Term 2 has just past..... Sigh... Time passes so quickly!
Anyway, this term, we had a new teacher, Mrs Koh! She started off the first lesson by giving a short introduction of herself and her expectations for us. I must say that Mrs Koh is much stricter, but as for the results... I am still not so sure.
Anyway, Mrs Koh went through with us a new topic-cells, diffusion & Osmosis. For cells, we needed to learn the name and functions of certain cells and cell parts, such as the cell membrane, nucleus, vacuole, cytoplasm, chloropasts(for green plants) and chromozones. Luckily, I already had a little knowledge on cells in Primary School so I could understand her lesson much easier.
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| (Example of an animal cell) |
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| (example of a plant cell) |
Diffusion:
Diffusion is a process which would distribute the particles uniformly throughout the system.
Quite hard to understand, eh?
Again, I did not really understand this section, but at least I get a rough idea of what it is after Mrs Koh's lesson. It is something about the atoms and molecules moving from a higher concentration to a region where they are at a lower concentration.
Osmosis:
Osmosis is something like diffusion. It is the net movement of water molecules through a partially permeable membrane, from a region where there is a higher concentration of water molecules to a region where there is a lower concentration of water molecules.
Did you spot the difference? In osmosis, only water molecules are involved. Also, there is a partially permeable membrane, which means that only certain molecules that are small enough can enter. An example of a partially permeable membrane is the visking tubing.
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| Animation of an osmosis experiment |
Digestion and Respiration:
The next topic we must learn is digestion and respiration. This is the hardest topic so far in term 3, as it is difficult to understand and memorize. We had to learn many new "stuff" such as enzymes, which I had never heard before. We must learn 4 different types of enzymes. They are the Amylase, Maltase, Protease and Lipase. Their function is to speed up chemical reactions in the body. Enzymes are specialised and they can only work on specific substrates.
Not only that, we must also learn the different parts of the digestive system. We must state its functions too.
Photosynthesis:
Photosynthesis is the process by which the plants use carbon dioxide, water and light trapped by chlorophyll to make food in the form of glucose, with oxygen being given off during the process.
(it is much easier to understand with the picture below)
This topic is much easier to understand as it is already covered in Primary school, and the process of photosynthesis is not that complicated :D
Respiration:
We must learn respiration too. Through this lesson, I realised that respiring is totally different from breathing. Breathing is taking in oxygen and expelling carbon dioxide. However, respiration is the process in which the glucose is burnt in the presence of oxygen to produce carbon dioxide, water and energy .
Respiration for plants is the exact opposite of the process of photosynthesis.
Photosynthesis is the taking in of water, carbon dioxide and energy (sunlight), and giving out glucose and oxygen.
Respiration is using glucose and oxygen to produce carbon dioxide, water and energy.
Hehe.... See the difference? :P
For the human respiration, we needed to learn and memorize the different parts of the respiratory system.
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