Water - Lectures 1 and 2

Question 1

What is an extreme environment?

Answer 1

Conditions which are challenging (or deadly) for most life forms
Conditions = extreme high/low ends of “normal”

Question 2

Why do people care about extremophiles

Answer 2

May be possible to transplant genes coding for these adaptations to enhance other species

Anthropogenic impacts are driving conditions away from what has been “normal” and towards the extremes… (e.g. climate change)

Question 3

Why do people care about extremophiles

Answer 3

Current extremes will likely get more extreme, and extreme habitat will become more widespread …

As such, many “normophile” species will become extinct or extirpated (extinct from areas they once were) and extremophiles will likely become more common

Question 4

Does natural selection work the same with extremophiles?

Answer 4

Extreme conditions generate selective pressure, which drives the evolution of adaptive traits….

Extreme environments “generate” species that are specially adapted to thrive within them

Typically, the more extreme the environment the fewer the number of adapted species

Fewer adapted species likely means less competition which confers an advantage and increases fitness

Question 5

Explain the formation of hydrogen, protons, and neurons

Answer 5

Hydrogen = produced in aftermath of big bang
Universe too hot for atoms (or sub-atomic particles) to form
Expansion and cooling allowed protons and neutrons to form in a 7:1 ratio

Question 6

Formation of deuterium

Answer 6

Protons repelled each other, but some got together to form positive deuterium
Some deuterium fused = stable helium nuclei (no electrons = still too hot)

Question 7

Atom formation

Answer 7

Lots of stable hydrogen and some helium - no atoms yet
Further cooling, then atoms
Eventually hydrogen and helium clouds coalesced and collapsed, creating a proto-star and triggering fusion of hydrogen

Question 8

What is fusion

Answer 8

Fusion is a nuclear reaction in which two or more atoms collide at a very high speed, join to form a new (heavier) element, and release energy

Question 9

What does it generate in the star

Answer 9

In the star, hydrogen fusion generates helium - so hydrogen decreases and helium increases

Eventually helium fusion begins (three helium nuclei are fused in the star to form carbon)

Question 10

How is oxygen produced?

Answer 10

Next, carbon fuses with another helium to produce oxygen

Oxygen atoms (along with other heavy elements) are released when the star explodes

Question 11

How does interstellar water form

Answer 11

Interstellar water (ice) forms when a hydrogen atom interacts with solid oxygen on a solid surface such as a dust grain in space

Question 12

How was water formed?

Answer 12

Dust grains (laced with water ice) coalesced to form rocks and eventually planets

Water ice in the interstellar dust has been thought by some to be the primary source of planetary water

Others have believed that most of the original water on Earth was lost, and then replenished by asteroid collisions over time

Recent data suggest up to 50% the water on Earth has interstellar origins and most of the rest likely came from comet strikes

Question 13

How do we know where the water came from?

Answer 13

Ratio of deuterium to hydrogen in water molecules reflects where and when they formed

Comets measured today have ratios that do not match those of water on Earth

Question 14

Common name for water with deuterium

Answer 14

Heavy water

Question 15

Important properties for life on Earth (9)

Answer 15

1) Water is abundant where most life exists (near the surface)
2) Water exists in 3 phases/states at temperatures (and pressures) that exist on Earth
3) Water has a very high specific heat capacity
4) The density of liquid water has an unusual relationship with temperature
5) Water moves against gravity into narrow spaces
6) Water resists compressive forces
7) Water is a very good solvent
8) Liquid water is transparent
9) Water conducts electricity

Question 16

Why is ice important

Answer 16

(1) Ice insulates the water below it, ensuring most water bodies do not freeze to the bottom
(2) Formation of ocean ice creates brine currents that mix water and bring nutrients to the surface

Salt doesn’t freeze into ice – falls to bottom of ocean. Creates an upwelling as it gets into the sea to replenish it in the top

(3) Formation of ocean ice extends the range for northern animals in winter (e.g. bears)
(4) Ice at the poles reflects sunlight keeping the earth cool and greatly impacting weather patterns and climate

Question 17

Why is water vapour important

Answer 17

(1) Water vapour plays a critical role in climate which in turn impacts almost all living things
(2) Water vapour is a key greenhouse gas in the atmosphere, keeping the earth warm
(3) Evaporation of liquid water on the ground (or from plants) absorbs heat and cools the surface of the Earth

Question 18

How are clouds formed and what do they do

Answer 18

Condensation of water vapour at altitude releases heat which creates updrafts and more condensation (clouds)

Clouds move and deliver water to terrestrial environments to be used by plants and animals

All this is part of the water cycle and water vapour is critical to the process

Question 19

Why is liquid water important

Answer 19

(1) Water supports the cell membranes and maintains the shape of the cell (in animal cells)
(2) Water cushions and protects organelles
(3) Water facilitates movement of dissolved substances (e.g. oxygen) in and out of the cell
(4) Water helps to maintain the proper 3D ultrastructure of key proteins
(5) Water is required for many biochemical processes

Question 20

What biochemical processes require water

Answer 20

• Liquid water is required for many biochemical processes…
  (a) Hydrolysis reactions - digestion of polymers, releasing energy from ATP
  (b) Condensation reactions - polymer synthesis
  (c) Oxidation reactions - Photosynthesis; Producing ATP through oxidative phosphorylation

Question 21

What does it mean to have a high specific heat

Answer 21

High specific heat capacity means that a great deal of heat can be added to liquid water before it vaporizes (can hold unusually large amount of heat)

In other words, water has an unusually high boiling point

Question 22

Chemical makeup of water

When is it stable

Answer 22

8p,8n,8e
2e in 1st valence, 6 in outer shell
Stable with 10 - 2 H form 2 covalent bonds with oxygen to worm water

Question 23

Electronegativity

Answer 23

The degree to which one atom attracts another’s electron
Atoms do not always share electrons equally
Oxygen = more electronegative; unequal sharing favours oxygen (neg charge on O, pos on H)

Question 24

Water bonds

Answer 24

Additional bonds (hydrogen) are formed between differently charged parts of different water molecules

These added bonds must be broken before water can vaporize, leading to the high boiling point

Question 25

What does having a high specific heat do for water

Answer 25

The ability to store heat means water can moderate conditions for nearby terrestrial life

Winter temperatures are warmer and summer temperatures are cooler

Can protect aquatic life from drastic fluctuations in air temperature

Question 26

How much extra heat from global warming is held in the oceans

Answer 26

80-90%

Question 27

What does buffering do

Answer 27

Helps animals to maintain a relatively stable body temperature

High boiling point means that water remains liquid over large temperature range … makes it very available

Question 28

In what ways are density and temperatures relationship atypical

Answer 28

Density increases as temperature drops (until 4 0C) then decreases with temp (water expanding as cooled from 4-0)

Above 4 OC = H bonds unstable - constantly breaking and reforming - allows “warm” water molecules to move closer together as temp decreases

Question 29

What happens at 4 OC

Answer 29

H bonds strengthen and begin forming lattice structures - molecules are furthest apart and density is lowest

Water bodies freeze from the top down rather than the bottom up

Aquatic organisms can survive underneath the ice in relatively warm water

Expansion of water in rock (when it freezes) also drives erosion creating soil for plants

Question 30

What’s it called when water moves against gravity into narrow spaces

Answer 30

Capillary polarity

Capillary action results from cohesion and adhesion

Question 31

What are cohesion and adhesion

Answer 31

Cohesion refers to the tendency of water molecules to stick to one via hydrogen bonds

Adhesion refers to the tendency of water molecules to stick to other charged surfaces due to their polarity

Question 32

When does capillary action occur

Answer 32

(1) Water near the edge of the glass “climbs” it due to strong adhesion forces
(2) Water not as near the edge of the glass sticks to the water climbing the edge (adhesion) and moves with it

Question 33

What is capillary action critical to

Answer 33

The movement of water within plants (roots to leaves)

As water moves out of leaves (evapotranspiration) it pulls water through xylem channels

Capillary action allows groundwater to move form wet deep areas to drier areas closer to the surface

Capillary action allows excess fluid to be drained from the eye into the nasal cavity

Question 34

Water resists compressive forces

Percentages

Answer 34

4000m below surface of ocean compressed less than 2%

Volume of air is reduced by about 50% for every 10m of water depth

This allows deep water organisms (that are mostly water) to avoid being crushed at depth

Incompressibility also makes it a good lubricant and shock absorber

Question 35

What are the keys to water solubility

Answer 35

(1) it is a polar molecule
- Charges associated with water polarity allow polar solutes to be pulled apart (ionization)
(2) the charges are on opposite sides of the molecule
- This facilitates relatively easy and unimpeded bonding between the water and the ion
(3) the water molecules are small
- So a lot of molecules can surround the ion so it is fully hidden from the rest of the liquid

Question 36

How is water a good solvent

Answer 36

Allows hundreds of critical elements, compounds and macromolecules to be transported within and among cells

Facilitates movement of food into the body and waste out of the body

Question 37

Why is water being transparent useful

Answer 37

Allows sunlight to penetrate water bodies and allow for photosynthesis in aquatic plants

Question 38

Why is water being able to conduct electricity useful

Answer 38

This allows nerve impulses to be used by the nervous system to control body functions

Question 39

Animal dependency on water

What happens if most terrestrial amphibious animals don’t remain moist

Answer 39

Most aquatic animals must be bathed in water or they quickly die

They will eventually die
They will be unable to reproduce

Question 40

What happens with a very little water present

Answer 40

Most terrestrial amniotes can exist and reproduce where there is no standing water, and can typically survive at least a few days without any source

As aquatic animals have moved (through history) from water to land (or vise versa)…

They have had to adapt to the challenges of a water related extreme environment