Lec 8: Excretion and Osmoregulation

Question 1

Complete the sentence below:
Anabolic wastes originate from the nitrogenous breaking down of ____________ and ____________.

Answer 1

proteins, nucleic acids

Question 2

Identify the 3 types of nitrogenous wastes.

Answer 2

• ammonia
• urea
• uric acid

Question 3

Are nitrogenous wastes excreted by the majority of marine organisms, including bony fishes.

Answer 3

ammonia

Question 4

Which organisms excrete urea?

Answer 4

• mammals
• (most) amphibians
• sharks
• (some) bony fishes

Question 5

Complete the sentence below:
Ammonia combines with ____________ in the ____________, forming the urea.

Answer 5

carbon dioxide, liver

Question 6

Which organisms excrete uric acid?

Answer 6

• birds
• reptiles
• insects
• land snails

Question 7

Complete the sentence below:
Uric acid is synthesized from ammonia, using ____________ in the process.

Answer 7

ATP

Question 8

It refers to the active regulation of internal molarity levels.

Answer 8

osmoregulation

Question 9

Identify the types of osmoregulation mechanisms.

Answer 9

• osmoregulator
• osmoconformer

Question 10

Are organisms which control their internal osmolarity independent of that of the external environment.

Answer 10

osmoregulator

Question 11

Are organisms which are iso-osmotic with their external environment.

Answer 11

osmoconformer

Question 12

Are osmoregulators which possess internal fluids with an osmolarity higher than that of their environment.

Answer 12

hyperosmotic animals (i.e. freshwater animals)

Question 13

Identify the issues encountered by hyperosmotic animals.

Answer 13

• too much water intake (via osmosis)
• too much salt loss (via diffusion)

Question 14

Identify the solutions to the issues encountered by hyperosmotic animals.

Answer 14

• excretion of dilute urine
• active uptake of Na+ and Cl-

Question 15

Complete the sentence below:
Hyperosmotic amphibians compensate for salt loss by actively absorbing salt using their ____________.

Answer 15

skin

Question 16

Are osmoregulators which possess internal salt levels lower than that of their external environment.

Answer 16

hypoosmotic animals

Question 17

Identify the issues encountered by hypoosmotic animals.

Answer 17

• too much water loss (via osmosis)
• too much salt intake (via diffusion)

Question 18

Identify the solutions to the issues encountered by hypoosmotic animals.

Answer 18

• excretion of concentrated urine
• active excretion of Na+ and Cl-

Question 19

Complete the sentence below:
In hypoosmotic animals, excess salts are eliminated through the ____________ or ____________.

Answer 19

gills, kidney

Question 20

How do terrestrial animals lose water?

Answer 20

• evaporation from respiratory and bodily surfaces
• excretion in urine
• elimination in feces