Tutor Niedino: Pri Science Questions and Concepts

[starlight1968sg]

elkniwt:

Hi,


There's this qn in the exam asking for the conditions for germination. Though it is a very basic qn, my dd got it marked wrong. Her answer is water, oxygen and warmth. Teacher says carbon dioxide is also needed hence no marks for her. When I surfed web, the websites says water, oxygen and warmth only. My dd says she's very confused cos what mummy say is different from what teacher. P3 teacher and P4 teacher also say different things.

During germination, the seed has no leaves and thus can't make food. If it can't make food, it does not need carbon dioxide.

[atutor2001]

elkniwt:

Hi,


There's this qn in the exam asking for the conditions for germination. Though it is a very basic qn, my dd got it marked wrong. Her answer is water, oxygen and warmth. Teacher says carbon dioxide is also needed hence no marks for her. When I surfed web, the websites says water, oxygen and warmth only. My dd says she's very confused cos what mummy say is different from what teacher. P3 teacher and P4 teacher also say different things.

God bless your dd. She gets the \"BEST\" science teacher if the question is limited to just germination.

However, sometimes they love to test \"England\" in science paper by adding a phrase \"and grow\" behind, which most students usually ignore. It there is \"grow\", then carbon dioxide, light are also needed. Maybe you would like to read the question again.

[Full.010894Cream]

hmmm..how come this thread is not maintained by the thread starter??! :?

[Tang]

elkniwt:

Hi,


There's this qn in the exam asking for the conditions for germination. Though it is a very basic qn, my dd got it marked wrong. Her answer is water, oxygen and warmth. Teacher says carbon dioxide is also needed hence no marks for her. When I surfed web, the websites says water, oxygen and warmth only. My dd says she's very confused cos what mummy say is different from what teacher. P3 teacher and P4 teacher also say different things.

Hi,

Unless the chapter 'Air' has been taught, there is no reason to state 'Oxygen' for germination.


So answer - Air, water (moist) and warmth - is the correct answer.


If diagram shows seedlings with leaves, then for the seedlings to survive, air, water and warmth will be required and not oxygen, waterr and warmth.

[elkniwt]

Hi,


Qn just says germination. I really think teacher should not mark her wrong. dd felt that she is being wronged for being specific. [Like to ask the teachers in the forum, is it wrong to write oxygen?]

I agree that writing air is good enough, but the reason teacher gives her for marking it wrong is that carbon dioxide is also needed for germination… ??

[atutor2001]

elkniwt:

Hi,


Qn just says germination. I really think teacher should not mark her wrong. dd felt that she is being wronged for being specific. [Like to ask the teachers in the forum, is it wrong to write oxygen?]

I agree that writing air is good enough, but the reason teacher gives her for marking it wrong is that carbon dioxide is also needed for germination... ??

I am/was not a teacher. However, if question only mentioned \"germination\", then your dd's answer is definitely correct. In fact oxygen is a more accurate answer than air because oxygen is that particular element inside \"air\" that is needed for germination.

If we put air as the answer, the assumption made is that it is normal air with oxygen content of about 20% (acceptable in primary school). If the air that the seeds were exposed to has very very low % of oxygen, (say high up in Mount Everest) the seeds may not germinate.

PS
Ask the teacher whether will the seed germinate if placed under 100% oxygen with warmth and water. If the answer is NO, then the teacher is correct in marking your dd's answer as wrong. However, we would then we need to clarify with MOE.

I have abstracted the info below on seed germination under 100% oxygen from http://www.amjbot.org/cgi/content/full/89/3/410:

\"The germination of giant foxtail seed in pure O2 was 87 ± 15% (Figs. 2 and 3). The time to germination was shorter (1 d) at all O2 concentrations greater than that of air (20%). Seed germination and time to germination did not decrease as O2 decreased from 20 to 10%.\"

[Joy]

DELETED

[atutor2001]

Joy:

May I ask, when we write Plant has a fixed cell wall, awarded full marks.

What about Plant has a rigid cell wal?Is it deduct half mark?

Thanks


Rgds
Joy

In my opinion \"rigid\" should be the correct word - not fixed. I will give zero mark for \"fixed\" as the meaning is totally different from rigid. But the wall cannot be spelled as \"wal\" - otherwise no mark as wall is the other key word.

Try googling for \"rigid cell wall\" and \"fixed cell wall\" you will find how the word \"fixed\" is used in relation to cell wall.

[Tang]

Joy:

May I ask, when we write Plant has a fixed cell wall, awarded full marks.

What about Plant has a rigid cell wal?Is it deduct half mark?

Thanks


Rgds
Joy

Hi,

Why is there a need to describe the cell wall?

I will just answer as follows:

Plants have cell walls.

or

Plants have cell walls that give them regular shape.

[Leanne]

I got a reply from her teacher:


In Science, the specific meanings of the words is important.
Different adjectives means different things in Science.
According to Longman, the word rigid means \"stiff, not moving or bending\" - a movement.
However, we are looking for the inability of the cell to change shape - because it has been fixed by the cell wall.

atutor2001:

Joy:

May I ask, when we write Plant has a fixed cell wall, awarded full marks.
What about Plant has a rigid cell wal?Is it deduct half mark?

Thanks


Rgds
Joy

In my opinion \"rigid\" should be the correct word - not fixed. I will give zero mark for \"fixed\" as the meaning is totally different from rigid. But the wall cannot be spelled as \"wal\" - otherwise no mark as wall is the other key word.

Try googling for \"rigid cell wall\" and \"fixed cell wall\" you will find how the word \"fixed\" is used in relation to cell wall.