Thursday, July 30, 2009

[Biology Form 4] Stage In Meiosis

  1. Anaphase II
    • The sister chromatids are pulled apart and head towards opposite ends of the cell.

  2. Prophase I
    • The homologous chromosomes, which are visible under a microscope, appear short, dense and thick. Each chromosome forms its own set of sister chromatids. The homologous chromosomes exist as two tetrads with a total of eight chromatids altogether. Crossing over may occur between non-sister chromatids of the homologous chromosomes.

  3. Telophase I
    • Spindle fibres disappear. The cell divides into two, each having two chromosomes each. The sister chromatids for each homologous chromosome are still present and attached to a common centromere.

  4. Telophase II
    • Each end of the cell now has two chromosomes. The nucleoli and nuclear membranes re-form. This stage is followed by cytokinesis.

  5. Anaphase I
    • The homologous chromosomes separate and move towards opposite ends of the cells.

  6. Prophase II
    • There are now two chromosomes, each with their sister chromatids present, in each of the two haploid cells. The chromatids thicken and shorten. The nuclear membrane around them disappears again and the chromatids are free to move.

  7. Metaphase II
    • The sister chromatids align themselves at the imaginary centre of the cell.

  8. Metaphase I
    • The homologous chromosomes, together with their chromatids, align themselves at an imaginary line along the centre of the cell.
***
English ~ Bahasa Melayu
anaphase
~ anafasa

cell division ~ pembahagian sel
chromosome ~ kromosom
cytokinesis ~ sitokinesis
daughter cell ~ sel anak
interphase ~ interfasa
metaphase ~ metafasa
parent cell ~ sel induk
prophase ~ profasa
telophase ~ telofasa
***

Wednesday, July 29, 2009

Making Life

It used to be that the idea of copying people was the stuff of science fiction. But now, cloning is a science.

About 80 years ago, Aldous Huxley wrote a bestseller called Brave New World. In his futuristic novel, everyone on earth is cloned and conditioned to be the same.

At the time Huxley was writing the novel, doctors were only finding out about blood types, vitamins, and drugs like penicillin. Cloning was as impossible as space flight then!

Cloning is a natural phenomenon. Plants like Quaking Asp, Japanese Yellow Rose, and Wisteria reproduce by making exact copies of themselves.

Bacteria, algae, and single-celled organisms such as paramecia and amoebas also reproduce by cloning. Some starfish also have this ability.

Cloning happens naturally when mammals like us give birth to identical twins. However, in this age, artificial cloning is becoming a science.

Farmers clone fruits and vegetables like grapes and potatoes to guarantee top taste and quality. After the scientists in Scotland successfully created Dolly the sheep in 1996, many hope livestock will be cloned soon too.

Others are excited at the thought of cloning endangered species. Although there are clear advantages of cloning, not everyone is happy about this new technology.

Critics warn that playing god has many dangers since we still do not quite understand how nature works.

If cloning becomes as easy as that depicted in Brave New World, would you be in favour of copying sheep, salmon, and may be people?

Dolly the Sheep remains are exhibited at the
Royal Museum of Scotland.

Tuesday, July 28, 2009

[Science Form 2] Different Stages For Water Treatment

  1. Filtration
    • Here, the remaining substances and sediment pass through layers of sand filters and are removed.

  2. Disinfection
    • In this tank, a small quantity of chlorine is added to the water to kill any remaining bacteria. A small amount of fluoride is also added to the water to help prevent tooth decay.

  3. Coagulation
    • From the reservoir, water is pumped into this tank and mixed with slaked lime and alum. Alum makes the fine solid particles stick together and form larger solid lumps, and slaked lime reduces the acidity of the water.

  4. Reservoirs
    • River water is pumped here and left for several days. During that time, sunlight kills most of the dangerous bacteria in the water. Mud, silt and other suspended substances will sink to the bottom and a metal screen removes large solid particles from the water.

  5. Storage
    • Water that has been treated enters these tanks before being pumped into the supply ponds, which are usually found on hilltops or at higher levels. From the supply ponds, water flows through pipes to houses.

  6. Sedimentation
    • The water then flows very slowly into these tanks, where the larger lumps sink to the bottom of the tank and are then removed.

Monday, July 27, 2009

[Science Form 2] Water

Water is perhaps the most important nutrient in our diets. In fact, a human adult needs to drink approximately two litres (8 glasses) of water every day to replenish the water that is lost from the body through the skin, respiratory tract, and urine.

However, 99.7% of the Earth's water supply is not usable by humans. This unusable water includes salt water, ice, and water vapour in the atmosphere.

Only fresh water, which is contained in rivers, lakes, and underground sources, can be used for human consumption. Furthermore, many freshwater sources are not suitable for human to drink.

Water containing dangerous microorganisms and large amounts of industrial waste or agriculture chemicals (eg pesticides) can be toxic and unfit for drinking. Hence, humans have a great need for a reliable source of clean fresh water for drinking.

In addition to the water needed for drinking, other uses of fresh water include household use (eg cooking and cleaning), industry, agriculture (eg irrigation), and recreation.

Hence, the quality of fresh water supply is important for virtually every aspect of our lives. Water that is supplied for domestic use must be treated to ensure it is clean.

The water supplied must meet the National Guidelines for the Quality of Drinking Water (1983), which is based on the World Health Organisation (WHO) Guidelines for the Quality of Drinking Water (1984).

Saturday, July 25, 2009

Air Pollution

We breathe in and out between 15 to 25 times a minute, inhaling between 11 and 13 cubic metres of air each day.

Every time we breathe in, our lungs take oxygen from the air and pump it into our body. The oxygen helps cells convert food into energy.

When we breathe out, the body washes out carbon dioxide. If the air is clean, everything work beautifully. Unfortunately, the way we live causes air pollution.

Burning fossil fuels for energy, manufacturing, getting rid of rubbish and using chemical fertilisers on farms all release toxins such as unburned hydrocarbons, carbon monoxide, sulphur dioxide, nitrogen oxides, ozone and lead.

Air pollution chokes up the lungs, causing breathing difficulties. Long-term exposure causes respiratory illnesses like asthma and bronchitis, heart disease and cancer.

The World Health Organization (WHO) warns that air pollution kills 2.4 million people annually. Bad air kills more people than car accidents!

The main causes of air pollution include burning fossil fuels for power and transport. Another big problem caused by farmers in Malaysia and Indonesia who burn forests to clear land for crops.

This means that every year in August and September, pollution from this "slash and burn" system causes people from Myanmar to Singapore to stay indoors.

Air pollution isn't a local problem - it's everyone's problem. Air pollution isn't just smelly, it can kill us.

Info:
  1. The Pollution Standard Index (PSI) calculates how many pollutants are in the air.

  2. A PSI reading of over 400 means hazardous!

  3. Trapped air pollution from coal fires killed 4,000 people in six days during the Great Smog of London in 1952. Around 8,000 more died during the following months.

  4. An industrial gas leak in 1984 in Bhopal, India, killed more than 2,000 people instantly, 6,000 in the following weeks, and injured between 150,000 and 600,000 more.

Wednesday, July 22, 2009

English Teachers In Rural Areas To Get Extra Incentives

The Star

SEREMBAN: English teachers will be given additional incentives to teach in rural schools, said Deputy Prime Minister Tan Sri Muhyiddin Yassin.

He said these incentives would be over and above those already accorded to teachers currently serving in rural areas.

“We have no choice but to do this as the command of English among pupils in rural schools is poor,” he said.

Muhyiddin said the ministry had yet to finalise the additional incentives.

He said the ministry would also send the best English teachers to these schools to help pupils.

“The ministry has in principle agreed to place the best English teachers in these schools. Good English teachers will be given priority if they want to move to these schools,” he said.

Muhyiddin said the concept would be similar to “Teach For Australia” where good teachers volunteered to serve in remote areas to help pupils who did not have access to facilities common in urban areas.

“We will model our programme after the one in Australia. Teachers must be prepared to make sacrifices and we will in return grant them additional incentives,” he said.

Since 2007, teachers posted to remote areas were given a special allowance of either RM1,500, RM1,000 or RM500 depending on the location they were in.

He was speaking to reporters after opening the National Headmasters’ Education Convention and the National Headmasters Council delegates conference here.

Muhyiddin said the ministry would also set up special English laboratories and encourage English literature in schools.

Another measure is to get retirees to teach.

“We are also looking at the content of the curriculum to ensure the teaching of English is effective,” he said adding that teachers would also be encouraged to use teaching aids such as the linguaphone.

(Linguaphone is one of the world’s leading language training provider of self-study and assisted learning language training solutions).

On the additional 13,000 English teachers the ministry hoped to recruit in the next few years, he said most would be from public and private universities and language institutes.

He said less than 10 per cent would be foreign teachers.

English Teachers For Pre-schools

NST
2009/07/21
Hamidah Atan

Pre-schools will be part of the national education system and will be provided with trained English teachers, deputy Prime Minister Tan Sri Muhyiddin Yassin announced this morning.

The education minister observed that students in such pre-schools learnt basic English in less than a year.

“The children were able to study and speak in English. My idea is that we should make learning of English at pre-schools a thrust in the early learning process. We will, therefore, add pre-schools to our education system,’ he told 3,000 educators, teachers and ministry officials at the Putrajaya International Convention Centre yesterday.

The meeting was part of efforts to explain the government's decision to revert to the teaching of science and mathematics in Bahasa Malaysia.

[Science Form 2] Protecting Our Water Resources

Conservation is the sustainable use and management of natural resources, including wildlife, water, air, and earth deposits. Natural resources may be renewable or non-renewable.

The conservation of water involves ensuring that is not consumed faster than it can be replaced and ensuring that sufficient quantities are maintained for future generations to utilise.

Preservation, in contrast to conservation, attempts to maintain natural resources in their present condition. This is due to the concern that mankind is encroaching onto the environment through farming, industry, housing, tourism and other human developments, and that we are losing too much of what is 'natural'.

Our water resources are part of a fragile system, which is potentially at risk. Generally, conservation and preservation of water quality takes place in two arenas: surface water quality - lakes, streams, rivers and ponds - and groundwater quality.

A combination of poor soils unsuitable for septic systems, a high water table, and an increasing amount of rural development may begin to threaten the quality of an area's water supply.

Specific regulations, such as those pertaining to soil erosion and sedimentation control practices, protection of wetland areas, increased water body set backs, the use of greenbelts or buffers, and density reductions are among the techniques that can assist in protecting water quality.

In the long run, it is cheaper to protect our water resources than it is to try to restore them.

Monday, July 20, 2009

[Science Form 4] Emissions That Stabilise

A radioactive substance with an unstable nucleus gains stability by emitting rays. This process is known as disintegration or radioactive decay.

The rays emitted can be in three forms: alpha rays, beta rays and gamma rays. All three rays may not be emitted at the same time for each disintegration.

In the process of decay, energy is lost and the decayed atom forms a new stable atom.

Alpha (α) decay:
An α-particle consists of two protons and two neutrons, or a helium nucleus. When a substance undergoes decay and emits α rays, the rays cannot penetrate even a piece of paper.
An example of an α decay: Pu-239 -> U-235 + α

Beta (β)- decay:
A β-particle has the same mass and charge as an electron. In a β decay, a neutron is converted to a proton and a negative charge called β-particle is released. The β-particle can be stopped by a sheet of aluminium.

Gamma (γ) decay:
Gamma rays are high-power electromagnetic waves whose penetration power is high and can only be blocked by a thick lead or concrete.

***
nuclear fission - pembelahan nukleus
nuclear fusion - pelakuran nukleus
nuclear reactor - reaktor nuklear
penetration power - kuasa penembusan
radioactive decay - pereputan radioaktif
***

Friday, July 17, 2009

[Chemistry Form 4] Acid Meets Base

One easy way to distinguish acid and base from one another is through indicators. An example is the litmus indicator.

Also, many natural dyes found in fruits vegetables, and flowers can act as indicators. For example, red cabbage extract is red in an acidic solution and blue in a base solution.

When an acid reacts with a base, the reaction yields water and an ionic compound known as salt. This acid-base reaction is called a neutralisation reaction.

***
Indicator: Litmus
Acid solution: RED
Neutral solution: PURPLE
Alkali solution: BLUE

***
Indicator: Phenolphthalein
Acid solution: Colourless
Neutral solution: Colourless
Alkali solution: PINK

***
Indicator: Methyl Orange
Acid solution: PINK
Neutral solution: ORANGE
Alkali solution: YELLOW

***
Indicator: Bromothymol Blue
Acid solution: YELLOW
Neutral solution: GREEN
Alkali solution: BLUE

***
Indicator: Cresol Puple
Acid solution: YELLOW
Neutral solution: GREEN
Alkali solution: PURPLE

***

Wednesday, July 15, 2009

Discovering Radioactive Elements

Marie Curie discovered the nature of radioactive elements - but it killed her.

In 1896, French scientist Henri Becquerel discovered that uranium salts gave off energy. But he couldn't figure out exactly what was going on.

Marie Curie, a Polish scientist living in France, called these rays "radioactivity". Marie's husband Pierre Curie was a noted chemist. Working together, the Curies discovered two other radioactive elements in 1898: polonium and radium.

By 1903, they worked out what was happening. Certain types of atoms are unstable. They decay over many years and eventually become different and stable elements.

For example, uranium-238 decays into thorium-234 over 4.5 billion years. It then takes about another 341,000 years to turn into a stable element called lead-206.

While the nucleus is changing, invisible radioactive radiation is released. As these rays carry a lot of energy, they can be very useful - or very dangerous.

Positive uses include using radioactive radiation to kill cancer cells. This is called "radiotherapy". It's also used to sterilise medical equipment, detect blood clots, and to treat food.

But radioactive radiation can also kill and mutate body cells, causing internal bleeding, infertility, cancer and many other health problems.

Back in the early 1900s, nobody realised how dangerous radioactive elements are. Marie Curie died as a result of leukaemia caused by the action of radiation.

Facts:
  1. Marie Curie was born Marie Skodowska on November 07, 1867 in Warsaw, Poland.

  2. Marie Curie won the Nobel Prize twice. In 1903, she shared the Nobel Prize for Physics with Henri Becquerel and Pierre Curie. She was also the sole winner of the 1911 Nobel Prize for Chemistry.

  3. Pierre Curie was killed in a street accident in 1906.

  4. Irradiation involves the use of radioactive radiation to kill bacteria in food.

  5. A Geiger Muller counter detects radioactive radiation. A sphygmomanometer measures blood pressure.

Tuesday, July 14, 2009

[Science Form 3] Course Of Nature

Menstruation is the blood discharge from the uterus through the vagina of a female every month. A menstrual cycle takes an average of 28 days, and begins 14 days following ovulation.

Ovulation is the release of a mature ovum from the ovary. The ovum travels into the uterus and is ready for fertilisation. Usually, ovaries take turns to release the ovum.

The fertile phase is the period in which ovulation occurs.

Changes in the males during puberty

When a baby boy is born, he has all the parts of his reproductive system in place, but it is only when he reaches puberty that he is able to reproduce.

Puberty usually begins when one is nearing the ages of between 10 and 14. The pituitary gland, which is located in the central part of the brain, secretes hormones that stimulate the testicles to produce testosterone.

The production of testosterone brings about several physical changes. During the first stage of male puberty, the scrotum and testes grow larger.

Then, the penis becomes longer, and the seminal vesicles and prostate gland start to grow. Hair begins to appear in the pubic are and later, on the face and underarms.

During this time, the voice also deepens. A male who has reached puberty produces millions of sperm cells every day.

Changes in the females during puberty

When a baby girl is born, her ovaries contain hundreds of thousands of eggs, which remain inactive until puberty begins.

At puberty, the pituitary gland starts making hormones that stimulate the ovaries to produce female sex hormones like estrogen.

The secretion of these hormones causes a girl to develop into a sexually mature woman. The hormones also stimulate physical development, such as growth and breast development.

Usually, a girl gets her first menstrual period about 2 to 2.5 years after her breasts begin to develop.

Menstrual cycle

[Science Form 4] Twins

Identical Twins
  • Formation: The fertilisation of an ovum by a sperm forms a zygote, which divides into half and produces two embryos.

  • Placenta: Share the same placenta in the mother's uterus.

  • Genetic make-up: Have the same chromosome make-up.

  • Physical appearance: Usually have similar physical appearances.

  • Sex: Are of the same sex.

Non-identical Twins
  • Formation: The fertilisation of two ova by two sperms, separately.

  • Placenta: Have separate placentas in the mother's uterus.

  • Genetic make-up: Have separate sets of chromosome make-up.

  • Physical appearance: Usually have different physical appearances.

  • Sex: May be of different sexes or the same sex.

[Science Form 1] Physical Appearance & Behaviour

A property describe the physical appearance and behaviour of an object.

Some properties of matter include: size, shape, colour, texture, reactivity, melting point and boiling point.

Below are the physical properties of each state of matter.

Solid
  • Shape: Fixed/definite.
  • Volume: Fixed/definite.
  • Density: High.
  • Compressibility: Not easily compressible.

Liquid
  • Shape: Indefinite (liquids take the shape of the part of the containers they occupy).
  • Volume: Fixed/definite.
  • Density: High.
  • Compressibility: Not easily compressible.

Gas
  • Shape: Indefinite (gases take the shape of their container).
  • Volume: Indefinite (gases take the volume of their containers).
  • Density: Low.
  • Compressibility: Easily compressible.

Monday, July 13, 2009

[Science Form 2] Two Important Solutions

Acids and alkalis are two important kinds of solutions.

Acid comes from the latin word acidus, which means "sharp" or "sour". Some of the acids can be found in:
  • Lemons/lemon juice, which contains citric acid,
  • Oranges, which contain ascorbic acids,
  • Ant and bee stings, which contain methanoic acid,
  • Tea, which contains tannic acid,
  • Soft drinks, which contain carbonic acid,
  • Vinegar, which contains ethanoic acid, and
  • Our body, which contains small compounds called amino acids.
There are different strengths of acids. The number of H+ ions formed in the solution determines the strength of an acid.

Examples of strong acids: hydrochloric acid, sulphuric acid and nitric acid.

Examples of weak acids: ethanoic acid, citric acid and carbonic acid.

Alkali comes from the Arabic word al-qaliy, which means "the ashes". Alkalis are present in many cleaning substances used in our homes today, especially in kitchen cleaners like oven spray, floor cleaners and creams for sinks.

Kitchen cleaners are alkaline because they contain ammonia or sodium hydroxide, which attack grease. Other common alkalis include sodium hydroxide, potassium hydroxide, calcium hydroxide and ammonia.

There are different strengths of alkalis. The number of OH- ions in the solution determines the strength of an alkali.

Some examples of strong alkalis are calcium hydroxide, sodium hydroxide and potassium hydroxide, while the most recognisable and common weak alkali is ammonia.

[Science Form 2] Acids vs Alkalis

Acids
  • Taste: Sour.
  • Touch: Like water.
  • Tested with litmus paper: Turn blue litmus red.
  • pH value: From 0 to less than 7.
  • Reaction with metals: Form hydrogen and a salt.
  • Reaction with carbonates: Form a salt, water and carbon dioxide.
  • Reaction with ammonium compounds: No reaction.

Alkalis
  • Taste: Bitter.
  • Touch: Soapy.
  • Tested with litmus paper: Turn red litmus blue.
  • pH value: From above 7 to 14.
  • Reaction with metals: No reaction.
  • Reaction with carbonates: No reaction.
  • Reaction with ammonium compounds: Give off ammonia gas.

Note: Strong acids and alkalis are corrosive and dangerous
.

Friday, July 10, 2009

Water Waves

Burning coal, oil and gas for fuel causes lots of pollution. Now scientists think the sea might give us clean power.

When breezes touch the surface of the ocean, waves appear. Mild winds produce low waves. But big winds can create waves that are 18m high - that's as tall as a six storey building.

We power cars, factories, air conditioning and other systems by burning fossil fuels. But burning oil, gas and coal causes pollution. Fossil fuels are also very expensive.

In the 1970s, scientists began to look for renewable, non-polluting energy sources. Today, there are several methods to harvest energy from the sea.

The Oscillating Water Column System (OWS) gathers the energy of waves breaking onto the shore. Engineers arrange a series of hollow pipes just under the water line. When the waves run in and out of the pipes, they create a stream of moving air. This movement turns a turbine and generates electricity.

The buoyant moored system is a type of rafr that floats on the ocean's surface. When waves move it up and down, the energy of this movement turns turbines to create electricity.

Wave farms do have some drawbacks. First, these projects take up a lot of space. Also, they need to be built with the strongest materials to survive corrosion and storms. This can be expensive.

But as fuel prices increase, more wave farms are built. Scotland and Portugal now have commercial wave farms. May be, we may have one in Malaysia soon too.

** How Wave Energy Works at science.howstuffworks.com/wave-energy.htm has great diagrams that show oscillating water column systems and buoyant moored systems. The also explain pros and cons of wave farms in detail.


Information:
  • The top of a wave is called the crest or peak.
  • The lowest part or hollow of a wave is called the trough.
  • No two ocean waves are exactly alike.
  • Tsunamis are not caused by wind but by geological changes like earthquakes.

Joke & Riddle
  1. What lies at the bottom of the sea and shakes?
    A nervous wreck.

  2. What has no beginning, end or middle, and touches every continent?
    The ocean.

Thursday, July 09, 2009

[Science Form 1] Basic Components Of Air

Nitrogen (N2)
The rather non-reactive nature of nitrogen balances the active nature of oxygen in air. It is also converted to plant nutrients by lightning and certain soil bacteria. Nitrogen is important to life processes. It is the backbone of amino acids, which are the building blocks of protein for all living things. Without nitrogen, even plants cannot maintain their structures.

Oxygen (O2)
Highly reactive; it is needed by all living things for respiration, that is to metabolise food into energy and excrete carbon dioxide gas. Without oxygen, we would be dead in minutes!

Inert Gases
Totally non-reactive gases like argon (Ar) 0.94%, hydrogen (H) 0.01%, neon (Ne) 0.012%, helium (He) 0.0005%, krypton (Kr) 0.0001%, xenon (Xe) 0.000009%.

Carbon Dioxide (CO2)
This gas is a product of respiration & combustion. Plants take in this gas through their leaves, keep the carbon portion of it and excrete the oxygen back into the environment through a process called photosynthesis. This gas has the ability to absorb radiated heat and thus, helps to keep the atmosphere warm.

Wednesday, July 08, 2009

Mathematics and Science To Be Taught In BM, Vernacular Languages

The Star

KUALA LUMPUR: The Cabinet has decided that the medium of instruction for Maths and Science will revert to Bahasa Malaysia in national schools and mother-tongue languages in national-type schools from 2012 onwards.

The reversal of the Teaching of Math and Science in English (PPSMI) policy will be done in stages, Deputy Prime Minister Tan Sri Muhyiddin Yassin said on Wednesday.

He however added that there will be greater emphasis on learning the English language.

English literature will be re-introduced, as will subjects on grammar and composition.

Beginning 2012, students in Year One and Year Four in primary schools, and Form One and Form Four in secondary schools, will learn Math and Science in Bahasa Malaysia.

The change will not affect those in Form Six and Matriculation.

The two subjects will be taught in two languages until 2014 for other students, he said.

“The gap between rural and urban students has widened since PPSMI started.

“Only 19.2% of secondary teachers and 9.96% of primary teachers were sufficiently proficient in English,” he said, explaining the Government’s decision to revert to the old system.

On efforts to emphasise the learning of English, the number of English teachers would be increased by 13,933 -- retirees would be hired, as well as foreigners if need be.

Primary schools will also increase English classes by 90 minutes a week.

There have been calls from various groups for the policy to revert to before 2003, when the subjects were taught in Bahasa Malaysia in national schools, and either in Chinese or Tamil in national-type schools.

The issue has seen a rare alliance between Malay and Chinese educationists, who are against the switch, although there are also calls by many parents and entrepreneurs for English to be maintained.

[Science Form 1] Other Components Of Air

The air in our atmosphere has some variable components to it as well. These variable components include water vapour, dust particles, and ozone. Although these are found in small amounts, they can have significant effects on weather and climate.

Water Vapour
The amount of water in the atmosphere varies between 1% to 4%. Why is such a small amount such a big deal? Water vapour is the source of all clouds and precipitation, and often that is the most common reason people think of for water. But water does other things too. It has the ability, like carbon dioxide, to absorb heat energy given off by the earth. It can also absorb solar energy. When water changes from one state to another, it absorbs or releases heat. This heat is often called latent (hidden) heat. This is the energy source that helps drives a lot of storms.

Dust
Dust is much more than just little specks of dirt. It includes microscopic particles that are invisible to the naked eye, including pollen, spores, and seeds. So why is dust a big deal? It acts as surfaces where water can condense or group together, forming clouds from which water droplets can grow large and fall to the ground as snow or rain. Without dust, you could not have clouds or fog. Dust can also absorb or reflect incoming solar radiation. When dust in the atmosphere is high, such as during the haze, the amount of sunlight reaching the earth's surface will decrease. Dust can also contribute to scattering light, giving rise to more orange and red sunrises or sunsets.

Other Gases
Methane, sulfur dioxide, hydrogen, nitrous oxide, nitrogen dioxide, iodine, carbon monoxide, ammonia.

Microorganisms
Bacteria, fungi, viruses.

Ozone
Ozone is a form of oxygen that combines three oxygeb atoms into one molecule (O3). There is very little of this gas in the atmosphere, and it is concentrated in the stratosphere. Ozone absorbs ultraviolet (UV) radiation, and without it the earth would be uninhabitable. There may be other components depending on the quality or condition of the air.

Monday, July 06, 2009

[Science Form 2] Neutralisation

The process in which an acid reacts with an alkali to form a neutral solution containing a salt and water is called neutralisation.

As an acid is added to an alkali, the pH of the solution decrease. The end point of neutralisation is when pH value of the solution is 7. When this happens, it means that the alkali has been neutralised.

The balance of acids and alkalis is crucial for our good health and for our environment. If one dominates too much over the other, all sorts of things can go wrong and life on earth would be in peril.

Acid rain, fish deaths from acid rain, dirty swimming pools, Legionnaire bacteria outbreaks and indigestion are examples of acids and alkalis being out of balance.

The following are the examples of the application of neutralisation in our daily life:
  1. Shampoos are usually slightly alkaline. They neutralise the acidic oil that the skin secretes to keep our hair healthy and strong.

  2. Hair conditioner, which is slightly acidic, neutralises the residue of shampoo on the hair and makes the hair smooth and shiny.

  3. Bee stings are acidic. They can be treated with bicarbonate powder, which is a weak alkali.

  4. Toothpastes are alkaline. They neutralise the acid produced by bacteria that act on the food in our mouth.

  5. Plants grow well in soil that is neutral. Farmers add slaked lime to reduce the acidity in the soil.
Facts:
  • The plant hydrangeas only produces pink or white flowers in an alkaline soil, and blue flowers in an acidic soil.

  • In order to digest food and kill the kinds of bacteria and viruses that come with the food, the inside of our stomach is acidic. As we drink more alkaline water; more hydrochloric acid is secreted to maintain the acidic pH value in our stomach.

[Science Form 1] The Air & It's Component

The earth is surrounded by a thick envelope of air called the atmosphere.

Air takes up space, has weight, is made of a mixture of different gases, changes from place to place, and has altitude.

Below is the component and its percentage for the mixture of different gases that make up the earth's atmosphere:
  • Nitrogen - 78%
  • Oxygen - 21%
  • Carbon Dioxide - 0.04%
  • Argon - 0.94%
  • Hydrogen - 0.01%
  • Neon - 0.012%
  • Helium - 0.0005%
  • Krypton - 0.0001%
  • Xenon - 0.000009%
The composition of air is not constant. It can vary from time to time and place to place.

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