Q&A - PSLE Science

[Michaelia0816]

:udaman: Dear Tianzhu and Charsen,


I need answer for it
Charsen, thx I understood how you are saying. But not sure with the two question answer, I need it for checking. If I am wrong, I will notice you.

http://i47.tinypic.com/hunmud.jpg\">

[Clairifina]

Please help with this question!


The organisms below are organisms that belong to the jungle habitat.

Plant>>>plakker gypsy moth>>>bird
Plant>>>Washington moth>>> bird

The player gypsy moth is characterised by its light colour whereas the Washington moth is dark coloured. The populations of both types of moths remained the same until the mahogany trees with dark trunks were fell for their timber. Within a month after all the mahogany trees were fell, the number of the two types of moths dropped. The number of Washington moths decreased more than the number of plakker gypsy moths.

1.Explain why the number of both moths decrease after the mahogany trees are fell.

2. Explain why there was a bigger drop for the population of Washington moths as compared to that of the plakker gypsy moths.

[charsen]

Clairifina:

Please help with this question!


The organisms below are organisms that belong to the jungle habitat.

Plant>>>plakker gypsy moth>>>bird
Plant>>>Washington moth>>> bird

The player gypsy moth is characterised by its light colour whereas the Washington moth is dark coloured. The populations of both types of moths remained the same until the mahogany trees with dark trunks were fell for their timber. Within a month after all the mahogany trees were fell, the number of the two types of moths dropped. The number of Washington moths decreased more than the number of plakker gypsy moths.

1.Explain why the number of both moths decrease after the mahogany trees are fell.

2. Explain why there was a bigger drop for the population of Washington moths as compared to that of the plakker gypsy moths.

Hi
1. After the trees are chopped, there are fewer plants for the moths to eat.Hence, the number of both moths decreased due to starvation of food.

2.For this question,you must see the relationship between the washington moth colour.If you read the sentence where they decribe the mahogany trees, they mentioned the tree is dark coloured.Relate this information to the food chain which involves the washington moth.The answer is:
The washington moths camouflaged to the mahogany trees to escape from the birds.Since there are no mahogany trees, the washington moths are easily spotted by the birds compared to plakker gyspy moth and more washington moths are eaten up.Hence,the population of washington moths drcerased more than the plakker gyspy moth.
Hope this helps.
cheers

[Clairifina]

Thank you so much!

[Michaelia0816]

Charsen, is this correct? The pink line?


http://i45.tinypic.com/9kvvgn.jpg\">

[charsen]

Michaelia0816:

Charsen, is this correct? The pink line?


http://i45.tinypic.com/9kvvgn.jpg\">

Yes.That is correct.

[Michaelia0816]

Thanks!

[Michaelia0816]

Charsen, pls help,


Link 1: http://t.co/NLSgYnKH
Link 2: http://t.co/4IoW9qkf
Link 3: http://t.co/yygRcPYh

[Michaelia0816]

Charsen help me with the questions on top

[charsen]

Michaelia0816:

Charsen, pls help,


Link 1: http://t.co/NLSgYnKH
Link 2: http://t.co/4IoW9qkf
Link 3: http://t.co/yygRcPYh

Hi,
I'm posting the answers based on what Ive learnt. Pls verify and post back if any of the answers are incorrect.
For link 1,the answer is (2).For food web questions,you should understand that the plant population is the highest among the populations in a community.Thus,the herbivores population is the second highest in the community.From there you know the rest are carnivore and omnivore.

For link 2, the answer is (4).Plant's main source of energy is the sun.Hence,you should look at the graph in which organism b is the highest population in the community.You can solve this by looking at the link 1 explanation.That is a related question.

For link 3,
Which of the following characteristics are structural adaptations that help plants to reduce loss of water by evaporation?

A. Clasping roots
B. Hairy leaf surfaces
C. Waxy leaf surfaces with very few tiny openings on the leaves

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

My answer would be (3) and here is my reasoning.
A --> Out of answer as clasping roots help to obtain sunlight and hence could help evaporation.
C --> shd be in the answer.
With elimination of A, I'm left with option (3)..