Science+ACE

__Term 2 ACE__
__Naked Numbers__ Firstly, I that naked numbers are a potentially dangerous threat and they cannot be overlooked. I think that the United Nations are doing a wrong thing by not imposing a law banning naked numbers. I think that in addition to the law, several other measures should be put in to place. The most basic measure would be to simply ensure that students get into the habit of writing units. This would be an important measure as students will pass this habit on to the next generation, but it is not enough. Secondly, I think that units should be standardised across the world, and that is why we have SI units. From the article, the Lockheed Martin spacecraft was using the English unit of the pound, which is not an SI unit. If SI units were better enforced, perhaps this incident would not have happened. Finally, I think that all machinery should be programmed to show the proper units. I think that it was a huge error on the part of NASA to design a billion dollar spacecraft that has such a large flaw. The other issue I did not understand was why engineers at the jet propulsion laboratory were not informed of what units the spacecraft would be using. However, the most amazing thing was that the United Nations took no action at all. It was lucky that no lives were lost but that does not mean that we should wait for a more serious tragedy to strike. “Prevention is better than cure” as the saying goes, and we should take action. In conclusion, naked numbers are a serious threat and we should all be part of the solution, not the problem.

__Reflection on Orchid Gardens__ On Labour Day, I visited the well known Orchid Gardens in the Singapore Botanic Garden. I feel that I learnt more about orchids from my visit and now I am able to appreciate them more. I was surprised at the variety of the orchids. Some of them looked like creepers, following a support or another organism, letting the roots hang downwards, while others stood up straight. Some of them had large flowers the size of my hand, while others had many small flowers, or none at all. I also learnt about orchid trade, and how it contributes to Singapore’s economy. Orchid trade brings in a surprisingly large sum of money, and my grandfather was involved in it when he was still working, and buyers bid hundreds of dollars on rare or improved hybrids. I also learnt about the uses of orchids. Many of them are used commercially as food products, and I was surprised to learn that vanilla actually comes from orchids! They are also used to flavour rum and for perfume, along with many others. Orchids are well known for their ease in hybridization, and orchids are often hybridized to improve their features. The most interesting part of the Orchid Gardens was the mist house, where many rare and exotic orchids are placed. It was cool and wet inside, and the orchids were much more colourful. Many of them cannot be found in Singapore, so I felt that this part of the orchid gardens were one of a kind. My favourite orchid was found in the mist house, where it was placed in a spherically shaped pot, as seen in the picture. The flowers were large and white, but unfortunately there was no information on it. My visit to the orchid garden was enriching and informative, and I would recommend others to view it in their free time. __Remote Forest__

This forest is torture. I keep tripping over these massive gnarled tree roots and falling flat on my face on the wet forest floor covered with leaves. These leaves taste disgusting and bitter and they somehow find their way into all my clothes. Even worse, some of them have beetles and worms on them and I can feel them moving on my body. The forest has a pleasantly rich, earthy smell, but occasionally I come across something rotting and the smell is horrible. I always quicken my pace when I come to these areas but one time I accidentally fell on a carcass of a dead animal! It was awfully slimy and wet and my face felt sticky with blood after that. After a while though, I began to feel hungry, and I decided to eat some tree bark. After all, don’t some animals eat bark too? After some searching, I finally found one and felt its bark. It was rough and craggy and I was glad that I had not fallen onto the tree, as my face would have been covered with scratches. I dug in with my nails and peeled off a long strip of bark. I cautiously broke off a piece then ate it. It was extremely tough and bitter but edible and after a period of chewing, I reduced the bark to pulp and swallowed it. Suddenly, I stepped into a river. Fortunately, it was pretty shallow but my entire boot sank into the soft mud below. I tried to get out quickly as I had heard about vicious freshwater fish that could take my leg off. However, I realised that my boot was stuck and I began to panic. After some strenuous pulling, I finally pulled myself out of the mud and onto the shore. After a couple of hours of walking fortunately without any mishaps, I walked out of that dreadful forest. __Interesting Units: Gallon__

The gallon was in use before the 18th century, where the volume of the gallon depended on what was being measured and where it was being measured. However, by the end of the 18th century, the corn gallon, the wine gallon and the ale gallon were in common use. The wine gallon has been the standard US gallon since the 19th century. The derived SI unit for volume is the meter cube. When converting in between the cubic metre and the standard US gallon, the conversion rate is 1 cubic metre to 264.172051242 gallons. A useful website is [] if you want to convert gallons to cubic metres or vice versa. The main problem with the gallon is that there are so many definitions of it. Currently, there are three main definitions used in different countries. Hence, it is difficult to standardize the gallon and some misinterpretations could lead to billions lost as seen in the NASA Mars Probe or even lives lost. The gallon is slowly becoming obsolete and as of 2005, only 22 countries used it as a measure of fuel. The United Arab Emirates converted to litres this year.

__﻿Term 3 ACE__
__Digestion__

1a) What is gastric juice?   Gastric juice is a strong acid, pH 1-3 in humans, that is secreted by the stomach walls. It is used to digest food in the stomach.    1b) What is ‘secretion’? Secretion is the act of releasing a substance that fulfills a function within the organism. 1c) In what way did Alexis St. Martin’s and Tom’s injuries enable research to be done on gastric secretion?   Researchers were able to take samples of gastric juice from their stomachs and they were also able to examine how the stomach digested food as both of them had holes opened in their stomachs and researchers were able to see the inside of the stomach.    1d) List 3 factors which speed up the rate if gastric secretion. Gastric juice secretion is speeded up when a person sees, smells or tastes food. 1e) Why is it sensible for protein containing foods to have the greatest effect on gastric secretion?   It is sensible as proteins are made up of many interlocking amino acids, making it very difficult to break down, thus requiring more gastric acid.    1f) It is well known that people who suffer from stress are more likely to suffer from stomach and duodenal ulcers. Explain why this might be. Stress can cause a person to overeat or not eat at all. When a person overeats, the stomach is forced to produce more acid to digest the food. This increase in acid can cause stomach ulcers. When a person does not eat, the acid attacks the stomach lining instead, causing ulcers. 1g) Why is it useful for the presence of food in the duodenum to reduce gastric secretion?   It prevents the gastric acid from attacking the stomach lining and causing ulcers.    2a) What percentage by weight of the ice cream is protein? 2.1%   2b) Which ingredients in the ice cream do you think provides this protein?    Milk, Eggs, Guar Gum, Locust Bean Gum    2c) What percentage by weight of the ice cream is probably water? 55% - 65%   2d) A boy had a 250g serving of ice cream. How much fat did he eat?    16g    2e) What ingredients in the ice cream do you think provide the fat? Milk, Double cream, Eggs, Emulsifier E471, Malt extract, Natural Flavouring 2f) The boy needs about 12000 kJ each day. How much ice cream would he need to eat to provide this much energy?   2505. 21921g    2g) Why would this not provide a balanced diet? A balanced diet must have carbohydrates, proteins, fats, vitamins, mineral salts and fibres. Although ice cream contains protein, fat, and carbohydrates, it is very lacking in terms of vitamins, mineral salts and fibres. It also does not contain enough carbohydrates as carbohydrates are out most important energy source. 2h) What is the purpose of the emulsifier in the ice cream?   Emulsifiers aid in developing the appropriate fat structures in ice cream and air distribution necessary for smooth eating and good meltdown characteristics.    3a) Which food types were present on this food sample? Protein 3b) What food could it have been?   Egg white, lettuce    3c) Which test would have involved heating the food? Sugar test 3d) What reagents would have been used for Test C?   The Biuret reagent. It is made of Potassium Hydroxide, Hydrated Copper (II) Sulfate, and Potassium Sodium Tartrate.   __ Expansion of Matter __

In a bimetallic thermometer, a bimetallic strip is wound in a helix. One end of the helix is held rigid. When the temperature rises and falls, the helix tries to wind and unwind. This causes the free end to rotate. The free end is connected to a pointer, which actually indicates the angular rotation of the helix, but since the rotation is linear and a function of temperature, the scale is marked in units of temperature. Hot riveting involves hammering a smooth bolt of malleable metal against a solid backing, shortening the rivet and drawing what is being connected together. The metal is heated to make it expand, and as it cools it further tightens the joints. This contraction produces a large force, around 60000 Newtons per square centimeter. In electric irons, part of the circuit is made up of a bimetallic strip. When the iron heats up to a certain temperature, the bimetallic strip bends as one metal expands more than the other. This breaks the circuits and prevents the iron from heating up further. In gas ovens, a gas filled bulb is connected to the control unit by a slim copper tube. It is normally located at the top of the oven. The tube ends in a chamber sealed by a diaphragm. As the temperature rises the gas expands applying pressure to the diaphragm, reducing the flow of gas to the burner.