PSLE 2009 - Science

[kohjl]

acelancer:

hot_chocolate:

[quote=\"justsay\"]
veg increase, fruit trees decreased ?

same answer... Hope it's correct...

yup[/quote]The Question:
The farmer found that alot of caterpillars were eating his crops. The farmer sprayed alot of pesticides onto them. Which of the following is correct?

My answer:
Crops-increased
Fruits-increased

Reason: Even if the pesticides kill some of the plants, pesticides will kill most of the caterpillars. Since there are no more caterpillars feeding on the leaves, the number of crops will increase and therefore, the number of fruits will increase.

From: kohjl Jr

[acelancer]

kohjl:

The Question:

The farmer found that alot of caterpillars were eating his crops. The farmer sprayed alot of pesticides onto them. Which of the following is correct?

My answer:
Crops-increased
Fruits-increased

Reason: Even if the pesticides kill some of the plants, pesticides will kill most of the caterpillars. Since there are no more caterpillars feeding on the leaves, the number of crops will increase and therefore, the number of fruits will increase.

From: kohjl Jr

wait, i think i changed it to ur ans. ah! i kei kiang again!

[kohjl]

Hello:

What are the need(s) for a bread to turn mouldy?


(A)Oxygen
(B)Can't remember
(C)Water.

Its something like that.

I put water and oxygen.

From: kohjl Jr

[kohjl]

acelancer:

Vaizard:

Hello, I am a candidate taking the PSLE.


What is the answer for the question about the flower wrapped with plastic bag? Is the answer B and anther? :shock:

yup! i put tht too! at first i was stump by it.....

I put B and anther.

From kohjl Jr

[kohjl]

atutor2001:

caroline3sg:

kohjl

thank you.

There is one question about which can travel a longer%20distancein a desert, lizard & snake.

My girl's ans sounds logical but I worry the way she phrased it.

2 reasons (my own words, but her meaning:)
1) snake has no legs, there is frictional force when gliding on the (hot - not sure this word was mentioned in her ans or not) sand.

Personally, I think the longer body also plays a part on its contact on larger surface of the sand.

2) lizard uses front legs to run, hind legs to push it faster. Faster must be linked to longer distance, but don't know / didn't state.

This is amazing! Are they kidding by setting such question? The key words is \"longer distance\".

Are they testing adaptation for heat? I remember snake moves under the sand in the desert to shield from the hot sun. If that is the case, then it should be snake because lizard cannot move under the sand.

Hi Kohjl Jr, what is your take?

The Question:
There are 2 diagrams. The first shows a snake slithering (but the question put it as crawling) and the other shows a lizard running.
NOTE: The question already stated that the lizard moves faster than the snake (not travel a longer distance).
Then the question asked: Give 2 reasons.

My answer:
Reason 1:As the whole snake's body is in contact with the sand while the lizard only has its feet on the sand, there will be more friction between the snake and the sand than the lizard and the sand. So the lizard will move faster.

Reason 2: As the snake moves in a zig-zag while the lizard moves in a straight line, the snake has to move a longer distance than the lizard.

But I am not sure whether my asnwer is correct. Can anyone confirm? Thanks.

From: kohjl Jr

[justsay]

kohjl:

acelancer:

[quote=\"hot_chocolate\"]
same answer... Hope it's correct...

yup

The Question:
The farmer found that alot of caterpillars were eating his crops. The farmer sprayed alot of pesticides onto them. Which of the following is correct?

My answer:
Crops-increased
Fruits-increased

Reason: Even if the pesticides kill some of the plants, pesticides will kill most of the caterpillars. Since there are no more caterpillars feeding on the leaves, the number of crops will increase and therefore, the number of fruits will increase.

From: kohjl Jr :D[/quote]As you have mentioned it killed most of the caterpillars but not all. The remaining caterpillars will then multiply and feed of the fruits. So shouldnt it be crop increased and fruit decreased ?

[shinystars]

Hi,

I am a candidate who have just taken the PSLE Science exam. Just wanted to know, what is the correct answer for this question:

Two bulbs are arranged in series. When one bulb is added to the circuit in parallel arrangement, what would happen to the brightness of the first bulb which was arranged in series?

1) It would not light up.
2) It would become brighter.
3) It would become dimmer.
4) It's brightness would remain the same.

Thank you

[acelancer]

kohjl:

atutor2001:

[quote=\"caroline3sg\"]kohjl

thank you.

There is one question about which can travel a longer%20distancein a desert, lizard & snake.

My girl's ans sounds logical but I worry the way she phrased it.

2 reasons (my own words, but her meaning:)
1) snake has no legs, there is frictional force when gliding on the (hot - not sure this word was mentioned in her ans or not) sand.

Personally, I think the longer body also plays a part on its contact on larger surface of the sand.

2) lizard uses front legs to run, hind legs to push it faster. Faster must be linked to longer distance, but don't know / didn't state.

This is amazing! Are they kidding by setting such question? The key words is \"longer distance\".

Are they testing adaptation for heat? I remember snake moves under the sand in the desert to shield from the hot sun. If that is the case, then it should be snake because lizard cannot move under the sand.

Hi Kohjl Jr, what is your take?

The Question:
There are 2 diagrams. The first shows a snake slithering (but the question put it as crawling) and the other shows a lizard running.
NOTE: The question already stated that the lizard moves faster than the snake (not travel a longer distance).
Then the question asked: Give 2 reasons.

My answer:
Reason 1:As the whole snake's body is in contact with the sand while the lizard only has its feet on the sand, there will be more friction between the snake and the sand than the lizard and the sand. So the lizard will move faster.

Reason 2: As the snake moves in a zig-zag while the lizard moves in a straight line, the snake has to move a longer distance than the lizard.

But I am not sure whether my asnwer is correct. Can anyone confirm? Thanks.

From: kohjl Jr :D[/quote]my first reason was sort of same as urs but the 2nd one is different. urs make great sense but i'm not tht sure. sry. but i read about some animal able to travel in a zig zag manner. but for 2nd reason i wrote tht as the lizard as less contact with the hot sand then the snake, it will be able to travel longer as it will experience less heat while the snake has its whole body having contact with the sand and has more heat so it will not travel as far as the lizard. is my reasoning ok?

[acelancer]

shinystars:

Hi,

I am a candidate who have just taken the PSLE Science exam. Just wanted to know, what is the correct answer for this question:

Two bulbs are arranged in series. When one bulb is added to the circuit in parallel arrangement, what would happen to the brightness of the first bulb which was arranged in series?

1) It would not light up.
2) It would become brighter.
3) It would become dimmer.
4) It's brightness would remain the same.

Thank you

i put 4.

[shinystars]

For that lizard question, I wrote:


1) The lizard runs by lifting its legs off the sand rapidly, causing it to have a smaller surface area which is exposed to the sand, therefore it does not need to overcome as much friction as the crawling snake.

2) The lizard has legs to help it run across the sand, faster than the crawling snake. :?

Please help. :?: