Q&A - PSLE Science

[stary]

Many thanks (if you've helped me)!!!

[atutor2001]

Hi Stary


1. In the food web, "A" must be the food producer. If "A" is not the food producer, then it cannot be called a "food web" because all food webs must have food producer/s.

2. The question is regarding "germination of a seed". With very strict interpretation, the question is limited to "conditions needed for germination." Therefore, the information that "A seed does not need to make food" is not related to condition for germination of a seed. I share your disagreement and imo, it is another "siao" question.

3. I agree with your interpretation that height and trunk thickness of trees can also be genetic traits for some types of trees. However, generally speaking, most trees have about the same kind of height and trunk thickness and are affected by the condition of the soil, etc. So at Pr level, these 2 points should be treated like the length of hair or nail and are NOT passed down genetically.

[stary]

Thanks atutor2001 for your prompt explanation.

[chrisu]

Question on population from Longman My Weekly Companion Science Book B;

http://img.photobucket.com/albums/v160/guppiesonli/Misc/QPopulation.jpg\">

I've problem explaining to my daughter on population in the sense as how to differentiate them. Anyone can explain in detail on how to derive the answer? Thank you.

[Tang]

chrisu:

Question on population from Longman My Weekly Companion Science Book B;

http://img.photobucket.com/albums/v160/guppiesonli/Misc/QPopulation.jpg\">

I've problem explaining to my daughter on population in the sense as how to differentiate them. Anyone can explain in detail on how to derive the answer? Thank you.

Hi,

My answer is (1) - 5.

Label the animals given as follows from left to right and top to bottom.
A B C D
E F G H

A and G - same population, damselfly.
B and D - same population, mosquito.
C and E - same population, frog.

[chrisu]

Thank you Tang. Yes the answer given by the book is (1) -5


My daughter and I find it difficult to relate G to A as damselfly and also F and H. Frankly I don't even know what are F and H.

Tang:

chrisu:

Question on population from Longman My Weekly Companion Science Book B;
http://img.photobucket.com/albums/v160/guppiesonli/Misc/QPopulation.jpg\">

I've problem explaining to my daughter on population in the sense as how to differentiate them. Anyone can explain in detail on how to derive the answer? Thank you.

Hi,

My answer is (1) - 5.

Label the animals given as follows from left to right and top to bottom.
A B C D
E F G H

A and G - same population, damselfly.
B and D - same population, mosquito.
C and E - same population, frog.

[Nebbermind]

CHIM!


I thought '5' if we ignore all the 'infants'.

[reddotresident]

2011 red swastika science prelim paper. assuming you all hv the papers now, can someone help pls? thank you!


Q32b - DS says
yes, as only the no. of plants per plot should be changed. all other variables should be constant.

ans.sheet says
yes, as diff. plants bear diff amt of fruits.

Q41b.
Describe one action michael has to carry out consistently thruout the expereiment in order to get reliable results?

DS says
timing.

ans.sheet says place the car from top of the ramp.

Q43b
My ds answer is
chemical potential energy -electrical energy - kinetic energy-sound energy.

alhtough ans.sheet is
kinetic energy-electrical energy - kinetic energy-sound energy.

[Tang]

reddotresident:

2011 red swastika science prelim paper. assuming you all hv the papers now, can someone help pls? thank you!


Q32b - DS says
yes, as only the no. of plants per plot should be changed. all other variables should be constant.

ans.sheet says
yes, as diff. plants bear diff amt of fruits.

Q41b.
Describe one action michael has to carry out consistently thruout the expereiment in order to get reliable results?

DS says
timing.

ans.sheet says place the car from top of the ramp.

Q43b
My ds answer is
chemical potential energy -electrical energy - kinetic energy-sound energy.

alhtough ans.sheet is
kinetic energy-electrical energy - kinetic energy-sound energy.

Hi,

All the answers provided by the worksheet are correct.

Q32b. Question asks whether the same type of types should be used, so there is no need to talk about the number and other variables.

Q41b. Timing is the results, so cannot be kept constant.

Q43b. Point A - Kinetic energy, as the point moves to make contact to close the circuit. [Question does not ask for the source of energy which is chemical potential energy]
Note: Answer to Q43b is incorrect and has been amended in subsequent reply.

[reddotresident]

Tang:

reddotresident:

2011 red swastika science prelim paper. assuming you all hv the papers now, can someone help pls? thank you!


Q32b - DS says
yes, as only the no. of plants per plot should be changed. all other variables should be constant.

ans.sheet says
yes, as diff. plants bear diff amt of fruits.

Q41b.
Describe one action michael has to carry out consistently thruout the expereiment in order to get reliable results?

DS says
timing.

ans.sheet says place the car from top of the ramp.

Q43b
My ds answer is
chemical potential energy -electrical energy - kinetic energy-sound energy.

alhtough ans.sheet is
kinetic energy-electrical energy - kinetic energy-sound energy.

Hi,

All the answers provided by the worksheet are correct.

Q32b. Question asks whether the same type of types should be used, so there is no need to talk about the number and other variables.

Q41b. Timing is the results, so cannot be kept constant.

Q43b. Point A - Kinetic energy, as the point moves to make contact to close the circuit. [Question does not ask for the source of energy which is chemical potential energy]

You are my saviour ::thankyou: yet again..