Q&A - P5 Science

[marstolive]

:thankyou:

PSLEguru:

marstolive:

Can someone help me with this?


why is the rate of evaporation decreases when a plant with leaves are covered with oil?


thanks in advance

There are tiny pores on the leaves of a plant called stomata (singular called stoma) where gaseous exchange can occur. Most water loss occurs through the stomata. When the leaves are covered with oil, the stomata are blocked, and water cannot escape from the leaves.

[marstolive]

:thankyou:

PSLEguru:

marstolive:

Can someone help me with this?


why is the rate of evaporation decreases when a plant with leaves are covered with oil?


thanks in advance

There are tiny pores on the leaves of a plant called stomata (singular called stoma) where gaseous exchange can occur. Most water loss occurs through the stomata. When the leaves are covered with oil, the stomata are blocked, and water cannot escape from the leaves.

[Jamesbond]

http://i44.tinypic.com/ra9kl5.jpg\">

Pl help me answer.

[StudyRoom]

Jamesbond:

http://i44.tinypic.com/ra9kl5.jpg\">

Pl help me answer.

Seems to be a little ambiguous. I suppose the question wants you to recognise that duckweed floats on water.
(1) littler won't obscure sunlight from the duckweed
(2) similarly, oil spill won't obscure sunlight. Although the water will still be polluted...
(3) chemicals will be an issue because the plants may get poisoned.
(4) soil erosion will cloudy the water, but since the plants float, it may be less affected.
So (3) seems to be the best answer.

Although (1), (2) and (4) may also cause the duckweed to die.

[Jamesbond]

PSLEguru:

Jamesbond:

http://i44.tinypic.com/ra9kl5.jpg\">

Pl help me answer.

Seems to be a little ambiguous. I suppose the question wants you to recognise that duckweed floats on water.
(1) littler won't obscure sunlight from the duckweed
(2) similarly, oil spill won't obscure sunlight. Although the water will still be polluted...
(3) chemicals will be an issue because the plants may get poisoned.
(4) soil erosion will cloudy the water, but since the plants float, it may be less affected.
So (3) seems to be the best answer.

Although (1), (2) and (4) may also cause the duckweed to die.

Answer given is 3. Was wondering how chemicals came in to pond? If it was a lake or river, then agreed. Can u pl tell me what is the source of chemicals here to clear my doubt? TIA.

[StudyRoom]

Jamesbond:

PSLEguru:

[quote=\"Jamesbond\"]http://i44.tinypic.com/ra9kl5.jpg\">

Pl help me answer.

Seems to be a little ambiguous. I suppose the question wants you to recognise that duckweed floats on water.
(1) littler won't obscure sunlight from the duckweed
(2) similarly, oil spill won't obscure sunlight. Although the water will still be polluted...
(3) chemicals will be an issue because the plants may get poisoned.
(4) soil erosion will cloudy the water, but since the plants float, it may be less affected.
So (3) seems to be the best answer.

Although (1), (2) and (4) may also cause the duckweed to die.

Answer given is 3. Was wondering how chemicals came in to pond? If it was a lake or river, then agreed. Can u pl tell me what is the source of chemicals here to clear my doubt? TIA.[/quote]You don't have to wonder how chemicals came to the pond. You only know something is causing the plants to die.

Some one could have poured chemicals in.

Maybe someone decided to do his laundry there and poured a whole bottle of bleach in.

It doesn't matter.

[Jamesbond]

Oh....I never thought such things could happen in a pond.... :scared: Shall learn now.....

[Jamesbond]

http://i44.tinypic.com/2yngfax.jpg\">

For the question,
1) The plant is dying.
2) The stem below the cut ring swells a little.
Is my answer correct or not?

[StudyRoom]

Jamesbond:

http://i44.tinypic.com/2yngfax.jpg\">

For the question,
1) The plant is dying.
2) The stem below the cut ring swells a little.
Is my answer correct or not?

I think:
1) is correct
2) should be there is no swelling around the cut ring. (if anything, the swelling should be above, not below, the cut ring.)

The swelling in Plant X is due to food being produced in the leaves - this gets transported down the stem. Since the food carrying tubes are cut away, the stem swells above the cut area.

However, since in Plant Y, the cut area is above the water, the plant is not able to transport water up to the leaves, so the leaves are unable to produce food, and therefore there is no swelling.

[Jamesbond]

PSLEguru:

Jamesbond:

http://i44.tinypic.com/2yngfax.jpg\">

For the question,
1) The plant is dying.
2) The stem below the cut ring swells a little.
Is my answer correct or not?

I think:
1) is correct
2) should be there is no swelling around the cut ring. (if anything, the swelling should be above, not below, the cut ring.)

The swelling in Plant X is due to food being produced in the leaves - this gets transported down the stem. Since the food carrying tubes are cut away, the stem swells above the cut area.

However, since in Plant Y, the cut area is above the water, the plant is not able to transport water up to the leaves, so the leaves are unable to produce food, and therefore there is no swelling.

My doubt is since the water tubes are cut, the absorbed water cannot be transported up and it causes to swell below the cut.