Q&A - PSLE Science

[ms_lim]

Please help on this question :


http://i56.tinypic.com/2d1u350.jpg\">

Ans key is (1) but my dd explains that D protects the spinal cord so her ans is (3). Is spinal cord a vital organ?

[atutor2001]

stary:

Hi all,


Need explanation for the following...

RGPS/SA1/P6/2010
Question 30:

http://www.flickr.com/photos/64113082@N03/6143567445/in/photostream
http://www.flickr.com/photos/64113082@N03/6143567451/in/photostream

My ans:3
Ans key:2

Many thanks!

Gravitational force is constant as long as the object is near the Earth surface. So answer is 2.

Gravitational force depends on the distance between the centre of the Earth to the ball. The greater the distance, the smaller will be the gravitational force.

However, the radius of the Earth (6370 km) is so very much longer than the vertical distance of the ball from the ground (only a few m). Therefore, the change in distance, caused by the movement of the ball, will be negligible i.e. changing a few metres to 6370 km has no significant effect. As such the gravitational force experienced by any object near the Earth surface is taken to be constant.

On the other hand, a plane flying many km up in the sky will experience lower gravitational force because the change is more significant.

[atutor2001]

ms_lim:

Please help on this question :


http://i56.tinypic.com/2d1u350.jpg\">

Ans key is (1) but my dd explains that D protects the spinal cord so her ans is (3). Is spinal cord a vital organ?

I agree with your dd answer. Spinal cord is an organ as it is made up of tissues (definition of an organ) and it is also a vital one.

[Verysuperkiasu]

atutor2001:

Yes, other words that allow the naming of actual materials are \"suggest\", \"likely\"... sorry can't remember leow

Ok, got it. Thanks, atutor!

[Alchemist]

Hi


1) ACS Prelim Science Booklet A - No 17. Can someone pls tell me what is the answer. The given answer is 2. However, my son's teacher told the class that flowers have chloroplasts as well. So he claims the only part without chloroplasts in the root. http://i55.tinypic.com/orsfpv.png\">

[Alchemist]

This is my second query for the St Nic 2011, Prelim Q 8. Given answer is 4.

[Alchemist]

trying repost picture as it was too small http://i56.tinypic.com/2yn2uqc.png\">

[Nebbermind]

(1) Just learnt that spinal cord is an organ. Thanks to this forum!! But is it taught as such in schools?


(2) Believe that it’s taught that flower do not have chloroplast.

(3) Mangrove fruits is also dispersed by water so shd be (4)

[atutor2001]

vidhyalog:

Hi


1) ACS Prelim Science Booklet A - No 17. Can someone pls tell me what is the answer. The given answer is 2. However, my son's teacher told the class that flowers have chloroplasts as well. So he claims the only part without chloroplasts in the root. http://i55.tinypic.com/orsfpv.png\">

The answer (2) is correct because part B is pointed to the petal (not flower).

Do flowers have chloroplast/chlorophyll?
Yes if we consider the sepals which is green in colour.

Are there other parts of a flower (excluding the sepals) that contain chloroplast?
Yes only for a small group of flowers e.g. broccoli, wild flowers with green petals - orchids...

Do flower buds contain chloroplast?
Yes, buds are usually green in colour and have chlorophyll. As they develop, the chlorophyll in the petal will change to other pigment (colour).

Do all roots have no chloroplast?
No some air roots of orchids have chloroplast to make food.

For primary level, lets just accept it as that roots and (non-green) petals have no chlorophyll.

If the word used in the question is \"flower\", then must read the question again carefully.

For the other question on dispersal, I think the given answer is wrong. Should be (2)

[Alchemist]

Nebbermind:

(1) Just learnt that spinal cord is an organ. Thanks to this forum!! But is it taught as such in schools?


(2) Believe that it's taught that flower do not have chloroplast.


(3) Mangrove fruits is also dispersed by water so shd be (4)

Hi Nebbermind -

For (2) I thought so too. But he claims teacher said it does. So wondering if any other teacher has this interpretation.


For (3) Can I then check what type of dispersal does the picture depict. I thought it depicts seed dispersal by water - and as the question asks not the same way as picture - I thought it should be (2). Angsana is by wind and durian is by animals - so does the picture depict seed dispersal by wind and animals?

Thanks