section 3 (4) explain why the processes of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms Flashcards

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1
Q

What is diffusion?

A

the movement of a substance from a place of high concentration to low concentration

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2
Q

What is osmosis?

A

The movement of water across a semi-permeable membrane to a place of lower concentration

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3
Q

Why is diffusion inadequate in the removal of dissolved nitrogenous wastes in some organisms?

A
  • passive transport: SLOW
  • more useful over short distances (between cells)
  • wastes are only able to move down a concentration gradient and movement would slow as equilibrium is approached. this may mean that, for example, urea would not be able to be excreted from the bloodstream
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4
Q

Why is osmosis inadequate in the removal of dissolved nitrogenous wastes in some organisms?

A
  • does not enable the removal of nitrogenous wastes; only able to dilute them
  • may cause too much water to be lost from the body in urine; if the urine has a high concentration of nitrogenous wastes, more water is drawn into the urine through osmosis
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