Q&A - PSLE Science

[Muffins]

baibai06:

Hi........

i am about to take PSLE this year

i came across a question showing a fish tank with a fish and hydrilla and the fish tank is placed
in sunlight, but yet the fish died after 12hours or so during the night that day....
the fish were given no food.....
so can we say that the fish ate the plants, and therefore there were no more plants that photosynthesised and produced oxygen, there the fish died due to a
lack of oxygen?

i heard that it was not reconmmended to say that fish ate the plants.....
can anyone clarify about that?
thanks :?

Ah... Here is the clue. It died during the night. In the night the plant would only respire, thus taking in too much oxygen, so the fish and the plant would have to compete for air. In the end, the fish died due to too little air being taken in by it....

[kitty2]

What’re the similarities between the lung and fish gills?Anyone can help?


Thanks

[P5G]

kitty2:

What're the similarities between the lung and fish gills?Anyone can help?


Thanks

Here are my answers.

Both organs have many blood vessels.

Both organs have large surface areas to absorb oxygen.

Both organs are for exchange of gases.

[P5G]

Please help.


Q23. The diagram below shows Kenny's family tree of 4 generations that carry the genetic trait of a disease, D. Study the family tree carefully and answer the following question.


Please refer attachment for the family tree
http://www.orlesson.org/orp/09Sc/2009-Sc-SA2-CHS.pdf


Which of the following statements are conclusions you can draw about the above famly tree?

A. Disease D is passed on to only the male members of the family.
B. There is a chance that Kenny's sister may bear a son with the disease.
C. The daughter of a male patient with Disease D will be a carrier of the Disease.
D. Kenny's mother inherited the genes of Disease D from her maternal grandmother.

(1) A and C only
(2) A and D only
(3) B and C only
(4) A, B and C only.


My answer is (1) while the answer in the worksheet is (3). Which is correct?


TIA.

[atutor2001]

P5G:

Please help.


Q23. The diagram below shows Kenny's family tree of 4 generations that carry the genetic trait of a disease, D. Study the family tree carefully and answer the following question.


Please refer attachment for the family tree
http://www.orlesson.org/orp/09Sc/2009-Sc-SA2-CHS.pdf


Which of the following statements are conclusions you can draw about the above famly tree?

A. Disease D is passed on to only the male members of the family.
B. There is a chance that Kenny's sister may bear a son with the disease.
C. The daughter of a male patient with Disease D will be a carrier of the Disease.
D. Kenny's mother inherited the genes of Disease D from her maternal grandmother.

(1) A and C only
(2) A and D only
(3) B and C only
(4) A, B and C only.


My answer is (1) while the answer in the worksheet is (3). Which is correct?


TIA.

(3) is correct.

[Tang]

atutor2001:

P5G:

Please help.


Q23. The diagram below shows Kenny's family tree of 4 generations that carry the genetic trait of a disease, D. Study the family tree carefully and answer the following question.


Please refer attachment for the family tree
http://www.orlesson.org/orp/09Sc/2009-Sc-SA2-CHS.pdf


Which of the following statements are conclusions you can draw about the above famly tree?

A. Disease D is passed on to only the male members of the family.
B. There is a chance that Kenny's sister may bear a son with the disease.
C. The daughter of a male patient with Disease D will be a carrier of the Disease.
D. Kenny's mother inherited the genes of Disease D from her maternal grandmother.

(1) A and C only
(2) A and D only
(3) B and C only
(4) A, B and C only.


My answer is (1) while the answer in the worksheet is (3). Which is correct?


TIA.

(3) is correct.

Hi,

Yes, B is correct if she marries someone who suffers from disease D.

[kitty2]

P5G:

kitty2:

What're the similarities between the lung and fish gills?Anyone can help?


Thanks

Here are my answers.

Both organs have many blood vessels.

Both organs have large surface areas to absorb oxygen.

Both organs are for exchange of gases.

Thank you

[joconde]

Hi, can anyone explain to me why option (1) is the correct answer :


http://www.postimage.org/image.php?v=Pqcg4kJ

I had thought that bulbs in parallel are suppose to draw more power from the battery. Thus, bulb Y should be dimmer after bulb Z is added. No ?

[Nebbermind]

joconde:

Hi, can anyone explain to me why option (1) is the correct answer :


http://www.postimage.org/image.php?v=Pqcg4kJ

I had thought that bulbs in parallel are suppose to draw more power from the battery. Thus, bulb Y should be dimmer after bulb Z is added. No ?

is this a acs revision paper?

from an engineer pov, Y shd be brighter coz when X//Z, the overall resistance is lower than before so more current will go thru Y.
But since this is P6, I'm not sure :oops:

[Sun_2010]

Nebbermind:

from an engineer pov, Y shd be brighter coz when X//Z, the overall resistance is lower than before so more current will go thru Y.
But since this is P6, I'm not sure :oops:

Exactly.

Joconde, the brightness of a bulb depends on the electric current flowing thru it. If more power is drawn the batteries will run out faster .

So I think unless a resistance(say bulb) is added in series there bulb Y wont get dimmer .