Osmoregulation and Excretion

Question 1

Osmoregulation balances the uptake and loss of

Answer 1

water and solutes.

Question 2

An animal’s nitrogenous wastes reflect its

Answer 2

phylogeny and habitat

Question 3

If the process of osmoregulation is based largely on the controlled movement of solutes between internal fluids and the external environment, then what’s the deal with water?

Answer 3

If water uptake is excessive, animal cells swell and burst; if water loss is substantial, they shrivel and die

Question 4

What is osmosis?

Answer 4

How water enters and leaves cells- occurs when two solutions separated by a membrane differ in total solute concentration

Question 5

What is osmolarity?

Answer 5

The unit of measurement for solute concentration- the number of moles of solute per liter of solution

Question 6

If two solutions are separated by a selectively permeable membrane, what are isoosmotic, hyperosmotic, and hypoosmotic solutions?

Answer 6

iso- two solutions with the same osmolarity
hyper- when two solutions differ in osmolarity, the solution with the higher concentration of solutes
hypo- when two solutions differ in osmolarity, the solution that is more dilute

Question 7

An animal can maintain water balance in

Answer 7

two ways.

Question 8

What are osmocomformers? What kinds of animals are they?

Answer 8

animals that maintain water balance by being isoosmotic with its surrounding; marine animals

Question 9

What are osmoregulators? What kinds of animals are they?

Answer 9

animals that maintain water balance internally indented of that of the external environment; freshwater and terrestrial animals

Question 10

Most marine invertebrates are

Answer 10

osmoconformers

Question 11

Many marine vertebrates and some marine invertebrates are

Answer 11

osmoregulators

Question 12

Compared to the osmolarity of the surrounding water, what must the body fluids of most marine animals be?

Answer 12

isoosmotic

Question 13

Freshwater animals have osmoregulatory problems that are opposite those of

Answer 13

marine animals.

Question 14

Compared to the osmolarity of the surrounding water, what must the body fluids of freshwater animals be?

Answer 14

hyperosmotic

Question 15

Salmon migrate between fresh water and seawater. How do they osmoregulate? What is it called when they adjust to different conditions?

Answer 15

when in freshwater they produce large amounts of dilute urine, when in ocean they produce only small concentrated urine and they excrete excess salt from their gills;
acclimatize

Question 16

What is anhydrobiosis?

Answer 16

“life without water” animals enter a dormant state when their habitats dry up

Question 17

What’s the deal with tardigrades?

Answer 17

tiny invertebrates less than 1mm long. In their active hydrated state they contain 85% water by weight; they can dehydrate to less than 2% water and survive in an inactive state, dry as dust, for a decade or more

Question 18

What is trehalose?

Answer 18

a disaccharide used to protect cells by replacing the water that is normally associated with proteins and membrane lipids; a membrane protectant

Question 19

Adaptations that reduce water loss are key to survival on land. What are some of these adaptations? How about body coverings? What about time of activity?

Answer 19

waxy layers of insect exoskeletons, the shells of land snails, and the layers of dead, keratinized skin cells covering most terrestrial vertebrates prevent dehydration; Some animals are nocturnal to prevent water loss;

Question 20

How do animals lose water?

Answer 20

In urine and feces, across their skin, and from the surfaces of gas exchange organs

Question 21

How do animals compensate for lost water?

Answer 21

Drinking and eating moist foods and by producing water metabolically through cellular respiration

Question 22

How do animals maintain osmotic gradients?

Answer 22

Use active transport to manipulate solute concentrations in their body fluids

Question 23

What does the energy cost of osmoregulation depend on?

Answer 23

how different an animal’s osmolarity is from its surroundings, how easily water and solutes can move across the animal’s surface, and how much work is required to pump solutes across the membrane

Question 24

How do many animals minimize energy costs associated with osmoregulation?

Answer 24

by having body fluids that are adapted to the salinity of the animal’s habitat

Question 25

The ultimate function of osmoregulation is

Answer 25

to control solute concentrations in cells.

Question 26

Most animals do osmoregulation indirectly by managing the solute content of an internal body fluid that bathes the cells. How does this work in vertebrates and other animals with closed circulatory systems?

Answer 26

the cells are bathed in an interstitial fluid that contains a mixture of solutes controlled indirectly by the blood

Question 27

In most animals, what do osmoregulation and metabolic waste disposal rely on?

Answer 27

transport epithelia

Question 28

What are transport epithelia?

Answer 28

one or more layers of epithelial cells specialized for moving particular solutes in controlled amounts in specific directions

Question 29

How is it possible for the albatross to survive on seawater?

Answer 29

they have nasal salt glands that use active transport of ions to secrete a fluid much altered than the ocean; they drink seawater brining in a lot of flak the gland enables them to achieve a net gain of water

Question 30

How does the albatross’ ability to use seawater compare with the ability of humans to use seawater?

Answer 30

humans who drink a given volume of seawater must use a greater volume of water to excrete the salt load, resulting in dehydration

Question 31

Because most metabolic wastes must be dissolved in water to be excreted from the body, the type and quantity of an animal’s waste products may have a large impact on its water balance. In this regard, some of the most significant waste products are the

Answer 31

nitrogenous breakdown products of proteins and nucleic acids.

Question 32

When nitrogen is removed from proteins and nucleic acids, what form is it in?

Answer 32

ammonia

Question 33

What is the problem with ammonia (NH3) and ammonium ions (NH4+)?

Answer 33

very toxic because its ion can interfere with oxidative phosphorylation

Question 34

Aquatic animals, including most bony fish, excrete ammonia directly. What do other animals do to counter the toxic effects of ammonia and ammonium ions?

Answer 34

they convert it to a less toxic compound before excretion

Question 35

How do aquatic organisms deal with ammonia?

Answer 35

they need access to lots of water because ammonia can be tolerated only at very low concentration

Question 36

Why is ammonia such a problem, especially for terrestrial animals?

Answer 36

they do not have access to sufficient water to routinely excrete ammonia

Question 37

How is urea made?

Answer 37

a product of a metabolic cycle that combines ammonia with carbon dioxide in the liver

Question 38

What are urea’s advantages?

Answer 38

very low toxicity

Question 39

What is urea’s main disadvantage?

Answer 39

energy cost

Question 40

How is uric acid excreted?

Answer 40

as a semisolid past with very little water loss

Question 41

What are the advantages of uric acid as a way of getting rid of nitrogen?

Answer 41

very little water loss

Question 42

What is the main disadvantage of Uric acid?

Answer 42

more energy cost than urea

Question 43

Do humans produce uric acid? What does it cause?

Answer 43

a small amount from purine breakdown; gout

Question 44

In general, the kind of nitrogenous wastes an animal excretes depends on both the species’ evolutionary history (phylogeny) and its habitat, especially the availability of water. What do you think that means?

Answer 44

depending on how much water you have access to is how you excrete nitrogenous wastes

Question 45

What’s the deal with terrestrial turtles versus aquatic turtles?

Answer 45

terrestrial excrete uric acid where aquatic excrete both urea and ammonia

Question 46

What does the immediate environment of an embryo have to do with the handling of nitrogen?

Answer 46

soluble wastes can diffuse out of a shell-less amphibian egg or be carried away from a mammalian embryo by the mothers blood; shelled eggs are permeable to gases but not to liquids, which means that soluble nitrogenous wastes released by an embryo would be trapped within the egg and accumulate to dangerous levels

Question 47

What is the amount of nitrogenous waste produced by animals linked to?

Answer 47

The animals energy budget; also diet