Bio250 Module 4 2025 Questions with
Accurate Solutions
respiratory surfaces - ANSWER can be internal vs. exposed, varies by habitat and organ types
marine invertebrates - ANSWER teleost, elasmobranchs, marine birds and reptiles.
- osmoconformers
- dilute blood = hyposomotic to sea water
Marine Teleosts (bony fish) - ANSWER HYPOregulators (want to keep hyposmotic fluid)
teleosts integument - ANSWER low permeability, low risk.
teleosts respiratory - ANSWER high permeability
gains ions and loses water use gills for N waste
teleosts gut - ANSWER drinks SW
actively moves ions into their blood -- water follows ions
teleosts excretory - ANSWER small amount of isometric urine produced, weak kidney
Teleosts U/P - ANSWER = 1
extra renal salt excretion - ANSWER - to expel salts from body they use specialized cells in the
gills
- secondary active transport of 1 Na+ 1K+ and 2 Cl- into (chloride cells)
, NKCC proteins - ANSWER (Na-K-2Cl cotransporter)
- Cl- exits to SW via channel
- Na+ exits via paracellular route
What do chloride cells run? - ANSWER sodium potassium pump
elasmobranchs (sharks and rays) - ANSWER - osmotic pressure of plasma is slightly higher
than seawater (TMAO and urea rises osm)
- Hyperosmotic but hypoionic to ambient water.
elasmobranchs gills - ANSWER gills have high permeability - gain both water by osmosis, and
salts by diffusion
elasmobranchs gut - ANSWER do not drink salt water
elasmobranchs excretory - ANSWER synthesize urea and retain it
excrete Mg and sulfates
rectal gland function - ANSWER secretes a salt solution isosmotic with plasma that
maintains the salt homeostasis of the fish. Osmoregulation
Hypoionic sharks - ANSWER net gain of ions; excess NaCl released through the butt
hyperosmotic - ANSWER A term describing organisms with body fluids with a lower
concentration of water and higher solute concentration than the external environment.
Accurate Solutions
respiratory surfaces - ANSWER can be internal vs. exposed, varies by habitat and organ types
marine invertebrates - ANSWER teleost, elasmobranchs, marine birds and reptiles.
- osmoconformers
- dilute blood = hyposomotic to sea water
Marine Teleosts (bony fish) - ANSWER HYPOregulators (want to keep hyposmotic fluid)
teleosts integument - ANSWER low permeability, low risk.
teleosts respiratory - ANSWER high permeability
gains ions and loses water use gills for N waste
teleosts gut - ANSWER drinks SW
actively moves ions into their blood -- water follows ions
teleosts excretory - ANSWER small amount of isometric urine produced, weak kidney
Teleosts U/P - ANSWER = 1
extra renal salt excretion - ANSWER - to expel salts from body they use specialized cells in the
gills
- secondary active transport of 1 Na+ 1K+ and 2 Cl- into (chloride cells)
, NKCC proteins - ANSWER (Na-K-2Cl cotransporter)
- Cl- exits to SW via channel
- Na+ exits via paracellular route
What do chloride cells run? - ANSWER sodium potassium pump
elasmobranchs (sharks and rays) - ANSWER - osmotic pressure of plasma is slightly higher
than seawater (TMAO and urea rises osm)
- Hyperosmotic but hypoionic to ambient water.
elasmobranchs gills - ANSWER gills have high permeability - gain both water by osmosis, and
salts by diffusion
elasmobranchs gut - ANSWER do not drink salt water
elasmobranchs excretory - ANSWER synthesize urea and retain it
excrete Mg and sulfates
rectal gland function - ANSWER secretes a salt solution isosmotic with plasma that
maintains the salt homeostasis of the fish. Osmoregulation
Hypoionic sharks - ANSWER net gain of ions; excess NaCl released through the butt
hyperosmotic - ANSWER A term describing organisms with body fluids with a lower
concentration of water and higher solute concentration than the external environment.
