help bio

[hassam]

 

[abcde]

I think the answer would be B.

 

[hassam]

yea it is....cn u xplain me a bit ....i was thinking A

 

[hassam]

one ER says that "The nature of the apoplast as being all the non-living water-conducting parts of a plant was not at all well
known. The direct effect of the fungal growth would be blockage of the xylem vessels, which are part of the
apoplast."
xylem arepart of appoplast.....cn anyone tell me is this true cos its difficult for me to accept this cos neva heard such kind of info

 

[abcde]

Why would the muscles suddenly contract when the person is standing still? For one, venous walls aren't muscular like arterial walls. So this contraction occurs in arteries and increases blood pressure.
C and D are kind of frivolous!
Basically, when the body is moving, skeletal muscles press on the veins, assisting the flow of the blood back to the heart. When the body is still, this does not happen. Blood accumulates in the veins of the feet. As the volume of blood increases, so does the blood pressure.
Did this help?

 

[libra94]

yea it is....cn u xplain me a bit ....i was thinking A

the muscles in the vein doesn't contract....they relax though! cuz the blood in the veins(low pressure) is actually moved up by the skeletal contraction. so when the person is standing for a longer period, the skeletal muscles dont contract, and therefore, the blood remains in the veins and accumulates there, and therefore the pressure increases.

 

[hassam]

explain why pressure in left ventricle falls to zero but that in arteries doeSNt fall below 10 KPa

 

[hassam]

Explain, using the term water potential, how water moves from the vascular tissue to
the atmosphere.
....need an exam-style anser ...just to asses what are the points i leave out....

 

[libra94]

Explain, using the term water potential, how water moves from the vascular tissue to
the atmosphere.
....need an exam-style anser ...just to asses what are the points i leave out....

1.water moves throught the xylem (vascular bundle) to the spongy mesophyll cells by either apoplast or symplast way [from the region of higher water potential to the region of lower water potential down the conc. gradient through a semi permeable membrane by osmosis.]
2.the water outlining the spongy cells evaporates in the air space.
3.the water vapour diffuses from the air space to the atmosphere through stomata.

 

[libra94]

explain why pressure in left ventricle falls to zero but that in arteries doeSNt fall below 10 KPa

the blood is always present in the arteries, while all the blood from the left ventricles is pumped out of the heart, so thts why the pressure drops to zero

 

[hassam]

but with appoplast pathway we must not mention osmosis

 

[Nibz]

^ NO!
Since there is no 'Semi-Permeable membrane' involved and water moves exclusive through the cell wall without crossing any membrane, you cannot call this osmosis!

 

[hassam]

nibz there was an examiner report referring the flow of water through xylem as appoplast......is it true

 

[libra94]

but with appoplast pathway we must not mention osmosis

yeah, only for symplast pathway we use osmosis