PSLE 2009 - Science

[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. :?:

[kohjl]

justsay:

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 ?

I think catepillars eat leaves and not fruits. Worms eat fruits.
From: kohjl Jr

[shinystars]

kohjl:

justsay:

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 ?

I think catepillars eat leaves and not fruits. Worms eat fruits.
From: kohjl Jr

Q: What do caterpillars eat?
A: Almost all caterpillars eat plant materials. Most eat leaves, but some eat seeds, stems, roots, fruits, seed pods or flowers. The caterpillar of the Harvester butterfly eats aphids. Some lycaenid caterpillars eat ant larvae.

(http://www.flmnh.ufl.edu/butterflies/qanda.htm)

[lovingmum]

the questions asked do not look like straight forward ones… i don’ t even dare to ask my girl for her answers, least in case she wrote different from everyone here and i cannot sleep after that…

[acelancer]

lovingmum:

the questions asked do not look like straight forward ones... i don' t even dare to ask my girl for her answers, least in case she wrote different from everyone here and i cannot sleep after that...

some of the q. in the paper are quite straightfoward though rest assure that your daughter would do well!

[Sahimi]

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 that too! :celebrate:

[acelancer]

The question about rod X and the magnet. They put a flame over rod x. what do u guys put? i put lose magnetism and the flame kinetic energy thing(sry can’t remember tht clearly)

[hot_chocolate]

kohjl:

justsay:

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 ?

I think catepillars eat leaves and not fruits. Worms eat fruits.
From: kohjl Jr

my answer was that the plant increased and the fruits decreased.

since the caterpillars feed on the plants, when the caterpillars' population decreases, the population of the plants will increase.

however, with less caterpillars, there will be less butterflies to pollinate the flowers of the fruit trees. wouldn't that result in the number of fruits born by the fruit trees decreasing?


that is my reasoning but i'm not sure though. hope someone can confirm it... hope i'm right....

[the ME]

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

My answer was:

Crops-increased
Fruits-decreased

My reason: The pesticides killed most of the caterpillars. Since there are less caterpillars which feed on the plants, the plants increased. When the caterpillars which were the young of the butterfly decreased, the butterflies will also decrease. The butterflies are needed to help the flowers to pollinate. If there are less butterflies to help the plants pollinate, there will be less fruits as a flower can only become a fruit if it goes through pollination. Therefore, there will be lesser fruits.

:?: Am I correct or wrong? :stupid: