Friday 29 January 2016

Wajah Anda Mirip Siapa?

Seringkali kita mendengar orang memperkatakan samada wajah seseorang itu lebih mirip wajah ibu atau bapanya  ataupun kekadang ada juga yang mengatakan wajahnya menyerupai gabungan kedua-dua wajah ibu bapa mereka ataupun juga tidak langsung menyerupai wajah ibu atau bapa mereka. Tetapi, mengapa ini terjadi?

Jawapannya ialah 'genetik'. Genetik adalah ciri-ciri perwarisan dalam semua benda hidup yang bukan  hanya menentukan rupa wajah  malah ia merangkumi segala-galanya dari warna rambut sehingga jenis kumpulan darah pada manusia. Gen yang kita warisi berasal daripada gabungan gen-gen induk iaitu ibu dan bapa kita yang mana gen yang mereka warisi berasal daripada gabungan gen-gen daripada ibu dan bapa mereka atau datuk dan nenek kita.

Apabila DNA daripada ibu dan bapa kita bergabung, ia akan membentuk satu set gen yang membentuk ciri-ciri fizikal kita. Kebarangkalian untuk mewarisi ciri-ciri ini adalah 50:50. Wajah seseorang adalah lebih mirip kepada bapanya kerana kebanyakkan gen yang diperolehi adalah daripada bapanya dan begitu juga sebaliknya. Sebab itulah tidak semestinya kita dan adik beradik kita memiliki wajah yang sama melainkan kita dilahirkan sebagai kembar seiras. 

Kemungkinan besar juga seseorang itu mewarisi gen daripada datuk dan nenek mereka seperti yang berlaku kepada anak bongsu saya. Dia mungkin kelihatan seperti kembar kepada neneknya kerana wajahnya tidak meyerupai langsung wajah saya atau bapanya.

Sungguh menakjubkan! Namun persoalan mengenai kenapa wajah seseorang itu lebih menyerupai bapanya dan adik beradik yang lain menyerupai wajah ibunya, ini semuanya adalah kerana genetik!

Posted by Ayu Royani
Petrosains Blogger

Friday 22 January 2016

A Bit of Science About Floods

Kuala Lumpur has been hit by rain almost every day recently and every time that happens people wonder if there will be a flood somewhere, followed by traffic jams and other calamities. What is a flood? A flood is an imbalance in a hydrological system. This means there is more water flowing through the hydrological system than it can carry. 

What causes floods?

Very heavy rain 
Over-saturated soil, when the ground can't hold anymore water 
High levels of water in a river, stream or reservoir caused by unusually large amounts of rain 
Construction, urbanisation or lots of buildings and parking lots

In cold countries floods can also be caused by run-off from deep snow cover, frozen soil and ice jams in rivers.

There are two basic types of floods. In a normal river flood, water slowly rises and spills over the edges of a river. However, flash floods are more dangerous and can cause loss of lives.

What is a flash flood?

A flash flood is sudden flooding that occurs when floodwaters rise rapidly with no warning within several hours of an intense rain. It usually occurs when a wall of water quickly sweeps over an area after intense rainfall from slow moving thunderstorms. In narrow waterways floodwaters flow faster than on flatter ground and can be destructive. 

How much water makes a car float?

People often underestimate the power of water. Did you know that it takes only 18 inches of water to float a vehicle? It takes two feet of flowing water to turn vehicles into dangerous boats. So don’t drive through flooded roads. Six inches of fast moving flood water can knock you down. 

Cities can be flooded by an amount of rainfall that would have had no impact in a rural area because there are less trees, grass, roots and soil to soak up and hold water in. City-dwellers, be extra careful because the concrete jungle is not always made for heavy rain and floods!

Shared by Melissa
Guest Blogger

Wednesday 20 January 2016

Blast Off!

Orville and Wilbur Wright were two American brothers who liked to build things. One of the things that they built was the world’s first successful airplane back in 1903.

Forty one years later, the Germans built the V-2 Rocket, which is the first rocket to reach space.
For both of these events, propulsion played a big part. 

For an object to gain forward thrust, a large amount of pressure needs to be released backwards. This is what our fellow scientist Newton states, which is that every action has an equal reaction in the opposite direction. Ever noticed a pistol or rifle jerking backwards when being shot? The same rule applies.

One of the ways of producing large amounts of energy under high pressure is by mixing fuel with oxygen. This pressure is released backwards through a nozzle that is smaller than the chamber where the combustion took place, creating a reaction that propels the airplane or rocket forward or upward. For a rocket to propel from the Earth’s surface towards outer space, it needs to travel at an astounding speed of 27,650 km/h!

Birds, on the other hand, propel their bodies forward by flapping their wings. The Spine-tailed Swift is the fastest-flying bird in flapping flight, being capable of speeds up to 170 km/h! At this speed, this bird can travel from KLCC to KLIA in twenty minutes!

Experiment: Propulsion by high-pressured air

balloon, string, drinking straw and sticky tape.

1. Cut a 1 meter length of string.
2. Thread the string through the drinking straw. 
3. Attach the string ends to opposite side of the room. Make sure the string is taut.
4. Blow up a balloon and clip the end. Do not tie it.
5. Sticky tape the balloon to the straw and position it at one end of the string.
6. Release the clip and watch what happens.
7. Increase the incline of the string and repeat steps 4 to 6

Glossary of terms:
Propulsion [pruh-puhl-shuhn] the act or process of propelling
Thrust [thruhst] to push with force
Combustion [kuhm-buhs-chuhn] the act or process of burning

Shared by Surain A. Victor
Guest Blogger

El Niño, Rain & Heat: What’s the connection?

El Niño. The latest buzz word.  Lately we see and hear it mentioned almost on a daily basis. So, what exactly is it & how does it affect rain and rising temperature?

Simply put, El Niño makes an appearance when there’s changes in wind patterns over the equatorial Pacific.  It doesn’t happen all the time, roughly once every 2-7 years.  Its arrival is never precise.  It appears when it appears!

Back to El Niño.  When wind patterns over the Pacific Ocean changes, there will be changes in heat distribution to other parts of Earth, as well as changes in weather & climate. One of the changes in weather caused by an El Niño is a redistribution of rainfall around the Pacific.

What actually happens?
During normal conditions, strong easterly winds blow across the Pacific.  This pushes the warm water across the Pacific toward Indonesia and Australia. Just like warm water in the bathtub that produces clouds of steam in the bathroom, the warm water in the Pacific carries with it its rain clouds.

 Credit: NASA

As the warm water moves west, the nutrient rich cold water moves up along the coast of South America. This is called upwelling. Because fish follow this source of food, upwelling means lots of fish for the fishermen.

During El Niño conditions, the wind is not strong enough.  Sometimes it just stops.  Warm water hence stay closer to the South American Coast, cold water can't upwell & there’s no food for the fish. Instead, there is a lot of warm water piled up against the coasts of South & North America. Since the warm water always has its circle of clouds, there is heavy rain all along these coasts. 

When the rain is confined to the eastern side of the Pacific, western Pacific countries like Indonesia & Australia experience drought.

Credit: NASA

How does it affect us in South-east Asia?
According to the World Meteorological Organization (WMO), El Niño in South-east Asia is typically associated with drought. This is evidenced by the worst wildfires on record in Indonesia in 2015 with significant health repercussions, including an increase in acute respiratory infection.

In South Asia, El Niño conditions generated a weaker southwest monsoon than usual. El Niño is believed to have played a key role in the rainfall deficit in India.

Source: Adapted from “El Niño: Potential Asia Pacific Impacts,” NOAA Report (Oct. 2015)

Bear in mind that El Niño is not a regular cycle, or predictable like ocean tides.  So what’s in store for Malaysia? Let’s wait and see!

Shared by Azni Zainal Abidin
Guest Blogger

Thursday 14 January 2016

Instructions for Construction

Architects, engineers and designers refer to a blueprint when they are constructing something. A blueprint is a technical drawing that has all the details of what and how something is constructed.

Now, how about the human body? Where is all the information about what our bodies need to do stored
Each cell in our body has its own job. Some cells help us detect light and see, other cells carry oxygen around, while some cells help us digest food by secreting enzymes. There are over 200 cell types in the body - that is 200 different jobs!

But how does each cell know what job to do? Our cells are told what to do by a very special molecule called DNA, which is like a blueprint. DNA is shaped like a twisted ladder, called the double helix. The letters of the DNA, called bases, make up the rungs, whereas special sugars and other atoms make up the handrail. The rungs are very special. Each one has a name, but they are usually referred to by their initials: A, T, C and G. A good way of looking at it is that A, T, G and C are like jigsaw pieces. A and T fit together, C and G fit together - you cannot force a jigsaw piece to fit with a wrong piece!

Think of all the words you can spell. Each word is made using the same selection of letters. Depending on how we arrange the letters of the alphabet we can make new words. The same is true in the four letter alphabet of DNA. These letters form a sentence, and each sentence tells a cell to make a special molecule called a protein. These proteins in turn, are like little tiny workers scurrying about in the cell transporting other molecules, rearranging molecules, repairing the cell, getting rid of wastes, making the cell move, and also, constructing newer cells. 

Experiment: To extract DNA from an onion

distilled water, baking soda, salt, shampoo, ethanol, onion, and a sieve.

1. Prepare the buffer solution by mixing a bottleful of water with a teaspoon of salt, 3 teaspoons of baking soda, and 3 teaspoons of shampoo. 
2. Keep this buffer solution in a refrigerator.
3. Next, take an onion and mince it to pieces, or crush it with a blender.
4. Collect the pulp in a tall glass container.
5. Take a tablespoon of the mashed up onion and mix it with the chilled buffer solution. Stir it for 3 minutes and then leave it in the freezer for 5 minutes.
6. Remove the bits and pieces of onion by filtering it through a sieve. You now have a solution.
7. Slowly add cold ethanol to the solution by trickling it down the sides of the tall glass container.
8. The DNA will appear as a white cloud, which can be removed with a toothpick.

Glossary of terms:
Protein [proh-teen] - organic molecules constituting a large portion of the mass of every life form and necessary in the diet of all animals. 
Enzymes [en-zahym] – any of various proteins producing certain chemical changes by catalytic action.

Shared by Surain A. Victor
Guest Blogger