Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

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

Exchange of substances- Topic 3 Flashcards

(101 cards)

Start Studying
1
Q

plasma membrane

A

the membrane around organelles and cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

phosphate head

A

polar and hydrophilic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

fatty acid tails

A

non-polar and hydrophobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

integral/ transmembrane proteins

A

span the whole width of the
membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

peripheral/ extrinsic proteins

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

glycoproteins

A

proteins with attached carbohydrate chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

passive process

A

does not require energy from ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

which molecules can diffuse directly through the plasma membrane

A

non-polar and lipid soluble molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

facilitated diffusion

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Channel proteins

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Carrier proteins

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

partially permeable membrane

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Water potential

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

highest water potential

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

more negative (lower) water potential

A

more concentrated solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

isotonic solutions

A

have the same water potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

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

A

higher, lower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
dynamic equilibrium
no net movement
26
active transport
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
27
ATP------>
ADP + Pi
28
steps of active transport
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
29
Sodium Potassium pump
Na+ moves out of cell, K+ taken into cell
30
Co-transport
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
31
sodium glucose co transport in small intestine
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+
32
dilution series
A dilution where successive concentrations increase/decrease in a logarithmic fashion
33
affect of increased temperature on phospholipid bilayer
Phospholipids gain kinetic energy, vibrate more and drift apart leaving gaps. Membrane proteins become denatured at high temperatures
34
practical to test membrane permeability
beetroot in different concentrations of alcohol or different temperatures
35
affect of ethanol on phospholipid bilayer
The embedded cell membrane proteins are denatured by the ethanol molecules causing the membrane to lose it’s integrity and become more leaky
36
surface area of a sphere
4 x pi x r^2
37
surface area of a cylinder
2 x pi x r x h + 2 x pi x r^2
38
volume of a sphere
4/3 x pi x r^3
39
large surface area to volume ratio
beneficial as short diffusion distance so quick
40
features of a gas exchange system
large SA to volume ratio, thin to shorten diffusion pathway, selectively permeable
41
insect adaptations to reduce water loss
small SA to volume ratio so less area for water to diffuse from, water proofing coverings, spiracles can be opened and closed
42
gas exchange in insects
spiracles --> tracheae --> tracheoles --> diffuse into cells CO2 diffuses opposite way abdomens rythmically moved to control air in and out
43
fish gill adaptations for gas exchange
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
countercurrent flow
water and blood flow in opposite directions so maximum amount of oxygen can diffuse into blood
45
structure of gills
composed of gill filaments with many lamellae to increase SA. lamellae are thin and contain lots of capillaries
46
how does CO2 reach mesophyll cells in the leaf
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
leaf adaptations
large SA, thin, air spaces for quick diffusion, lots of chloroplasts, waxy cuticle for waterproofing, stomata can open and close
47
reasons rate of water uptake may not be the same as rate of transpiration
1. Water used for support/turgidity 2. Water used in photosynthesis 3. Water used in hydrolysis 4. Water produced during respiration
48
where are stomata mainly found and why
underside of leaves to reduce water loss
49
how do guard cells work
in low CO2 levels, the guard cells gain water so become turgid and open the stomata. the opposite happens in high CO2 levels
50
units for distribution of stomata
stomata per mm^2 or cm^2
51
xerophytes
plants adapted to dry environment
52
mesophytes
plants adapted to environment with adequate water
53
halophytes
plants adapted to salty habitat
54
hydropytes
plants adapted to freshwater environment
55
xerophyte adaptations
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
inspiration
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
expiration
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
FEV
how much air a person can exhale in one breath
59
total lung capacity
the total volume of air the lungs can hold after a maximal inhalation
60
tidal volume
the volume inhaled and exhaled in normal breathing
61
inspiratory capacity
the maximum amount of air that can be inhaled after a normal exhale
62
expiratory capacity
the maximum amount of air that can be exhaled after a normal inhale
63
vital capacity
the maximum amount of air that can be exhaled after a maximum inhalation
64
residual volume
the amount of air left in the lungs after maximum exhalation
65
pulmonary ventilation =
tidal volume x ventilation rate
66
trachea structure
c-shaped rings of cartilage to prevent from collapsing
67
alveoli structure
one cell thick, folded to provide huge SA, surrounded by capillaries for short diffusion distance
68
digestion definition
Hydrolysis of large insoluble substances to smaller soluble substances, which can be absorbed and assimilated
69
physical breakdown in digestion
broken down by teeth, churned by muscles in stomach wall, provides larger SA for chemical breakdown
70
chemical breakdown in digestion
enzymes hydrolyse large, insoluble molecules to smaller soluble molecules
71
digestion of carbohydrates/ starch
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
digestion of proteins
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
digestion of lipids
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
where are the products of digestion absorbed
ileum
75
adaptations of villi in ileum
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
absorption of products of carbohydrate/ protein digestion
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
absorption of lipid digestion
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
haemoglobin structure
quaternary protein made of 2 beta chains and 2 alpha chains, each polypeptide is linked with a haem group
79
how many oxygen molecules and atoms can be carried by 1 haemoglobin
4 molecules, 8 atoms
80
haemoglobin with high affinity for oxygen
take up oxygen more easily, release oxygen less easily
81
haemoglobin with low affinity for oxygen
take up oxygen less easily, release oxygen more easily
82
affect of CO2 on haemoglobin
shape changes to cause haemoglobin to release oxygen, so less affinity for oxygen
83
high pO2 means
lots of dissolved oxygen
84
what cells carry haemoglobin
red blood cells
85
shape of oxyhaemoglobin association graph and why
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
double circulatory system means
blood passes twice through the heart for each complete circuit of the body
87
flow of blood
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
diastole
relaxation of heart muscles
89
systole
contraction of heart muscles
90
cardiac output =
heart rate x stroke volume
91
arteries
carry blood away from heart, thick muscle layer, thick elastic layer, folded endothelium, high blood pressure and can stretch
92
arterioles
thick muscle layer, thinner elastic layer, controls blood flow to capillaries, lower blood pressure than arteries
93
veins
carry blood towards heart, thin muscle layer, thin wall, valves to prevent backflow, lower pressure
94
capillaries
one cell thick, narrow lumen, short diffusion distance
95
tissue fluid formation
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
lymphatic system
drains tissue fluid back to the heart, network of vessels around the body
97
cohesion-tension theory of transpiration
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
transpiration
water evaporates out of open stomata down water potential gradient
99
phloem
tissue that transports biomolecules made of sieve tubes
100

A level Biology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions