Air

Dear all,

We have started on a new topic for Science, "Air and the different gases".

But before we recap about the important points, lets' go through the answers for the 3 questions posed in the earlier post below.

The arrows show the movement of food being made from the leaves to the rest of the plant. Water and minerals are transported from the roots upwards to the rest of the plants. Carbon dioxide and oxygen is exchanged in the stomata. 

So the answer is (1) B only.

You need to know the different plant parts. Some of the questions will not directly give you a picture of the plant and its parts but give you another diagram which symbolizes a plant and you have to apply what you have learnt to complete the question. 

In this question here, A and C are the leaves while B and D are the roots. Roots are found beneath the soil most of the time and the movement of the non-dotted line shows the movement of food from the leaves to the other parts of the plants. The movement of the dotted line shows the movement of water from the roots to the rest of the plant. 

You must remember the positions of the xylem and phloem tubes given a cross section of a stem of a plant. Here is one tip. "PX" P comes first and is the top part furthest away from the centre. X comes next and is the inner part nearest to the centre. P stands for Phloem. X stands for Xylem. In this case, it is one good way to help you remember the positions. 

In this question, P represents the Phloem tubes and helps to transport food from the leaves  to the rest of the plants. 

Q represents the xylem tubes and transports water and minerals from the roots to the rest of the plants.

Moving on to today's topic, we learn about air, what are the gases that make up air and some important uses of certain gases and its characteristics.

Air is made up of nitrogen (78%), oxygen (21%) and other gases (1%) (such as water vapour, carbon dioxide, argon, helium, hydrogen, etc)

Note the percentage and which gases are of more percentage than the others. **

Also, human beings and living things need oxygen to breathe, as such the percentage of oxygen has to be higher than carbon dioxide or other gases apart from nitrogen.

Most gases are odourless and colourless. Some are reactive (react readily with the surrounding air and other objects to cause an reaction such as burning / combustion). Some are non-reactive (does not reactive readily with other objects or surrounding air to cause any reaction).

There are many functions of each gas,
e.g Oxygen - For living things to breathe and for burning to take place.
Carbon Dioxide - makes soft drinks fizzy and needed for plants to photosynthesize.
Nitrogen - Used as a coolant in refrigerators in liquid form and to seal food packages to preserve it.
Methane - Used as a natural gas as a fuel for cooking.
Argon - Used to fill the light bulb to protect the filament from combustion.

Revise on your reading, english grammar and vocabulary and science notes this long weekend. Rest well, especially with the hazy weather. See you all next week. If there are any questions to be posted, I will post it here so check your blog regularly.

Leaving you with one last note,

Rumours are false statements. Don't spread rumours about your friends unnecessarily. It will only cause discomfort for your friends. I am sure you do not want others to spread rumours about you so respect your friends and respect yourself. Do not speak if you have nothing nice to say that cause hurt. I still believe in #Rule 1 and that one day, you all will believe in it as much as I do. We are all equal and no one should be made to feel inferior to another person.

Thank You,
Sincerely,
Mr Nelson Ong