UNIT 1 - A 1.1 - Water Flashcards
What advantages does water have for the aquatic and marine organisms that use it as a habitat?
Water provides buoyancy, stable thermal properties for organisms
What disadvantages does water have for the aquatic and marine organisms that use it as a habitat?
Water has a relatively high viscosity compared to air meaning many organisms have adapted to move easily through water
Why would the primitive Earth not have any water?
Because of the extremely high temperatures at Earth’s center and surface
What does Earth’s varied temperatures allow water to do that was not possible in Earth’s early stages?
Change states
What is needed for the complex series of biochemical reactions which cells require to occur?
A solvent
What provided the source for the solvent needed in biochemical reactions?
The ocean
What are the six statements completing “Water is a solvent that…”?
- makes up cytoplasm in cells where all cellular reactions occur
- makes up fluid inside all organelles
- is found between cells of multicellular organisms
- permits the transportation of substances in and out of cells
- is essential to blood and other fluids in the body and other organisms
- provides medium in which organisms in bodies of water live
What can the covalent bonds between the oxygen atom and two hydrogen atoms of a water molecule be categorized as?
polar covalent bonds
What are non-polar covalent bonds created by?
Equally shared electrons
What does an unequal sharing of electrons result in?
Polar covalent bonds
Which end of a water molecule is positive?
The hydrogen end
Why is water a polar molecule?
It has different charges at each end
Which end of a water molecule is the negative end?
The oxygen end
When does cohesion occur?
When molecules of the same type are attracted to each other
What is hydrogen bonding?
When two water molecules are near each other, the positive end attracts the negative end (hydrogens attract the oxygen)
What is surface tension due to?
The layer of water molecules at the surface does not have molecules of water above so the molecules have a strong cohesive force to the molecules immediately around them
How do ice crystals form?
When water cools bellow freezing, the molecules slow to the point where the hydrogen bonds become locked in place
What are xylem?
Small tubes in plants which act like straws
In plants, what is tension created by?
The evaporation of water from a leaf with corresponding cohesion
What does the tension in a plant do?
Pulls on the other water molecules in the xylem tubes so they move up towards the leaf
What is adhesion?
An attraction between two unlike molecules due to hydrogen bonding
What is an aqueous solution?
Any solution that has water as the solvent
What are hydrophilic substances?
Substances that readily dissolve in water
What are hydrophobic substances?
Substances that do not easily dissolve in water
What are some examples of hydrophilic substances contained in the cytoplasm of a cell?
glucose, ions, amino acids, proteins
What do reactions within cytoplasm depend on to proceed at a rate necessary for life and at a temperature tolerated by that type of cell?
enzymes
What are examples of hydrophilic substances which are transported by the aqueous solution in xylem tubes?
sodium, potassium, calcium
What are red and white blood cells suspended in?
Plasma, an aqueous solution
What are examples of hydrophobic molecules?
Steroid hormones (ex. oestradiol, testosterone), sections of proteins, wax cuticle
What allows protein to stay attached to the membrane of a cell but still interact with soluble substances in the surrounding cell fluids?
Hydrophobic areas of proteins may be used to embed into the hydrophobic layers of the membrane while hydrophilic section(s) of the proteins extend into the intercellular fluid of cytoplasm
What kind of cells are capable of secreting a wax used to coat leaves?
epidermal cells of leaves
What is the cuticle?
Wax coating leaves
For what purpose does the cuticle act as a barrier?
To keep water from entering and exiting by evaporation
What would happen without the cuticle on leaves?
Leaves would dehydrate quickly
What are “ordinary” hydrogen atoms?
Hydrogen atoms without any neutrons`
What is “heavy water”?
The hydrogen atoms have a neutron
What is the hydrogen with a nucleus called?
deuterium
What is the evidence that points towards water coming from astroids?
The ratio of hydrogen to deuterium in oceans is similar to the ration found in astroids
What was brought in the astroids that struck Earth?
Hydrated minerals that released water
What is the Goldilocks zone?
An area in the solar system with a position to the sun that would allow water to exist as a liquid
What allows water to remain on and just under Earth’s surface?
Earth’s size allowing for a suitable gravitational pull
What has Earth developed to protect it from harmful ionizing radiation being emitted from the sun?
An atmosphere and magnetic field
What is buoyancy/buoyant force?
An upward force exerted on an object placed in water or air
In water, what is the buoyant force equal to?
The weight of the water displaced by the object
Why is the buoyant force upwards in water?
Because there is more pressure from below in water than above in air
What is the buoyant force on an object in air?
Almost insignificant, the weight of the air displaced by the object
What is viscosity in terms of water?
Water’s resistance to an object moving through it
What is air’s viscosity compared to water?
Air’s viscosity is far less compared to water because air is much less dense than water
What is thermal conductivity?
The ability of a substance to transfer heat
What is water’s thermal conductivity?
High
What is air’s thermal conductivity compared to water?
Very low
What does the specific heat capacity for water mean for it?
Water can absorb or give off much heat without changing temperature very much
What does the specific heat capacity for air mean for it?
Air does not have a good ability to absorb or give off heat without changing temperature in comparison to water
What are two examples of animals which are affected by the physical properties of water?
The black-throated loon and the ringed seal
What do black-throated loons depend on to float in water?
Buoyant force
What help black-throated loons overcome water’s viscosity as they swim and dive under water?
Webbed feet and their body shape
What causes loons to lose more body heat in water than in air?
Water’s high thermal conductivity
What adaptation do loons have to prevent the loss of body heat in water?
They have an oil gland near their tail and they use their beaks to rub oil over their feathers to make them waterproof
Why is water likely to be warmer than very cold air?
Because of water’s high specific heat capacity which allows the temperature of water to remain relatively stable compared to air
How do ringed seals have an easily available supply of air?
The buoyant force is just enough to keep their snouts above water easily
What helps seals overcome water’s viscosity while swimming under the surface?
Their paddle-like feet and body shape
How do seals minimize body heat loss?
With their thick blubber under their skin
