Q&A - PSLE Science

[bestwishes]

Selfan4ever♥23:

Koky462:

I have an question on the method of reproduction from my son's exercise.


x - Man, Frog, Polar bear\t\t
y - Yeast, Amoeba, Paramecium
\t
a)What is the main difference between the two methods of reproduction for X & Y?
b)Name the reproduction method under the sub-heading X.

b) External

a) X: Sexual reproduction (involves 2 parents of opposite sexes; involves fertilisation)
Y: Asexual reproduction (involves a single parent; not involve fertilisation)

Frogs in X -- external fertilisation
Mammals in X -- internal fertilisation
Yeast in Y -- budding (a kind of cell division)
Amoeba & Paramecium in Y -- binary fission (a kind of cell division)

[Koky462]

Thank you Selfan4ever23 & bestwishes for your replies!

[elkniwt]

Hi,


Need some advises on this qn :

Which of the following is/are the correct functions of the trunk of a rain tree?
A. It transports water and mineral salts to all parts of the plant.
B. It keeps the plant upright.
C. It twines round a support to help the plant reach for more sunlight.
D. It transports food from the leaves to all parts of the plant.

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

The answer in answer key is (4). My dd’s questions are "is it correct to say the trunk transports food, isn’t it the phloem that does that?" And she also asks, if a qn asks for the function of a trunk, can she actually write "it transports food to all parts of the plant"??

Many thanks.

[anneshirleygilbert]

Can these two terms "chemical energy" and "chemical potential energy" be used interchangeably in answering Open-Ended questions in PSLE? Do they mean the same thing? I see these terms in different answer sheets. Please help.

[elkniwt]

anneshirleygilbert:

Can these two terms \"chemical energy\" and \"chemical potential energy\" be used interchangeably in answering Open-Ended questions in PSLE? Do they mean the same thing? I see these terms in different answer sheets. Please help.

Hi anneshirleygilbert,

According to my dd, their teacher told them to use the term \"chemical potential energy\" instead of \"chemical energy\".

Regards.

[tianzhu]

Hi elkniwt


B (upright) is definitely correct, so the selected option has to include B. C (twine) is also out.This immediately rules out option (1) and (3).

The trunk provides a source of structural stability for the tree. Its two main components are the Xylem and Phloem which act as a main pathway for water, nutrients and food between the leaves and roots.

As in any MCQ questions, one is required to select an answer based on the four options given in the question.Based on the context in the question, (4) is a logical choice.

For more information,please go to page 5 of this link.
http://www.pennsylvaniahorticulturalsociety.org/phlgreen/PlantaTree.pdf

Best wishes

[atutor2001]

elkniwt:

... My dd's questions are \"is it correct to say the trunk transports food, isn't it the phloem that does that?\" And she also asks, if a qn asks for the function of a trunk, can she actually write \"it transports food to all parts of the plant\"??

The phloem is part of a tree trunk. Therefore, it is ok to say tree trunk transports food. Attached below is an article for easy reference :

The trunk of a tree is composed of several basic parts. The bark of the tree is probably one of the most familiar parts of a tree. The bark is an outer covering of dead tissue, which protects the tree from weather, disease, insects, fire and mechanical injury. Bark characteristics can vary greatly from tree to tree and can be useful in identification. The next layer immediately inside the bark is called the phloem. The phloem is a thin layer of living cells and is responsible for transporting food around the tree. Large amounts of sugar travel down the phloem to the roots. Sugar may also travel up the phloem to other parts of a tree that need energy for growth and maintenance. The next portion of the trunk is called the vascular cambium. The cambium is a very thin layer of living tissue which produces new phloem to its outside and new xylem to its inside. The cambium is most active in the spring and early summer when most tree growth is taking place. During this time of the year the bark of a tree is very loose and can be easily knocked off the tree. Inside the vascular cambium is the largest portion of the trunk known as the xylem.

[atutor2001]

anneshirleygilbert:

Can these two terms \"chemical energy\" and \"chemical potential energy\" be used interchangeably in answering Open-Ended questions in PSLE? Do they mean the same thing? I see these terms in different answer sheets. Please help.

It is wrong to use \"Chemical energy\" as a replacement for \"Chemical Potential Energy\" \"Chemical energy\" means a totally different thing and is not the potential energy that Pr sch is learning. It should be covered in either Sec or JC, can't remember. Use only \"chemical potential energy\" Ignore those answer sheets.

[elkniwt]

Dear tianzhu and atutor2001,


Thank you very much for your help!!!

[anneshirleygilbert]

Thanks, elkniwt and atutor2001, for the clarification. Appreciate your help very much.