Lecture 8 Flashcards

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1
Q

Humans and other mammals can tolerate how much dehydradtion

A

~12-14%

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2
Q

Most organisms are what percent in water?

A

50-90%

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3
Q

Water budgets - aquatic organisms

A

Water (internal) = Water gain (drinking) - Water loss (secretion) + or - Water (osmosis)

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4
Q

Salinity in aquatic systems

A

Freshwater - 5 ppt
Estuaries - 10-25 ppt
Oceans - 35 ppt
Lakes - 1-400 ppt

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5
Q

What’s Diffusion

A

movement of soluble salts or water due to random movement of particles (down a concentration gradient)

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6
Q

What’s Osmosis

A

Similar to diffusion but involves movement across a semipermeable membrane

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7
Q

What’s Hypoosmotic

A

low solute concentration, high water concentration
- prefix relates to [solute]

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8
Q

What’s Hyperosmotic

A

High solute concentration, low water concentration
- prefix relates to [solute]

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9
Q

What’s Isosmotic

A

same solute and water concentration
- prefix relates to [solute]
- iso means equal
- most marine fish and invertebrates

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10
Q

Osmolarity

A

Refers amount of solute/water in an organism in relation to its environment

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11
Q

Hypoosmotic (some) marine organisms

A
  • internal [salt] is lower and [water] is higher compared to environment
  • risk dehydration and surplus salt intake through gills, therefore drink constantly, low urination rates, excess salt excreted through specialized chloride cells
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12
Q

Most Freshwater organisms are hyperosmotic

A
  • internal [salt] is higher and [water] is lower compared to environment
  • risk is too much water enters organism
  • solution: produce high amounts of dilute (minimize salt loss) urine
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13
Q

Relationship between [salt] and [water]

A
  • inverse relationship, if water is moving in, salt is moving out and vice versa
  • high salt conc. equals low water conc. and vice versa
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14
Q

What’s Acclimation

A

It’s a reversible physical change due to an organism being placed in a new environment

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15
Q

What’s Anadromous

A
  • Fish born in fresh water, spend most of its life in the sea, returns to freshwater to spawn
  • i.e. salmon, striped bass
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16
Q

How do salmon cope with changes in salinity

A

By shifting their secretion cells
freshwater = take in salt (hypoosmotic)
ocean = excrete salt (hyperosmotic)

17
Q

What’s Catadromous

A
  • Fish born in the ocean, spends most of its life in fresh water, returns to ocean to spawn
  • i.e eels
18
Q

Water Budgets - Terrestrial Systems (Plants)

A

Water (internal) = +Wr (gained from roots) + Wa (from air) - Wt (to transpiration) - Ws (to secretion)

19
Q

Water Budgets - Terrestrial Systems (Animals)

A

Water (internal = + Wd (from drinking) + Wf ( from food) + Wa (from air) - We (to evaporation) - Ws (to secretion)

20
Q

Water Potential

A

Water moves from high to low water potential
- usually a negative value
- different from osmosis because of pressure

21
Q

Water Vapour pressure

A

As temperature of air increases, its ability to hold water vapour increases = high water vapour pressure
- cold air can hold less water vapour = low water vapour pressure

22
Q

Saturation water vapour density

A

maximum amount of water vapour that air can potentially hold

23
Q

Water potential in plants

A

Soil -> Roots -> Tree trunk -> Tree Canopy -> air
Highest to lowest water potential

24
Q

How do terrestrial animals minimize water loss

A

conservation of urine, feces and sweat
behavioural adaptations i.e burrows

25
Q

How do terrestrial plants reduce water loss

A

wilting (reduces surface area= lower transpiration and photosynthesis)