poured.

Friday, May 11, 2012

Why do we have silent alphabets in English words?


There are hundreds of rules to help figure out how to spell and read words, but they do not work all the time. There are more exceptions than rules. :)
Silent letters show up because English has a lot of influences. Many words in the English language are derived from foreign words. English takes words and spellings from many different languages. A lot of times, when there is a silent H at the begging of a word, it comes from a rule in French language pronunciation. That’s why hour sounds like our. Silent Ks come from Old English, which was spoken in England before 1100 CE. They actually used to be pronounced, but over hundreds of years, the sound was dropped, leaving us with the words knife and knight, where we don’t pronounce the first letters. 
Since accent and pronunciation differ, letters may be silent for some speakers but not others. 

Wednesday, May 9, 2012

Why do some things melt and some things burn?


Melting and burning are actually quite different processes; melting is an example of a physical change while burning is an example of a chemical change. Most materials have high melting point. Combustion temperature determines when the material will burn.
The energy required to start the reaction (called the energy of activation) determines whether the material will melt or burn. This energy is in form of temperature or other conditions like oxygen availibilty etc. For some materials, the melting point is much higher than the combustion temperature, hence they burn before they can melt.

Why does Your Nose Run When You Cry?

Tears leave the surface of your eye by evaporating or by falling of from eye surface or by entering the tear drainage system. A thin tube drains the tears from the inner corner of the eyelids down into the nose. Therefore, when your eyes fill with tears, such as when you cry or cut an onion, most of that fluid ends up in your nose. Tears mix with mucus there and your nose runs.

Tuesday, May 8, 2012

Why does a year have 12 months?

All calendars began with people recording time by using natural cycles: days, lunar cycles (months), and solar cycles (years). Ancient Egyptians followed lunar calendar for the year. New moon occurs every 29.5 days. We have twelve months because there are twelve periods from full moon to full moon in a year. Thus ancient Greek calendar had 12 months of 30 days. The lunar calculation however when summed up, did not fit the solar cycle. This was evolved gradually to have unequal 12 months. This evolved Egyptian year was almost a quarter of a day shorter than the solar year.  Julius Caesar hired an ethnic Greek from Alexandria Egypt to create the 365 day calendar with an extra day every fourth year (leap year). We now follow Gregorian calendar.  


Why do fingernails grow faster than toenails?


The nail is an important structure made of keratin that has 2 purposes. It acts as a protective plate and enhances sensation of the fingertip.
It takes fingernails 3 to 6 months to regrow completely, while taking toenails anywhere from 12 to 18 months. The rate of nail growth is based on the length of the outermost finger bones. Therefore, fingernails grow faster than toenails and the nail of a person's index finger grows faster than their pinky fingernail. The blood supply to the fingers is almost always better than the blood supply to the toes. The rate of nail growth may reflect this.

Monday, May 7, 2012

Why does long exposure to sun lighten our hair but darken our skin?


Our skin and hair has a brownish-black pigment in it called melanin, which gives them the certain color. Our skin is a living tissue. When we are exposed to the sun the rays, the ultraviolet rays cause the skin to produce more of melanin, which helps to lessen the damage caused by radiation. Production of more melanin darkens our skin and protects it against furthern UV radiation. The lighter our skin, more likely that our skin burns because our skin can not produce sufficant amount of melanin.
Our hair on the other hand is dead and can not continue to reproduce anything. So when exposed to radiation by the sun, the hair gets bleached.  It starts to fade color since no new melanin is produced to protect the hair. The root of hair produces melanin which will give color to only the new hair growing, but not the faded hair.

Does ice melt faster in air or in water?


Ice melts when heat is transferred away from it to its surroundings. Water is denser than air, so heat is conducted away from the ice faster in water than in air. 
Ice will melt fastest in whatever delivers heat to it fastest. In general that will be water because water conducts heat and carries heat better than air. But extremely hot air, such as that from a torch, will beat out very cold water, such as ice water, in melting the ice.

Sunday, May 6, 2012

Why do veins look blue if blood is red?


Blood is ALWAYS red. Oxygen-rich blood is bright red as it leaves the heart. When it returns in veins without much oxygen, it’s still red, but it’s a deeper, darker red. But our veins look blue. Ever wonder why?
The colors we see are the result of which wavelengths of light are reflected back to our eyes. Veins appear blue because blue light is reflected back to our eyes even though veins contain deep, dark red blood.  Blue light does not penetrate human tissue as deeply as red light does. As a result, veins that are close to the surface of the skin will be more likely to reflect blue light back to the eye. The oxygen-depleted blood that veins carry also tends to absorb red light more than blue light. When the dark red blood absorbs more red light, blue light is more likely to be reflected back to our eyes.

Friday, May 4, 2012

What are wisdom teeth and why are they called so?



Wisdom teeth are the third molar teeth. They are located all the way back in the jaw, and tend to come in some time between the ages of 16 and 25, if they come in at all. For many people their wisdom teeth coming in impacts other teeth, requiring surgery to remove the wisdom teeth to allow their jaw to remain healthy. Generally infants form a first set of teeth, commonly called baby teeth, which eventually fall out and give way to the adult teeth, that will remain until old age. Wisdom Teeth come quite a bit after the full set of adult teeth have grown.
Wisdom teeth are so named because of the time they appear, generally in the late teens or early twenties, when people are  presumably "wiser" than as a child, when the other teeth erupt.

How do fish sleep?

Most of the fish do sleep.  The way they sleep is slightly different than the way humans and lots of other land animals sleep. Fish have a period of reduced activity and metabolism which seems to perform the same restorative functions as nocturnal sleep does in humans.Most scientists agree that the way fish sleep might be more like what we consider rest. The sleep of fish involves spending time staying mostly still, conserving energy.

Wednesday, May 2, 2012

What is the difference between a fruit and a vegetable?


Generally we tell apart fruits and veetables based on how they taste and how they are eaten or cooked. We think of fruits as foods that grow on trees, taste sweet, and can almost always be eaten without cooking. We tend to think of vegetables, as foods that grow in or near the ground, and are eaten after cooking, sometimes can be eaten raw too. 
According to science, a vegetable is any part of a plant that can be eaten, like leaves, stems, or roots. So vegetable is any edible part of a plant. A fruit is also the edible part of a plant, but refers specifically to the edible part of a plant that has come from its ripe flower. The major fruit and vegetable difference is that most of the fruits contain seeds, which are capable of developing into new plants and vegetables lack seeds (there are exceptions to this though).

Tuesday, May 1, 2012

Why does milk overflow when boiled but water does not?


Milk is not a simple liquid - it contains tiny globules of fat and casein which are not dissolved but suspended in water.  When heated, fat being lighter than water, floats as a creamy layer on the top and water vapor, in the form of steam bubbles, is trapped under it. Further heating results in the formation of more number of bubble. These bubbles expand and lift the creamy layer causing it to overflow. 
In the case of water, the steam bubbles break as they reach the surface. No film is formed and the bubbles of steam formed by boiling escape easily without any resistance. Hence, water does not overflow on boiling.

Why do we blink our eyes?


We blink our eyes every six seconds. Although blinking eyes ins an involuntary action, we can raise or lower the number of blinks voluntarily. Blinking our eyes automatically supplies two forms of safety to our eyes, to keep them from drying out, and to keep foreign matter from entering and irritating our eyes. The rims of our eyelids are lined with 20-30  oil-producing glands. Blinking automatically coats the eyelid and eyelashes with the lubricant it secretes, to prevent them from drying out.
When we are concentrating on a particular thing or looking continuously on a keyboard, screen, needle, etc we blink less as compare to the normal situation. This happens because our brain forgets to blink as a result our eyes feel tired. Research has shown that we blink more quickly when we are not interested in a particular task and also not taking the information inside for processing and vice versa. Some animals like the snake for example, do not have eyelids and hence cannot blink. But there is a hard film or scale over the eyes to protect them from dust and injury.

Monday, April 30, 2012

Why does hair turn grey as we age?


Each hair on our heads is made up of two parts:
 -  shaft: the colored part we see growing out of our heads
 - root: the bottom part, which keeps the hair anchored under the scalp
The root of every strand of hair is surrounded by a tube of tissue under the skin that is called the hair follicle which contains a number of pigment cells. These pigment cells continuously produce a chemical called melanin which gives the growing shaft of hair its color of brown, blonde, red, and anything in between.

Hair turns gray as people age because the follicles at the base of the hair shaft cease to produce melanin. The darkness or lightness of the hair depends on how much melanin each strand contains. Genetics is the most common cause of gray hair, but other things can contribute to graying, including a poor nutrition.

Can birds fly backwards?


Most animals can walk backwards if they want to, even though they don’t choose to do it very often. There are a few birds who can move backwards in small amounts, but only hummingbird can actually fly backwards. 

The reason a hummingbird is so good at flying backwards (as well as sideways, up, down, or even just hovering in mid-air) is because of how they use their wings. While most birds flap their wings in an up-down fashion, hummingbirds use a stroke more similar to a circle made with a twisting motion. By using this special wing stroke and being able to fly so many ways, hummingbirds can successfully approach and feed from a flower in any number of directions!

Thursday, April 26, 2012

What do B.C and A.D. (years) mean?


B.C. and A.D. are two abbreviations you usually see following years: 1,000 B.C., 1620 A.D., 2010 A.D.  Sometimes A.D. will come before the year: A.D. 400.

B.C. stands for "Before Christ".  Jesus Christ is the central figure of Christian religions. A.D. stands for the Latin term, "anno Domini" which means "in the year of the Lord". This term also refers to Jesus Christ. 1 A.D. was thought to be the year that he was born.  It was such an important and well-known event for Christians that it made sense as a starting point for a new calendar.  Any year before 1 A.D. is considered B.C.

Why do Analog Clocks show ten past ten (10:10) in advertising?


There are various speculations for setting the clock to ten past ten:
  •  Clock and watch makers normally put their logo under the number 12. So placing the hands of the clock to 10 and 2, helps to frame and show the logo.
  • Astrologers predicted that American President Mr. Abraham Lincon would die at the time of 10.15AM. So, entire Americans stopped their watches at 10.12AM 37sec in american clock tower. 
  • 10:10 makes a resemblance to a smiley face and a "V" for victory.
  • Clocks set on 10:10 time looks more symmetrical, therefore it is better for advertisement.
  • In second world war American dropped their atom bomb on Hiroshima & Nagasaki . The first bomb was dropped at 10:10 AM. In remembrance of all the victims, all unused clocks or the clocks which are presented in show-cases have the same time of 10:10. 

Tuesday, April 24, 2012

Why do some people laugh when they are tickled?


When we are tickled by someone else, the sensation causes a form of anxiety or panic, as does not knowing where we will be touched or tickled next. Certain types of laughter stem from nervous reactions like anxiety and surprise. Hence, laughter is normally an involuntary, non-aggressive response in this situation. 
The surprise and tension happens when the tickler initially strikes and the laughter is an relief and reaction to that process. The reason we do not stop after the initial touch is because we do not know what is going to happen next, so the brain is tensed in anticipation of the tickler's next movement. Our body is actually in a state of panic & doesn't know what to do. The reason we squirm is because our body is trying to escape from whatever is tickling it, not knowing whether or not it is going to cause any harm. 
The reason we do not laugh when we tickle ourselves is because the brain is already aware of what is going to happen and where, thus there is no surprise and no need for tension.

Why Do Birds Fly in V-Formation?

The most accepted reason is that the flight formation plays an aerodynamic role. It conserves the energy of birds. Each bird flies slightly above the bird in front of him, resulting in a reduction of wind resistance. The birds take turns being in the front, falling back when they get tired. In this way, the birds can fly for a long time before they must stop for rest especially during migration. This formation also enables visual communication among members of the flock and reduces the possibility of collisions and of birds becoming separated from the flock. 

Why do stars twinkle?

We see the stars through the atmosphere. Their light passes through millions of miles of constantly moving pockets and streams of air, which distort the image of the stars. Even though many stars are much larger than planets, they're so far away from us that they seem smaller, like tiny dots. The distortions make it seem as if the shining lights are moving or blinking. Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere. In outer space, where there is no atmosphere, stars don't twinkle.

Sunday, April 22, 2012

Why are most people right-handed?

Handedness is the idea that one hand is better able to perform certain tasks than the other. The most common answer for people being right-handed is that handedness is determined by the structure of our brains, which are divided into two hemispheres. One theory suggests that it's more efficient for the brain to cluster control of these two major tasks in one hemisphere rather than having it spread throughout the brain. Since the vast majority of people have their language functions centered in the left hemisphere, it follows that most people's fine motor skills would be controlled by the left hemisphere too. Each hemisphere generally controls the opposite side of the body, so the end result is that most people are right-handed. In humans, the hemispheres tend to specialize: Nearly all righties process language in the left side of the brain, while many lefties process language on the right. Aga, thisis just a proposed theory, the reasons still being explored. :)

Friday, April 20, 2012

How are diamonds formed?


Diamonds are made of carbon. All carbon containing minerals do not turn into diamond. Diamonds were formed in the earth thousands of years ago under extreme heat and pressure. This extreme heat and pressure in the earth transformed the carbon into crystals and turned it colorless. Although diamonds formed deep in the earth, volcanic activity is what brought them to the surface. 
Most diamonds discovered on the surface in mining operations are at least one billion years old. When minerals mix with diamond in nature, it gives the diamond color. The raw diamond goes through a process of exploration, discovery and then cutting and polishing to appear in the shining state as seen in jewellery.

Thursday, April 19, 2012

What is the difference between bacteria and virus?


Bacteria are tiny, one-celled living organisms that can only be seen with a microscope. They live and breed in warm, moist environments in the body and elsewhere, growing quickly and causing infection. They can reproduce independently, and inhabit virtually every environment on earth, including soil, water, hot springs, ice packs, and the bodies of plants and animals. Viruses are tiny geometric structures and cannot be seen with a microscope. They grow inside the body and produce toxins (poisons) that can cause rashes, aches and fevers. 

Bacteria carry all the machinery needed for their growth and multiplication, while Viruses carry mainly information. Viruses are not truly "living," but are essentially information that float around until they encounter a suitable living host. Outside of a living cell, a virus is dormant, but once inside, it takes over the resources of the host cell and begins the production of more virus particles. 

Wednesday, April 18, 2012

Why do I feel dizzy when I spin?


Within your inner ear you have a small organ system called the vestibular system. This system is basically made up of three tubular circles that contain fluid. The liquid moves when you move, telling your brain what position your body is in. When you spin, the liquid also spins and gains momentum. The liquid continues to spin after you stop. Imagine stirring a cup of coffee for a while - even when you stop stirring, the coffee keeps swirling around in the mug.
So while the fluid in our vestibular system keeps spinning, we keep on getting messages telling us we’re still turning around. Our eyes are trying to adjust for this movement but can’t, and are simultaneously noticing that actually, we’re standing (more or less) still. All these confusing and conflicting messages cause our muscles to move us off balance and our vision to get very mixed up - the combination of which gives us the feeling we know as dizziness! Your brain thinks you’re still spinning, so you continue to feel that everything is going in circles-until the liquid stops moving.

How is blood formed?


Blood consists of two basic components: the cellular components or the red and white blood cells. They are made in the bone marrow(a tissue in the central cavity inside almost all of the bones in the body) and some white cells in the lymph nodes. The bone marrow releases about 10-15 million red blood cells per second.  In children, the marrow of most of the bones produces blood. But in adults, only the marrow of certain bones -- the spine, ribs, pelvis, and some others -- continues to make blood. The other component is the watery part is the blood plasma and contains all the hormones, the water, the sugars, dissolved blood gasses, plasma proteins made in the bone marrow and liver and a host of other substances.
Red blood cells carry oxygen from the lungs to the tissues and carbon dioxide from the tissue to the lungs. Blood plasma transports antibodies, which protect the body from infection, carries food substances absorbed from the intestines and takes waste products to the kidneys for excretion. It also transports hormones, secreted by endocrine glands, to their sites of action.

Tuesday, April 17, 2012

Why do we cry when we are sad, angry or happy?


We have tear ducts to lubricate and protect our eyes from dust and other particles. The ducts are under the upper eyelids and produce a salty liquid(a tear)that gets spread throughout the eye after each blink. Three types of tears are generated by the human eye. Basal tears are very necessary as they keep the eyes well lubricated. Reflex tears flush out the eye when it becomes irritated. And emotional tears flow in response to sadness, distress, or physical pain.
People cry when they are feeling emotions that are beyond words. The emotion being felt can be extreme sadness, happiness, anger, frustration, resentment etc. When people are mildly happy or mildly sad, they don't usually cry. It's not WHICH emotion the person is feeling that causes crying, it's the LEVEL of emotion being felt that causes it. Emotional tears contain more manganese, an element that affects temperament, and more prolactin, a hormone that regulates milk production. Sobbing out manganese and prolactin is thought to relieve tension by balancing the body’s stress levels and eliminating build ups of the chemicals, making the crier feel better.

Monday, April 16, 2012

Why doesn't glue stick to its bottle?


Most glue in bottles consists of two components, some synthetic chemicals called polymers and a solvent that prevents the glue from drying or sticking. When glue is used to join two things together, the water in the glue evaporates, allowing the polymers to bond the items glued together. 

If we keep the glue bottle tightly closed, there is very little air captured in the bottle. Hence a very minute amount of water in the glue evaporates, which is not enough to dry up the whole bottle. The air in the bottle is usually insufficient for enough solvent to evaporate and dry out the complete glue. Hence glue bottles are recommended to be tightly closed. This is why, sometimes, a nearly-empty glue bottle might dry up. 

What are coral reefs and how are they formed?


Corals are small colony-forming marine invertebrate animals. Coral colonies are composed of these tiny, cup-shaped animals called polyps, which are related to jellyfish. Corals begin life in tropical waters as free-floating larvae. After a relatively short period of time, the larva eventually attaches itself to a hard surface and becomes a polyp. Polyps divide and form colonies.
Corals extract calcium and carbonate from seawater to build an inner skeleton that is external to the coral. This external skeleton lies underneath a thin layer of tissue. Over the years millions of coral polyps in colonies create the framework of the coral reef. Coral reefs grow very slowly.  These coral reef are very colourful and attractive. The colour, shape ordesign of coral reefs vary according to the coral-genus that produce the reef.
Deepwater and shallow water coral reef communities are rich in diversity and provide habitat for many species.

Sunday, April 15, 2012

What causes waves?


The winds cause waves on the surface of the ocean (and on lakes). Winds blowing across the surface of the ocean push water through the friction forces and build up energy. Stronger winds (like storm surges) cause larger waves. As the wind blows over the water, it tries to drag the surface of the water with it. The surface water cannot move as fast as air, so the water rises. After it rises, the water is pulled back down by gravity. The falling water's momentum is carried below the surface, and water pressure from below pushes this swell back up again. This tug of war between gravity and water pressure creates wave motion.

As a wave approaches shore, friction between the bottom of the wave and the seafloor affects the wave's motion. The lower portion of the wave slows, while the upper portion continues to travel at the wave's speed in deep water. The wave rises with the slope of the sea bottom. Because the wave's top moves faster than its bottom, it begins to curl, break and collapse. Waves can travel thousands of miles from their sources of origin. But it's the wave energy that moves, not the water.
Waves are also caused sometimes by disturbances in sea by earthquake, volacnoes etc.

Why does coke fizz when you open a new bottle or shake it?


The key ingredient of coke or any other similar product is soda, which contains carbon dioxide (CO2). When Coke is purchased in a bottles, the drink is actually under very high pressure to keep the CO2 gas in a stable, liquid state. So, bubbles and fizz cannot be seen inside an unopened Coke bottle. Opening the bottle releases this pressutre and Co2 gas starts escaping, which causes the fizz.


When you shake a can, the carbon dioxide at the top of the can is spread throughout the liquid. Most of the air makes its way to the top of the can quickly, but some become bubbles that can stick to the sides and bottom of the can for a time. These bubbles can't escape when the can is opened, but the pressure is still there. So, instead of a pop of air escaping from the opened can, the pressure is relieved by the release of a burst of liquid.

Thursday, April 12, 2012

Why is "I" always written with a capital letter?

Modern English ultimately derives from Old English, which is a Germanic language. Up until the 14th century, the first person pronoun in English was ich. When the old English "Ich" (like in German) became reduced to "i" it was thought to be too small and insignificant to be a real word and could easily get attached to the end or beginning of another word. So, "i" was capitalized to "I" to avoid misreading handwritten manuscripts. And now it is a grammar rule.

Wednesday, April 11, 2012

Why is it hot in summer and cold in winter?


This behavior is primarily because the earth's axis is tilted.
The earth revolves around the sun and completes one revolution each year, This causes various seasons. The earth is tilted on its axis, and in summer in the northern hemisphere, the northern hemisphere is tilted toward the sun. This makes the days longer, but more importantly, the suns rays hit the earth in the northern hemisphere more directly and therefore are more intense. This makes it warmer. 

When it's summer in the northern hemisphere, the southern hemisphere is tilted away from the summer, and it is winter there.During the summer, the sun's rays hit the Earth at a steep angle. The light does not spread out as much, thus increasing the amount of energy hitting any given spot. Also, the long daylight hours allow the Earth plenty of time to reach warm temperatures. During the winter, the sun's rays hit the Earth at a shallow angle. These rays are more spread out, which minimizes the amount of energy that hits any given spot. Also, the long nights and short days prevent the Earth from warming up. 

Tuesday, April 10, 2012

Do people who were born blind, see visuals in their dreams?


People who were born blind never saw anything, hence they wouldn't see dreams. They do not retain visual imagery because it was never acquired in the first place.  Dreams are not only visual in nature, its an amalgamation of one's senses. Blind people have heightened senses of hearing, touch, smell, and taste, because of their lack of sight. Their dreams are based around the senses they use most often, just as people with sight have dreams based on their sight (because we use that sense most often).  
Our dreams reflect our waking life experiences - conscious and unconscious. If someone has been totally blind since birth, they may only have auditory dreams. People whose vision has been blurred from birth dream of blurred images, people who have been deaf from birth do not hear in their dreams, and the colourblind are equally colourblind in their dreams.

Monday, April 9, 2012

How many senses do sharks have?


Sharks have 8 unique senses. They are hearing, smell, lateral line, pit organs, vision, Lorenzini, touch, and taste. The shark shares many sense that humans do such as taste and smell, but it has three senses that we do not have. The lateral line, pit organs and Lorenzini are senses that have been discovered over the past 10 to 20 years, and play an important role in how the shark functions when swimming around.

The six senses which shark use very effectively for searching and hunting their prey are - Smell, Eyesight, Electrosense, Water Pressure, Hearing and Taste. Two thirds of a shark’s brain is devoted to smell.  It can detect one drop of blood in a million drops of water, 1/4th of a mile away.  Water continually flows through their nostrils, giving them olfactory information. Sharks have colour vision and see well in dim light (because of a mirror-like layer in the back of the eye.) It is thought that sharks use the ampullae of Lorenzini as a navigational device to swim by the earth’s magnetic field. The lateral line is a sense organ used to detect movement and vibration in the surrounding water. The pit organs are used to sense temperature change.

Sunday, April 8, 2012

Why do people need to sleep?


Sleep is vital to every mammal, bird, reptile, amphibian and fish on the planet. Scientists have explored the question of why we sleep from many different angles. Various reasons thought of are:

1 - Sleep enables the body to rest; in contrast to the highly active anabolic state that dominates during waking hours. It helps replenish fuel, which is burned while awake
2 - The primary function of sleep is to reduce an individual’s energy demand and expenditure
3 - During sleep, the body has a chance to clear adenosine (which is responsible for feeling of tiredness) from the system, and, as a result, we feel more alert when we wake up.
4 - Humans sleep to dream. Dreams allow the mind to file away important memories (including new skills) and discard unwanted information at the end of a busy day. Sleep might also be a time for your brain to do a little housekeeping.
5 -  Inactivity at night is an adaptation that served a survival function by keeping organisms out of harm’s way at times when they would be particularly vulnerable.
6 - Sleeping protects all animals from attack during the night, because they sleep in a safe, dark place out of reach from predators.
7- Sleep helps the body to heal, by dedicating energy to repairing the immune and nervous systems


The real reason for sleep could be any combination of these ideas :)

Wednesday, April 4, 2012

How Do Fish Get Their Oxygen?


Fish have gills. The gills work exactly the way human lungs work, except that oxygen is absorbed from water instead of air. When a fish opens and closes its mouth, it is actually pumping water back through the gills and is thus breathing. The fish allows water which contains dissolved oxygen, to pass into its mouth and over its gills. These are rich in blood vessels and also have a large surface area. The oxygen from the water passes into the blood of the fish by diffusion, and waste carbon dioxide passes out the same way.

As long as there is plenty of oxygen dissolved in the water, the fish can extract enough through its gills to gain enough oxygen for cellular respiration. Fish do get in trouble if the oxygen content of the water falls. When fishes are taken out of water, they suffocate, because their gills collapse and they are unable to absorb oxygen.

Tuesday, April 3, 2012

What causes hiccups?


A hiccup is an involuntary action involving a reflex arc over which we have no control. Hiccups are caused by a spasm in the diaphragm.The diaphragm is the muscle that separates the chest from the abdomen and has a key function in breathing.

The diaphragm almost always works perfectly. When you inhale, it pulls down to help pull air into the lungs. When you exhale, the diaphragm relaxes and air flows out of the lungs back out through the nose and mouth. But sometimes the diaphragm becomes irritated. When this happens, it pulls down in a jerky way, which makes you suck air into your throat suddenly. The sudden rush of air into the lungs causes the epiglottis to close, creating that hic sound.

How is bulletproof glass made bulletproof?


Bulletproof glass is a type of glass that is resistant to being struck by bullets. The correct term for "bulletproof" glass is bullet resistant. Basically it is layering of a polycarbonate material (usually consisting of products such as Armormax, Makroclear, Cyrolon, Lexan or Tuffak) between pieces of ordinary glass in a process called lamination. This process creates a glass-like material that is thicker than normal glass. The strength and durability of bullet-resistant glass depends on how it is made and the thickness of the final product. 

The use of plastic in the laminate provides impact-resistance. A bullet fired at a sheet of bullet-resistant glass will pierce the outside layer of the glass, but the layered polycarbonate-glass material is able to absorb the bullet's energy.  The ability of bullet-resistant glass to stop a bullet is determined by the thickness of the glass. A rifle bullet will collide with the glass with a lot more force than a bullet from a handgun, so a thicker piece of bullet-resistant glass would be needed to stop a rifle bullet as opposed to a handgun bullet.