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Life on Earth 2 > Extreme environments > Flashcards

Extreme environments Flashcards

1
Q

How much of earth’s surface is covered in water?

A

2/3rds

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2
Q

How much of water is fresh?

A

1%

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3
Q

Why does the composition of freshwater vary so much?

A

Because of variation in geographical location.

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4
Q

What problems do living in freshwater, brackish or marine water pose?

A

Osmoregulatory problems

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5
Q

What is osmoregulation?

A

The maintenance of solute and water balance.

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6
Q

What is osmosis?

A

The passage of water through a semi permeable membrane from a weaker solution to a stronger solution.

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7
Q

What does the movement of water molecules depend on?

A

Depends on the number of particles and osmotic pressure.

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8
Q

What is osmotic pressure measured in?

A

osmoles - milliosmoles

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9
Q

What is the osmotic pressure for sea water?

A

1000 mOsm

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10
Q

What is the osmotic pressure for a marine invertebrate?

A

Same osmotic pressure as sea water but ionic composition may be different.

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11
Q

What is an osmoconformer?

A

If the external medium changes then the vertebrate changes its fluids to match the external medium.

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12
Q

What is an osmoregulator?

A

A vertebrate that maintains or regulates osmotic concentration despite external changes.

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13
Q

When would a vertebrate use hyper osmotic regulation and why?

A

If a freshwater or marine invert was living in an estuary which would cause a loss of ions due to inflow of water.

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14
Q

What is carried out during hyper osmotic regulation?

A

Active ion transport.

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15
Q

What do inverts use for active ion transport?

A

Organs

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16
Q

What do crustaceans and aquatic animals use for active ion transport?

A

Gills

17
Q

What are the problems with hyper osmotic regulation?

A

Body fluids are more dilute than environment and there is an accumulation of ions and loss of water.

18
Q

In Artemia (brine shrimp) how do they deal with living in salt lakes?

A

Artemia swallow vast quantities of water but actively secrete salts either from the neck gland in larvae or from the gills in an adult.

19
Q

What is the osmotic concentration of a marine living hagfish?

A

Similar to sea water at 1000 mOms

20
Q

What do iso osmotic hagfish regulate?

A

Sodium

21
Q

What is the osmotic concentration of a fresh/marine living lamprey?

A

1/3 of the sea so 333 mOms.

22
Q

What is the osmotic balance of elasmobranchs (sharks/rays)?

A

Similar to sea water (1000 mOms) but salt content remains at about 1/3 of sea water.

23
Q

How do elasmobranchs eliminate sodium?

A

Through the kidneys, gills and rectal glands.

24
Q

What is the osmotic concentration of freshwater and marine Teleosts?

A

1/3 of sea water. (333 mOms)

25
Q

What are marine teleosts in danger of?

A

Drinking lots of water.
Increased salt concentration.
Chloride cells eliminate excess.
Mg and Sulphate excreted by kidneys.

26
Q

What are freshwater teleosts in danger of?

A

Vast amounts of dilute urine.

27
Q

How do sea mammals excrete salt?

A

Through concentrated urine.

28
Q

Describe an ideal gas exchange site.

A

Large surface area.
Thin epithelial layers.
In contact with medium.

29
Q

What is the definition of diffusion?

A

Substance moves from a higher to lower concentration.

30
Q

What is cutaneous gas exchange?

A

Gas exchange that occurs over the general body surface through skin.

31
Q

What is a gill?

A

Respiratory surface protruding, turned outwards forming an evagination.

32
Q

Describe a tuft gill and what animal can it be found on.

A

A raised thin area of skin or simple tuft. Can be found on the papulae of starfish.

33
Q

Describe a filament gill

A

Feather like structures supported by thin external cuticle with elaborate blood flow.

34
Q

Describe a lamellate gill

A

Flat plates extend from a central strut or gill arch with specific orientation to water flow. Maybe protected by a gill cover.

35
Q

What is an operculum?

A

The protective cover over the gill cavity.

36
Q

How do fish get oxygen?

A

Oxygen rich water flows between lamellae in gills and blood flows within them in the opposite direction. (counter-current flow)

37
Q

When would there be uni-directional flow over gill surface.

A

When water is pumped over gill by the mouth and opercular pump.

38
Q

Why would a fish need to keep swimming in order to keep the uni-directional flow?

A

If there is no opercular pump.

39
Q

What is a lung?

A

Respiratory surface completely internalised and forms from an invagination.

Life on Earth 2 (9 decks)

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