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Title: H2 Biology Paper 2 common questions and answers
Description: This document contains a list of common questions and answers from H2 Biology A Level (Singapore) paper 2 (core curriculum). Includes a contents page which links to the relevant section. Covers: biomolecules/cell membranes, DNA and genomics, bacteria/viruses, photosynthesis/respiration, meiosis/mitosis, Mendelian genetics, cell signalling/homeostasis and evolution.
Description: This document contains a list of common questions and answers from H2 Biology A Level (Singapore) paper 2 (core curriculum). Includes a contents page which links to the relevant section. Covers: biomolecules/cell membranes, DNA and genomics, bacteria/viruses, photosynthesis/respiration, meiosis/mitosis, Mendelian genetics, cell signalling/homeostasis and evolution.
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BIOMOLECULES
Carbohydrates- Explain how structure of starch makes it a good storage molecule
...
[6]
Enzymes- Describe how enzymes take part in chemical reactions
Explain why an increase in substrate concentration at low substrate concentrations
increases the initial rate of rxn but an increase at high substrate concentrations
does not do so
...
[6]
DNA AND GENOMICS
Definition: gain in function mutation
Definition: Template DNA
Describe how the structures of RNA are adapted for translation
...
Describe how T4 bacteriophage enters a bacterial cell
...
[7]
Rolling circle replication
Binary fission
Bacterial conjugation
Bacterial transformation
How would transduction lead to transfer of genes from one strain of bacteria to
another?
Describe how the prokaryote, E
...
Describe the main structural features of the lac operon
...
Suggest why operons are necessary in bacteria
...
Describe the process of chemiosmosis in the chloroplast
Describe the processes that generate and maintain the proton gradient
...
Explain the shape of the action spectrum
...
DNA/GENOMICS
Describe how structure of tRNA is adapted to its function
...
Arrangement of genetic sequences within an operon
MENDELIAN GENETICS
Standard answer for chi-square test
Explain the term epistasis
...
[8]
PRO/EUK GENOME
How does an enhancer sequence work?
Controlling strength of promoter in prokaryotes to regulate transcription
Role of telomeres
End replication problem
Outline the significance of post-translational modifications of euk proteins
...
[8]
CELL SIGNALLING/HOMEOSTASIS
With reference to the stages of cell signalling, describe the response of liver cells
to insulin
...
[6]
Advantages of mtDNA to construct phylogenetic tree
Suggest why cytochrome b gene is used to measure changes in DNA seqs in
closely related species
...
Compare sympatric and allopatric speciation
...
Explain the various species concepts and their limitations
...
[5]
Comparison - Contrast a fibrous and globular protein
...
COMPARISON TABLES: MIT/MEI/DNA/GENOMICS
State four ways in which the behaviour of chromosomes in meiosis differs from
their behaviour in mitosis
...
[3]
COMPARISON TABLES: PHOTO/RESPI
Describe how the Calvin cycle differs from the Krebs cycle
...
1
...
Compact structure
allows many starch molecules to be stored within a small volume
3
...
Hundreds of glucose residues ⇒ many
hydrogen atoms
storing chemical energy
5
...
Anomeric carbon involved in glycosidic bond formation makes it relatively stable and
unreactive
Explain why cellulose / starch is insoluble in water
1
...
and
2
...
Hence there are
insufficient free hydroxyl groups enable cellulose to be soluble in
to
water (or effect solubilisation)
Proteins- Describe an
alpha helix
1
...
Is maintained by hydrogen bonds between the and NH
CO
groups of
every 4th
amino
acid residue on the polypeptide backbone
3
...
6 amino acid residues in every turn of the alpha-helix
Proteins- Describe structure of
beta-pleated sheet
Hydrogen bonds form between the C=O group of a
peptide one strand and the N-H group of
in
another peptide in the
adjacent
strand
...
Proteins- Describe the structure of a protein
Idea: Mention the
structure holds the protein together, then mention the
that
bonds
that
maintain the structure and what they are between
...
Primary structure - peptide bonds between amino acid residues
2
...
a
...
Tertiary structure - hydrogen bonds, ionic bonds, disulfide bonds and hydrophobic
interactions between R-groups of amino acid residues
4
...
Best example = haemoglobin
Proteins - Outline how a structure of a
named
globular protein is related to its specific
function
...
makes it
soluble in blood
, capable of carrying O2 from lungs to tissues and vice
versa
5
...
each haem group consists of a porphyrin ring and an iron ion
a
...
4 subunits held together by intermolecular bonds allows movement that influences
affinity for oxygen → enabling
cooperative binding of oxygen
a
...
2
...
4
...
hesitant loading first oxygen molecule results in rapid loading of the other
of
three
...
Specific active site where substrate complementary in shape and charge binds by the
lock and key model
2
...
Lowers activation energy by:
a
...
Straining of bonds to be broken increases chance of breakage
c
...
1
...
As the substrate concentration increases, the rate of reaction increases as more active
sites are occupied by substrates
3
...
Thus, enzyme concentration becomes limiting while substrate concentration is
no longer limiting
...
(inhibitor) acts as a
non-competitive inhibitor
which binds to site other than the
a
active site
2
...
Prevents it from being
complementary in shape and charge the substrate
to
4
...
Explain how temperature affects the rate of an ez-cat rxn
1
...
Increases
frequency successful collisions between the ez and sub forming the
of
ez-sub complex
3
...
Reaction rate increases with temperature up to the optimum temperature
5
...
State formula
...
Each enzyme has an optimal temperature that allows the greatest number of
molecular collisions and thus rate of reaction
7
...
of
Describe the mode of action of an enzyme
1
...
Active site is complementary to (
substrate herecleaving the ( name here
),
bond
) bond,
in a (
reaction type here
) reaction
...
The enzyme works by
induced fit which the binding of the substrate to the contact
in
residues on the active site cause conformational changes for a more
precise fit
4
...
This is done by distorting the bond between the reactants, causing strain on the bond /
Presence of acidic and basic R groups on the catalytic residues facilitate catalysis of
the bond
...
[6]
2014/NJC/P2/Q9a
1
...
Unsaturated hydrocarbon tails have kinks that keep the phospholipid molecules in the
membrane from packing closely at lower temperatures
3
...
Cholesterol restricts phospholipid movement and stabilises the lipid bilayer through
hydrophobic interactions
5
...
Template refers to the DNA strands of a DNA molecule
one of
2
...
Resultant RNA molecule has a
sequence complementary that of the DNA
to
4
...
[6]
of
mRNA
1
...
One codon codes for an amino acid
...
mRNA has
ribosome attachment site
4
...
Contains start codon (AUG) and STOP (UGA, UAA, UAG) codon
6
...
Mature mRNA does not contain introns and a 5’ methyl guanosine cap and 3’ poly-A
tail to ensure mRNA stability
tRNA
1
...
At least 20 different tRNAs, one for each amino acid
3
...
Has shape complementary to amino-acyl tRNA synthetase for activation of amino acid
5
...
Structural component of
ribosome to complementary base pairing
due
2
...
)
3
...
N2008/P2/Q3a, N2011/P2/Q2c
1
...
Virus enters host cell by
endocytosis
...
3
...
The
drop
stimulates fusion of viral
envelope with vesicle membrane, releasing the nucleocapsid into the cytosol
Describe how T4 bacteriophage enters a bacterial cell
...
When T4 bacteriophage
attaches anchors to the bacterial cell wall will
and
host
, it
release
lysozyme
, which digests the bacterial cell wall
...
Molecules released from the digestion diffuse back to the bacteriophage and initiate a
change in the base plate conformation
3
...
4
...
Explain why viruses may be regarded as non-living organisms
...
require host cells t make products such as their coat proteins
6
...
do not respond to stimuli outside the host cell
1
...
3
...
Rolling circle replication
(RI/2013/P2/Q2c(ii))
1
...
DNA pol adds
nucleotides the free 3’ OH and to synthesise a
to
complementary
DNA
strand
3
...
5’ end of the nicked strand is displaced as synthesis/strand elongation proceeds
5
...
Comments: don’t use terms like ‘inner’ and ‘outer’ strand since DNA is a double helix
...
Bacterial conjugation
1
...
One of the 2 strands of the plasmid DNA in F+ cell is nicked and
transferred from the
F+ cell to the F- cell
through a mating bridge via rolling circle mechanism as the other
DNA strand is used as a template for replication
...
Single stranded F plasmid DNA
circularises F- and is used as a template to
in
cell
synthesise a
complementary strand a double-stranded F plasmid DNA, resulting in
for
+
a cell
F
Binary fission
1
...
Replication takes place outward from the origin in
both direction with replication forks
2
...
2
...
The cell elongates to prepare for division
4
...
When the daughter DNA molecules are separated, the bacterial cell will have reached
twice its initial size
...
Bacterial conjugation
--
1
...
One of the 2 strands of the plasmid DNA in F+ cell is nicked and
transferred from the
F+ cell to the F- cell
through a mating bridge via rolling circle mechanism as the other
DNA strand is used as a template for replication
...
Single stranded F plasmid DNA
circularises F- and is used as a template to
in
cell
synthesise a
complementary strand a double-stranded F plasmid DNA, resulting in
for
a
F+ cell
Bacterial transformation
1
...
The foreign DNA is incorporated into the bacterial chromosome via
crossing
over/homologous recombination the homologous regions
at
2
found on the bacterial
chromosome and the foreign DNA
3
...
How would transduction lead to transfer of genes from one strain of bacteria to
another?
(or any reference to variation/introduction of a new gene/etc
...
Bacteriophage infects strain of bacteria containing
DNA
...
When phage replicates within the bacteria, bacterial DNA is
hydrolysed to small
fragments prophage was
OR
improperly excised
during
spontaneous induction
, picking
up adjacent bacterial
3
...
Virus then infected bacterial cell containing the gene
not
5
...
, is
concentrations of lactose
...
E
...
Beta galactosidase
and permease constitutively produced in the cell
are
3
...
Lactose is converted by beta galactosidase into
allolactose
, which
binds to
and
inactivates repressor proteins
5
...
Promoter is unblocked and
RNA pol can bind to promoter and transcribe
structural genes
6
...
Lactose is also converted by beta-galactosidase to glucose + galactose
Describe the main structural features of the lac operon
...
1
...
Lac Z
which codes for
beta-galactosidase
3
...
Lac A
which codes for lactose
transacetylase
5
...
There is also a
regulator gene
upstream, Lac I, which codes for the repressor
protein
7
...
Situated within the promoter is a
Catabolic activator protein binding site
9
...
Explain what is meant by a
repressible
operon
...
one where transcription is
usually turned on
2
...
This
changes the shape the inactive repressor protein to the
of
active conformation
4
...
blocking the binding of RNA polymerase the promoter
to
6
...
Suggest why operons are necessary in bacteria
...
Clustering genes of related functions together
under the control of a
common promoter
allows
regulation of gene expression
...
Allows bacteria to only
produce
enzymes
when required allow for quick responses
and
to changes in the external environment
3
...
Confers a
selective advantage bacteria
to
How would a point mutation in lac Z leads to a truncated beta galactosidase protein)
(that
affect expression of lac Y and lac A?
1
...
2
...
PHOTO/RESPI
Role of NAD in aerobic respiration
(2010/RI/P2/Q8b)
1
...
Organic molecules are oxidised during glycolysis, link reaction and Krebs cycle
...
to
3
...
As electrons pass down the chain, the release of energy in a series of redox reactions
is coupled to the phosphorylation of ADP to form ADP
5
...
1 NADH yields ATP
3
7
...
Describe the involvement of the chloroplast envelope in photosynthesis
...
Allows for compartmentalisation of the cell
2
...
NAD regenerated when electrons from NADH transferred to pyruvate/ethanal
2
...
NB: role of NAD in
glycolysis
= coenzyme
which carries both protons and electrons
3 similarities in ATP production in respiration and photosynthesis
1
...
generation of
proton gradient
across membrane
3
...
mobile electron carriers pass electrons to electron carriers of electron transport chain
such as NAD+
and FAD in respiration vs NADP+ photosynthesis pass electrons
in
Describe how anaerobic respiration in mammalian cells differs from anaerobic
respiration in yeast cells
...
In mammals:
lactate
produced instead of ethanol
2
...
Involves a
single step
catalysed by lactate dehydrogenase
Explain the small yield of ATP under anaerobic conditions in yeast and mammals
(N2008/P2/Q8b, N2012/P2/Q???)
1
...
oxidative phosphorylation
eventually stops as no further electrons are passed down
the chain, hence ATP will be produced via chemiosmosis
no
3
...
No ATP produced via
Krebs cycle
in substrate level phosphorylation
5
...
produced 2 net ATP per glucose molecule via substrate level phosphorylation
7
...
In mammal cytoplasm, pyruvate is reduced to NADH via lactate fermentation
remember! EACH NAD PRODUCES 2
...
1
...
and
2
...
The energy released is coupled to the pumping of H+ into the intermembrane space to
generate a
proton gradient
4
...
5
...
so
Describe the process of chemiosmosis in the chloroplast
(2010/RI/P2/Q7b)
1
...
As electrons travel down a series of
progressively more electronegative electron
carriers energy released used
, the free
is
3
...
which contributes toward a H+ oncentration in the thylakoid space relative to the
high
c
stroma
5
...
ADP phosphorylated to ATP the process
in
Explain the shape of the action spectrum
...
Peaks action spectrum correspond to absorption peaks (of photosynthetic
of
pigments)
2
...
Region between 500-600nm is an exact match
not
between absorption and action
spectra
4
...
Describe the processes that generate and maintain the proton gradient
...
Splitting of H H H+
O
O,
and electrons in the thylakoid space contributes to the
2 into
2
accumulation of H+ the thylakoid space
...
NADP+ reduced to NADPH by
is
NADP+
reductaseakes up H+
;
t
ions from stroma
MEIOSIS/MITOSIS
Description of chromatids during anaphase
1
...
sister chromatids separate
, becoming daughter chromosomes which are
pulled apart
by shortening spindle fibres opposite poles
to
Role of centromeres in cell division
Nature of centromeres:
1
...
facilitate sister chromatid adhesion at a particular region of the chromosome
3
...
allows separation of sister chromatids to
opposite poles by centromeres
led
5
...
Nature of centrioles: of centrioles at each pole; their position determines the polarity
pair
of the cells
2
...
which leads to separation of chromosomes after centromeres divide
Structure of centrioles
1
...
contains triplets of microtubules
nine
arranged in a ring, found in the
centrosome
3
...
Restores diploid
number/prevents
doubling chromosome number
of
2
...
Pair of chromosomes, of paternal and one of maternal origin
one
2
...
same genes at corresponding loci
Comments: most students lacked details/ Cambridge always requires mention of paternal and maternal origin,
hence student will not be awarded mark for mentioning that each comes from one parent
...
1
...
thus daughter cells are genetically identical to parents
3
...
Each strand of parental DNA acts as template for the exact replication to form the new
daughter strand through
complementary base pairing
5
...
During metaphase, sister chromatids are attached to microtubules from either pole
7
...
which ensures sister chromatids are separated to opposite pole during anaphase
9
...
In asexual reproduction, mitosis produces genetically identical daughter cells
11
...
(2012/JJC/P2/Q8a)
Structure
Function
ssRNA with 3 loops and a stem
held by hydrogen bonds
shape is complementary to active site of amino
acyl-tRNA synthetase for amino acid activation
CCA stem at 3’ end
Attaches covalently to amino acids coded for by the
anticodon of the tRNA
Ribosome recognition site
makes specific base pairing with rRNA of ribosome
Anticodon
Complementary base pairs with specific codon on
mRNA/act as intermediate
Explain how the correct amino acid is joined to a tRNA
...
Aminoacyl-tRNA synthetase a
has specific active site recognises tRNA with a
that
specific anticodon
2
...
Double specificity ensures there is a correct match between amino acid and tRNA with
a specific anticodon
Arrangement of genetic sequences within an operon
1
...
Two or more structural genes encode different proteins are found between these
that
two sequences
3
...
At chi-squared value of [value], p is greater than [value]
...
05/p is
p
less than 0
...
We not reject null hypothesis that there is no
do
the
significant difference
between
observed and expected ratios any difference is due to
and
random chance
...
Only state what the difference in observed phenotype is if absolutely sure!
Explain the term epistasis
...
form of gene interaction where a gene at one locus alters the phenotypic expression of
a gene at a second locus
2
...
The homozygous
recessive alleles result in a lack of production of this enzyme/ Gene B codes for
enzyme B, which converts the colourless intermediate into the purple pigment
...
3
...
When either enzyme is missing, purple pigment
cannot be made and the flower remains white
...
[8]
Definition of genotype and phenotype
1
...
The
phenotype an organism is the physical characteristic / trait that is expressed
* of
or observed and results from a specific genotype;
3
...
Ref
...
Ref
...
Different alleles will result in the production of different polypeptide chain(s) /
protein(s);
7
...
The alleles present for each particular gene may be dominant* or recessive*;
9
...
Hence only the dominant allele will be expressed in the phenotypes of homozygous
dominant and heterozygous organisms;
11
...
Controlling strength of promoter in prokaryotes to regulate transcription
Strength of promoter is determined by how similar the -10 and -35 sequences are to the
consensus sequences
(which are:
-10: 5' - TATAAT - 3'
-35: 5' - TTGACA - 3')
Stronger promoters have
higher frequency transcription
...
Ensure
genes are not lost/eroded to replication problem
due end
, preventing loss of
vital genetic information
2
...
3
...
Occurs during replication of linear (euk) chromosomes
2
...
An RNA primer is synthesised to provide free 3’ OH end for addition of free nucleotides
4
...
Hence chromosomes shorten after every round of replication
...
Since telomeres are non-coding, shortening of chromosomal ends leads to shortening
of telomeres without deleterious effects (i
...
doesn’t result in loss of vital genetic
information)
Outline the significance of post-translational modifications of euk proteins
...
Cleavage/covalent modification example (glycosylation/attachment of prosthetic
+
groups)
2
...
Regulation controls cellular activity + example (phosphorylation may
→
activate/inactivate (ORA) proteins)
4
...
g
...
Conserve resources → unused/unneeded proteins can be hydrolysed to amino acids
to be used to synthesise new proteins
6
...
[8]
(2013/RI/P2/Q9a)
● Both involve regulation of RNA half-life longer half-life allows for translation of
m
→
more proteins from mRNA
● Both require
initiation factors the proper positioning of the small ribosomal subunit
for
together with initiator tRNA on the mRNA and recruitment of the large ribosomal
subunit/assembly of translation initiation complex
...
[6]
2014/ACJC/P2/Q9c
1
...
Ligand-binding causes RTK to undergo
changes in conformation its intracellular,
in
cytoplasmic domain;
3
...
Phosphorylated tyrosine residues serve as
docking sites other proteins
for
relay
;
5
...
Relay proteins may be
kinases
which can go on to
phosphorylate
other proteins when
activated;
7
...
activation of
glycogen synthase
which catalyses glycogen synthesis from
glucose
...
e
...
translocation of glucose transporters
from the membrane of cytoplasmic
vesicles to the cell membrane, increasing glucose intake into cells
c
...
increased lipid & protein synthesis
Comparative effects of glucagon and insulin
Basis of
comparison
Insulin (aim: decrease blood
glucose level)
● Increases glucose intake
through translocation of
glucose transporters to the
cell surface membrane
● increases glycolysis
● increases glycogenesis
mainly in liver and muscles
● decreases gluconeogenesis
Glucagon
● Increase glycogenolysis
● increase gluconeogenesis
● increase breakdown of lipids
Target cells: liver cells
Disadvantages of a signalling cascade
● Error along any segment of the cascade would result in a non-specific response
● Prone to error
EVOLUTION
Suggest how (_____) supports Darwin’s theory of natural selection
1
...
suggests
adaptive radiation
b
...
MOLECULAR EVIDENCE:
a
...
is
3
...
These favourable traits are passed on to the
in
offspring
...
Speciation
occurs when there is an
accumulation of mutations and changes in allele
frequencies time between the sub-populations due to
over
disruption of gene flow
...
Natural populations have great reproductive potential
2
...
Due to environmental factors,
competition resources, predators, other selection
for
pressures, that impose a limit on their number and organisms
struggle to survive
4
...
Variants with a
selective advantage/which are best adapted to their environment
are
more likely to survive and reproduce
6
...
Over many generations, evolutionary changes by natural selection and may form new
species if
reproductive isolation
occurs which is necessary for
speciation
8
...
[6]
1
...
Mitochondrial DNA has a
faster mutation rate
compared to nuclear DNA, hence it is useful for
comparing individuals within a species/closely related species, as it requires discernible
differences between DNA of organisms being compared
...
1
...
was found in their common ancestor; forms the basis of comparison
3
...
It is found in the itochondria hence not undergo recombination
m
and
do
and any
mutation
accumulates at a regular rate in the maternal line → can be used for
molecular clock
Explain how species are formed with reference to reproductive isolation
...
Species defined as a group of organisms capable of
interbreeding
, producing viable
and fertile offspring
2
...
For speciation to occur,
reproductive barriers/isolation
must exist
4
...
Pre-zygotic mech
prevents mating or fertilisation
, which involves
habitat/geographical/temporal/behavioural/mechanical/gamete isolation
b
...
Repro isolation mechs will prevent production of viable, fertile offspring/prevent
interbreeding/prevent formation of hybrids
6
...
Isolated population subjected to different selection pressures
8
...
(Link allopatric and sympatric speciation to repro isolation)
Compare sympatric and allopatric speciation
...
SIMILARITY: Both require disruption of gene flow
...
DIFFERENCE:
Allopatric speciation formation of species from populations due to
is
geographic isolation
between 2 populations whereas
sympatric speciation the
is
formation of species from populations in the
same geographic location
/by behaviour
or physiological isolation
Explain why the scientific name is better than the common names
...
Unambiguous one unique name for each species
with
2
...
while common names do not reveal their
position in the (plant)
kingdom
/attempt to categorise them
...
[6]
and
(2012/NJC/P2/Q9b)
Approach is generally to
define the concept give one limitation
...
Ecological species concept: views a species in terms of its ecological niche
a
...
Biological species concept: define species as a population or group of organisms
whose members have the potential to interbreed in nature and produce viable fertile
offspring
a
...
Hybridisation is possible between species previously thought to be distinct
3
...
Subjective
b
...
Describe how cellulose differs from starch
...
FIbrous (eg Collagen)
Globular (eg
Phosphofructokinase)
Variety
Less variety of a
...
used to
construct the protein
...
a used to
construct the protein
Solubility
Insoluble
Soluble
Errors
Length of polypeptide may vary
slightly between two samples of
the same protein, yet protein is
still function
Length of pptd is always
identical
Function
Collagen is a structural protein
PFK and other ez are involved in
metabolic and enzymatic roles
Shape
Made of up of straight long pptd
chains
Spherical in shape
Comparison - Compare cellulose and insulin (a carbohydrate and a protein)
Cellulose
Insulin
Monomers
Cellulose is comprised of
beta-glucose monomers
Insulin is comprised of amino
acid residues
Bonds –
intramolecular
Cellulose is held together by
beta(1-4) glycosidic bonds
Insulin is held together by
peptide bonds
Bonds –
intermolecular
Cellulose has intermolecular
hydrogen bonds between OH
groups of parallel cellulose
molecules
3D conformation of the protein
is maintained by hydrogen,
ionic, hydrophobic interactions
and disulphide linkages
...
Basis of
comparison
Glucagon
Glycogen
Type of
macromolecule
globular
extensively branched polysaccharide
made of helical chains
Type of
monomer
amino acid residues with
different R groups
alpha glucose only
Type of bonds
between
monomer
peptide bonds
alpha 1,4-glycosidic linkages with
branched alpha 1,6-glycosidic
linkages
Number of
monomers per
molecule
fixed number of amino acids per
molecule
variable number of glucose per
molecule
Solubility in
water
soluble (globular)
insoluble (large molecular weight)
Synthesis
in alpha cells in islets of
Langerhans in pancreas
in liver and muscle cells when blood
glucose is high
Function
hormone that regulates blood
glucose
energy store in muscle and liver
Note that Cambridge will mark as 0 if you don’t write sentences
full
!
COMPARISON TABLES: MIT/MEI/DNA/GENOMICS
State four ways in which the behaviour of chromosomes in meiosis differs from their
behaviour in mitosis
...
This is purely for
organisational purposes)
Meiosis
Mitosis
Homologous chromosomes pair up to form
bivalents
Chromosomes align singly
Crossing over between non-sister chromatids
of homologous chromosomes occurs
Crossing over does not occur
Homologous chromosomes separate in
anaphase 1
Sister chromatids separate in anaphase of
mitosis
List three ways in which transcription is different from DNA replication
...
This is purely for
organisational purposes)
Basis of
comparison
DNA replication
Transcription
Template
Both DNA strands
serve as a
template
Only one strand as a template
acts
Product
2 double-stranded DNA
molecules
are synthesised
1 single stranded RNA olecule is
m
synthesised
Enzyme
involved
DNA polymerase
DNA-dependent polymerase
RNA
Nucleotides
used
Deoxyribonucleotides and
ribonucleotides used
are
Ribonucleotides used
are
COMPARISON TABLES: PHOTO/RESPI
Describe how the Calvin cycle differs from the Krebs cycle
...
Oxygen is the final electron
acceptor
How the proton
gradient is
established
Protons are pumped inwards, from
the stroma, across the thylakoid
membrane into the thylakoid space
Protons are pumped outwards,
from the matrix into the
intermembrane space across the
inner membrane
Title: H2 Biology Paper 2 common questions and answers
Description: This document contains a list of common questions and answers from H2 Biology A Level (Singapore) paper 2 (core curriculum). Includes a contents page which links to the relevant section. Covers: biomolecules/cell membranes, DNA and genomics, bacteria/viruses, photosynthesis/respiration, meiosis/mitosis, Mendelian genetics, cell signalling/homeostasis and evolution.
Description: This document contains a list of common questions and answers from H2 Biology A Level (Singapore) paper 2 (core curriculum). Includes a contents page which links to the relevant section. Covers: biomolecules/cell membranes, DNA and genomics, bacteria/viruses, photosynthesis/respiration, meiosis/mitosis, Mendelian genetics, cell signalling/homeostasis and evolution.