Tutor Niedino: Pri Science Questions and Concepts

[starlight1968sg]

Leanne:

Hi everyone


Am new to the forum and trying to learn as much as I can to help my ds.

I have been trying to understand into the details of this simple equation and hope someone can help to get it right.thanks

Carbon dioxide + Sunlight + Water => Sugar + Oxygen.

LHS is for photosynthesis to take place, RIGHT hand side as in sugar, can someone pls explain how starch and sugar link into this?thanks alot.

caroline3sg:

[quote]When the insect eat the leaves, how does it know it is eating the food carrying tubes only and not the water carrying tubes?The food and water carrying tubes are the transport system, how does the insect differentiate them?

Photosynthesis is carried out on the leaves (that's where chlorophyll is). So the leaves would have water, using this formula :
Carbon dioxide + Sunlight + Water => Sugar + Oxygen.

Food carrying tubes flow downwards, I mean the nutrients.

Water carrying tubes flow upwards, I mean the water.

[/quote]Thanks Neidino and others who have responded to my question.

The food made by plants is usually (or loosely at the primary school's level) referred to as sugar but the more appropriate term is glucose.

http://en.wikipedia.org/wiki/Glucose

http://en.wikipedia.org/wiki/Starch

\"In photosynthesis, plants use light energy to produce glucose from carbon dioxide. The glucose is stored mainly in the form of starch granules, in plastids such as chloroplasts and especially amyloplasts. Toward the end of the growing season, starch accumulates in twigs of trees near the buds. Fruit, seeds, rhizomes, and tubers store starch to prepare for the next growing season.\"

During photosynthesis, glucose is produced which eventually stored as starch. To test starch ie presence of food made by the green leaves, use an iodine solution.

In addition, water carrying tubes ie xylems are uni-directional ie upward but food carrying tubes ie phloems are bi-directional ie both upward and downward.

Science is such interesting and amazing!

[caroline3sg]

starlight

Thank you for pointing out food carrying tubes are 2 directional. I was too eager to show one up and one down, although at the back of my mind I know nutrients from the soil also go upwards.

[livewith_vanilla]

In my opinion,mindmaps are better. No it does not mean one line=one sentence, two lines=two combined sentences and so on. You have to note the marks. If the question is like asking:


a)Who is correct, John or Ben? (1m)

________________________________________________________
________________________________________________________

U are given two lines, but ur ans can be just sweet and short.

a)Who is correct, John or Ben? (1m)

John is correct.___________________________________________
_______________________________________________________


Explain the answer given in (a). (2m)

________________________________________________________
________________________________________________________


U are given 2 lines, but the marks awarded in 2 marks,hence you must fully explain why.

Explain the answer given in (a). (2m)

Plants can only carry out photosynthesis when there is a light source, taking in carbon dioxide and giving out oxygen. However, when no light is present, plants will carry out respiration and take in oxygen while giving out carbon dioxide.

My explanation might require more than 2 lines, but if it fully explains why, then you will be awarded 2 full marks. So it doesn't mean that if given more lines, must use up all the lines.

[atutor2001]

caroline3sg:

starlight

Thank you for pointing out food carrying tubes are 2 directional. I was too eager to show one up and one down, although at the back of my mind I know nutrients from the soil also go upwards.

Hi caroline3sg

There are many past exam questions, asking \"What do the upward and downward arrows (drawn next to a plant) represent?\"

Such questions give the children the wrong impression that food only travels downwards. Had to tell my kids in those days that those upward arrows, (especially those above branches with leaves) can be \"food\". However, to avoid confrontation, they were told to put the answer as \"water\". Hopefully such question does not appear anymore.

Incidentally, brown stem can also carry out photosynthesis because if we scrape away the external brown layer, there is chlorophyll behind it.

[caroline3sg]

[quote]Incidentally, brown stem can also carry out photosynthesis because if we scrape away the external brown layer, there is chlorophyll behind it.[/quote]
atutor,
I didn't know that, thank you for sharing.

[Niedino]

Hi Starlight,


Great of you to clarify the phloem’s directions. Atutor, I agree that some questions are not set well indeed and they often are a result of existing misconceptions. Leanne, Richard Paul is a famous author on Critical Thinking. Google and you’ll find the titles of his books.

Hope it helps

[starlight1968sg]

Why kids usually do not do well in sect b of the pri Sc papers? Is it the way they answered the questions?

[Niedino]

starlight1968sg:

Why kids usually do not do well in sect b of the pri Sc papers? Is it the way they answered the questions?

Hi Starlight,

I usually see kids not doing well for a variety of reasons.

1. Lack of Knowledge.
They don't know what the question is asking them.

2. Lack of Understanding
They know what the question is asking them, but their basic concepts are wrong.

3. Lack of Accuracy
They do not craft their answers to answer to the question. They answer in a broad manner (too general) or do not explain the theory behind their answers clearly.

E.g. Where does the water on the outside from a cup of cold orange juice come from?

Example 1: From the ice in the orange juice (Lack of knowledge so the child guesses)

Example 2: The orange juice evaporate and condense on the outside of the cup (Misconception of orange juice evaporating before condensing)

Example 3: The water comes from the water vapour in the air. (Does not talk about condensation of the water vapour so too broad)

[Tang]

Niedino:

starlight1968sg:

Why kids usually do not do well in sect b of the pri Sc papers? Is it the way they answered the questions?

Hi Starlight,

I usually see kids not doing well for a variety of reasons.

1. Lack of Knowledge.
They don't know what the question is asking them.

2. Lack of Understanding
They know what the question is asking them, but their basic concepts are wrong.

3. Lack of Accuracy
They do not craft their answers to answer to the question. They answer in a broad manner (too general) or do not explain the theory behind their answers clearly.

E.g. Where does the water on the outside from a cup of cold orange juice come from?

Example 1: From the ice in the orange juice (Lack of knowledge so the child guesses)

Example 2: The orange juice evaporate and condense on the outside of the cup (Misconception of orange juice evaporating before condensing)

Example 3: The water comes from the water vapour in the air. (Does not talk about condensation of the water vapour so too broad)

Hello,

\"Example 3: The water comes from the water vapour in the air. (Does not talk about condensation of the water vapour so too broad)\"

You meant 'incomplete' rather than 'too broad'?

Expected answer?

The water vapour from the surrounding air comes into contact with the cool outer surface of the cup and condenses into water droplets.

[Niedino]

Tang:

Hello,


\"Example 3: The water comes from the water vapour in the air. (Does not talk about condensation of the water vapour so too broad)\"

You meant 'incomplete' rather than 'too broad'?

Expected answer?

The water vapour from the surrounding air comes into contact with the cool outer surface of the cup and condenses into water droplets.

Hi Tang,

Your answer is definitely the ideal answer. What I was trying to show in the example was that pupils often answer either without explaining clearly or in a general manner. It can be termed as an incomplete answer, and the child would not get full marks.