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A level Biology > Exchange of substances- Topic 3 > Flashcards

Exchange of substances- Topic 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

plasma membrane

A

the membrane around organelles and cells

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2
Q

functions of plasma membrane

A

Cell signalling and recognition

Important for recognition by neurotransmitters and hormones

Isolates the contents of the cell and organelles

Entry and exit of substances

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3
Q

The fluid mosaic model of the plasma
membrane

A

Mosaic because proteins in the membrane are dotted around in a mosaic pattern. Fluid because the proteins and phospholipids are constantly moving.

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4
Q

phosphate head

A

polar and hydrophilic

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5
Q

fatty acid tails

A

non-polar and hydrophobic

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6
Q

cholesterol function in membranes

A

controlling membrane fluidity. It does this by
fitting between the phospholipids and binding to the tails, which results in their movement being restricted. The more cholesterol, the less fluid – and the less permeable –
the membrane.

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7
Q

integral/ transmembrane proteins

A

span the whole width of the
membrane.

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8
Q

peripheral/ extrinsic proteins

A

confined to the inner or outer surface of the
membrane, usually receptors or involved in cell recognition

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9
Q

glycoproteins

A

proteins with attached carbohydrate chains

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10
Q

carrier molecules or channels

A

integral proteins that transport substances such as ions, sugars and amino acids these cannot diffuse across the membrane but are still vital to a cell’s functioning.

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11
Q

simple diffusion

A

the net movement of molecules or ions from a region where they are at high concentration to a region of low concentration. It is a passive process

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12
Q

passive process

A

does not require energy from ATP

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13
Q

rate of diffusion depends on

A

1.the concentration gradient

2.the distance over which diffusion occurs

3.the area over which diffusion occurs

4.the size and nature of the diffusing molecule

5.the size of the pores over which diffusion occurs

6.the temperature

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14
Q

which molecules can diffuse directly through the plasma membrane

A

non-polar and lipid soluble molecules

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15
Q

facilitated diffusion

A

diffusion which takes place through transmembrane channels and carriers. needed for polar and lipid insoluble molecules. Passive process.

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16
Q

Channel proteins

A

for water soluble molecules. Some channels are open all the time others open when a hormone is attached.

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17
Q

Carrier proteins

A

change shape when molecules bind with them allowing the molecule to diffuse through the membrane.

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18
Q

osmosis

A

The passage of water from a region where it has a higher water potential to a region where it has a lower water potential through a partially permeable membrane

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19
Q

partially permeable membrane

A

permeable to water molecules and a few other small molecules, but not to larger molecules

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20
Q

Water potential

A

the pressure created by water molecules, measured in kiloPascals (kPa).

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21
Q

highest water potential

A

0

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22
Q

more negative (lower) water potential

A

more concentrated solution

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23
Q

isotonic solutions

A

have the same water potential

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24
Q

water moves from a ….. water potential to a ……. water potential in osmosis

A

higher, lower

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25
Q

dynamic equilibrium

A

no net movement

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26
Q

active transport

A

The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration (against concentration gradient) using ATP and carrier protein

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27
Q

ATP——>

A

ADP + Pi

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28
Q

steps of active transport

A

1) molecule binds to receptor sites on carrier protein
2) on the inside ATP binds to protein
3) this splits ATP causing the shape of the protein to change so it opens on the other side
4) molecule released through open side
5) Pi released so protein returns to original shape. Pi recombines with ADP

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29
Q

Sodium Potassium pump

A

Na+ moves out of cell, K+ taken into cell

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30
Q

Co-transport

A

bind two molecules at a time, one moves down its concentration gradient and this is used to move the other molecule across the membrane against its concentration gradient

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31
Q

sodium glucose co transport in small intestine

A

1) Na+ ions actively transported out of epithelial cells by Na+/K+ pump
2) creates a concentration gradient
3) concentration gradient causes Na+ ions to diffuse from the ileum lumen into epithelial cells through Na+/glucose co transporter
4) glucose enters the cell with Na+

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32
Q

dilution series

A

A dilution where successive concentrations
increase/decrease in a logarithmic fashion

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33
Q

affect of increased temperature on phospholipid bilayer

A

Phospholipids gain kinetic energy, vibrate more and drift apart leaving gaps. Membrane proteins become denatured at high temperatures

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34
Q

practical to test membrane permeability

A

beetroot in different concentrations of alcohol or different temperatures

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35
Q

affect of ethanol on phospholipid bilayer

A

The embedded cell membrane proteins are denatured by the ethanol molecules causing the membrane to lose it’s integrity and become more leaky

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36
Q

surface area of a sphere

A

4 x pi x r^2

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37
Q

surface area of a cylinder

A

2 x pi x r x h + 2 x pi x r^2

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38
Q

volume of a sphere

A

4/3 x pi x r^3

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39
Q

large surface area to volume ratio

A

beneficial as short diffusion distance so quick

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40
Q

features of a gas exchange system

A

large SA to volume ratio, thin to shorten diffusion pathway, selectively permeable

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41
Q

insect adaptations to reduce water loss

A

small SA to volume ratio so less area for water to diffuse from, water proofing coverings, spiracles can be opened and closed

42
Q

gas exchange in insects

A

spiracles –> tracheae –> tracheoles –> diffuse into cells
CO2 diffuses opposite way
abdomens rythmically moved to control air in and out

43
Q

fish gill adaptations for gas exchange

A

large SA due to lamellae, thin epithelium so short diffusion distance, water and blood countercurrent, circulation so constant deoxygenated blood to be oxygenated, ventilation replaces water

44
Q

countercurrent flow

A

water and blood flow in opposite directions so maximum amount of oxygen can diffuse into blood

45
Q

structure of gills

A

composed of gill filaments with many lamellae to increase SA. lamellae are thin and contain lots of capillaries

46
Q

how does CO2 reach mesophyll cells in the leaf

A
  1. Carbon dioxide enters the leaf via stomata
  2. Stomata is opened by guard cells
  3. Carbon dioxide diffuses through air spaces
  4. Down diffusion gradient
46
Q

leaf adaptations

A

large SA, thin, air spaces for quick diffusion, lots of chloroplasts, waxy cuticle for waterproofing, stomata can open and close

47
Q

reasons rate of water uptake may not be the same as rate of transpiration

A
  1. Water used for support/turgidity
  2. Water used in photosynthesis
  3. Water used in hydrolysis
  4. Water produced during respiration
48
Q

where are stomata mainly found and why

A

underside of leaves to reduce water loss

49
Q

how do guard cells work

A

in low CO2 levels, the guard cells gain water so become turgid and open the stomata. the opposite happens in high CO2 levels

50
Q

units for distribution of stomata

A

stomata per mm^2 or cm^2

51
Q

xerophytes

A

plants adapted to dry environment

52
Q

mesophytes

A

plants adapted to environment with adequate water

53
Q

halophytes

A

plants adapted to salty habitat

54
Q

hydropytes

A

plants adapted to freshwater environment

55
Q

xerophyte adaptations

A

waxy cuticle, sunken stomata and rolled leaves to trap humid air to lower water potential gradient so less water leaves by osmosis, hairs to trap water droplets, spines as leaves to reduce SA: volume

56
Q

inspiration

A

external intercostal muscles and diaphragm contract (flattens), internal intercostal muscles relax. Ribs move up and out, increased volume in cavity so decreased pressure, air flows in down pressure gradient so forced into lungs.
active process

57
Q

expiration

A

external intercostal muscles and diaphragm relax, internal intercostals contract. ribcage moves down and in. decreased volume in cavity, air pressure increases, air forced out lungs down pressure gradient
passive process

58
Q

FEV

A

how much air a person can exhale in one breath

59
Q

total lung capacity

A

the total volume of air the lungs can hold after a maximal inhalation

60
Q

tidal volume

A

the volume inhaled and exhaled in normal breathing

61
Q

inspiratory capacity

A

the maximum amount of air that can be inhaled after a normal exhale

62
Q

expiratory capacity

A

the maximum amount of air that can be exhaled after a normal inhale

63
Q

vital capacity

A

the maximum amount of air that can be exhaled after a maximum inhalation

64
Q

residual volume

A

the amount of air left in the lungs after maximum exhalation

65
Q

pulmonary ventilation =

A

tidal volume x ventilation rate

66
Q

trachea structure

A

c-shaped rings of cartilage to prevent from collapsing

67
Q

alveoli structure

A

one cell thick, folded to provide huge SA, surrounded by capillaries for short diffusion distance

68
Q

digestion definition

A

Hydrolysis of large insoluble substances to smaller soluble substances, which can be absorbed and assimilated

69
Q

physical breakdown in digestion

A

broken down by teeth, churned by muscles in stomach wall, provides larger SA for chemical breakdown

70
Q

chemical breakdown in digestion

A

enzymes hydrolyse large, insoluble molecules to smaller soluble molecules

71
Q

digestion of carbohydrates/ starch

A

salivary amylase breaks down starch into maltose, stomach acid denatures amylase, mixed with pancreatic amylase in small intestine, maltase on epithelial lining of ileum hydrolyses maltose to glucose

72
Q

digestion of proteins

A

endopeptidases hydrolyse bonds randomly between amino acids, exopeptidases remove 1 amino acids from the end of polypeptide chains, dipeptidases hydrolyse bonds between 2 amino acids

73
Q

digestion of lipids

A

bile salts produced in the liver cause lipids to form micelles (emulsification), this increases the SA for lipase to act on, lipase produced in pancreas hydrolyses lipids into monoglycerides and fatty acids

74
Q

where are the products of digestion absorbed

A

ileum

75
Q

adaptations of villi in ileum

A

increase SA for diffusion, thin walled so short diffusion path, contain muscle so can move to mix contents to maintain conc grad, lots of blood vessels to carry away products, microvilli increase SA

76
Q

absorption of products of carbohydrate/ protein digestion

A

Na+ actively transported out of epithelial cells by Na+- K+ pump. maintains a higher conc of Na+ in small intestine than epithelial cells, Na+ diffuses into epithelial cells, co-transporting glucose/ amino acids, glucose/ amino acids passes into blood by facilitated diffusion

77
Q

absorption of lipid digestion

A

micelles break down into fatty acids and monoglycerides, these diffuse into epithelial cells, form triglycerides in ER, associate with cholesterol in golgi apparatus to form chylomicrons, move out of cells by exocytosis and enter lacteals (lymphatic system), hydrolysed by enzyme in endothelial cells, diffuse into cells

78
Q

haemoglobin structure

A

quaternary protein made of 2 beta chains and 2 alpha chains, each polypeptide is linked with a haem group

79
Q

how many oxygen molecules and atoms can be carried by 1 haemoglobin

A

4 molecules, 8 atoms

80
Q

haemoglobin with high affinity for oxygen

A

take up oxygen more easily, release oxygen less easily

81
Q

haemoglobin with low affinity for oxygen

A

take up oxygen less easily, release oxygen more easily

82
Q

affect of CO2 on haemoglobin

A

shape changes to cause haemoglobin to release oxygen, so less affinity for oxygen

83
Q

high pO2 means

A

lots of dissolved oxygen

84
Q

what cells carry haemoglobin

A

red blood cells

85
Q

shape of oxyhaemoglobin association graph and why

A

S shape, difficult for 1st oxygen to bind, causes a change in shape when binded, allows 2nd and 3rd to bind easily, hard for 4th oxygen to bind as haemoglobin is saturated

86
Q

double circulatory system means

A

blood passes twice through the heart for each complete circuit of the body

87
Q

flow of blood

A

blood from body –> superior + inferior vena cava –> right atrium –> tricupsid valve –> right ventricle –> pulmonary valve –> pulmonary artery –> lungs –> pulmonary veins –> pulmonary atrium –> bicupsid valve –> left ventricle –> aortic valve–> aorta –> body

88
Q

diastole

A

relaxation of heart muscles

89
Q

systole

A

contraction of heart muscles

90
Q

cardiac output =

A

heart rate x stroke volume

91
Q

arteries

A

carry blood away from heart, thick muscle layer, thick elastic layer, folded endothelium, high blood pressure and can stretch

92
Q

arterioles

A

thick muscle layer, thinner elastic layer, controls blood flow to capillaries, lower blood pressure than arteries

93
Q

veins

A

carry blood towards heart, thin muscle layer, thin wall, valves to prevent backflow, lower pressure

94
Q

capillaries

A

one cell thick, narrow lumen, short diffusion distance

95
Q

tissue fluid formation

A

hydrostatic pressure forces tissue fluid out of capillaries, decreased water potential in capillaries, tissue fluid re enters capillaries by osmosis at end of capillary, excess tissue fluid deposited into lymphatic system

96
Q

lymphatic system

A

drains tissue fluid back to the heart, network of vessels around the body

97
Q

cohesion-tension theory of transpiration

A

water lost from leave by transpiration, lowers water potential of mesophyll, water is pulled up xylem, water molecules stick together by H bonding, forms continuous water column (transpiration pull), adhesion of water molecules to xylem walls, passive process

98
Q

transpiration

A

water evaporates out of open stomata down water potential gradient

99
Q

phloem

A

tissue that transports biomolecules made of sieve tubes

100
Q
A

A level Biology (8 decks)

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