Excretion Flashcards
(23 cards)
Name 3 waste products from the breakdown of food.
- CO2
- H2O
- Nitrogenous waste products (ammonia) from protein & amino acid metabolism
What does deaminated mean?
Removal of NH2 group from amino acid
What are the 3 most common types nitrogenous waste?
- Ammonia
- Urea
- Uric acid/urates
What is an ammonotelic organism?
An organism that excretes ammonia
What is a ureotelic organism?
An organism that excites urea
What is a uricotelic organism?
An organism that excretes uric acid
What is the chemical compound of ammonia?
NH3
At typical body pH, what does ammonia react with and what does it form?
- Hydrogen
- Forms the ammonium ion (NH4+)
Why does Ammonia need to be very dilute?
It is highly soluble so has to be dilute to avoid harmful effects
Give 3 feature of urea (NH2)
- Soluble
- Diffuses rapidly across membranes
- Much less toxic than ammonia
Where is urea synthesised?
In liver in ornithine cycle
Give 3 features of uric acid
- Purine
- Very low toxicity
- Relatively insoluble in water so can be excreted as semi-solid paste or as dry pellets
What is the main end product in some spiders, scorpions, ticks and other arthropods?
Guanine
What is the main excretory product of most heterptera (bugs) + stick insect?
Allantoin
What can be found in some mammals but only in very low concentrations?
Creatine & creatinine
Why isn’t ammonotelism found in most terrestrial species?
Due to its toxicity & high solubility, which would put a severe strain on terrestrial animal’s scarce water resources
What are some advantages of ureotelism & uricotelism to terrestrial animals?
- Both products contain > nitrogen than ammonia & as they are relatively non-toxic, they can be allowed to accumulate in the body to much higher levels than could ammonia
- This is useful when water is in short supply because terrestrial animals can reduce or cease urine production to conserve water and allow urea/uric acid to accumulate
Are aquatic invertebrates ammonotelic, ureotelic or uricotelic?
Ammonotelic
How do aquatic invertebrates lose their ammonia?
Across the gills & integument
Give an example of an animal that can be both ammonotelic & ureotelic
- Lungfish
- Ammonotelic in water
- Ureotelic when aestivating
- Urine production decreases to conserve water & urea accumulates
Are amphibians ammonotelic, ureotelic or uricotelic?
- Ammonotelic as tadpoles
- Ureotelic as adults
Are reptiles & birds ammonotelic, ureotelic or uricotelic?
- Uricotelic
Are mammals ammonotelic, ureotelic or uricotelic?
- All mammals are ureotelic regardless of habitat
