Water - Lectures 1 and 2 Flashcards
What is an extreme environment?
Conditions which are challenging (or deadly) for most life forms
Conditions = extreme high/low ends of “normal”
Why do people care about extremophiles
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)
Why do people care about extremophiles
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
Does natural selection work the same with extremophiles?
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
Explain the formation of hydrogen, protons, and neurons
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
Formation of deuterium
Protons repelled each other, but some got together to form positive deuterium
Some deuterium fused = stable helium nuclei (no electrons = still too hot)
Atom formation
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
What is fusion
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
What does it generate in the star
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)
How is oxygen produced?
Next, carbon fuses with another helium to produce oxygen
Oxygen atoms (along with other heavy elements) are released when the star explodes
How does interstellar water form
Interstellar water (ice) forms when a hydrogen atom interacts with solid oxygen on a solid surface such as a dust grain in space
How was water formed?
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
How do we know where the water came from?
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
Common name for water with deuterium
Heavy water
Important properties for life on Earth (9)
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
Why is ice important
(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
Why is water vapour important
(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
How are clouds formed and what do they do
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
Why is liquid water important
(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
What biochemical processes require water
- 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
What does it mean to have a high specific heat
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
Chemical makeup of water
When is it stable
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
Electronegativity
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)
Water bonds
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
What does having a high specific heat do for water
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
How much extra heat from global warming is held in the oceans
80-90%
What does buffering do
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
In what ways are density and temperatures relationship atypical
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
What happens at 4 OC
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
What’s it called when water moves against gravity into narrow spaces
Capillary polarity
Capillary action results from cohesion and adhesion
What are cohesion and adhesion
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
When does capillary action occur
(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
What is capillary action critical to
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
Water resists compressive forces
Percentages
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
What are the keys to water solubility
(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
How is water a good solvent
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
Why is water being transparent useful
Allows sunlight to penetrate water bodies and allow for photosynthesis in aquatic plants
Why is water being able to conduct electricity useful
This allows nerve impulses to be used by the nervous system to control body functions
Animal dependency on water
What happens if most terrestrial amphibious animals don’t remain moist
Most aquatic animals must be bathed in water or they quickly die
They will eventually die
They will be unable to reproduce
What happens with a very little water present
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
