Q&A - PSLE Science

[fightingmom]

mathfreak:

fightingmom:

Hi again,


Sorry , can anyone also help with the following question: http://i41.tinypic.com/kdsldl.jpg\">

The answer sheet is (4) but my answer is (3)... eh... possible for anyone to enlighten me why (4) ?

TIA !

Solution:
When the steel bar AB was magnetised, the North pole of the magnet was touching the steel bar. That means the end of the steel bar from which the magnet was removed would become a South pole, as, in simple terms, the magnetism \"things\" in the steel bar which have a South polarity would be attracted to the magnet and be \"dragged\" across to the end of the steel bar. This means the top of the first thumbtack is a North pole, its tip is a South pole, the top of the second thumbtack is a North pole, its tip is a South pole, the top of the third thumbtack is a North pole and finally its tip is a South pole. Since like poles repel, the thumbtack would move away from the magnet. Hence the answer is (4).

:thankyou: for your clear explanation ! Appreciate it !

[fightingmom]

isetan:

Hi Fighting Mom,


Anyway to enlarge your diagram? Thanks.

oh ok ... hope this is big enough (sorry am still a newbie ) http://i42.tinypic.com/2im1637.jpg\">

[isetan]

Hi Fightingmom,


I concur with your answer. Should be 3 my opinon.

[G Tan]

fightingmom:

http://i43.tinypic.com/2956b2p.jpg\"> Hi all,


Can also help with this question also from Ai Tong 2011 CA1 Q25? Answer provided was (1) but i think it is (4) ... :?

Please help

TIA !

yup, u r right. the answr key is wrong. it should be 4

[portal]

tianzhu:

portal:

I have this question to ask.

Which of the following statements about human reproduction is true?

A-To produce an offspring, two differnt sex cells are needed.
B-Sperm cells are made in large numbers in a special organ called the ovary.
C-A healty female normally produces an egg cell once in every three months.
D-The sperm cell carries half of the information needed for reproduction and the egg cell carries the other half.

1)A and B
2)B and C
3)C and D
4)A and D4)
Hi

In males, the testes produce sperm.

In females, from puberty, an egg is usually released from one of the ovaries every month.

So, this eliminates (1), (2) and (3).

The male produces reproductive cells called sperms.The female produces reproductive cells called eggs. The sperm cell carries half of the information needed for reproduction and the egg cell carries the other half.

The answer is (4).

Best wishes

Thank you for the answer.

[atutor2001]

fightingmom:

oh ok ... hope this is big enough (sorry am still a newbie ) http://i42.tinypic.com/2im1637.jpg\">

The change requested is \"after this process\" i.e. what will happens next after the pollen grain has landed on the stigma? (2) will occur first and then very much later, (3). Since (2) can be observed with the help of a microscope, and there is no condition that observation must be made with the naked eyes, (2) is more appropriate as it occurs immediately \"after the process.\"

[fightingmom]

atutor2001:

fightingmom:

oh ok ... hope this is big enough (sorry am still a newbie ) http://i42.tinypic.com/2im1637.jpg\">

The change requested is \"after this process\" i.e. what will happens next after the pollen grain has landed on the stigma? (2) will occur first and then very much later, (3). Since (2) can be observed with the help of a microscope, and there is no condition that observation must be made with the naked eyes, (2) is more appropriate as it occurs immediately \"after the process.\"

hi atutor2001,

Eh... if i am not wrong, pollen tube cannot be growing in the filament, right ? :?

[atutor2001]

fightingmom:

hi atutor2001,

Eh... if i am not wrong, pollen tube cannot be growing in the filament, right ? :?

Thanks fightingmon. I am wrong, got tricked !

[fightingmom]

atutor2001:

fightingmom:

hi atutor2001,

Eh... if i am not wrong, pollen tube cannot be growing in the filament, right ? :?

Thanks fightingmon. I am wrong, got tricked !

No worries... i was tricked initially too

[underthesea]

fightingmom:

atutor2001:

[quote=\"fightingmom\"]
hi atutor2001,

Eh... if i am not wrong, pollen tube cannot be growing in the filament, right ? :?

Thanks fightingmon. I am wrong, got tricked !

No worries... i was tricked initially too [/quote]haha, I got tricked too, but my dd's eys were sharp enough to catch the word \"filament\".