Tutor Niedino: Pri Science Questions and Concepts

[Niedino]

starlight1968sg:

MOE Hater:

Both are absolutely correct but there is something that I want to point out here.....


Arteries are NOT defined by the fact that they carry blood rich in oxygen and veins are NOT classified by the fact they contain large amounts of carbon dioxide.

They are actually classified based on the thickness of their walls. Arteries have thick walls while veins have thin walls. The reason behind is that arteries are blood vessels transporting blood leaving the heart while veins carry blood back to the heart. When the heart pumps, it pumps with great force so the artery walls have to be thick so that they do not burst under the high pressure of the blood flowing. Conversely, blood travelling in the veins have lost most of their momentum thus the vein walls do not have to be thick.

Generally, yes, arteries carry oxygen rich blood while veins transport carbon dioxide rich blood. However, there are 2 exceptions, one in each case. Blood pumped from the heart to the lungs is rich in carbon dioxide but still travels in an artery as it is leaving the heart. On the other hand, blood leaving the lungs to the heart is rich in oxygen but travels in a vein as it is returning to the heart.

Although it is not in the syllabus, I believe it is essential for us to take note of this. I have seen questions when they ask why is the artery wall thick. Of course, the chid's prior knowledge on forces would be sufficient to answer the question but some children, despite getting the right answer, may have second thoughts. Blood leaving the heart to the lungs is rich in carbon dioxide. According to their answer, it should be an artery but then again they think its carbon dioxide rich, a vein. As a result, some children change their answer to another ridiculous one and lose their marks. Having such external knowledge certainly give them an edge over others and they do not start panicking when they see a confusing question.

Hope I have not bored you to death. Please reply if this explanation is confusing. Sometimes my language gets in over my head and makes it difficult to comprehend the scientific concept behind.

Thanks so much for sharing esp on why arteries have thicker walls!

Yes, I know about the pulmonary artery and pulmonary vein.

To make it more precise, arteries carrying blood from the heart to the rest of the body is richer in oxygen except pulmonary artery.

Back to the thickness of artery, vein and capillaries, why capillaries have the thinner walls than veins?

MTIA.

Wow, I've learnt alot as well. Thanks MOE Hater, and Starlight. In the primary syllabus, we teach that capillaries have the thinnest walls as they allow substances such as oxygen, digested food to pass through to other parts of the body. This is a simple explanation, as we have to understand that our pupils are only 11 years old when they learn this topic.

[Sun_2010]

starlight1968sg:

Thanks so much for sharing esp on why arteries have thicker walls!

Yes, I know about the pulmonary artery and pulmonary vein.

To make it more precise, arteries carrying blood from the heart to the rest of the body is richer in oxygen except pulmonary artery.

Back to the thickness of artery, vein and capillaries, why capillaries have the thinner walls than veins?

MTIA.

the exchange of gases between the artery and the surrounding body tissues take place thru capillaries. The thin wall of the capillaries (cappilaries are just a single cell thick, i think) facilitates this.

[atutor2001]

Sorry, I am kay pohing

Sun_2010:

the exchange of gases, nutrient/food; waste; water ... between the blood vessels and the surrounding body tissues take place thru capillaries. The thin wall of the capillaries (cappilaries are just a single cell thick, i think) facilitates this.

[leesf]

Is water hyacinth a floating or partially-submerged plant? Different Science guidebook categorise them differently.


What about Cattail? It was indicated as partially-submerged plant in one of the guidebooks but my child says his tutor told him it should be totally-submerged.

Thanks

[Nebbermind]

leesf:

Is water hyacinth a floating or partially-submerged plant? Different Science guidebook categorise them differently.


What about Cattail? It was indicated as partially-submerged plant in one of the guidebooks but my child says his tutor told him it should be totally-submerged.

Thanks

Cattail shd be partially submerged since the 'cattail' is above water.

As for water hyacinth, it shd be floating since it roots is not anchored to the bed of the pond/pool.

Juz my 2c

[Niedino]

Hi all,


Its been some time since I last posted. Here are some misconceptions on the digestive system that your child might have.

Gullet: This is an organ that contains quite a few misconceptions.

1. Is it an organ? Yes it is. Many pupils often think that it is just a tube, but it is an organ. It is a muscular tube that pushes food down.

2. There is no digestion in the gullet. True and False. The gullet does not produce digestive juices, so it does not digest food. But the food that goes down the gullet is mixed with saliva and hence, a little digestion does take place in the gullet.

3. The gullet and the windpipe are one and the same. False. The gullet and the windpipe are often seen in rudimentary diagrams as being in the same position, hence the misunderstanding. They are actually different tubes, and there is a flap that prevents food from entering the windpipe during swallowing.

Hope it helps. I'm thinking of setting up a blog for Science misconceptions and sharing as it does take a bit of time for me to do it on a forum. If I do, I'll post up a link here.

[Sun_2010]

:thankyou:


Thanks niedino, quite useful.

[Jennifer]

Niedino:

Hi all,


Its been some time since I last posted. Here are some misconceptions on the digestive system that your child might have.

Gullet: This is an organ that contains quite a few misconceptions.

1. Is it an organ? Yes it is. Many pupils often think that it is just a tube, but it is an organ. It is a muscular tube that pushes food down.

2. There is no digestion in the gullet. True and False. The gullet does not produce digestive juices, so it does not digest food. But the food that goes down the gullet is mixed with saliva and hence, a little digestion does take place in the gullet.

3. The gullet and the windpipe are one and the same. False. The gullet and the windpipe are often seen in rudimentary diagrams as being in the same position, hence the misunderstanding. They are actually different tubes, and there is a flap that prevents food from entering the windpipe during swallowing.

Hope it helps. I'm thinking of setting up a blog for Science misconceptions and sharing as it does take a bit of time for me to do it on a forum. If I do, I'll post up a link here.

Many thanks and would appreciate your efforts in setting the Science blog.

We had a disagreement with the Sc teacher on pt 2. That's when he bluntly told us some classmates' parents who are doctors did not hv an issue with this :roll:

[kitty2]

Niedino:

Hi all,


Its been some time since I last posted. Here are some misconceptions on the digestive system that your child might have.

Gullet: This is an organ that contains quite a few misconceptions.

1. Is it an organ? Yes it is. Many pupils often think that it is just a tube, but it is an organ. It is a muscular tube that pushes food down.

2. There is no digestion in the gullet. True and False. The gullet does not produce digestive juices, so it does not digest food. But the food that goes down the gullet is mixed with saliva and hence, a little digestion does take place in the gullet.

3. The gullet and the windpipe are one and the same. False. The gullet and the windpipe are often seen in rudimentary diagrams as being in the same position, hence the misunderstanding. They are actually different tubes, and there is a flap that prevents food from entering the windpipe during swallowing.

Hope it helps. I'm thinking of setting up a blog for Science misconceptions and sharing as it does take a bit of time for me to do it on a forum. If I do, I'll post up a link here.

Thank you,you're very kind and helpful

[naggo-nitemare]

Ur help is v much appreciated! my DS has no science tuition n sometimes his science concepts may not be correctly understood. Additional help from kind generous angels like urself, will benefit many.