bio random Flashcards
(275 cards)
1
Q
active vs passive immunity
A
- active involves memory cells but passive doesnt
- active involves antibody production by plasma cells
- passive involves antibody introduced from external source
- active = long term as antibody is produced in response to antigen
- passive = short term as antibody broken down
- active takes time to develop, passive fast acting
2
Q
viral replication
A
reverse transcriptase converts RNA to DNA
DNA joined to host cells DNA and DNA used to transcribe HIV mRNA at the ribosome to be translated into viral proteins
assembly of new virus
budding off from membrane - cell lysis
3
Q
antibiotics dont treat viruses
A
antibiotics stop metabolism but viruses are acellular and have no metabolism
+ viruses are found in cells that antibiotics cant reach
4
Q
role of T cells (general summary)
A
Th cells bind to antigen presenting macrophage stimulating Th cell to divide by mitosis into memory or Tc cells - cell mediated response
Tc releases perforin (holes) in infected cells
Th produce cytokines activating B cells to rapidly divide by mitosis into plasma/memory b cells - humoral
5
Q
potometers arent an accurate measure of transpiration
A
water used in photosynthesis, respiration, supporting turgidity (or leaking apparatus)
6
Q
epistasis
A
when one gene controls/inhibits expression of another
7
Q
prolonged stimulation of cone cells
A
staring at a colour -> prolonged stimulation leading to cone fatigue and afterimages of another colour for minutes or more
8
Q
why do cone cells have high visual acuity
A
each cone cell is connected to a seperate bipolar neurone so no retinal convergence/summation of impulse (when multiple photoreceptors are connected to a single ganglian/bipolar cell
9
Q
why does it take time to adjust to darkness
A
rhodopsin is bleached/broken down by light so need time to resynthesise
10
Q
role of a reflex arc
A
rapid
protect against damage to body tissue
do not have to be learnt
aids escape from predators
enables homeostatic control
11
Q
gene machine
A
creates DNA fragments by computerised methods
scientists identify amino acid sequence of protein of interest and mRNA and DNA sequence from that
DNA sequence entered into computer which passes biosafety and security checks
computer creates small sections of overlapping DNA strands - oligonucleotides
joined together to form DNA sequence of entire gene
12
Q
cotransport mechanism
A
uses ATP hydrolysis
eg: Na+ and proton bind to protein changing shape to move Na+/proton across membrane
13
Q
loop of henle in dry conditions
A
thicker medulla = longer loop of henle
sodium ion gradient maintained for longer so more water reabsorbed from loop of henle/ collecting duct by osmosis
14
Q
founder effect
A
new population established by a small group of individuals from a larger population
reduced genetic diversity + more inbreeding
15
Q
treatment eval things to mention
A
over lap in SD - significance
stats test
reduction or elimination (treats or reduces virus conc only?)
investigated in humans?
sample size - representative?
side effects / long term effects
in vitro (cells) or in vivo (organism)
16
Q
diabetics glucose
A
high blood glucose concentrations mean less glucose reabsorbed at proximal convulated tubule and carrier/cotransporters working at maximum rate
17
Q
index of diversity > species diversity
A
measures number of individuals and number of species
some species only present in small numbers
18
Q
gas exchange adaptations
A
many alveoli = provide a large surface area
many capillaries = large SA so fast diffusion
alveoli/capillary epithelium thin = short diffusion distance
flattened squamous epithelial cells = short diffusion distance so fast diffusion
ventilation/circulation maintains diffusion/conc gradient
19
Q
ATP in respiration
A
aerobic = 36 ATP
2 from krebs
2 from glycolysis
32 from oxidative phospho
anaerobic = 2 ATP
2 from glycolysis
2 from fermentation
20
Q
why does anaerobic resp lead to fatigue
A
lactate lowers PH
so inhibits enzymes causing fatigue
lactate oxidised as energy source for ATP to restore PH levels
21
Q
direct vs indirect elisa
A
direct = testing for antigen
antigen - antibody with enzyme - substrate
indirect = testing for antibody
antigen binds then antibody????
22
Q
where does oxidative phospho occur
A
cristaE
23
Q
p + q = 1 vs p2 + 2pq+ q2
A
p + q = 1 for allele frequency
p2 + 2pq+ q2 for number of individuals
24
Q
insect adaptations
A
trachioles = thin wall so short diffusion distance
highly branched = large SA + short diffusion distance
tracheae provide tubes full of air so fast diffusion
fluid in ends of trachiole moves out into tissue during exercise so larger SA forgas exchange / faster diffusion to gas exchange surface
body can be moved by muscles to move air so maintains diffusion conc gradient
25
asthma
smooth muscle of bronchioles contract secreting mucus
airway constricts so air flow reduces ans less oxygen in blood
26
emphysema (smoking)
smoke inflames alveoli attracting phagocytes breaking down elastin so alveoli cant expel air so trapped air destroys alveoli lowering SA
27
fibrosis
formation of scar tissue so thicker and less elastic so slow diffusion
lungs expand less and tidal volume decreases
28
tuberculosis
TB bacteria stimulates immune response killing bacteria but damaged exchange surface so tidal volume decreases
29
ways to make DNA fragments
restriction endonucleases cut at restriction sites complimentary to base sequence and always palindromic near desired gene
converting mRNA of desired gene to cDNA using reverse transcriptase
double stranded cDNA synthesised using dna polymerase
gene machine - gene sequence determined by primary protein structure
30
hydrolysis of peptide bonds
endopeptidases break polypeptides into smaller peptide chains
exopeptidases remove terminal amino acids
dipeptidases hydrolyse dipeptides into amino acids
31
community
all populations of different species in the same area at the same time
32
ecosystem
a community and the non living (abiotic) components of an environment
33
how to find mean capillary num from field of view
measure diameter of field of view and calculate area
use micrometer slide and and eyepiece graticule
count number of capillaries in large number of fields of view and calc mean
select fields of view randomly
34
metabolic rates influence on nervous control of heart rate
lower metabolism so less CO2 in blood detected by chemoreceptors in carotid artery
fewer impulses to medulla oblongata so more impulses along parasympathetic pathway/ fewer on sympathetic to SAN
35
maintaining resting potential
membrane more permeable to K+ and less permeable to Na+
Na+ actively transported out and potassium in
36
cotransport mechanism of absorption of glucose (textbook)
lumen -> epithelial cell -> blood
Na+ actively transported out of epithelial cells by Na+ /K+ ion pump
maintains a higher concentration of Na+ in lumen than epithelial cells
Na+ diffuses into epithelial cells down concentration gradient via cotransporter so brings glucose/amino acids from lumen to epithelial cells
glucose facilitatedly diffuses into blood
37
binary fission
Binary fission;
2. Replication of (circular) DNA;
3. Division of cytoplasm to produce 2 daughter
cells;
4. Each with single copy of (circular) DNA;
38
how the structure of DNA is related to its function
double stranded / sugar phosphate backbone so stable/strong/protects bases
long/large molecule so stores lots of genetic information
helix/coiled so compact
base sequence codes for amino acid/proteins
double stranded so replication can occur semi conservatively
weak hydrogen bonds between base pairs for replication
or many hydrogen bonds so stable/strong
39
why is it important to identify specific strain of bacteria affecting patient in an outbreak
To see if strain is resistant to any antibiotics;
So can prescribe effective/right antibiotic;
OR
To see whether (any) vaccine works against this strain/ see which vaccine to use/ to produce specific vaccine;
(So) can vaccinate potential contacts/to stop spread;
OR
Can test other people to see if they have the same strain/ to trace where people caught TB;
Allowing control of spread of disease/vaccinate/treat contacts (of people with same strain) before they get TB;
40
role of RER in formation of chylomicrons
proteins are synthesised by RER via involvement of ribosomes
protein transport (inside RER);
vesicle formation to golgi
41
how are epithelial cells adapted to their function in the small intestine
Microvilli provide a large / increased surface area;
2. Many mitochondria produce ATP / release or provide energy (for active transport);
3. Carrier proteins for active transport;
4. Channel / carrier proteins for facilitated diffusion;
5. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose;
6. Membrane-bound enzymes digest disaccharides / produce glucose;
42
techniques to determine if bacteria/virus are closely related
The polymerase chain reaction
Genetic/DNA fingerprinting
(Gel) electrophoresis
DNA/genome sequencing (compare base sequence/amino acid etc)
43
PCR
1 DNA heated to 90°C;
2 strands separate;
3 cooled to 60°C
4 primers bind;
5 nucleotides attach;
6 by complementary base pairing;
7 temperature 70°C;
8 DNA polymerase joins nucleotides together;
9 cycle repeated;
44
what happens when muscles contract
When contracted:
Thick & thin filaments/myosin & actin overlap more;
Interaction between myosin heads & actin / cross-links form;
Movement of myosin head;
Thin filaments / actin moved along thick filaments / myosin;
Movement of thin filaments / actin pulls Z-lines closer together;
45
control of HR in cardiac cycle
SAN initiates heartbeat / acts as a pacemaker / myogenic;
(SAN) sends wave of electrical activity / across atria causing atrial contraction;
AVN delays electrical impulses
(Allowing) atria to empty before ventricles contract
non conductive layer prevents premature contraction of ventricles
(AVN) sends wave of electrical impulses down Bundle of His / Purkyne fibres;
(Causing) ventricles to contract (from base up) / ventricular systole;
46
mark release recapture equation
Capture/collect/sample, mark with non invasive marker and release;
Leave time for mosquitoes to disperse
before second sampling/collection;
(Population =) number in first sample × number
in second sample divided by number of marked
in second sample
47
sympatric
Occurs in the same
habitat/environment/population;
2. Mutation/s cause different flowering times;
3. Reproductive separation/isolation
OR
No gene flow
OR
Gene pools remain separate;
4. Different allele/s passed on/selected
OR
Change in frequency of allele/s;
5. Disruptive (natural) selection;
6. Eventually different species cannot (inter)breed
to produce fertile offspring;
48
graph questions
say increase on variable instead of greater of variable
eg: greater shoot biomass from graph = increase in plant growth for that variable
lower biomass = reduced growth
49
phenotype
expression of a gene as an observable characteristic due to interactions with the environment (?)
50
hardy weinberg -dominance
if an allele is dominant then it can be 2Pq and q2
ALWAYS CHECK IF ITS DOMINANT
51
why is DNA hydrolysed before PCR
removes any unwanted DNA present that isnt the specific target sequence of interest
as unwanted DNA would be replicated in PCR
52
ratios
always give ratio as something : 1
eg:
A:B
0.05:0.03
5:3
1.6:1 (correct)
52
percentage change
final - initial
---------------- x100
initial
53
why would natural selection not have reduced the frequency of an unwanted mutation?
could be because symptoms develop late so reproduction has already occured and frequency of allele has increased
54
why would there be a high frequency of an allele in an isolated population?
(genetic drift)
allele inherited from a common ancestor - founder effect
isolated population so inbreeding lowering the genetic diversity
55
why would the age a mutation is expressed at vary?
methylation of DNA and acetylation of histones affecting transcription of the gene
epigenetics/environment eg: diet/exercise/toxins
56
why would a dna probe of a mutated triplet not be suitable for detection of mutation?
mutation GCc -> GCa
GCA common triplet in other places in DNA
produces false positives as it would bind to other regions with same triplet sequence
57
why is modification of a bacterial possible for genetic engineering in humans
genetic code is universal so the same triplets code for the same amino acid
transcription and translation mechanism are universal
58
evaluate use of genetically engineered crop
(potential) pros:
save millions of lives
rigorous testing - no allergies
can be grown without new equipment for farmer
cheaper than supplements
cons:
public dissprove GM products
colour unappetising so unlikely to eat
genetically modified seeds might cross pollinate with other species affecting ecosystem
may have long term side effects
59
why are viruses used in recombinant tech
inject genetic material directly into cell
efficient at infecting human cells
replicate (?)
reverse transcriptase uses mRNA acting as a template to produce cDNA by adding nucleotides
60
gene machine and its adavantages
DNA sequence generated by computer
mRNA sequence of protein of interest identified
DNA sequence entered and used to make fragments
passes biosafety and security checks - DNA being made is ethical
gene machine assembles short strands of overlapping DNA - oligonucleotides and joins them together
ADV:
DNA template not needed - made from scratch
quick process - not reliant on enzyme catalysed reactions
DNA free of introns so can be transcribed/translated by prokaryotes
any sequence of nucleotides can be produced
high accuracy
61
positive feedback
stimulus produces a responsethat causes the factor to deviate further than normal range
62
maintaining resting potential
Sodium potassium pump allows 3Na+ out and 2K+ in through the membrane into neurone via active transport
Overall lost 1 charge so inside of membrane more negative than outside and electrochemical gradient is established
Potassium link channel open and K+ out of membrane
But voltage gated sodium ion channels close and Na+ stays in membrane
63
insulin and glucagon action
both bind to receptors on target cells
64
role of SiRNA on gene
single stranded RNA complimentary to gene mRNA so binds and reduces translation
reducing photosynthesis
65
synaptic transmission
before calcium ion influx always say Ca2+ CHANNELS OPEN
66
why might heterozygotes not be affected by gene mutation
dependent on whether gene is dominant or recessive, needs two copies of mutated gene (same in diploid organisms)
67
fast and slow muscle fibres
fast twitch muscles rely on anaerobic respiration for ATP and slow muscle fibres rely on aerobic for ATP
fast muscles have large concentrations of phosphocreatine and slow has small concentrations of phosphocreatine
fast muscles have fewer mitochondria and slow have more
fast muscles fatigue faster than slow
more lactate produced in fast muscle than slow
68
why would osmoregulation not prevent dehydration
only prevents further decrease in blood water potential and doesnt increase blood wp
further intake of water needed to prevent dehydration
69
why do diabetics have large volume or urine
high concentrations of glucose in glomerular filtrate
carrier proteins all occupied at max rate in PCT
glucose in filtrate lowers wp
less water reabsorbed into blood by osmosis ?
70
how are the cells of the proximal convulated tubule adapted for reabsorption
microvilli provide large surface area;
carrier proteins (in membrane) for active transport;
channel proteins for facilitated diffusion;
specific carriers for specific molecules / sodium pumps;
(many) mitochondria for active transport;
71
carrier vs channel proteins
carrier = active transport and undergoes conformational changes
channel = facilitated diffusion and
has pores allowing ions through
72
semi conservative replication of parent with heavy nitrogen
band at the bottom as both strands have heavy nitrogen
generation 1 = heavy + light nitrogen
medium band as one strand is 14 and one is 15
generation 2 = one medium and one light further up the tube
so for replication of generation 2
both light and heavy strands must act as a template for new DNA molecules
73
prokaryote vs eukaryote DNA
p = circular E= linear
P = no histones E = histones
P = cytoplasm E = nucleus
P = shorter E = longer
P = no introns E = introns
74
glycosidic bonds in cellulose vs glycogen
glycogen = 1-4 and 1-6 but cellulose only 1-4
75
how does mitosis produce geneitcally identical cells
DNA replicated in s phase
by complementary base-pairing;
forming two identical sister chromatids;
Each sister chromatid moves to opposite poles of cell
76
why do we need thin sections of tissue for optical microscope
to allow light through and for a single layer of cells to be viewed
77
rna polymerase vs dna polymerase
rna polymerase used in transcription and dna polymerase used in dna replication
78
DNA synthesis prime
Dna synthesised 5 prime to 3 prime so DNA polymerase only binds to 3 prime end
79
why would a cellular response be more effective at treating viral infection than humoral
viruses invade cells so are protected from antibodies
T cells bind to antigen presenting cells producing tc cells to kill infected cells?
80
membrane fluidity definition
ability of proteins/lipids to diffuse laterally in the plane of the membrane
81
cholesterols role in the membrane
high cholesterol = reduced membrane fluidity as cholesterol fits between fatty acids and phospholipids increasing packing of the membrane and restricting movement of membrane components
82
specific heat capacity vs latent heat of vaporisation
Specific heat capacity measures the energy needed to change the temperature of a substance, while latent heat of vaporization measures the energy absorbed by water needed to change the state of a substance from liquid to gas without changing its temperature
SHC changes temp LHV doesnt
83
plasmolysed palisade cells
cytoplasm shrinks and membrane detaches from the wall
in a hypertonic solution causing water to leave by osmosis
(dirupts rigidity by loss of turgor pressure)
84
method to determine water potential of a plant
place plant tissue in different concentrations of solution -dilution series
record change in mass
plot calibration curve
record the solute concentration where there is no change in mass of plant tissue
this solute concentration has the same WP As plant tissue
85
correlation coefficient
-1 -> +1
-1 = negative correlation
+1 = positive correlation
0.3+ = weak positive correlation coefficient
-0.3 = weak negative
86
refractory period
period after an action potential where sodium potassium pump is closed and the movement of sodium ions into the membrane is prevented so an additional action potential is prevented and ensures impulses are discrete
87
max frequency of impulses per second equation
1 / duration of refractory period
88
action potential graph
A - resting potential of -70
B - depolarisation - voltage-gated sodium channels open, causing sodium ions to enter the cell
resting potential becomes more positive;
C: Influx of sodium ions into cell/sodium ions entering the cell triggers the action potential
+40 mV is the peak of the action potential, voltage-gated sodium channels close, voltage-gated potassium channels open
D - repolarisation - efflux of potassium ions out of the cell (making it more negative) as potassium ion channels are still open
E - hyperpolarisation - overshoot of potassium ions leaving the cell (making the cell even more negative
F - is the threshold value (of membrane potential), around -55
89
chromatography
Mobile phase/solvent moves through the stationary phase/filter paper;
Different pigments have different affinities and solubilities in the mobile phase/solvent;
Pigments that spend longer in the mobile phaseare more soluble in the solvent and travel further up the stationary phase/filter paper
Smaller molecules tend to be more soluble in mobile phase/solvent
90
inversion vs translocation
Inversion reverses a base sequence;
Translocation moves a base sequence to another location / chromosome.
91
stem cells
Undifferentiated/unspecialised;
(So) can differentiate/specialise into specific heart cell/cell types;
Can self-replicate/divide by mitosis.
92
stem cell evaluation
Embryonic stem cell harvesting has ethical issues
Possibility for (embryonic) stem cells to be rejected;
Low numbers of (adult) stem cell donors;
Risk of (viral) infections via stem cells;
Risk of accumulation of mutations / cancer in stem cells;
Obtaining the cell culture can be challenging;
A costly process / great financial cost;
Using stem cells means more can be learned about the process of development for other diseases;
New established protocols ensure safety of embryo and others throughout process;
The procedure to plant them is relatively non-invasive;
Stem cells are already used to treat many diseases/proof that it works;
If a patient's own stem cells are used, lower chance of rejection;
Stem cells can be collected from umbilical cord / amniotic fluid (so less ethical issues).
93
methylation vs acetylation
Methylation is of DNA AND acetylation is of histones;
increased methylation (of DNA) but decreased acetylation (of histones) inhibits transcription
Methylation causes DNA to be more tightly wound AND acetylation causes DNA to be less tightly wound
94
lacteals
chylomicrons enter lacteals which are SPECIALISED LYMPHATIC VESSELS THAT CARRY chlomicrons into LYMPHATIC SYSTEM and then into BLOOD
95
homologous chromosomes
(Two chromosomes that) carry the same
genes
same loci
96
naming organisms taxonomically
Genus species
Genus capital
species lower case
97
why would affecting habitat decrease index of diversity
fewer food SOURCES
fewer habitats/niches
removes species/types of insects
98
sources of stem cells
stem cells are undifferentiated and unspecialised
umbilical cord
bone marrow
converting somatic cells to pluripotent cells
99
embryonic stem cell ethics
embryo is destryoyed/killed/discarded
can use excess embryos from assisted fertilisation OR from IVF
debate about when life begins
embryo cannot give consent
100
mitosis stages
(During prophase)
1. Chromosomes coil,condense,become visible;
and appear as (two sister) chromatids joined at the centromere;
(During metaphase)
3. Chromosomes line up on the equator of the cell attached to spindle fibres By their centromere;
(During anaphase)
6. The centromere divides;
7. (Sister) chromatids / chromosomes are pulled to opposite poles
(During telophase)
8. chromosomes uncoil.
101
template strands
both strands act as a template in DNA replication but only one acts as a template in protein synthesis/transcription
new DNA molecules contain one old strand and one new strand - semi conservative
102
role of centromere
Holds chromatids together;
Attaches (chromatids) to spindle;
Allows chromatids to be separated / move to (opposite) poles
103
why is PH meter > indicator
greater accuracy and precision due to numerical data
colour change not subjective
103
Describe the role of the rough endoplasmic reticulum in the formation of chylomicrons?
Proteins are synthesised by ribosomes on the surface of the RER
vesicles formed by the RER are then used to transport the chylomicron to the golgi and leaves epithelial cell by exocytosis
103
why would a RBC need more cholesterol in its membranr
more cholesterol = more stable membrane so membrane less flexible
RBC free in blood so not supported by other cells to maintain shape
unlike cells lining ileum
104
how does heating beetroot release pigment
1. Damage to (cell surface) membrane;
2. (membrane) proteins denature;
3. Increased fluidity / damage to the phospholipid bilayer;
105
mark release recapture equation
(Population =) number in first sample × number in second sample divided by number of marked lizards recaptured in second sample
106
acetylation vs methylation effect on transcription
acetylation increases transcription and methylation decreases
107
how can drugs reverse epigenetic changes
(drugs may) increase methylation of oncogenes inhibiting transcription
(drugs may) decrease methylation of tumour suppressor genes stimulate transcription
decreased acetylation of histones inhibits transcription (of oncogenes)
OR
increased acetylation of histones stimulates transcription (of tumour suppressor genes)
108
starch vs cellulose
Starch formed from α-glucose but cellulose
formed from β-glucose;
Position of hydrogen and hydroxyl groups on carbon atom 1 inverted;
109
why does a baby test positive for HIV but not have it
Children receive (HIV) antibodies from their
mothers/maternal antibodies;
2. (So) solution will always
test positive (before 18 months);
110
purpose of control well in elisa
(Shows that)
1. Only the enzyme/nothing else is causing a
colour change;
2. Washing is effective/all unbound antibody is
washed away;
111
percentage of bases eg
DNA strand Percentage of each base
A C G T
Strand 1 (16) 34 21 29
Strand 2 29 (21) (34) 16
% are equal to opposite strand
A1 with T2 etc
112
phloem
1. In source/leaf sugars actively transported into
phloem;
2. By companion cells;
3. Lowers water potential of sieve cell/tube and
water enters by osmosis;
4. Increase in pressure causes mass movement
(towards sink/root);
5. Sugars used/converted in root for respiration for
storage;
113
definitions of
gene
allele
locus
gene -length of DNA coding for a polypeptide
allele - different forms of a gene
locus - position of a gene on a chromosome
114
homologous chromosome
homologous chromosome - a pair of chromosomes (maternal paternal) that have the same gene loci
Same shape/size;
Carry the same genes;
Found at the same loci
but carry different alleles
115
possible chromosome combinations after meiosis
after meiosis without crossing over:
2^n
4 homologous chromosomes = 16
after random fertilisation:
(2^n)2
4 homologous chromosomes = 256
116
genetic diversity definition
The number of different alleles of genes in a population
117
muscle contraction
Calcium ions diffuse into myofibrils from
(sarcoplasmic) reticulum;
2. (Calcium ions) cause movement of tropomyosin
(on actin);
3. (This movement causes) exposure of the
binding sites on the actin;
4. Myosin heads attach to binding sites on actin;
5. Hydrolysis of ATP (on myosin heads) causes
myosin heads to bend;
6. (Bending) pulling actin molecules;
7. Attachment of a new ATP molecule to each myosin head causes myosin heads to detach
(from actin sites); MEMORISE
118
ATP adaptations
1.Releases relatively small amount of energy
2. Releases energy instantaneously;
3. Phosphorylates other compounds, making them more reactive;
4. Can be rapidly re-synthesised;
5. Is not lost from/does not leave cells;
119
gene linking q
1. GN and gn linked;
2. GgNn individual produces mainly GN and gn
gametes;
3. Crossing over produces some/few Gn and gN
gametes;
4. So few(er) Ggnn and ggNn individuals;
120
why is it good to use island populations
Can record all individuals on (small) islands;
2. (So) no / less sampling error;
3. (Maybe) different rates of mutation / different selection pressures / different environmental conditions;
4. Inbreeding / breeding with close relatives (more likely);
5. (Little) gene flow / (more chance of) genetic drift;
Accept reference to either of these ideas for this point
121
why would phenotype not be same as expected
(a) 1. Small sample size;
2. Fusion/fertilisation of gametes is random;
3. Linked Genes;
Accept crossing over / sex linkage
4. Epistasis;
5. Lethal genotypes;
122
scatter graphs
1. Scatter graph;
2. Fat on x axis and death rate on y axis;
3. (Because) looking at relationship between two
discrete/independent variables;
123
questions on why a characteristic cant be because of a single gene thats dominant or recessive
mention what recessive would produce and why that doesnt align with results observed
124
if a gene was on the x chromosome
all daughters would be affected as daughters always inherit their fathers x chromosome (sons would be unaffected)
125
recessive
Only expressed / shown (in the phenotype) when homozygous
126
dominant
always expressed in the phenotype
127
Male fruit flies are more likely than female fruit flies to show a phenotype produced by a recessive allele carried on the X chromosome. Explain why.
males have one x chromosome SO ONE ALLELE
females need 2 recessive alleles
128
Explain why the scientists used the same restriction endonuclease enzymes on each DNA sample.
Cut DNA at same base sequence
so get fragments with required gene
129
codominant
both alleles are expressed in the phenotype
130
negative feedback
where a change triggers a response which reduces the effect of a change
a mechanism that reverses a change in a system to maintain a stable internal environment
131
why would a recessive allele with harmful effects increase in frequency more than a dominant harmful allele
recessive alleles can be carried by individuals without showing effects - not always expressed
organism that are carriers more likely to reproduce
therefore recessive alleles are more likely to be passed on and dominant alleles less likely to be passed on;
132
pulmonary ventilation rate formula
tidal volume x breathing rate
Find the tidal volume for person A by calculating the difference between the high and low points of each breath
(the amount of air inhaled or exhaled during a normal breath)
Find the breathing rate for person A by counting the number of breaths in one minute
133
adaptations of alveolar epithelium
Many alveoli
(so) large surface area;
Walls of alveoli are one cell thick
(so) short diffusion pathway/distance;
Walls of alveoli have flattened cells
(so) short diffusion pathway/distance;
Alveoli are close to capillaries
(so) short diffusion pathway/distance;
Alveolar wall is permeable to gases
(so) ventilation maintains diffusion gradient;
. Alveolar wall is lined with fluid
(so) gases are absorbed.
134
“Push down hard on the cover slip, but do not push the cover slip
sideways.”
push hard to spread and squash cells - 1 cell thick
not push sideways to avoid rolling cells together and breaking chromosomes
135
how do you know this cell is in anaphase
chromosomes are pulled to opposite poles of the cell at the ends of spindles
V-SHAPE shows that sister chromatids have been pulled apart
136
when comparing photosynthesis and respiration in graph between day and night mention
photosynthesis ONLY occurs in DAY and respiration only at NIGHT
137
cell fractionation
1. Ice-cold – stops enzyme activity to prevent digestion of organelles
2. Buffered – Maintains pH so that enzymes / proteins are not denatured;
3. Same water potential – Prevents osmosis so no lysis / shrinkage of organelles
138
vector
transfers/carries genes from one organism to another
139
cardiac cycle
blood enters from vena cava in right side of the heart
ventricular pressure lower than atrial pressure so AV valves open
blood passively fills ventricle
pressure in the ventricle increases
blood fills atria
both atria contract (systole) and forces blood into ventricles increasing ventricular pressure
pressure in ventricle exceeds atria so AV valves close
pressure in ventricles is lower than arteries so SL valves open and ventricular systole occurs
140
chlorophyll wavelengths absorbed
every colour except green as chlorophyll is green
141
species
group of organisms with similar features that can interbreed to produce fertile offspring
142
hierarchy
smaller groups are placed within larger groups, with no overlap between groups
+
larger groups containing smaller groups
143
explain how a phylogenetic system differs from a simple hierarchy
(phylogenetic) based on evolutionary history;
shows points of divergence
e.g. reptiles and birds separated after mammals
and birds more closely related than mammals;
(hierarchical) based on shared characteristics (seen today);
144
kingdoms
prokaryotes, Protoctista (unicellular eukaryotes), Fungi, Plantae (plants), and Animalia (animals)
145
role of amino acids in phylogenetic classification
those with similar sequences put in same groups + are more closely related;
the greater difference in amino acid sequence the longer ago the groups
diverged
146
evidence to classify different animals as different species
fossil record
evolutionary history / phylogeny
biochemical differences e.g. DNA / proteins
homologous features (characteristics in different species that share a common evolutionary origin, meaning they were inherited from a common ancestor)
karyotype / number and form of chromosomes;
147
population
all the individuals of the same species living in a specific area at a particular time, who can potentially interbreed
148
isolating mechanisms of sympatric speciation
temporal − different breeding seasons / feeding times /
ecological / behavioural − different courtship displays / different niches / habitats / feeding areas /
mechanical − mismatch of reproductive parts
gamete incompatibility − sperm killed in female’s reproductive tract /
hybrid inviability / hybrid infertility;
149
enzyme activity graph that plateaus with increasing concentration - limiting factors
as graph increases initially, substrate concentration is limiting because as substrate concentration increases so does rate
at plateau, enzyme concentration is limiting as enzyme active sites are all occupied
150
polymer
made up of many identical monomers
151
aerobic respirometer - why was it left for 10 minutes
1. Equilibrium reached.
2. Allow for pressure change in apparatus
3. Allow respiration rate of seeds to stabilise.
152
why is lactose free milk sweeter
lactose hydrolysed to GALACTOSE AND GLUCOSE
SO more sugars so sweeter than lactose
153
amylase vs maltase
amylase found in pancreas and produces maltose
maltase found in EPITHELIUM of small intestine and produces glucose
154
structure and function of starch
1. Coiled / helical
2. (So) compact
3. Insoluble;
4. so does not affect water potential;
5. Large molecule / long chain;
6. (So) does not leave cell / contains large number of glucose units;
7. Branched chains;
8. (So) easy to remove glucose;
155
sieve cell adaptations
no organelles so EASIER FLOW resisting pressure in phloem
156
golgi vs RER
golgi = site of protein modification - modifies and packages protein
RER/ribosome = makes a polypeptide - protein synthesis
157
how does increase in harmful lipids affect risk of developing coronary heart disease
more harmful lipids increase risk of ATHEROMA (a build-up of fatty deposits, within the walls of arteries)
leads to blockage of coronary artery
atheroma is the plaque buildup, and a myocardial infarction is the damage caused by a blockage resulting from that plaque oxygen cant reach heart
158
induced fit model
the enzyme attempts to mould itself around the substrate to form an enzyme-substrate complex
This puts stress on the bonds in the substrate
deforms (?) active site
activation energy for the reaction is lower than what it would be normally, and so the reaction has been catalysed
The reaction occurs, and then the substrate leaves the active site. The enzyme returns to its normal shape, too.
159
mRNA vs tRNA
1. mRNA longer
2. mRNA is a straight molecule but tRNA clover-leaf shaped molecule;
3. mRNA contains no paired bases / hydrogen bonds but tRNA has some paired bases / hydrogen bonds.
160
role of stop codons
3 bases on mRNA coding for an amino acid
stop codons Stop translation and Result in detachment of polypeptide chain from ribosome.
161
Suggest one advantage of showing the genetic code as base sequences on mRNA, rather than triplets on DNA
(Because) ribosomes assemble polypeptides using mRNA code
DNA has two strands each with a different (complementary) base sequence;
162
assumptions of mark release recapture
marking doesn't affect survival
no immigration/emigration
no losses to predation
birth rate = death rate
all belong to one population
163
how to remove all water in a sample
heat and weigh at intervals until constant mass is obtained
164
why is dry mass an appropriate measure of growth
water content varies between plants
dry mass determines increase in organic material
165
how to make a temporary mount of a piece of plant tissue to observe starch grains
● Add a drop of water to the slide
● Remove a thin section of tissue and place it onto the slide (flat as possible)
● Add 1 drop of iodine dissolved in potassium iodide to stain the sample if its plant tissue
● Lower a coverslip on top using a mounting needle
166
where does light dependent and independent occur
dependent = thyakoid membrane
independent = stroma
167
Calvin cycle
carbon dioxide combines with RuBP
to produce 2 molecules of GP
GP is reduced to TP
using reduced NADP
using energy from ATP
TP is converted into glucose/RuBP
168
how does a carrier protein work
● Substance binds to a carrier protein
● ATP binds to carrier protein
● ATP is hydrolysed into ADP and Pi and this releases energy
● This causes the carrier protein’s tertiary structure to change (undergoes a conformational change)
● The substance is released on the other side of the membrane
169
glycolipid vs glycoprotein
Glycoprotein (carbohydrate chain
attached to protein)
Important in cell recognition and cell signaling
So that the immune system can tell the difference between
body cells & e.g. invading bacteria
Glycolipid (carbohydrate chain
attached to phospholipid)
For cell recognition and to provide energy in respiration if needed
170
active transport vs facilitated diffusion
Facilitated diffusion involves channel or carrier proteins whereas active transport only involves carrier proteins
● Facilitated diffusion does not use ATP whereas active transport uses ATP
● Facilitated diffusion takes place down a conc gradient whereas active transport is against
171
Vegetables are made of different types of tissue, in an experiment where do you take a cutting from and why?
● When taking a cutting you must ensure it’s through one tissue only in order for it to be a fair test. As different tissues may affect water potential differently.
172
When you need to find the concentration of the solution that has the SAME water potential as the vegetable/fruit you are investigating you:
a. Plot data on a graph (give titles of the x and y axis)
b. Draw a line of best fit
c. From the graph either: (depending on question)
i. Find when the ratio is 1 (there is no change in mass/length)
ii. extrapolate the line of best fit and read off
iii. Find where it crosses the x axis
173
cotransport for absoption
. Na+/K+
pump moves 3 Na+
ions out of the cell (into the
blood) and 2K+
ions into the cell by active transport. This
uses ATP.
2. This creates a lower concentration of Na+
in the
epithelial cell than in the lumen of the intestine
3. Na+
ions move into the epithelial cell by facilitated
diffusion. They travel through a symport protein and
bring glucose with them. This is called co-transport.
4. The glucose is moving into the cell cell against its
concentration gradient
5. The glucose concentration in the epithelial cell increases
6. Glucose moves into the blood from the epithelial cell
through a carrier protein
174
adaptations of epithelial cells
Adaptations of the epithelial cell
● Lots of mitochondria Release energy in the form of ATP ATP is needed for active transport
● Lots of enzymes attached to their membrane Breaks down maltose into glucose
● Microvilli provide a large surface area for maximum absorption
● Carrier proteins for active transport
● Channel/Carrier proteins for facilitated diffusion
● Co-transport (or symport protein for the transport) of sodium ions and glucose or for sodium ions and amino acids
175
golgi
Modifies proteins (e.g. by adding carbohydrate groups
to form a glycoprotein or lipid groups to make a
lipoprotein)
Stores proteins
Packages proteins into vesicles
Transport vesicles to cell surface
176
chloroplasts
Chlorophyll absorb light for photosynthesis to produce carbohydrates
Has a double membrane. Inside there are thylakoid
membranes which can form a stack called a granum
The grana are linked by lamellae.
Contain starch grains
177
binary fission of bacteria
Binary Fission
● Circular DNA and plasmids replicate
● Circular DNA attaches to opposite ends of cell membrane
● Bacterial cell grows
● The cell membrane pinches inwards in the middle of the cell
● cytoplasm divides to form two daughter cells (each has a variable number of plasmids)
● A cell wall is formed around each daughter cell.
178
cellular response
T-lymphocytes will only respond to antigens that are attached to a body cell rather than
to antigens within the body’s fluid.
● Phagocyte engulfs pathogen and presents the antigens on its cell surface membrane
●Th with specific shape receptors complementary to the specific antigen bind to antigens presenting cell
The T-helper cells become activated.
● T-helper cells secrete chemicals which activate other T-cells which have the same receptors
● T helper cells divide by mitosis.
● T-helper cells:
i. Activate Cytotoxic T-cells - secrete perforin making membrane more permeable
which kills the infected cell
The holes also allow toxins to get in, which will definitely kill the cell and everything in it
ii. Become T-memory cells - Enable rapid response to future infections by the same pathogen
b. Activate B-cells
c. Stimulate more phagocytosis by phagocytes
179
humoral response
● specific B-cell with receptors complimentary to antigens engulfs and presents the antigens on its own cell surface membrane
● The receptor of the activated T-helper cell binds to the complementary antigen presented on the cell
surface membrane of the SPECIFIC B-cell
● This activates B cell to divide by mitosis (clonal selection) forming
a. B plasma cells - Produce antibodies - resulting in the pathogens being killed by agglutination.
b. B memory cells - remain in the blood so if the pathogen re-invades, these cells divide by
mitosis to make B plasma cells
secondary response is much faster
180
why is secondary response faster than primary
● There are already lots of B-memory cells in the blood
● The B-memory cells divide by mitosis to make plasma cells (without needing to be activated by TH cells)
● So MORE antibodies are produced MORE QUICKLY
181
vaccination
1. A vaccine is made from dead or weakened bacteria or antigens from them.
2. B cells with complementary receptors bind to the antigen
3. Specific T helper cells, activate these B cells.
4. B cells divide by mitosis to produce B-plasma cells.
5. The B plasma cells release antibodies, which are complementary to the bacterial antigens
6. Some B plasma cells become B memory cells
7. If the person is exposed again to the antigen or pathogen, the B memory cells become active and
divide by mitosis to produce B plasma cells , which produce more antibodies more quickly.
8. These antibodies lead to the destruction of the pathogen before symptoms appear
9. Vaccinating a large proportion of the population results in the herd immunity effect
182
(indirect) Elisa test
1. Antibodies complementary to the antigen are bound to the test plate
2. The sample containing antigens is added
3. The first antibody binds to the antigen
4. The plate is washed
5. Second antibody is added. This antibody is complementary to the first antibody AND has an enzyme
attached to it.
6. The second antibody attaches to the primary antibody.
7. The plate is washed again and any unbound antibody is removed
8. A substrate is added and it will change colour if the antigen is present
183
2 ways monoclonal antibodies stop cancer
E.g. 1 - direct
● The monoclonal antibody is complementary to a receptor protein on cancer cells
● When the monoclonal antibody is present it binds to the receptor so the growth factor doesn’t bind
and the cell doesn’t divide
E.g. 2 - indirect
● Use a monoclonal antibody that is complementary to an antigen on the cancer cell
● Bind a drug to the monoclonal antibody
● The monoclonal antibody will bind to the cancer cell and thus take the drug to the cell
which causes the cell to be killed
184
HIV replication
The HIV’s attachment proteins binds to the CD4 receptor proteins on the surface of the Th cell.
2. The virus’s lipid envelope fuses with the cell membrane of the Th cell.
3. The protein capsid breaks down
4. RNA and enzymes (e.g. reverse transcriptase) of the virus are now released into the cytoplasm of the
host cell.
5. Reverse transcriptase converts the viral RNA to DNA.
6. The viral DNA is incorporated into the cell’s DNA.
7. The viral DNA can now be transcribed into mRNA
8. Viral mRNA passes through the nuclear pore and attaches to a ribosome
9. Viral mRNA is translated into viral proteins that can be assembled into new HIV particles.
10. HIV particles bud off the Th cell (so that the Th cell’s membrane forms the lipid envelope of the
virus).
185
calibrating a stage micrometer
1) Find out the length of the stage micrometer? e.g. 10mm long = 10000μm
2) Find out how many divisions there are? e.g 100 divisions
3) Work out how big each division is in μm? e.g 10000/100 = 100μm = 1 division
4) Place the stage micrometer on the stage
5) Line up the divisions on the eyepiece graticule with those of the micrometer
6) Lets say 100 units on the eyepiece graticule fit 30 units of the stage micrometer
7) Now work out the length of one eyepiece graticule unit in μm
186
Why are electron microscopes used to view cells?
● They have a HIGH resolution
● because electrons have a shorter wavelength than light.
● This allows you to view internal structures/organelles of a cell.
(Remember using this – Light microscope = Low resolution = Longer wavelength)
187
magnification with scale bars
The scale bar represents the size of the image.
1) Measure the scale bar, using a ruler, in mm
2) Convert to micrometers - Use value as image size
3) The value written underneath the scale bar is actual size
4) Use these both to work out magnification
188
What usually happens to the rate of respiration (metabolic rate) as the surface area to volume ratio of a
mammal increases?
The rate of respiration increases to maintain body temperature.
189
cohesion tension theory
water evaporates from the leaves;
this reduces water potential in the mesophyll cells in the leaf
so water moves out of the xylem down a water potential gradient by osmosis
this creates tension (negative pressure) in the xylem
so water is pulled up the xylem as a continuous column
there is cohesion between water molecules due to H-bonding
the column doesn’t break because of adhesion between the water molecules and the xylem
walls
190
temp, LI affect on transpiration
temp, light intensity etc cause:
more water vapour to diffuse out of the leaves
So more tension in the xylem
So bigger transpirational pull
Higher rate of transpiration
(but decreases for humidity)
191
why do large organisms need a specialized exchange surface
Small organisms have large surface/volume ratio;
All cells are close to the gas exchange surface
So diffusion/exchange can take place over the whole body surface/skin;
But cells of larger organisms are a long way from gas exchange surface;
and because diffusion is a slow process;
gases (and other substances) must be supplied by transport system/circulatory system/blood;
192
plmonary ventilation formula
Pulmonary ventilation (dm 3 min -1 ) = breathing rate ( min -1 ) x tidal volume ( dm 3)
193
breathing rate formula
Breathing rate = 60 / time taken for one breath
194
absorption
1. Monoglycerides and fatty acids associate with bile salts to form micelles
2. Micelles transport fatty acid and glycerol to the lining of the ileum
3. Micelles release monoglycerides and fatty acids when they come into contact with epithelial
cells
4. Monoglycerides + fatty acids diffuse across the phospholipid bilayer and enter epithelial
cells
5. Enter the smooth endoplasmic reticulum and are converted back into triglycerides
6. A vesicle buds off the SER and moves to the golgi apparatus and fuses with it
7. Triglycerides associate with proteins to form lipoprotein before combining with cholesterol
to form a chylomicron (which are wrapped in a vesicle – from the golgi)
8. Chylomicrons leave epithelial cells by exocytosis in lacteals
9. Chylomicrons enter the lymphatic capillaries
10. The lymphatic vessels transport the chylomicrons to the blood
195
percentage saturate of haemoglobin with O2 formula
Percentage saturate of
haemoglobin with oxygen
= Oxygenated haemoglobin / maximumm saturation x 100
196
genome vs proteome
1. What is a ‘genome’ - All the DNA/ complete set of genes in a cell
2. What is a ‘proteome’ - The full range of different proteins that a cell is able to produce
197
mRNA vs tRNA
linear vs folded clover leafe shape
no hydrogen bonds vs H bonds
no amino acid binding site vs specific amino acid binding sites
length varies and more nucleotides vs same length
codons vs anticodons
198
translation process
1. mRNA leaves (nucleus) through nuclear pore
2. mRNA associates with a ribosome;
3. Ribosomes moves to find the start codon
4. tRNA brings a specific amino acid;
5. The anticodon on tRNA is complementary to the codon on mRNA
6. Ribosome moves along to the next codon on mRNA
7. Another tRNA binds to the 2 nd binding site in the ribosome (bringing another specific amino acid)
8. The process continues and a peptide bond forms between the amino acids in a condensation reaction
(using energy from ATP) to form a polypeptide chain
9. the tRNA detaches and collects another amino acid and the process continues
10. The sequence of codons determines the order of amino acids in the polypeptide
199
why do we flame a bottle neck
Passing the neck of the bottle through a flame produces a convection current away
from the opening, and helps to prevent contamination
This ensures that no microorganisms enter the mouth of the vessel to contaminate
the culture or the medium.
200
How do mycorrhizae facilitate the uptake of water and ions by plants?
They extend out from the roots of plants increasing the area from which ions and water
can be absorbed
They are able to grow into rocks in the soil and extract phosphates which the plants
would not be able to access otherwise
201
oxidative phosphorylation
Reduced NAD and reduced FAD release electrons and H+ ions
The electrons move down the electron transport chain (ETC) on the cristae of the
mitochondria, losing energy as they go
The energy is used to pump H+ ions from the matrix into the intermembrane space
This increases the concentration of H+ ions in the intermembrane space so they diffuse
through ATP synthase back into the matrix
This causes ADP + Pi to join together to form ATP
Oxygen is the terminal electron and H+ ion acceptor that picks up the electrons at the
end of the ETC
202
adrenaline vs glucagon action
same process but
glucagon action stimulates glycogenolysis AND gluconeogenesis
but
adrenaline action only stimulates glycogenolysis
203
second messenger model
glucagon / adrenaline are primary messengers
cyclic AMP is second messenger
204
generator potential
The change in potential difference across the cell-surface membrane of a receptor as a result of a
stimulus. Usually the depolarisation of the cell.
(If the generator potential is large enough it will reach threshold and result in an action potential in the
sensory neurone)
205
where are rods and cones found
rods =retina
cones = fovea
206
cholinergic synapse vs neuromuscular junction
Cholinergic Synapse vs Neuromuscular junction:
Neurone to neurone vs Neurone to muscle
An action potential occurs in the post-synaptic neurone vs There is no action potential in the
muscle/sarcolemma
The response in the post-synaptic neurone could be excitatory or inhibitory vs The response in the muscle is always excitatory
A cholinergic synapse always uses acetylcholine as the neurotransmitter vs Some neuromuscular junctions have different neurotransmitters
207
ultrafiltration
there is a HIGH hydrostatic pressure in the glomerular capillaries
it is higher hydrostatic pressure in the glomerular capillaries than in the Bowman’s
capusle
therefore small molecules are forced out of the capillaries
they pass through the fenestrations between the capillary endothelial cells
then they pass through the basement membrane which acts as a filter
then they pass through the gaps between the podocytes in the epithelium of the
Bowman’s capsule
The large molecules are too large to get through so they stay in the glomerular
capillaries
208
How do you explain evidence from a pedigree chart to show that an individual is
heterozygous?
1. The Individual has the dominant allele – because s/he has the dominant phenotype
2. The individual has the recessive allele because
EITHER: his/her parent has the recessive phenotype so the individual must have
inherited the recessive allele
OR: his/her offspring has the recessive phenotype so the individual must have
passed on the recessive allele
209
Assuming the gene is not sex linked: What is the evidence you look for in a pedigree
chart to confirm that an allele is recessive?
Find an example of an offspring with a different phenotype to BOTH parents. The
parents must therefore be heterozygous, so whatever phenotype they express must be
the dominant one. Use the answer structure below:
Name the two parents who have the same phenotype as each other (the dominant
phenotype)
Name the offspring who has a different phenotype (the recessive phenotype)
Then state: the parents must both be heterozygous because
o They have the dominant phenotype, so must have the dominant allele
o They pass on the recessive allele to their offspring
210
If the gene is sex linked what is the evidence you look for in a pedigree chart to confirm
that an allele is recessive?
Name the mother and her dominant phenotype
Name the offspring who has a different phenotype (the recessive phenotype)
The MOTHER must be heterozygous because
o She has the dominant phenotype, so must have the dominant allele
o She passes on the recessive allele to her offspring
(NOTE: The father cannot be heterozygous because he only has one copy of the X
chromosome – so only has one copy of the allele)
211
What evidence should you look for to show that a gene is NOT found on the X-
chromosome?
A dominant dad that has a recessive daughter
A recessive mum that has a dominant son
State the relevant parent + offspring with their phenotypes
If the gene was on the X chromosome, parent’s genotype would be …
So offspring # would inherit the X chromosome with the …………… allele and would
have the …….{fill in the name of the phenotype} phenotype
This is impossible because offspring has the …….{fill in the name of the phenotype}
phenotype
212
RNAi
The RNAi binds to the mRNA by
complementary base pairing
EITHER
The enzyme cleaves the mRNA into
pieces
OR
The mRNA is blocked from binding to
a ribosome
So either way:
translation is prevented
213
oestrogen>?
Oestrogen binds to oestrogen receptors
So the tertiary structure of the oestrogen receptor changes, so that the DNA binding
site is exposed
The oestrogen receptor binds to promoter of an oncogene
This allows RNA polymerase to bind and causes transcription to occur
more of the protein will be produced uncontrollable cell division
idk?
Oestrogen diffuses through the cell surface membrane into the cytoplasm
Oestrogen diffuses through a nuclear pore into the nucleus
Within the nucleus, oestrogen attaches to an ERα oestrogen receptor that is held within a protein complex, this causes the ERα oestrogen receptor to undergo a conformational change
The new shape of the ERα oestrogen receptor allows it to detach from the protein complex and diffuse towards the gene to be expressed
The ERα oestrogen receptor binds to a cofactor which enables it to bind to the promoter region of the gene, this stimulates RNA polymerase binding and gene transcription
214
why is O2 volume measured in photosynthesis
O2 produced in the light dependent reaction
faster O2 produced, faster light dependent reaction
215
2 respiratory substrates
How lipids can be used as a respiratory substrate:
Lipids are hydrolysed into glycerol and fatty acids.
Glycerol is converted into triose phosphate and enters the glycolysis pathway.
Fatty acids are broken down into two-carbon fragments and converted into acetyl coenzyme A, which enters the Krebs cycle.
Proteins as respiratory substrates
How proteins can be used as a respiratory substrate:
Proteins are hydrolysed into amino acids.
The amino group is removed from the amino acids (deamination).
Three-carbon compounds are converted into pyruvate
four- and five-carbon compounds are converted into intermediates in the Krebs cycle.
216
epigenome
all the chemical changes to the DNA and histone proteins of an organism not including changes to base sequence
217
reinfection graph questions
allergies/reinfection/secondary response
ALWAYS MENTION memory cells and faster response
218
properties of triglycerides related to their function
high H to O ratio so acts as a water source when oxidised
high ratio of energy storing C-H bonds compared to C atoms so are an excellent source of energy
low mass to energy ratio so good storage molecules with more energy being stored in a smaller volume
large non polar molecules, triglycerides are insoluble in water
storage does not affect water potential
219
properties of phospholipids related to their function
polar molecule - hydrophilic phosphate head and hydrophobic tail = forms a hydrophobic bilayer between inside/outside of cells
hydrophilic phosphate heads help hold at the surface of the cell membrane
forms glycolipids by combining with carbohydrates involved in cell recognition
220
chloroplasts structure
thylakoids = disc like structures that stack to form grana
double membraned
grana contain photosystems of light dependent reaction
thylakoids contain chlorophyll pigment
stroma = fluid filled matrix - light independent reaction occurs
starch grains in stroma
221
mitochondrial structure
double membrane
inner membrane folds to form extensions called cristae (site of ox phos)
matrix - contains proteins/lipids/ribosomes/DNA to control production of own proteins
= site of aerobic respiration
222
RER vs SER
RER = ribosomes on outer surface
provide a large surface area for synthesis of proteins/glycoproteins
site of protein synthesis
SER = lacks ribosomes
synthesises stores and transports lipids and carbohydrates
site of lipid synthesis
223
golgi apparatus
site of protein and lipid modification
adss carbs to proteins to form glycoproteins
produces secretory enzymes eg of pancreas
secrete carbs used to make cell walls in plants
form lysosomes
224
glycoproteins vs glycolipids
both act as recognition sites
and help cells attach to one another to form tissues
glycolipids maintain stability of membrane
glycoproteins allow cells to recognize one another eg lymphocytes recognise host vs foreign cells
225
DNA vs mRNA
1. DNA has deoxyribose, mRNA has ribose;
2. DNA has thymine, mRNA has uracil;
3. DNA long, mRNA short;
4. DNA is double stranded, mRNA is single stranded
5. DNA has hydrogen bonds, mRNA has no hydrogen bonds
226
ribosome is made of
RNA + protein
227
magnification formula
actual image = image size/magnification
I on top
228
calculating mitotic index
count cells in mitosis in FOV
divide by total num of cells in FOV
repeat 5 times with random FOVs
229
Calvin cycle
3 carbon dioxide combine with 3 RuBP via Rubisco action to form 3 unstable carbon intermediates that form 6 glycerate-3-phosphate
6 glycerate-3-phosphate reduced to triose phosphate
using NADPH -> NADP
and energy from ATP -> ADP + Pi
1 triose phosphate forms beta glucose
5 form RuBP
230
Sex-linked genes on the Y chromosome have been found in humans and other animal species. Suggest and explain one piece of evidence which would support the presence of such a gene.
All males possess Y chromosome so all affected/ Only males possess Y chromosome so no females affected
231
Use the information in the diagram 1 to give one piece of evidence that the allele for the Rhesus negative condition is recessive.
Rh negative phenotype produced from parents which are both Rh positive
232
Explain the evidence from the cross between individuals 3 and 4 that the gene controlling Rhesus blood group is not sex-linked.
with sex linkage daughter cannot have (recessive) condition unless male parent has the condition
as male passes X chromosome to his daughter
233
temporal vs spatial summation
Temporal summation involves the addition of multiple signals from a single source over time, while spatial summation involves the addition of signals from multiple sources simultaneously
234
Explain one piece of evidence from the pedigree which indicates that (i) the allele for the nail-patella syndrome is dominant
3 and 4 produce unaffected male/8 / female/10, so must carry recessive
but both affected by nail-patella which must be dominant.
235
how to screen DNA for known mutations
1. Use of PCR to amplify (DNA sample);.
2. Cut (DNA) using restriction endonuclease/enzymes;
3. Separate (DNA fragments) using electrophoresis;
4. Addition of (labelled) DNA probes and binding (by DNA hybridisation);
5. (Mutations) identified by fluorescence/radioactivity
OR
Compare positions/bands (to known) DNA sample with (all harmful) mutations;
236
gene
A sequence of DNA bases that codes for a polypeptide;
237
Describe how organisms are grouped in a phylogenetic classification system.
Hierarchy
(smaller) groups within (larger) groups with no overlaps;
(Grouped) according to evolutionary origins
238
DNA is universal
(Universal) The same codon always codes for the same amino acid;
239
A student prepared a plant root to observe cells undergoing mitosis.
He put the root in a small bottle of hydrochloric acid in a 40 °C water bath.
Why did he put the plant root in acid?
To break down links between cells/cell walls
To separate cells/cell walls
To break down/hydrolyse cellulose/cell wall
Allowing the stain to pass/diffuse into the cells
Allowing the cells to be (more easily) squashed
To stop mitosis
240
genes can code for:
proteins
polypeptides
rRNA
mRNA
tRNA
241
how does ATP synthase catalyse the formation of ATP
1. Active site complementary to ADP + Pi;
2. Enzyme-substrate complex forms;
REMEMBER ITS AN ENZYME
242
Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise.
Arteriole;
(Circular/smooth) muscle relaxes;
Vasodilation increases blood flow
243
functions of bile salts
1. Emulsify lipids/fats;
2. Increases surface area (of lipid/fat) for (increased) lipase activity;
3. Form micelles;
244
mitosis graph high at 1 then low fluctuation then little bit higher at 2
explain
Mass of DNA equals 1 (indicates) (early) interphase
2. Mass of DNA equals 2 (indicates) mitosis
each chromosome consists of 2 chromatids;
3. Mass of DNA between 1 and 2 (indicates) some of the DNA has been replicated;
245
conversions
metres -> mm -> Micrometre -> nanometre
246
RNA vs DNA
Similarities
1. Polymers of nucleotides;
2. (Nucleotide has) pentose, (nitrogen-containing organic) base and a phosphate (group);
3. Cytosine, guanine and adenine (as bases);
4. Have phosphodiester bonds;
Differences
5. Deoxyribose v ribose;
6. Thymine v uracil;
7. Long v short;
8. double v single
247
Outline the similarities in, and the differences between, the structures of chloroplasts and mitochondria.
Similarities
1. Double membrane;
2. Both contain (circular) DNA;
3. Both contain ribosomes;
Differences
4. Thylakoids/lamellae/grana v cristae;
5. Stroma v matrix;
6. Pigments v no pigments;
7. Starch grains v no starch grains;
248
cytokinesis vs telophase
nuclear membrane reforms in telophase
cell surface membrane reforms in cytokinesis and pinches
249
chlorplast DNA
eukaryotic but has prokaryotic features of DNA
circular + not associated with histones
250
site of transcription
nucleus
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how can genetic analysis support phylogenetic classifications
Compare the DNA base/nucleotide sequence;
More closely related (species) the more similar the genes/DNA;
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uncertainty
absolute uncertainty = 1/2 smallest division on scale
% uncertainty = absolute uncertainty/measurement x 100
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percentage cover formula
divide total % by num of quadrats
(Number of squares/points where the species occupies over half the square/point) / (Total number of squares/points in the quadrat) x 100
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ultracentrifugation
1. Added to the liver tissues an ice-cold, buffered isotonic
solution
2. Mixed the liver and solution in a blender.
3. Filtered the mixture from the blender.
4. Spun the filtered liquid in a centrifuge at a low speed. A pellet appeared in the bottom of the centrifuge tube.
5. Poured off the liquid above the pellet into a second centrifuge tube and spun this at a higher speed to obtain the sample of organelles
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why cold isotonic buffer
1. Ice-cold – Slows / stops enzyme activity to prevent digestion of organelles / mitochondria;
2. Buffered – Maintains pH so that enzymes / proteins are not denatured;
Reject reference to cells
3. Same water potential – Prevents osmosis so no lysis / shrinkage of organelles / mitochondria
256
The formula for galactose is C6H12O6. What is the formula for lactose?
C12 ; H22 ; O11
remove 2 H and 1 O from water
257
making mitotic index more accurate
1. Examine large number of fields of view / many cells;
2. To ensure representative sample;
OR
3. Repeat count;
4. To ensure figures are correct;
OR
5. Method to deal with part cells shown at edge /count only whole cells;
6. To standardise counting;
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why use a stain for cells in mitosis
to distinguish chromosomes / chromosomes not visible
without stain;
259
why use HCL in mitosis root tip
1. To break down links between cells/cell walls
To separate cells/cell walls
To break down/hydrolyse cellulose/cell wall;
2. Allowing the stain to pass/diffuse into the cells
Allowing the cells to be (more easily) squashed;
3. To stop mitosis;
260
why would mitotic index different between students
1. (Garlic roots) are a different age
OR
(Garlic) grown in different conditions;
2. (Root tips) from different (garlic) plants/bulbs/species;
3. Single field of view is not representative of a root tip
OR
(Other) students may have looked at more fields of view
OR
(Other) students may have calculated a mean;
4. (Different fields of view are from) different parts of the root tip;
5. Cells/roots undergo mitosis/cell division at different times/rates;
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properties of water
(a) 1. A metabolite in condensation/hydrolysis/ photosynthesis/respiration;
2. A solvent so (metabolic) reactions can occur
3. High (specific) heat capacity so buffers changes in temperature;
4. Large latent heat of vaporisation so provides a cooling effect (through evaporation);
5. Cohesion (between water molecules) so supports columns of water (in plants);
6. Cohesion (between water molecules) so produces surface tension supporting (small) organisms; - pondskaters
262
non reducing sugar test
Do Benedict’s test and stays blue/negative;
Boil with acid then neutralise with alkali
Heat with Benedict’s and becomes brick red ppt
(All monosaccharides and some disaccharides are reducing sugars. Some disaccharides and all polysaccharides are non-reducing sugars)
263
condensation vs hydrolysis
1. A condensation reaction joins monomers together and forms a (chemical) bond and releases water;
2. A hydrolysis reaction breaks a (chemical) bond between monomers and uses water;
264
Give two properties of water that are important in the cytoplasm of cells.
1. Polar molecule;
2. Acts as a (universal) solvent;
3. (Universal) solvent;
4. (Metabolic) reactions occur faster in solution;
5. Reactive;
6. Takes place in hydrolysis / condensation / named reaction;
265
UPDATED cardiac cycle
diastole:
atria and ventricles relaxed and AV valves closed
pressure in vena cava exceeds atria and blood fills atria passively
when pressure in atria exceed ventricles
AV valves open
blood flows into ventricles passively
atrial systole:
atria contract to empty remainder of blood into ventricles
pressure in ventricles exceeds atria and AV valves close
ventricular systole:
ventricles contract so pressure in ventricles exceeds aorta/pulmonary artery
semi lunar valves open
blood leaves ventricles
pressure decreases and semi lunar valves close
266
components of ATP
adenine, ribose/pentose, three phosphates
267
uncertainty of a single measurement
For instruments like thermometers, rulers, or measuring cylinders, the uncertainty is half the smallest division on the scale.
Example: A thermometer with markings every 1.0°C has an uncertainty of ±0.5°C.
268
reducing uncertainty
use an instrument with small graduations
269
plotting and reading a calibration curve
1. Create a calibration curve:
Prepare a series of standard solutions with known concentrations of the substance you are measuring (e.g., glucose, starch, etc.).
Measure the absorbance (or other relevant measurement) of each standard solution using a colorimeter (or other appropriate instrument).
Plot the data: known concentrations on the x-axis and the corresponding absorbance (or other measurement) on the y-axis.
Draw a line of best fit through the data points, ensuring a balance of points above and below the line.
2. Read the unknown concentration:
Measure the absorbance (or other relevant measurement) of your unknown sample using the same method and instrument as the standards.
Find the absorbance value of the unknown sample on the y-axis of your calibration curve.
Draw a line from that absorbance value on the y-axis to the line of best fit on the graph.
Follow this line down to the x-axis to find the corresponding concentration.
270
non coding base sequence and where are they found
DNA that does not code for a polypeptide
found between genes
271
mark release recapture equation
N = (M x S) / R
N = population estimate
M = marked individuals released
S = size of second sample
R = marked animals recaptured
272
how does succession increase biodiversity
increases the number of habitats and food sources so more species
