This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Friday, June 06, 2008

Majestic Niagara Falls

Besides being a tourist attraction, Niagara Falls is also known to generate electricity for both Canada and US.

Hydro Electric Power is electricity generated by water. A dam is built to increase the height of the water. As the height of the water increases, gravitational potential energy increases. Water at the bottom of the dam thus experiences high pressure. This causes the water to be released at a high speed, with a lot of kinetic energy.

The kinetic energy is then used to turn the turbine, which then turns the generator to produce electricity.

Pictures of Niagara Falls.


Rainbow Falls, on the US side of the border



Horseshoe Falls, on the Canadian side of the border. Yes, we all got wet as the boat approached the falls.

A couple more shots of the falls below.







Picture shot of the dam at the Hydro Electric Power Plant, on the Canadian side of the border. (below)



The dam is situated a few kilometres downstream of the falls.

That's all for now.

18 comments:

keentolearn said...

Dear Mr Song

Does boiled water affect the hydrilla's ability to make food or a seed's ability to germinate?In both cases, the hydrilla and seed are immersed in a beaker of boiled water covered with a layer of oil.What is the reason? What is the purpose of the layer of oil?

keentolearn said...

In an experiment to find out whether plants take in oxygen and give out carbon dioxide during respiration,Mei Ling covered a potted plant with blackcardboard and left the set up for 10 hours.(ACS P5 SA1 2007).Just out of interest,What is the purpose of covering up the pot with a plastic bag?

keentolearn said...

Dear Mr Song
1) Jessie plucked a leaf from a rose plant in the garden and placed into a beaker of hot water.
The correct answer as in MCQ is a) Tiny openings on the leaf surface allow air to escape b) There are more bubbles escaping on the underside of the leaf.

Is the leaf still alive? What is the process that allows the air to escape?Can a leaf which had been plucked from the plant still photosynthesise (presence of light), respire or transpire?

2) In animals, the heart is the organ which pumps blood to all parts of the body. In plants’ transport system, what causes the water ,nutrients and sugar to be transported to all parts of the plants.
Please advise.

Excel Eduservice said...

Q: Does boiled water affect the hydrilla's ability to make food or a seed's ability to germinate?

A: Yes, when you boil water, you are expelling dissolved gases, including oxygen from the water. Oxygen is needed for respiration.

Q: In both cases, the hydrilla and seed are immersed in a beaker of boiled water covered with a layer of oil.What is the reason? What is the purpose of the layer of oil?

A: The oil is to prevent oxygen from the atmosphere re-dissolving into the water when the water cools down. Gases dissolve in water better in lower temperatures. That’s why your fizzy soft drink has most gas when it is cold.

Q: In an experiment to find out whether plants take in oxygen and give out carbon dioxide during respiration,Mei Ling covered a potted plant with blackcardboard and left the set up for 10 hours.(ACS P5 SA1 2007).Just out of interest,What is the purpose of covering up the pot with a plastic bag?

A: I think got the Q wrongly structured. What plastic bag are you referring to? Is there a diagram that comes with the Q?

Q: 1) Jessie plucked a leaf from a rose plant in the garden and placed into a beaker of hot water.
The correct answer as in MCQ is a) Tiny openings on the leaf surface allow air to escape b) There are more bubbles escaping on the underside of the leaf.

Is the leaf still alive? What is the process that allows the air to escape? Can a leaf which had been plucked from the plant still photosynthesise (presence of light), respire or transpire?

A: The plucked leaf will be able to photosynthesise for a short while only. It has no roots to absorb water and nutrients to live as an independent organism.

2) In animals, the heart is the organ which pumps blood to all parts of the body. In plants’ transport system, what causes the water ,nutrients and sugar to be transported to all parts of the plants.

A: At PSLE level, what the student needs to know is that the tubes that carry water (xylem) are on the inside, and food carrying tubes (phloem) are on the outside. It is also good to know that water is being transported upwards to the leaves by the process of transpiration.

It is not necessary to know how food is transported. In any case, here is a link to satisfy your curiosity if you really want to know. Click here.

Excel Eduservice said...

About the ACS Sc Q. I got to see the actual Q finally. There is a diagram attached.

I can think of only 1 reason why the plastic bag is used. The plastic is to isolate the soil, which contains micro-organisms, from the air in the cardbox box.

This is to ensure that all carbon dioxide came from the plant and not from other organisms.

Can't think of any other logical answer.

keentolearn said...

Dear Mr Song

Thank You for your fast reply.It's certainly of great help.

Best Wishes

keentolearn said...

Q: 1) Jessie plucked a leaf from a rose plant in the garden and placed into a beaker of hot water.
The correct answer as in MCQ is a) Tiny openings on the leaf surface allow air to escape b) There are more bubbles escaping on the underside of the leaf.

A: The plucked leaf will be able to photosynthesise for a short while only. It has no roots to absorb water and nutrients to live as an independent organism.

Dear Mr Song

a) If the beaker of hot water is replaced by a beaker of tap water, do we still get bubbles from the underside of the leaf?

b) Can a plucked leaf still respire or transpire?

c) If a plucked leaf is immersed into a beaker of water, can it still absorb water? If I understand correctly,a cut portion of a stem without roots can still draw in water.

d) Is transpiration in PSLE Science syllabus?

keentolearn said...

Dear Mr Song

a)What is the difference between seed leaves and seed coat?

b)Some green beans are immersed into a beaker of water for a week.What can we observe about the beans?

keentolearn said...

Dear Mr. Song
Is it better to have an early morning jog or evening jog? Who will get to breathe air with more oxygen?

keentolearn said...

Dear Mr. Song
Is it better to have an early morning jog or evening jog? Who will get to breathe air with more oxygen?

Excel Eduservice said...

Q: If the beaker of hot water is replaced by a beaker of tap water, do we still get bubbles from the underside of the leaf?

A: Yes.

Q: Can a plucked leaf still respire or transpire?

A: I believe so, as long as there is water, air and food for the leaf.

Q: If a plucked leaf is immersed into a beaker of water, can it still absorb water? If I understand correctly, a cut portion of a stem without roots can still draw in water.

A: I think you mean can transpiration still occur? If the leaf blade is ABOVE water and the stalk is submerged, I don’t see any reason why it cannot transpire. However, it must be remembered that there is no nutrients in the water. So I do not know for how long that leaf can last. Maybe you can try it at home and tell everyone about that experiment.

As for the leaf remaining submerged, I don’t think it can transpire much, other than just for a few hours. After all, when water is lost through leaves, it evaporates into the air. If the leaf is submerged, how is evaporation going to happen?

Q: Is transpiration in PSLE Science syllabus?

A: I see the topic of transpiration appearing in different textbooks and science practice papers from schools. Here is the link to MOE’s syllabus if you bother to find out. http://www.moe.gov.sg/education/syllabuses/sciences/

Transpiration is a very small topic (if you can call it a topic). The Qs you put up are already more than what most textbooks and practice papers ask.

Q: What is the difference between seed leaves and seed coat?

A: Seed coat is the covering of the seed. Seed leaves are the “food storage compartment” for the seedling. It must be remembered that seedlings do not have leaves to photosynthesise. Until the leaves grow, the seedling has to depend on an alternative food source – the seed leaves.

Q: Some green beans are immersed into a beaker of water for a week. What can we observe about the beans?

A: If the temperature is right, the seeds will germinate. I don’t think you need a week though.

Q: Is it better to have an early morning jog or evening jog? Who will get to breathe air with more oxygen?

A: If you are talking about the topic of photosynthesis, then of course evening jog will give you more oxygen. Plants photosynthesise the whole day when there is light. In the morning, after a dark night, the plants had not photosynthesised the night before.

PS – Is that a “creative” Q from some Science book somewhere? If it is, I would advise that you do not use it. For PSLE Science, thinking “out of the box” will not score you extra points. In fact, it may even cause you to lose points because key words may be missing.

You should keeping close to what is taught in schools, using keywords and key concepts.

keentolearn said...

Q: Some green beans are immersed into a beaker of water for a week. What can we observe about the beans?

A: If the temperature is right, the seeds will germinate. I don’t think you need a week though.

Dear Mr Song

Thank You for your speedy reply.

Sorry, I missed out some key words in my question earlier. It should read as

Q)Some green beans are immersed into a beaker of boiled water covered by a layer of oil for a week. What can we observe about the beans?

keentolearn said...

Q: Is it better to have an early morning jog or evening jog? Who will get to breathe air with more oxygen?

Dear Mr Song

I rephrase it from a question in i -Science Workbook B.

Thank you for your advice.Students who have the blessings of reading your blog will certainly find them useful.You've brighten up our days.

Excel Eduservice said...

Keen to learn posted:
"Sorry, I missed out some key words in my question earlier. It should read as

Q)Some green beans are immersed into a beaker of boiled water covered by a layer of oil for a week. What can we observe about the beans?"


Wow! Now that makes a BIG difference!

By boiling the water, oxygen would have been expelled from the water. By covering it with oil, the oxygen won't be able to be redissolved in the water when it cools down.

That means the seeds WILL NOT germinate. The water will also probably enter the cells of the beans and they will swell up after a week.

In other words, the seed will expand and the seed coats will probably be torn.

keentolearn said...

Dear Mr Song

Thank You for your reply.

keentolearn said...

Dear Mr Song

I’ve checked Primary Science Syllabus 2001(for current P5 and P6 students); transpiration was not mentioned in it. However I found one question Q9 on page 36 of PSLE Science (2002-2006) where transpiration was mentioned as one of the answer.I'm not too sure if this question is in the latest copy as I don't have one.

So, maybe, not too wise to spend too much time on it. At this level, just have to know that transpiration refers to the loss of water through stomata.

Just out of interest, does transpiration occur at any temperature or at higher temperature, such as under sunlight? If we cover the leaves of a plant with a plastic bag, are the water droplets which had condensed on the surface of the bag caused by respiration or transpiration? Can transpiration, respiration and photosynthesis occur simultaneously under light?

keentolearn said...

Dear Mr Song

Wishing you and your loved ones Good Health and a Happy National Day 08.

Best Wishes

Excel Eduservice said...

Happy National Day to you and your loved ones too.

=======

Rate of evaporation is greater at higher temperature. Logically, rate of transpiration should be higher too.

Transpiration, respiration and photosynthesis occur at the same time when the plant is under light. However, that has never been asked in PSLE. Not that I know of at least.