L16 - Excretion

Question 1

What are the 5 ways animals can intake water?

Answer 1

1) Drinking
2) Via body Surfaces - from water or air
3) Food
4) Metabolic water production
5) Milk (in the desert environment mammals produce very dilute urine

Question 2

What 4 ways do animals lose water?

Answer 2

1) Evapouration - repiration and body suraces
2) Faeces
3) Urine
4) Specialised secretions

Question 3

What condtions does air have to be in to be used within the respiratory system>

Answer 3

Air has to be at 100% humidity and at body temperature, therefore the body humidifies and heats it.

The problem is when we breath it back out this means, even with effort to dehumidify it, we lose water through breathing

Question 4

Givr examples of how aniamsl have evolved to conserve water when breathing out

Answer 4

Increased nasal surface area by evolution of nasal architecture - water has a larger surface to be absorbed and also vessels can pass through here are remove some of the heat from the air

Question 5

What are the 3 types of nitrogen excretion categories an animal can be in?

Answer 5

They could be:

1) Ammonotelic - excrete nitrogen in the form of ammonia
2) Ureotelic - excrete nitrogen in the form of urea
3) Uricotelic - excrete nitrogen in the form of uric acid

Question 6

How i) soluble ii) toxic in animals is:

a) Ammonia
b) Urea
c) Uric acid

Answer 6

a) i) Ammonia - needs 0.5l to excrete 1g
a) ii) very toxic - must get rid ASAP

b) i) Urea - needs 0.05l to excrete 1g
b) ii) a little toxic

c) Uric Acid - very insoluble - only needs 0.001l to get rid 1g, and can be excreted in solid form
c) ii) not toxic

Question 7

What are the advantages of excreting Nitrogen as Uric acid than Ammonia?

Answer 7

There are 4Ns per Uric acid molecule, while only 1N in ammonia

its insoluble so can be excreted in solid form

Its non toxic