Topic 1: Water Flashcards
Explain the Dipolar nature/polarity of water
4 points
- the shared ELECRTONS (negatively charged) are pulled towards the oxygen atom giving it a SLIGHT NEGATIVE CHARGE
- the hydrogen atom is left with a SLIGHT POSITIVE CHARGE
- SO THERE IS AN UNEVEN DISTRIBUTION OF ELECTRICAL CHARGE
- so water is a POLAR molecule - it has a slight negative charge (-) on its oxygen end and a slight positive charge (+) on its hydrogen end
Key Summary
(Water) Describe the dipolar nature of water
(2 points)
- A water molecule has an uneven distribution of electrical charge
- so water is a POLAR molecule - it has a slight negative charge (-) on its oxygen end and a slight positive charge (+) on its hydrogen end
Explain hydrogen bonding between water molecules
4 points
- The dipole nature of water molecules allows HYDROGEN BONDS to form between water molecules (or between water and polar molecules or ions)
- The slightly positive hydrogen end of one water molecule attracts the slightly negative oxygen end of another water molecule
- A HYDROGEN BOND forms - A WEAK ELECTROSTATIC ATTRACTION BETWEEN POLAR MOLECULES (glucose, water, some amino acids)
- Hydrogen bonds are WEAK, but many of them together are strong
Key definition (Water) Hydrogen bond definition (1 point)
- a weak electrostatic attraction between the slightly negatively charged part of one polar molecule and the slightly positively charged part of another polar molecule
A water molecule has a _____ (it is dipolar or polar)
The dipolar nature of water means it can form _________ _____
These __________ _____ give water many special _________
These _________ are important for animals and plants
dipole
hydrogen bonds
hydrogen bonds
properties
properties
Water is a good solvent as it is a polar molecule, this means that… (4 points)
- it SURROUNDS {IONS / POLAR MOLECULES} which allows them to DISSOLVE and be TRANSPORTED in water
- HYDROGEN BONDS FORM BETWEEN WATER MOLECULES AND {IONS / POLAR MOLECULES}
- OXYGEN, IONS, GLUCOSE AND OTHER SUBSTANCES dissolve in blood and can be carried to tissues
- mineral ions (eg. nitrate ions, calcium ions, magnesium ions) can be transported in water in plant xylem
Explain high surface tension of water
2 points
- Water molecules are polar, so form hydrogen bonds, therefore are cohesive
- Results in an inward force at its surface
What is specific heat capacity? (1 point)
- energy needed to raise the temperature of 1 gram of a substance by 1 degree C.
Explain specific heat capacity in water (3 points)
- HYDROGEN BONDS BETWEEN WATER MOLECULES CAN ABSORB A LOT OF ENERGY BEFORE THEY BREAK
- So it has a high specific heat capacity
- therefore it takes a lot of energy to heat water up
How is a high specific heat capacity in water useful for organisms (1 point)
- useful for stopping rapid temperature changes in organisms or aquatic habitats when the temperature of surroundings change
Key Summary (Water) Why is water important in plants? (6 points)
- As a REACTANT IN PHOTOSYNTHESIS
- To TRANSPORT PLANT MINERAL IONS IN XYLEM AND SUCROSE IN PHLOEM - as it is a SOLVENT and also a LIQUID WHICH CAN FLOW
- For HYDROLYSIS OF BONDS in chemical reactions eg. glycosidic bonds in starch to release glucose
- As a MEDIUM FOR CHEMICAL REACTIONS
- Create TURGOR PRESSURE TO PROVIDE SUPPORT
- TEMPERATURE REGULATION BY EVAPORATION
Key Summary (Water) Why is water important in animals? (5 points)
- To TRANSPORT OXYGEN AND GLUCOSE IN BLOOD PLASMA, AS IT IS A SOLVENT AND ALSO A LIQUID WHICH CAN FLOW
- For HYDROLYSIS OF BONDS in chemical reactions eg. glycosidic bonds in glycogen to release glucose
- As a MEDIUM FOR CHEMICAL REACTIONS eg. water in cytoplasm
- Temperature regulation by evaporation
- Distribution of thermal energy around the body
Water is a good ________ - many substances dissolve in it. This is important in _____, as it carries many dissolved substances
NOTE (just as a reminder)
Because water is polar, its + end will be attracted to a {negative ion/ - part of a polar molecule}, and its - end will be attracted to a {positive ion/ + part of a polar molecule}.
solvent
blood
Hydrogen bonds hold water together as a liquid, so that it
can flow and move in _____ _____ _______ – allows
bloodstream to function to carry _______. Water in blood
distributes ________ _______ around body
mass flow systems
oxygen
thermal energy
Hydrogen bonding allows _______ to allow water
to move up ______ _______ (in plants) and carry minerals and create
________ _______ on a pond (good for pond skaters which
move across surface)
cohesion
xylem vessels
surface tension
