lecture 24 - osmoregulation

Question 1

What is osmosis?

Answer 1

Diffusion of water molecules from an area of higher water concentration to an area of lower water concentration

Question 2

What is an isotonic solution?

Answer 2

same osmotic pressure as cell

Question 3

What is a hypertonic solution?

Answer 3

higher osmotic pressure as cell

Question 4

What is a hypotonic solution?

Answer 4

lower osmotic pressure as cell

Question 5

What are osmoconformers?

Answer 5

an animal whose body fluids are isosmotic with the external medium

Question 6

What are osmoregulators?

Answer 6

an animal that maintains osmotic pressure of its body fluids independent of the external medium

Question 7

What are euryhaline animals?

Answer 7

tolerate wide variations in osmotic pressure of the external medium

Question 8

What are stenohaline animals?

Answer 8

have very limited tolerance of variation in osmotic pressure of external medium

Question 9

Describe osmoregulation in saltwater fish

Answer 9

hypertonic environment
drink the seawater
some water lost at skin and some lost in urination
gill chloride cells - actively pump chloride out of gills and sodium follows
sharks retain urea so internal + external environments match

Question 10

Describe osmoregulation in freshwater fish

Answer 10

Do not drink water
Uptake of salt by gills
Skin impermeable to water
Produce large amount of dilute urine (goldfish produce 30% of body weight in urine a day!)

Question 11

What is the excretory organ in insects?

Answer 11

Malphigian tubules - similar role to kidney