AP5

Question 1

How do marine teleosts actively get rid of salts?

Answer 1

• Na+/ K+ ATPase builds huge Na+ gradient within chloride cell
• Cl- transported using Na+ gradient
• Cl- builds up and diffuses out
• Na+ follows Cl- change by sneaking through leaky tight cell junctions

Question 2

How do freshwater teleosts actively take up salt?

Answer 2

• Lots of mitochonria and Na+/ K+ ATPase
• Cell cytoplasm very low in Na+ and Cl-
• Apical membranes have ion pumps to pump ions IN
• Cell junctions dont leak

Question 3

How do freshwater teleosts stop gaining too much water?

Answer 3

1) Large amounts of dilute urine

2) Active take up of salt through gills

Question 4

What are 3 ways marine teleosts keep their body fluids at the correct concentration?

Answer 4

• Actively remove salt from their bodies
• Small amounts of concentrated urine
• A lot of mitochondria in gills to expel salt by active transport

Question 5

What is the difference between osmoregulators and osmoconformers?

Answer 5

Osmoreguators: as osmolarity of environment changes the osmolanty of body fluids is regulated within a small range

Osmoconformers: concentration of body fluids changes with the environment

Question 6

What is hyperosmotic, hypoosmotic and isomotic?

Answer 6

Hyperosmotic = a higher concentration of solutes within it (saltwater)

Hypoosmotic= a lower concentration of solutes within it (freshwater)

Isomotic= equal concentration, no net movement

Question 7

What is Tonicity and 2 things it depends on?

Answer 7

The effect of a solution on a cells volume
Depends on:
1) Solutes
2) Membrane permeability

Question 8

What is the equation for osmolasty and what is it measured in?

Answer 8

number of particles per molecule of solute x moles/ litres

Measured in osmoles/ litre

Question 9

What is osmolarity?

Answer 9

Measure of the osmotic pressure exerted by a solution across a perfect semi permeable membrane compared to pure water

Question 10

What are the 5 things that influence the rate of passive movement? (solutes)

Answer 10

1) Temperature (higher=faster)
2) Size of particles (smaller=faster)
3) Electrical change of ion (can prevent passage)
4) Concentration gradient

Question 11

What is osmoregulation

Answer 11

• Process that balances the uptake and loss of water

- Homeostatic control