Nitrogen waste metabolism Flashcards

1
Q

What are the 3 possible forms of nitrogenous waste?

A

Ammonia, urea, uric acid

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2
Q

What is the problem with using ammonia as your form of nitrogenous waste?

A

Its super toxic and requires a ton of water to get rid of

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3
Q

What is the problem with using uric acid as your form of nitrogenous waste?

A

Metabolically expensive

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4
Q

What are the two insoluble of uric acid breakdown?

A

Allantoin and allantoic acid

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5
Q

How is ammonia transported around?

A

As ammonium, NH4+

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6
Q

What form of nitrogenous waste do ammonotelic animals use?

A

Ammonia, NH3

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7
Q

What type of animals are ammonotelic?

A

Aquatic animals and humidic animals. Seen in fish, aquatic molluscs, simple invertebrates, larval amphibians

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8
Q

Why are pill bugs an exception to how ammonotelic animals usually process NH3?

A

They are able to exhale NH3 as a gas

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9
Q

How do ammonotelic animals get ammonium across cell membranes?

A

NH4+/H+ antiporter

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10
Q

What form of nitrogenous waste do uricotelic animals use?

A

Uric acid

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11
Q

Why is uric acid so metabolically expensive?

A

Requires a lot of ATP to get rid of

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12
Q

How is uric acid excreted?

A

As a semi-solid paste along with its related derivatives (guanine and allantoin)

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13
Q

Why is uric acid not toxic?

A

It isn’t very soluble, so it can’t do very much

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14
Q

Which animals use uriotelic nitrogen metabolism?

A

Terrestrial molluscs and arthropods, birds, reptiles

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15
Q

What nitrogenous waste product do ureotellic animals use?

A

Urea

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16
Q

What animals use ureotelic nitrogen metabolism?

A

All mammals, some larval teleosts, some lung fish, elasmobranchs

17
Q

How toxic is urea?

A

Not as toxic as NH3, but an animal can still only tolerate so much

18
Q

What is required to get rid of urea?

A

Lots of different enzymes and lots of ATP

19
Q

How is urea transported across membranes in elasmobranchs?

A

Their gills and kidneys have an Na+/urea antiporter to be able to reuptake urea to maintain the hyperosmotic and hypoionic blood

20
Q

Does making NH3 use ATP?

A

No, but it requires energy to get rid of