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