Q&A - PSLE Science
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youngtay:
HiHi, please help
Which statement about the circulatory system is correct?
1) It consists of the nose, windpipe and lungs.
2) It carries water to different parts of the body.
3) It digests food and passes it to the blood.
4) It removes carbon dioxide from our body.
TIA
In PSLE Science, students learned that the blood transports digested food, oxygen, water, carbon dioxide and other waste materials to different parts of the body.
Option(1) and (3) are out.
Carbon dioxide is transported from the heart to the lungs to be breathed out or removed from the body. This rules out option(4).
I'd like to go for option (2).
Best wishes -
Compare the following differences between the respiratory and circulatory system in plants and in human beings. Which of them is wrong?
Option 1
Plant: Exchange of gases takes place in the leaves
Human: Exchange of gases takes place in the lungs
Option 2
Plant: Oxygen is pumped to all parts of the plant
Human: Oxygen is pumped to all parts of the body
Option 3
Plant: Carbon dioxide is not returned to leaves
Human: Carbon dioxide is returned to the lungs.
Option 4
Plant: There is no blood to carry food around the plant
Human: Blood carries food around the body
Answer given is option (2).
Is this correct?
Option (1) and option (4) are obviously correct.
Pls help to explain why option (2) is chosen instead of option (3) for this question.
TIA for your time and effort. -
Vanilla Cake:
Hi VCCompare the following differences between the respiratory and circulatory system in plants and in human beings. Which of them is wrong?
The question asks which of them is wrong.
Option 2 is correct.
The plant does not have a pumping device similar to the heart.
Best wishes -
tianzhu:
Hi Uncle tianzhu,Hi VC
The question asks which of them is wrong.
Option 2 is correct.
The plant does not have a pumping device similar to the heart.
Best wishes
Thks for your explanation and super fast response.
Here's another one - Q32 from the same paper.
There are 2 diagrams for this question and I will try my best to describe them.
Q32
Albert noticed that a \"cloud\" formed near the spout of a kettle of water when the water boiled.
Diagram 1 showing a kettle with a spout and \"cloud\" coming out from it. The \"cloud\" is drawn near to the spout.
(a) What actually made up the \"cloud\"? (1 mark)
No problem for part (a). Answer is \"tiny water droplets\".
Albert also noticed that the \"cloud\" moved higher and higher as the water continued to boil.
Diagram 2 showing the same kettle with the \"cloud\" is drawn is such a way that it appears to \"grow\" larger and rising upwards.
(b) Why did the \"cloud\" move higher and higher? (2 marls)
Answer given: The air above the spout got warmer and so condensation would like place higher where it was cooler.
Is the answer given correct? Could you pls help to answer part (b) of this question? TIA for your time and effort. Much appreciated. -
Vanilla Cake:
Didnt expect this ans but think of it, quite true as the hot air right from the spout pushes the \"cloud\" higher.(b) Why did the \"cloud\" move higher and higher? (2 marls)
Answer given: The air above the spout got warmer and so condensation would like place higher where it was cooler.
Is the answer given correct? Could you pls help to answer part (b) of this question? TIA for your time and effort. Much appreciated. -
Hi VC
The answer from the WS is a logical one.
Best wishes -
Watermist Gun
The gun works by spraying the water out into a fine mist instead of spurting a jet of water as a conventional hose does.
http://www.youtube.com/watch?v=24PdBM-phVQ
How are water mists more effective than conventional water jets in fighting fire?
Give it some thoughts using concepts within PSLE Science syllabus.
Best wishes -
starlight1968sg:
Didnt expect this ans but think of it, quite true as the hot air right from the spout pushes the \"cloud\" higher.Vanilla Cake:
(b) Why did the \"cloud\" move higher and higher? (2 marls)
Answer given: The air above the spout got warmer and so condensation would like place higher where it was cooler.
Is the answer given correct? Could you pls help to answer part (b) of this question? TIA for your time and effort. Much appreciated.tianzhu:
Hi Uncle tianzhu/starlight1968sg,Hi VC
The answer from the WS is a logical one.
Best wishes
Thks for your response to my question. Pls pardon my ignorance as I still cannot come up with the right answer after watching the video clip and reading the answer given. Could you pls enlighten and share how the correct answer is to be written?
Also back to MCQ Q30 - Option (3) of the same paper. I don't understand option 3 that \"Carbon dioxide is not returned to leaves\" is correct in concept. Pls kindly guide and explain on this.
Sorry to bother you and thks in advance for your help. -
Vanilla Cake:
Didnt expect this ans but think of it, quite true as the hot air right from the spout pushes the \"cloud\" higher.starlight1968sg:
[quote=\"Vanilla Cake\"] (b) Why did the \"cloud\" move higher and higher? (2 marls)
Answer given: The air above the spout got warmer and so condensation would like place higher where it was cooler.
Is the answer given correct? Could you pls help to answer part (b) of this question? TIA for your time and effort. Much appreciated.tianzhu:
Hi Uncle tianzhu/starlight1968sg,Hi VC
The answer from the WS is a logical one.
Best wishes
Thks for your response to my question. Pls pardon my ignorance as I still cannot come up with the right answer after watching the video clip and reading the answer given. Could you pls enlighten and share how the correct answer is to be written?
Also back to MCQ Q30 - Option (3) of the same paper. I don't understand option 3 that \"Carbon dioxide is not returned to leaves\" is correct in concept. Pls kindly guide and explain on this.
Sorry to bother you and thks in advance for your help.[/quote]Sorry I can't answer your question properly.
I am thinking of the actual cloud formation. As water vapour in the air rises, it cools, condensation occurs and thus a (real) cloud is formed.
Similarly, the hot air from the spout rises = pushing the \"cloud\" higher. Thus pushing the location of condensation (to occur) to higher.... :roll: -
Vanilla Cake:
Condensation needs to happen on a cool environment (water vapour needs to lose heat). The air near the spout, like stated in your answer, would get too warm for condensation to occur. Since hot air rises, the hot water vapour rises until it is cool enough for condensation to occur.(b) Why did the \"cloud\" move higher and higher? (2 marls)
Answer given: The air above the spout got warmer and so condensation would like place higher where it was cooler.
Is the answer given correct? Could you pls help to answer part (b) of this question? TIA for your time and effort. Much appreciated.
Hope that explains why the \"cloud\" move higher and higher.
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