Chapter 2 Flashcards
Thermal properties of water
Pure water becomes a solid below 0°C and vapor above 100°C.
When water contains dissolved compounds, such as salts, its freezing temperature drops below 0°C.
Water has a high specific heat; which is the energy required to raise water temperature by 1°C.
Density of water
Water is at its highest density at 4°C.
Above and below 4°C, the density of water decreases.
Ice is less dense than liquid water, so it floats on the surface. As a result, the lower layers of lakes and ponds are typically ice-free during winter.
Adaptations to water density
Some body tissues are more dense than water (e.g., bone); some are less dense (e.g., fats).
Organisms have developed many adaptations to cope with their tendencies to sink or float.
saturation
Every mineral has an upper limit of solubility in water, known as saturation.
Beyond saturation, minerals precipitate out of water.
Acidity
the concentration of H+ ions in a solution.
Acidity is measured as pH: pH = –log(H+ concentration).
Water with low pH is acidic, medium pH is neutral, and high pH is basic or alkaline.
Acidic water can dissolve toxic metals and negatively affect enzyme activity.
Acid rain
In the 1960s, many bodies of water downwind of coal-powered factories were becoming more acidic.
This was due to acid deposition, also known as acid rain; sulfur and nitrogen dioxides emitted by smokestacks were carried down to land by precipitation.
Water became toxic to many species of aquatic organisms.
On land, acid deposition caused nutrients to leach out of leaves and soils, and reduced the ability of plants to take up nutrients.
Semipermeable membranes
membranes that allow only particular molecules to pass through; reduces free movement of solutes
Osmotic potential
the force with which a solution attracts water by osmosis.
Marine fish
hypo-osmotic (tends to gain salts and lose water)
continually drink seawater
excrete salts through gills
excretes small amounts of dilute urine
Freshwater fish
hyper osmotic (tends to lose gain water and lose salts)
water enters body (does not drink water)
pees a lot but absorbs salts from urine
large amounts off urine
Ammonia in sharks and rays
Sharks and rays convert ammonia, a by-product of protein digestion, into urea.
Most urea is excreted, but some is retained in the bloodstream.
This raises the osmotic potential of their blood to that of seawater, which balances water movement.
They accumulate trimethylamine oxide in blood to protect proteins from the harmful effects of urea.
Diffusion of carbon dioxide
Plants need carbon dioxide (CO2) for photosynthesis.
CO2 diffuses slowly through water; plants use CO2 faster than it diffuses into leaf tissues.
CO2 is rapidly converted to bicarbonate (HCO3–) or carbonate (CO3–) ions, which accumulate in massive quantities and can be used for photosynthesis.
Even when CO2 and HCO3– are abundant, they diffuse slowly and limit plant growth.
Boundary layer
a region of unstirred air or water that surrounds the surface of an object. Removed gases from this region are slow to be replaced; this further limits carbon availability.
Oxygen gas (O2) in air is ___% by volume; in water it is ___%.
21% ; 1%
Countercurrent circulation
is an adaptation where blood and water flow in opposite directions so that the concentration of O2 in water is always greater than the concentration in blood.
