Term 3 Summary and Reflections

In this term, I learnt about elements and compounds, solutions and suspensions, seperation techiniques, cells, and also energy.

Firstly, we learnt about elements and compounds. We were supposed to learn this last term, but were unable to due to time constraint. As a result, we had to rush through this topic and I could not really revise much about it; we learnt about elements, compounds and mixtures. I felt that this topic was fairly difficult, as memorising the different word equations for different compounds was quite tedious. Also, we had to memorise the short-forms of some elements of the Periodic Table. One thing I remembered clearly was the differences between compounds and mixtures. Some of these differences include: 

• In terms of properties, a compound has its own set of properties and does not have the properties of its elements, whereas a mixture has the same properties of the substance it is made of.
• In terms of separation, a compound cannot be broken down into simpler substances by physical means- a chemical reaction is needed to do this, whereas a mixture can easily be separated into its substances by physical means.
• In terms of preparation, a compound is made only when a chemical reaction takes place, whereby the atoms of elements are joined together, whereas a mixture can be made easily without any chemical reaction.

Periodic table of elements

Next, we learnt about solutions and suspensions. We learnt the differences between solvent, solute and solution. I was quite confused in the beginning because all three words were so identical. We also learnt the factors which affect the rate of dissolving, e.g temperature of solvent, stirring, etc. After that, we moved on to separation techniques. This includes different techiniques such as filtration, crystallisation, etc. Thankfully this topic was not really tested in the common test. I had difficulty identifying and differentiating all the different separation techniques. This is a point I must improve on.

Crystallisation

After that, we learnt about cells. I felt that this was an easy topic as I touched on it before in primary school, thus I had some prior knowledge of it. I did not have much trouble identifying the differences between plant and animal cells, etc.
Moving on, we learnt about diffusion and osmosis. Diffusion is the net movement of molecules from a region of higher concentration to a region of lower concentration. Osmosis, on the other hand, is the net movement of water molecules through a partially permeable membrane from a region of higher concentration to a region of lower concentration. Put simply, osmosis is diffusion through a partially permeable membrane. Osmosis stops when the two solutions involved are of equal water concentration.

An animation explaining osmosis

Lastly, we learnt about energy. This included digestion. Firstly, we learnt about enzymes. This included;

• Amylase- starch-> maltose
• Maltase- maltose-> glucose
• Protease- protein-> amino acids
• Lipase- fats-> glycerol+fatty acids

Again, I had to take some time to memorise all this. Next, we learnt about digestion and enzymes' effects in different parts of the digestive system. Lastly, we learnt about photosynthesis and respiration. We learnt how to test for starch (iodine test) and also the importance of photosynthesis- it makes chemical energy available to animals and removes carbon dioxide from the air. We also learnt about respiration, which occurs all the time and is a vital process for both plants and animals. Also, we learnt about aerobic respiration- the process whereby glucose is broken down in the presence of oxygen with the release of large amount of energy in living cells. This was fairly different from what I learnt in primary school; I did not know there were different kinds of respiration.

explaining enzymes

For this term's test, I scored a 76(A1). I was extremely pleased with myself for making a big jump from E8 to A1. I will strive to achieve the same result for my EOY science exam! :)