Q&A - PSLE Science

[charsen]

Bottle Gardens

A really attractive and unsual way of growing plants indoors is to create a bottle garden. If carefully made a bottle garden can last a long time needing very little attention and with great advantage that the plants do not get dusty and pest, draughts and fumes are excluded. Select a suitable glass container with a lid. The more air tight the lid the less watering the plants will need.
(abstract from: http://www.greenchronicle.com/gardening/bottle_gardens.htm)
Based on the information from the abstract above, explain how the plants in the bottle garden can last a long time with little watering.
Given answer in the assessment paper :
When the plants transpire, water is given out in the form of water vapor. This water vapour will condense on the cool surface of the glass container to form water droplets. The water droplets will flow back into the soil to moisten it.
Can this be explained with an alternative answer?
The plants have a controlled transpiration. As the bottle is air tight, the water vapour in the air gets saturated with transpiration by plants after sometime. Hence the rate of transpiration will be slower thus retaining the water for a longer period of time

[charsen]

paranoid:

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Answer key says 2 but my answer is 3...please help :?:
Thanks in advance.

The answer 2 is correct I think. The aim is to check if the plant grows towards light. Independant variable should be the position of the light source. Change the position of the light source and see if the plant grows towards different directions. Option 3,4 is crossed out as it deals with brightness of bulb which is not the aim. Option 1 does not say anything about bulb A, C in Set up Y. Hence the answer should be 2, with which position of the bulbs are varied with 2 set up.

[NY1969]

NY1969:

I think your ans is correct. Given all conditions remains the same, the only variable is the direction of the light bulb.

Correction....not 'your answer' but 'the given answer'. Answer is 2.

[Robertpattinsonidle]

http://i45.tinypic.com/2zicxeq.jpg\"> http://i46.tinypic.com/1zfkb6c.jpg\"> what is the answer to this qsn?

[fightingmom]

charsen:

paranoid:

http://i48.tinypic.com/24268ll.jpg\">


Answer key says 2 but my answer is 3...please help :?:
Thanks in advance.

The answer 2 is correct I think. The aim is to check if the plant grows towards light. Independant variable should be the position of the light source. Change the position of the light source and see if the plant grows towards different directions. Option 3,4 is crossed out as it deals with brightness of bulb which is not the aim. Option 1 does not say anything about bulb A, C in Set up Y. Hence the answer should be 2, with which position of the bulbs are varied with 2 set up.

Answer key provided is correct.

[kuts]

Hi,


Can anybody explain wat is the difference between cell division and budding

[charsen]

Robertpattinsonidle:

http://i45.tinypic.com/2zicxeq.jpg\"> http://i46.tinypic.com/1zfkb6c.jpg\"> what is the answer to this qsn?

Editing my answer after I thought again.
Hi
The answer is 2 .
Diseased mouse is eaten by Owl. And it's the only prey for OWL. Hence owl population will decrease drastically and eventually die due to lack of food.
Wildcats, snakes end up eating diseased mouse and hence they might be infected as well causing the lion to be infected and die. There is possibility that lion population starts to decrease as well.
Charsen.

[Robertpattinsonidle]

verykiasumummy:

NY1969:

Can someone ans this question in a scientific way:-


A metal rod is partially is submerged into an ice water. After sometimes, why is the other end of the rod becomes cool also?

Metal is a good conductor of heat, so the part that is submerged will lose its heat to the ice water quickly. And since heat travels from a hotter place to a colder place, the other end of the metal will also lose heat to the ice, causing it to be cold eventually.

note: there is no such thing as colder place. it is called cooler place.
thanks,
robertpattinsonidle ft.JB

[Robertpattinsonidle]

charsen:

Robertpattinsonidle:

http://i45.tinypic.com/2zicxeq.jpg\"> http://i46.tinypic.com/1zfkb6c.jpg\"> what is the answer to this qsn?

Hi
The answer is 1 as the owl ONLY feeds on the mouse.Thus,when the mouse population decreased,the owl population was directly affected and would decrease.The lion population would decrease slightly as the population of the snakes decreased as there were fewer mice to eat and result in the decrease of the kite population.When the kite population decreased,the lion population would decrease as there is fewer kites to eat.But,it will remain after some time as there is still the goat and the wild cat populations to feed on.

Charsen.

my answer was 1. but ans key says 2. any reasons?

[charsen]

kuts:

Hi,


Can anybody explain wat is the difference between cell division and budding

Hi
Cell division means that the nucleus makes a copy of itself before splitting into two nuclei.Thus,two daughter cells are produced.

Budding does not have the parent cell divide into two daughter cells.Instead,a bud would grow on the parent cell and would break off from the parent cell when one of the duplicated nuclei is in the daughter cell.
The nucleus in the parent cell would make a copy of itself when the new bud enlargens but have not break off from the cell.

Charsen