Extreme environments

Question 1

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

Answer 1

2/3rds

Question 2

How much of water is fresh?

Answer 2

1%

Question 3

Why does the composition of freshwater vary so much?

Answer 3

Because of variation in geographical location.

Question 4

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

Answer 4

Osmoregulatory problems

Question 5

What is osmoregulation?

Answer 5

The maintenance of solute and water balance.

Question 6

What is osmosis?

Answer 6

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

Question 7

What does the movement of water molecules depend on?

Answer 7

Depends on the number of particles and osmotic pressure.

Question 8

What is osmotic pressure measured in?

Answer 8

osmoles - milliosmoles

Question 9

What is the osmotic pressure for sea water?

Answer 9

1000 mOsm

Question 10

What is the osmotic pressure for a marine invertebrate?

Answer 10

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

Question 11

What is an osmoconformer?

Answer 11

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

Question 12

What is an osmoregulator?

Answer 12

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

Question 13

When would a vertebrate use hyper osmotic regulation and why?

Answer 13

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

Question 14

What is carried out during hyper osmotic regulation?

Answer 14

Active ion transport.

Question 15

What do inverts use for active ion transport?

Answer 15

Organs

Question 16

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

Answer 16

Gills

Question 17

What are the problems with hyper osmotic regulation?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

What is the osmotic concentration of a marine living hagfish?

Answer 19

Similar to sea water at 1000 mOms

Question 20

What do iso osmotic hagfish regulate?

Answer 20

Sodium

Question 21

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

Answer 21

1/3 of the sea so 333 mOms.

Question 22

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

Answer 22

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

Question 23

How do elasmobranchs eliminate sodium?

Answer 23

Through the kidneys, gills and rectal glands.

Question 24

What is the osmotic concentration of freshwater and marine Teleosts?

Answer 24

1/3 of sea water. (333 mOms)

Question 25

What are marine teleosts in danger of?

Answer 25

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

Question 26

What are freshwater teleosts in danger of?

Answer 26

Vast amounts of dilute urine.

Question 27

How do sea mammals excrete salt?

Answer 27

Through concentrated urine.

Question 28

Describe an ideal gas exchange site.

Answer 28

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

Question 29

What is the definition of diffusion?

Answer 29

Substance moves from a higher to lower concentration.

Question 30

What is cutaneous gas exchange?

Answer 30

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

Question 31

What is a gill?

Answer 31

Respiratory surface protruding, turned outwards forming an evagination.

Question 32

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

Answer 32

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

Question 33

Describe a filament gill

Answer 33

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

Question 34

Describe a lamellate gill

Answer 34

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

Question 35

What is an operculum?

Answer 35

The protective cover over the gill cavity.

Question 36

How do fish get oxygen?

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

If there is no opercular pump.

Question 39

What is a lung?

Answer 39

Respiratory surface completely internalised and forms from an invagination.