unit 1 big idea
Big idea 1 Big idea 2 Big idea 3
- System interactions - Energetics - Information storage and
how would living systems function what is the role of energy in the transmission
without the polarity of the water making and breaking of polymers? how do living systems transmit information
molecule? in order to ensure their survival?
(2.3 chemistry of water in AP biology book, twelfth edition)
structure of water: 2 hydrogen atoms + 1 oxygen atom.
● bonded by single covalent bonds.
○ electrons of the covalent bond are not shared equally between both atoms →
making water a polar molecule. (O ↑ electronegativity than H.)
■ polarity leads to hydrogen bonds (weak electrical attractions with other
water molecules.) multiple hydrogen bonds collectively are strong
(electronegativity: tendency of an atom participating in a covalent bond to attract the bonding electrons.)
(polarity: having two opposite tendencies or opposite electrical charges.)
(covalent bond: chemical bond caused by the sharing of one or more electrons or 2 interacting monomers)
(ionic bond: chemical bond caused by the attraction of oppositely charged ions)
(solution: liquid of 2 or more structures mixed equally)
(solute: the dissolved substance)
❖ polarity + hydrogen bonding → the cause for several of water's properties
➢ Cohesion: water's ability to cling to one another due to hydrogen bonding. (stick together)
➢ Adhesion: water's ability to cling to other polar surfaces due to its polarity. (stick to polar
substances)
■ capillary action: liquid flowing in a narrow space without the assistance of external forces
➢ High heat capacity: strong resistance to sudden temperature change, can absorb heat without
having a great change in its temperature.
■ specific heat: amount of heat absorbed or lost to change the temperature of 1g of
substance by 1°c.
■ organisms are able to maintain their normal internal temperatures because of the slow
change in temperature.
■ heat is absorbed to break hydrogen bonds, not ↑ K.E. (↑ in K.E leads to change in
form)
➢ Universal solvent: dissolves a great number of substances due to its polarity.
■ hydrophilic: molecules that can attract water, ions and molecules disperse in water →
reactions. (attract polar molecules)
■ hydrophobic: nonionized + nonpolar molecules that cant attract water. (attract nonpolar
molecules)
➢ The density of ice is lower than liquid water: ice moves apart when it gets cold → fewer
molecules. (ice floats above the water) (held in hexagons, dipole structure, 8% less dense)
■ bodies of water don't freeze completely allowing marine life to survive under the ice.
➢ Surface tension: difficulty to stretch or break the surface due to hydrogen bonds and cohesion.
, (2.4 acids and bases in AP biology book, twelfth edition)
when water ionizes → releases an equal # of hydrogen ions (H+) and hydroxide ions (OH-)
H -- O -- H ⇌ (H+) + (OH-)
● acids: substances that release H ions (H+) when dissolved in water
○ ↑ H released the ↑ acidic the solution becomes
○ ↑ acidic ↓ pH # on pH scale
○ pH # lower than 7
● bases: substances that release hydroxide ions (OH-) when dissolved in water
○ ↑ OH- released the ↑ basic the solution becomes
○ ↑ basic ↑ pH #on pH scale
○ pH # higher than 7
■ most living cells must remain close to pH 7
■ most chemical reactions occur between pH 6.7 - 7.5
● buffers: substances that minimize changes in concentration of (H+) (OH-) in a solution (keeps pH within
normal range)
○ acid-base pair that combines with (H+)
(state of dynamic equilibrium: molecules dissociate at the same rate they're being formed)
(pH scale: used to describe whether solution is acidic or basic)
(pH: measure of concentration of H in a solution)
(homeostasis: maintaining internal environment)
(3.1 organic molecules in AP biology book, twelfth edition)
atom → molecule → compound → cell → tissue → organ → organ system → organism → structural hierarchy
the law of conservation of energy: energy cannot be created or destroyed only transformed
- living systems need a constant input of energy to grow, reproduce and maintain organization
❖ classes of organic biomolecules
1. carbohydrates
2. lipids
3. proteins
4. nucleic acid
Big idea 1 Big idea 2 Big idea 3
- System interactions - Energetics - Information storage and
how would living systems function what is the role of energy in the transmission
without the polarity of the water making and breaking of polymers? how do living systems transmit information
molecule? in order to ensure their survival?
(2.3 chemistry of water in AP biology book, twelfth edition)
structure of water: 2 hydrogen atoms + 1 oxygen atom.
● bonded by single covalent bonds.
○ electrons of the covalent bond are not shared equally between both atoms →
making water a polar molecule. (O ↑ electronegativity than H.)
■ polarity leads to hydrogen bonds (weak electrical attractions with other
water molecules.) multiple hydrogen bonds collectively are strong
(electronegativity: tendency of an atom participating in a covalent bond to attract the bonding electrons.)
(polarity: having two opposite tendencies or opposite electrical charges.)
(covalent bond: chemical bond caused by the sharing of one or more electrons or 2 interacting monomers)
(ionic bond: chemical bond caused by the attraction of oppositely charged ions)
(solution: liquid of 2 or more structures mixed equally)
(solute: the dissolved substance)
❖ polarity + hydrogen bonding → the cause for several of water's properties
➢ Cohesion: water's ability to cling to one another due to hydrogen bonding. (stick together)
➢ Adhesion: water's ability to cling to other polar surfaces due to its polarity. (stick to polar
substances)
■ capillary action: liquid flowing in a narrow space without the assistance of external forces
➢ High heat capacity: strong resistance to sudden temperature change, can absorb heat without
having a great change in its temperature.
■ specific heat: amount of heat absorbed or lost to change the temperature of 1g of
substance by 1°c.
■ organisms are able to maintain their normal internal temperatures because of the slow
change in temperature.
■ heat is absorbed to break hydrogen bonds, not ↑ K.E. (↑ in K.E leads to change in
form)
➢ Universal solvent: dissolves a great number of substances due to its polarity.
■ hydrophilic: molecules that can attract water, ions and molecules disperse in water →
reactions. (attract polar molecules)
■ hydrophobic: nonionized + nonpolar molecules that cant attract water. (attract nonpolar
molecules)
➢ The density of ice is lower than liquid water: ice moves apart when it gets cold → fewer
molecules. (ice floats above the water) (held in hexagons, dipole structure, 8% less dense)
■ bodies of water don't freeze completely allowing marine life to survive under the ice.
➢ Surface tension: difficulty to stretch or break the surface due to hydrogen bonds and cohesion.
, (2.4 acids and bases in AP biology book, twelfth edition)
when water ionizes → releases an equal # of hydrogen ions (H+) and hydroxide ions (OH-)
H -- O -- H ⇌ (H+) + (OH-)
● acids: substances that release H ions (H+) when dissolved in water
○ ↑ H released the ↑ acidic the solution becomes
○ ↑ acidic ↓ pH # on pH scale
○ pH # lower than 7
● bases: substances that release hydroxide ions (OH-) when dissolved in water
○ ↑ OH- released the ↑ basic the solution becomes
○ ↑ basic ↑ pH #on pH scale
○ pH # higher than 7
■ most living cells must remain close to pH 7
■ most chemical reactions occur between pH 6.7 - 7.5
● buffers: substances that minimize changes in concentration of (H+) (OH-) in a solution (keeps pH within
normal range)
○ acid-base pair that combines with (H+)
(state of dynamic equilibrium: molecules dissociate at the same rate they're being formed)
(pH scale: used to describe whether solution is acidic or basic)
(pH: measure of concentration of H in a solution)
(homeostasis: maintaining internal environment)
(3.1 organic molecules in AP biology book, twelfth edition)
atom → molecule → compound → cell → tissue → organ → organ system → organism → structural hierarchy
the law of conservation of energy: energy cannot be created or destroyed only transformed
- living systems need a constant input of energy to grow, reproduce and maintain organization
❖ classes of organic biomolecules
1. carbohydrates
2. lipids
3. proteins
4. nucleic acid
