study help please!! *distraught* (1 Viewer)

[jordie4]

i have started studying for biology and am going through the syllabus and writing answering each dot point, so its a little bit of work, lucky with biology its about remembering it all and not doing calcuations as much as it is in chemistry *does both*

anyways, i got up to the 3rd section of the 9.2 of the syllabus, the 4th dot point which states:

' explain why the processes of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms'

and im totally stuck, im thinking maybe because osmo-regulation works better, or because osmosis and diffusion only do specific organic compounds or something..

any help would be greatly appreciated

 

[mr_brightside]

Diffusion and osmosis are both examples of passive transport. Diffusion is insufficient for the body’s disposal of nitrogenous wastes because if diffusion was the only process used the urine concentration in the collecting tube could never be greater than that in the blood vessels running into it, so the urine would be too dilute and too much water would be lost. Osmosis can only move water so it is not useful for the excretion of nitrogenous wastes.

 

[jordie4]

thank you

but then, what is used to move nitrogenous wastes to the bladder etc etc absorption, reabsorption in the kidneys, or osmo-regulation? *pulls at straws*

thanks though GREATLY appeciated!

 

[Pimpcess.Snaz]

Well my notes are just like yours (answered dot points) so here's what i got down for this point:

Diffusion and osmosis occur in the kidney but are helped by the blood pressure and the increased permeability of the capillaries in the glomerulus.

Diffusion and osmosis...
- are too slow
- can't occur unless there is a sufficient concentration gradient

and large, active, multicellular animals quickly accumulate toxic levels of nitrogenous wastes so they need other mechanisms of removal.
______
In this dot point, you're not actually talking about reabsorption or anything but rather the problems of diffusion and osmosis, which coincides with the reasons for why organisms don't only use passive transport but, as my notes mention, use high blood pressure and the increased permeability of the capillaries in the glomerulus.

 

[jordie4]

thank you ive done SOO much bio study its ridiculous..


if you go to google and type in 'csu biology' there a help to,

i suppose i was looking into the dot point too much haha damn brain

thanks *stress leaves lower* although they werent that high to begin with

 

[rooeys2]

Well my notes are just like yours (answered dot points) so here's what i got down for this point:

Diffusion and osmosis occur in the kidney but are helped by the blood pressure and the increased permeability of the capillaries in the glomerulus.

Diffusion and osmosis...
- are too slow
- can't occur unless there is a sufficient concentration gradient

and large, active, multicellular animals quickly accumulate toxic levels of nitrogenous wastes so they need other mechanisms of removal.
______
In this dot point, you're not actually talking about reabsorption or anything but rather the problems of diffusion and osmosis, which coincides with the reasons for why organisms don't only use passive transport but, as my notes mention, use high blood pressure and the increased permeability of the capillaries in the glomerulus.

good point. but i think you need to add:
-osmosis is only responsible for the transportation of water molecules, not nitrogenous wastes
-you do need to talk about reabsorption, diffusion and osmosis cannot reabsorb useful materials back into the blood (its how the kidney functions), its a major difference and also, osmosis without active reasbsorption of water will result in excessive water loss
-organisms require to quickly excrete the accumulation of nitrogenous wastes, like you mentioned difusion and osmosis are too slow, and this could cause fatal risks to the animals/their metabolic processes will slow down.

 

[aussiechick007]

interesting, i can't find anything about this in my notes and i've followed the syllabus points all the way through.... will have to add some of this