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IB HL Biology I > Unit 2 > Flashcards

Unit 2 Flashcards

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1
Q

What is the biological medium of earth?

A

Water

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2
Q

What can water do?

A

Exist in nature in all 3 physical states

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3
Q

What type of molecule is water?

A

Polar

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4
Q

Why is water polar?

A

Because of oxygen (-) on one side and hydrogen (+) on the other side

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5
Q

Why is oxygen negative and hydrogen positive?

A

Oxygen is more electronegative while hydrogen is less electronegative

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6
Q

Polarity

A

to have sides

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7
Q

What happens as a result of water being polar?

A

hydrogen bonding between molecules

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8
Q

Hydrogen Bonds

A

forces of attraction between water molecules

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9
Q

How are hydrogen bonds represented?

A

dotted lines

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10
Q

Intermolecular Forces

A

forces between molecules

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11
Q

What is an example of an intermolecular force?

A

hydrogen bonds

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12
Q

How do hydrogen bonds happen?

A

the positive region of one water molecule attracts the negative region of another water molecule

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13
Q

What does the strength of hydrogen bonds do?

A

it orders molecules into a higher level of structural organization

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14
Q

Intramolecular Forces

A

exist within a molecule

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15
Q

What is an example of an intramolecular force?

A

covalent bonds between atoms

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16
Q

What is cohesion?

A

ability of molecules of the same substance to stick together

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17
Q

Why is water cohesive?

A

Because of hydrogen bonds between water molecules

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18
Q

What is surface tension?

A

measure of how difficult it is to stretch or break the surface of a liquid.

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19
Q

What can surface tension do?

A

allow animals to live on the surface of water and maintain lung structure

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20
Q

What is adhesion?

A

ability of different types of molecules to stick to each other.

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21
Q

What does the polarity of water molecules allow?

A

For water to attract to other polar molecules

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22
Q

What is capillary action?

A

spontaneous movement of liquid through narrow passage (even against gravity)

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23
Q

Why is adhesion stronger?

A

because adhesion to walls is stronger than cohesive forces between molecules

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24
Q

What is an example of capillary action?

A

The transport of water upwards in plants from roots to leaves

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25
Q

How does adhesion work with capillary action?

A

Adhesion of water to walls causes an upwards force on water at edges of narrow passages

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26
Q

How does cohesion work with capillary action?

A

Cohesion causes surface tension that holds surface of water in tact as it moves up narrow passage

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27
Q

What is a solution?

A

uniform mixture of two or more substances

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28
Q

What is a solvent?

A

dissolver in a solution

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29
Q

What is solute?

A

what is being dissolved

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30
Q

What is an aqueous solution?

A

A solution in which water is the solvent

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31
Q

Why is water a versatile solvent?

A

because its fluidity at body temperature allows it to dissolve many solutes

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32
Q

What are some helpful things that water can do as a versatile solvent?

A

transport materials around organisms and serve as a solvent for chemical reactions in living things

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33
Q

What makes water versatile?

A

its polarity

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34
Q

What can water dissolve?

A

polar solutes

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35
Q

Hydration Shell

A

water molecules around a solute due to the attraction between water and solute particles

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36
Q

What do hydration shells do?

A

spread out/dissolve solutes in water

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37
Q

Hydrophilic

A

dissolve in water

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38
Q

Hydrophobic

A

do not dissolve in water

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39
Q

What do nonpolar solutes do?

A

dissolve in nonpolar solvents.

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40
Q

What does blood do?

A

transport polar and nonpolar molecules

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41
Q

What types of polar molecules does blood transport?

A

glucose, amino acids, sodium chloride, and other salts

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42
Q

What types of nonpolar molecules does blood transport?

A

cholesterol and fats (transported using lipoproteins)

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43
Q

Why are hydrophobic substances important to biological systems?

A

forces nonpolar molecules to associate together, shapes molecules with nonpolar regions, forms important interfaces with nonpolar substances

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44
Q

What are water’s 2 thermal properties?

A

High specific heat capacity and high heat of vaporization

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45
Q

Specific heat capacity

A

the amount of heat that must be absorbed or lost of 1 g of the substance to change its temperature by 1°C

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46
Q

True or false: Water must absorb large amounts of heat to raise its temperature

A

true

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47
Q

What does specific heat capacity measure?

A

How well a substance resists changing its temperature when it absorbs or releases heat

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48
Q

How is hydrogen bonding responsible for water’s high specific heat capacity?

A

a large amount of hydrogen bonding means that water can absorb a great deal of heat energy before its temperature increases significantly

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49
Q

What is the result of water’s heat specific capacity concerning the environment?

A

Maintains the fluctuations in temperature in air and water in order to permit life

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50
Q

Heat of vaporization

A

the quantity of heat a liquid must absorb for 1 g of it to be vaporized

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51
Q

Why does water have a high heat of vaporization?

A

due to the hydrogen bonds that must be broken for water molecules to vaporize

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52
Q

What des water’s high heat of vaporization lead to?

A

Evaporative cooling

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53
Q

Evaporative cooling

A

the cooling of a surface of a liquid that occurs as liquids evaporate

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54
Q

Phospholipid structure

A

A glycerol that is attached to one phosphate group and two acid tails

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55
Q

Is a phosphate head hydrophobic or hydrophilic?

A

hydrophilic

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56
Q

Is a fatty acid tail hydrophobic or hydrophilic?

A

hydrophobic

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57
Q

What do phospholipids form?

A

bilayers

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58
Q

What direction do phosphate heads face?

A

outward

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59
Q

What direction do fatty acid tails face?

A

inward

60
Q

What does the plasma membrane do? (4 things)

A

separate contents of the cell, allow selected substances into the cell, support the cell, maintain its shape

61
Q

What was the evidence for the Davson-Danielli Model?

A

In electron micrograph images proteins were dark and phospholipids were lights

62
Q

Davson-Danielli Model

A

lipid bilayer coated with proteins on both sides (protein lipid sandwich), polar molecules would pass through the membrane through gaps

63
Q

Fluid Mosaic Model

A

phospholipid bilayer with proteins imbedded

64
Q

Singer-Nicolson Fluid Mosaic Model

A

current understanding of the plasma membrane

65
Q

Fluid Membrane

A

fluid (like olive oil) at body temperature

66
Q

What do most lipids and some proteins do?

A

drift laterally

67
Q

Mosaic Membrane

A

lipids, carbohydrates, and many different types of membrane proteins are associated with either side of the lipid bilayer (form a mosaic)

68
Q

What are the 2 main membrane protein classifications?

A

integral and peripheral

69
Q

Integral protein

A

span the membrane/embedded in the hydrophobic region of the membrane

70
Q

Peripheral protein

A

on the membrane surface

71
Q

6 classes of membrane proteins with different functions

A

J - junctions
E - enzymes
T - transports
R - recognition
A - anchorage
T- transductions

72
Q

Junction/Adhesion Proteins

A

join cells together (tight junctions and gap junctions)

73
Q

Tight junctions

A

seal adjacent cells, precent cell movement and limit passage of particle between cells

74
Q

Gap junctions

A

channels that allow passage of particle between cells

75
Q

Enzymatic proteins

A

proteins that speed up chemical reactions at the membrane

76
Q

What are some examples of enzymatic proteins?

A

-reactants bind to the enzyme and products form
-localizes metabolic pathways

77
Q

Transport Proteins

A

channels and pumps move things across the membrane

78
Q

Channel proteins

A

move molecules across the membranes without energy

79
Q

Pumps

A

move molecules across membranes using energy

80
Q

Recognition proteins

A

help cells identify other cells and viruses

81
Q

Glycoproteins

A

carbohydrate chain attaches to protein within membrane

82
Q

Glycolipids (not protein):

A

carbohydrate chin attached to lipid within membrane

83
Q

Anchorage Proteins

A

attachment point for cytoskeleton and extracellular matrix

84
Q

Cytoskeleton

A

complex network of interlinking filaments and tubules in the cytoplasm

85
Q

Extracellular Matrix

A

mesh of protein fibers and glycoproteins outside of the cell in multicellular organisms

86
Q

What else do anchorage proteins do?

A

maintain cell shape and stabilize proteins

87
Q

Transduction proteins

A

bind chemical messengers and relay signals to inside cells

88
Q

hormone receptors

A

bind hormones and relay signals inside of cells

89
Q

Cholesterol

A

a lipid found in membranes, maintains stability of animal cell membrane by regulating fluidity and permeability, also a steroid

90
Q

Why is cholesterol not present in plants?

A

the plasma membrane is supported by a cell wall

91
Q

What is the structure of cholesterol in animal cells?

A

polar hydroxyl group at the top (attracted to phosphate heads), nonpolar tail at the bottom (attracted to fatty acid tails)

92
Q

What are cholesterol’s abilities?

A

reduce the fluidity of the membrane, makes the membrane less permeable, prevents solidification of the membrane at low temperatures

93
Q

How does cholesterol reduce the fluidity of membranes?

A

By making the phospholipids pack tightly, cells need to regulate fluidity in order to be able to move

94
Q

How does cholesterol decrease permeability?

A

makes the phospholipids pack tightly, membranes need to regulate the permeability of the membrane so substance can move into and out of the cell

95
Q

How does cholesterol prevent the solidification of the membrane at low temperatures?

A

it disrupts the regular packing of the phospholipid tails

96
Q

Concentration

A

quantity of solute that is dissolved in a given quantity of solvent

97
Q

Diffusion

A

passive movement of particles from an area of high concentration to an area of low concentration, tendency for particles to spread out evenly in an available space

98
Q

Passive

A

no energy required

99
Q

How do particles move on the concentration gradient?

A

Particles move down the concentration gradient when they move from an area of high concentration to low concentration

100
Q

Passive transport

A

-when a molecule diffuses down a concentration gradient
-Movement from high to low particle concentration
-No input of energy needed/due to random motion of molecules

101
Q

Diffusive Equilibrium

A

when the concentrations of the diffusing substance in the two compartments becomes equal

102
Q

Simple diffusion (definition and example)

A

movement of particles directly through plasma membrane which is selectively permeable.
-small, nonpolar molecules (O2 and CO2) move
across by simple diffusion

103
Q

Facilitated Diffusion

A

diffusion of a substance across a membrane through a channel or carrier protein

104
Q

What are the requirements of simple diffusion?

A

-Solutes move across porous membranes between phospholipids
-solutes move from high to low concentration
-no ATP/energy is involved
-diffusion continues until concentrations are equal

105
Q

What are the requirements of facilitated diffusion?

A

-Occurs down concentration gradient (high to low)
-No energy needed
-Proteins only let specific solutes pass through
-Faster than simple diffusion

106
Q

What is an example of facilitated diffusion?

A

Voltage-gated potassium channels

107
Q

What are voltage-gated potassium channels?

A

-Opens/closes with changes in electrical potential across the membrane
-Protein pore for K+ to cross membrane

108
Q

What are the requirements for voltage-gated potassium channels?

A

-channels move K+ across the membrane down a concentration gradient
-K moves through a protein channel
-no ATP (energy)

109
Q

Where does facilitated diffusion occur?

A

occurs through channel or carrier proteins

110
Q

What do protein channels do?

A

create pores in the membrane

111
Q

What do carriers do?

A

bind a solute and then change shape to deliver the solute to the other side.

112
Q

How does water cross the plasma membrane?

A

by simple diffusion and facilitated diffusion

113
Q

Aquaporin

A

an integral protein that speeds the movement of water molecules

114
Q

What are the 5 factors that affect diffusion across membranes?

A

-concentration gradient
-temperature
-surface area
-length of diffusion path
-size of particles

115
Q

How does the concentration gradient effect diffusion?

A

↑ gradient, faster diffusion

116
Q

How does the surface area effect diffusion?

A

↑ surface area, faster diffusion

117
Q

How does the length of the diffusion path effect diffusion?

A

↑ length, slower diffusion

118
Q

How does the temperature effect diffusion?

A

↑ temperature, faster diffusion

119
Q

How do the size of particles effect diffusion? (in the case of them being smaller)

A

smaller particles, faster diffusion

120
Q

Osmosis

A

the movement of water across a membrane

121
Q

What does the difference in total solute concentration do?

A

determine the direction of the movement of water

122
Q

How does water diffuse?

A

from an area of low solute concentration to high solute concentration until the solution is equally concentrated on both sides of the membrane

123
Q

True or False: Osmosis is passive transport.

A

True

124
Q

Osmoregulation

A

control of water balance, which is crucial to organisms

125
Q

Hypotonic extracellular solution

A

solute concentration is lower outside the cell so the cell gains water

126
Q

What do animal cells do in a hypotonic solution?

A

lyse (burst)

126
Q

What do plant cells do in a hypotonic solution?

A

become turgid

127
Q

Isotonic extracellular solution

A

solute concentration is the same inside and outside
so no net water movement

128
Q

What do animal cells do in an isotonic solution?

A

have a constant volume

129
Q

What do plant cells do in an isotonic solution?

A

becomes flaccid

130
Q

Hypertonic extracellular solution

A

solute concentration is higher outside the cell so the cell loses water

131
Q

What do animal cells do in a hypertonic solution?

A

it shrivels

132
Q

What do plant cells do in a hypertonic solution?

A

it plazmolyzes

133
Q

Osmolarity

A

the concentration of a solution expressed as the total number of solute particles per liter

134
Q

What medical procedures are isotonic solutions used for?

A

-fluid introduction to blood system via intravenous drip (rehydration)
-used to rinse wounds, skin abrasions etc.
-keep areas of damaged skin moist, eye drops/wash

135
Q

Active transport

A

the movement of solutes across membranes that requires energy (ATP) to move solutes against the
concentration gradient

136
Q

What is needed for active transport?

A

protein pumps

137
Q

What is an example of active transport?

A

Na+,K+-ATPase Pump

138
Q

What are the requirements for Na+,K+-ATPase Pumps?

A

-it’s a protein pump
-it uses energy
-it moves particles against their concentration gradient

139
Q

What is the solution if particles are too large for proteins or pumps?

A

Using energy and vesicles for endo and exocytosis

140
Q

Endocytosis

A

cells take in molecules or substances from outside of the cell by engulfing them in the cell membrane to form a vesicle.

141
Q

What are the steps of endocytosis?

A

-endocytosis occurs when a membrane encloses a target particle
-fluidity of membrane permits movement of membrane
-membrane invaginates to enclose particle
-membrane seals back on itself
-two phospholipid layers enclose particle making vesicle
-vesicle breaks away from membrane/moves into cytoplasm
-changes in membrane shape require energy

142
Q

Exocytosis

A

ejection of waste products (excretion) or useful substances (secretion) from the inside of the cell when a vesicle joins with the cell plasma membrane

143
Q

What are the steps of exocytosis?

A

-vesicles carry material to plasma membrane
-vesicle fuses with membrane by joining of phospholipid bilayers
-aided by the fluidity of the membrane
-material released/expelled from the cell
-membrane flattens through movement

144
Q

What is an example of exocytosis?

A

hormone secretion

145
Q

What does the fluidity of the membrane allow?

A

vesicle formation and materials to be taken into cells by endocytosis or released by exocytosis

IB HL Biology I (10 decks)

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