Higher Biology
Cell Biology
Core Essay
‘Give an account of how the following cell structures are
related to function:
i) xylem
ii) red blood cell
Mark
Xylem
Consists of xylem and tracheid vessels
Vessel consists of hollow tubes formed by end walls breaking
down
Tube consists of very fine bore
So water adheres to vessel walls (capillarity) which helps upward
transport
Walls strengthened by lignin
Lignin as rings or spirals which allow contraction/expansion
Walls contain pits for lateral transport of water
Tracheids consist of long narrow cells
Red Blood Cells
Small in size
So can fit through narrow capillaries
No nucleus as space saving measure
Bi-concave shape allows for a large surface area
Contains haemoglobin
Which combines with oxygen to form oxy-haemoglobin
1
1
1
1
1
1
1
1
Maximum 5
1
1
1
1
1
1
Maximum 5
Maximum
Total
10
Higher Biology
Cell Biology
Core Essay
‘Give an account of respiration under the following headings:
i) glycolysis
ii) the Kreb’s (Citric Acid) cycle
Mark
Glycolysis
Occurs in the cytoplasm
Glucose broken down to/converted to/reduced to/oxidised to/ (two
molecules) of pyruvic acid
C6 compound broken down to 2 X C3
Step by step breakdown by enzymes OR series of enzyme
controlled reactions
Net gain/production of ATP/explanation of net gain of ATP
NAD accepts hydrogen/NADH produced and transferred to
cytochrome system/cristae/electron transfer system (NOT stage 3)
Oxygen not required/anaerobic/occurs in aerobic and anaerobic
conditions.
Kreb’s Cycle
Occurs in the matrix of the mitochondrion
Requires oxygen OR aerobic phase (DO NOT AWARD IF
ALREADY AWARDED LAST MARK IN GLYCOLYSIS SECTION)
C2 acetyl group produced from pyruvic acid
Acetyl group joins with CoA
Acetyl CoA reacts/combines with a C4 compound to form C6
compound/citric acid
Cyclical series of reactions back to C4 compound
Carbon dioxide produced/given off/released
NAD accepts hydrogen/NADH produced and transferred to
cytochrome system (DO NOT AWARD IF ALREADY AWARDED
IN GLYCOLYSIS SECTION)
Kreb’s cycle needs/requires/is controlled by enzymes (DO NOT
AWARD IF ALREADY AWARDED IN GLYCOLYSIS SECTION)
1
1
1
1
1
1
1
Maximum 5
1
1
1
1
1
1
1
1
1
Maximum 5
Maximum
Total
10
Higher Biology
Cell Biology
Core Essay
‘Give an account of the absorption of light energy by
photosynthetic pigments and the light dependent stage of
photosynthesis.’
Note: The marks may be awarded for information in a diagram. The relevant piece of
information must be clearly shown in a carefully drawn and labelled diagram.
Mark
Absorption of Light Energy
Chlorophyll a and b, xanthophyll and carotene named
Chlorophyll absorbs red and blue light/colours/wavelengths
Xanthophyll AND carotene/accessory pigments absorb light from other
regions of the spectrum/of other colours/of other wavelengths
Light absorption occurs over a wide range of spectrum/wider range of
colours/more wavelengths
Energy absorbed by xanthophyll/carotene/accessory pigments is passed on
to chlorophyll
Occurs in the grana (AWARD MARK ONCE ONLY)
Light-Dependent Stage
Occurs in the grana (AWARD MARK ONCE ONLY)
Light energy converted to chemical energy
Regenerate ATP from ADP and Pi
Split water OR energy used in photolysis of water
Hydrogen combines with NADP OR NADPH2/NADPH/reduced NADP formed
1
1
1
1
1
1
Maximum 4
1
1
1
1
1
Oxygen is a by-product OR oxygen diffuses/passes/goes out of cells/leaf
NADPH2 and ATP diffuse/passes/goes to stroma/are used in Calvin cycle
Coherence
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’ headings
above.
- Related information should be grouped together. Information as listed
under bold headings above should be grouped together
- There must be a minimum of 5 points with at least 1 point given for each
group.
All must apply correctly to gain the coherence mark.
Relevance
- Must not give details of carbon fixation stage
- Must give a minimum of 5 relevant points with at least 2 points from each of
the two headings.
Both must apply correctly to gain the relevance mark.
1
1
Maximum 4
1
1
Maximum
Total
10
Higher Biology
Cell Biology
Core Essay
‘Give an account of the structure of RNA and its role in
protein synthesis’
Note: The marks may be awarded for information in a diagram. The relevant piece of
information must be clearly shown in a carefully drawn and labelled diagram.
Mark
Structure of RNA
Single stranded
Made of nucleotides
Has a base, ribose (sugar) and a phosphate
Bases are guanine, cytosine, adenine, and uracil (NOT letters A, U, G,
C)
Role in Protein Synthesis
mRNA carries information/code (for protein) from nucleus/from DNA
mRNA attaches to ribosome
Three bases on mRNA is a codon
tRNA transport amino acid to ribosome
tRNA transports specific amino acids
Three bases on tRNA is an anticodon
Codons match/pair with their anticodon
Joins/adds correct amino acid onto growing protein/polypeptide
Sequence of bases/codons on mRNA gives sequence of amino acids
1
1
1
1
Maximum 3
1
1
1
1
1
1
1
1
Maximum 5
Coherence
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’
headings above.
- Related information should be grouped together. Information as
listed under bold headings above should be grouped together
- There must be a minimum of 5 points with at least 2 points given
for Structure section and at least 3 points for Role section
All must apply correctly to gain the coherence mark.
Relevance
- Must not give details of DNA structure or replication, protein
transport or secretion
- Must be a minimum of 5 points with at least 2 points given
for Structure section and at least 3 points for Role section
1
1
Both must apply correctly to gain the relevance mark.
Maximum
Total
10
Higher Biology
Cell Biology
Core Essay
‘Give an account of cellular defence mechanisms in animals
under the following headings:
i) phagocytosis
ii) antibody production and tissue rejection
Mark
Phagocytosis
Carried out by phagocytes/monocytes/macrophages.
(Penalise once for lymphocytes)
Non-specific nature of process
Bacteria/foreign material/virus (NOT antigen) engulfed/enveloped
OR description/diagram (NOT trapped)
Into a vacuole/vesicle (NOT pocket/pouch)
Lysosomes fuse/join to vacuole AND add enzymes to vacuole
Bacteria/foreign material/virus (NOT antigen)
digested/destroyed/broken down by enzymes
IF ANTIGEN ALREADY PENALISED ABOVE DO NOT PENALISE
AGAIN
IF ENZYMES MENTIONED IN PREVIOUS MARK THEN NOT
REQUIRED HERE.
1
1
1
1
1
1
Maximum 4
Antibody Production
Antibodies are proteins
They are produced by lymphocytes
Production stimulated by/in response to foreign/non-self
antigens/proteins
Antibodies are specific/match the shape of the antigens/lock and
key diagram
Antibody renders
harmless/destroys/attacks/combats/neutralises/combines with
antigen (NOT kill antigen)
1
1
1
1
1
Maximum 4
Tissue Rejection
Transplanted tissues are antigenic/have foreign antigens/proteins
are recognised as foreign/non-self
Will be rejected/attacked by patient’s antibodies OR antibodies
made against transplant tissue (NOT kills transplant)
Risk of rejection is reduced by
suppressors/immunosuppressors/drugs whish suppress/inhibit
immune system OR repressors which inhibit/suppress the immune
system
1
1
1
Maximum 2
Maximum
Total
10
Higher Biology
Genetics & Adaptation
Core Essay
‘Give an account of meiosis under the following headings:
i) first meiotic division
ii) second meiotic division
iii) importance of meiosis
Note: Marks may be awarded for carefully drawn and labelled diagrams.
Mark
First Meiotic Division
Start with a gamete mother cell/diploid cell
Each chromosome made up of two chromatids
Homologous chromosomes pair up (NOT homologous pairs join up)
Crossing over may occur
At chiasmata
Nuclear membrane disappears OR spindle forms
Independent assortment occurs OR (homologous) chromosomes line up on
equator
Homologous chromosomes/pairs are pulled apart
New nuclear membrane formed OR division of cytoplasm
Second Meiotic Division
Chromosomes line up on the equator and chromatids pulled apart
New nuclear membrane formed OR division of cytoplasm
Mark awarded here OR in First Meiotic Division section
Four cells produced
Importance of Meiosis
Produces haploid gametes
Crossing over gives recombination/variation/diversity
Meiosis/it gives variation/diversity
(Only award mark if neither of previous two marks awarded)
1
1
1
1
1
1
1
1
1
Maximum 6
1
1
1
Maximum 2
1
1
1
Maximum 2
Maximum
Total
10
Higher Biology
Genetics & Adaptation
Core Essay
‘Give an account of gene mutation under the following headings:
i) occurrence of mutant alleles and the effect of mutagenic agents
ii)types of gene mutation and how they alter amino acid sequences
Mark
Occurrence of mutant alleles and the effect of mutagenic agents
Random/spontaneous/by chance
Low frequency/rare
One type of mutagenic agent, eg chemicals or named chemical such as
mustard gas
Second type of mutagenic agent, eg radiation or named type – X-ray, gamma
rays, UV light
Mutagenic agents cause or induce mutations/increase mutation rate/increase
chance of mutation occurring/increase frequency of mutation
Types of gene mutation and how they alter amino acid sequences
Gene mutation is a change in bases/base types/base sequence/base order
(This must be stated and not shown in diagram. Also nucleotide equivalent to
base)
Substitution: base/bases replaced with another/others
Inversion: oreder of bases reversed/bases turned round
Previous two points may be shown as suitably labelled diagrams with only
bases A, T, G and C used
Substitution/inversion may change base order of codon
Substitution/inversion may change only one/two amino acid(s)
Deletion: base/bases deleted from chromosome/removed/taken out
Previous point may be shown as suitably labelled diagrams with only bases A,
T, G and C used
Insertion: base/bases inserted into chromosome/added/put in
Deletion/insertion changes codons/triplets after the mutation
Deletion/insertion changes all amino acids after the mutation
Protein made (following substitution or inversion) will work/be unaffected OR
protein made (after deletion or insertion) will not function/will not work/is the
wrong protein/enzyme.
1
1
1
1
1
Maximum 3
1
1
1
1
1
1
1
1
1
1
Maximum 7
Maximum
Total
10
Higher Biology
Genetics & Adaptation
Core Essay
‘Give an account of evolution of new species under the following
headings:
i) isolating mechanisms
ii)effects of mutations and natural selection
Note: Marks may be awarded for carefully drawn and correctly labelled diagrams.
Mark
Isolating Mechanisms
A species is a group of interbreeding organisms capable of producing fertile
young
Common gene pool
A species/a population separated into two by an isolating mechanism/barrier
Prevents gene exchange/gene flow/interbreeding between populations/groups
Two types of isolation given (eg geographical/ecological)
Third type of isolation given (eg reproductive)
Effects of Mutation and Natural Selection
Mutations occurring in each population/group will be different OR mutation
occurs in one group
(Mutation) gives variation/different phenotypes/new genes/new alleles/alters
gene pool
Different environments
Selection is different for each population/group
Best adapted/best suited survive OR survival of the fittest OR converse
(They/best adapted/best suited/fittest) pass on favourable
characteristics/genes/alleles to offspring/next generation OR less well
adapted/less suited/less fit do not pass their characteristics/genes/alleles to
offspring/next generation
Many generations/long period of time
New species formed when populations/groups can no longer interbreed.
1
1
1
1
1
1
Maximum 4
1
1
1
1
1
1
1
1
Maximum 6
Maximum
Total
10
Higher Biology
Genetics & Adaptation
Core Essay
‘Give an account of the problems of osmoregulation in freshwater bony
fish and outline their adaptations to overcome these problems’
Mark
Problems
Fish (tissues)/body fluids hypertonic to surroundings/description OR converse
Water enters through gills and/or mouth by osmosis
Potentially leading to bursting of/damage to cells OR dilutes cytoplasm OR
increases water content of cells
OR excess water must be removed OR water must be removed to keep water
balance
Salts lost in urine through mouth lining/gills
Any 2 from 4
Adaptations
Kidneys have many glomeruli
Kidneys have large glomeruli
Kidneys have many large glomeruli
(Award only if above two marks not given)
Filtration rate of kidneys/glomeruli/blood is high
Urine produced is dilute
Large volume/amount/quantity of urine produced
Chloride secretory cells present in gills absorb salts
Against the concentration gradient/by active transport/uptake/activity
Any 6 from 7
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’ headings
above.
- Related information should be grouped together. Information as listed
under bold headings above should be grouped together
- There must be a minimum of 5 points with at least 1 point given for the
Problems section and at least 4 points from the Adaptation section.
All must apply correctly to gain the coherence mark.
Relevance
- Must not give details of salt water fish or desert mammals.
- There must be a minimum of 5 points with at least 1 point given for the
Problems section and at least 4 points from the Adaptation section.
Both must apply correctly to gain the relevance mark.
1
1
1
1
1
Maximum 2
1
1
1
1
1
1
1
1
Maximum 6
1
1
Maximum
Total
10
Higher Biology
Genetics & Adaptation
Core Essay
‘Give an account of the problems of obtaining food in animals by
reference to co-operative hunting, dominance hierarchy and territorial
behaviour’
Mark
Co-operative Hunting
(Co-operative hunting means) animals/or example hunting in a social
group/pack/team OR means working together in hunting/to get food
Advantage, eg larger prey/more successful, less energy used/pursuit time per
individual, net gain of energy is greater than by foraging alone
Another different advantage from list
Dominance Heirarchy
Is a rank/pecking order within a social group
Consists of dominant/alpha and subordinate individuals.
NOT smaller/weaker, larger/stronger/leader
In feeding dominant/alpha individuals eat first (followed by subordinate) OR
dominant gets bigger share of food OR converse
Ensured survival of dominant if food is scarce
Subordinate animal may gain more food than by foraging alone.
Penalise only once for lack of dominant
1
1
1
Maximum 2
1
1
1
1
1
1
Maximum 3
Territorial Behaviour
Territory is (an area) marked/defended for feeding/hunting
Ensures food supply/must contain enough food OR the more food available
the smaller the territory OR converse
Territorial behaviour reduces competition
Energy expended in marking, patrolling, defending
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’ headings
above.
- Related information should be grouped together. Information as listed
under bold headings above should be grouped together
- There must be a minimum of 3 points from Co-operative Hunting and
Dominance Heirarchy and 2 points from Territorial Behaviour
All must apply correctly to gain the coherence mark.
Relevance
- Must not give details of individual foraging, mating behaviour or social
defence.
- There must be a minimum of 3 points from Co-operative Hunting and
Dominance Heirarchy and 2 points from Territorial Behaviour
Both must apply correctly to gain the relevance mark.
1
1
1
1
Maximum 3
1
1
Maximum
Total
10
Higher Biology
Control & Regulation
Core Essay
‘Give an account of the effect of light on shoot growth and development,
and on the timing of flowering in plants and breeding in animals’
Mark
Shoot Growth and Development
Plants/shoot show phototropism OR shoots grow towards the light
Greater conc. of auxin/IAA on dark side OR less auxin/IAA on light side
Greater elongation of cells on dark side OR less elongation of cells on light
side
Etiolation in absence of light/in the dark
Description of etiolation: small leaves; yellow/chlorotic leaves; long
internodes/long and thin stems (any TWO for the mark) OR description of
appearance of plant in light: large leaves; green leaves; short internodes/short
and thick stems (any TWO for the mark)
1
1
1
1
1
Maximum 3
Timing of Flowering in Plants
Plants show photoperiodism OR flowering is affected by the photoperiod
Photoperiod is the number of hours of light in a day/in 24 hours
Long day plants flower when:
The photoperiod reaches/is above a critical level/a certain number of hours
OR hours of darkness below a critical level/below a certain number of hours
Short day plants flower when:
The photoperiod is below a critical level/below a certain number of hours OR
hours of darkness above a critical level/above a certain number of hours
1
1
1
Maximum 3
Timing of Breeding in Animals
Long day breeders/birds/small mammals/named example – breed in spring as
photoperiod increases
Short day breeders/large mammals/named example – breed in Autumn as
photoperiod decreases
Young are born when conditions favourable/when food abundant OR young
have long period of growth before winter/before unfavourable conditions
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’ headings
above.
- Related information should be grouped together. Information as listed
under bold headings above should be grouped together
- There must be a minimum of 5 points with at least 1 point given for each
group.
All must apply correctly to gain the coherence mark.
Relevance
- Must not give details of any other effects of IAA or any effects of GA
- Must give a minimum of 5 relevant points with at least 1 point from each of
the three headings.
Both must apply correctly to gain the relevance mark.
1
1
1
Maximum 2
1
1
Maximum
Total
10
Higher Biology
Control & Regulation
Core Essay
‘Give an account of the effect of the Jacob-Monod hypothesis of lactose
metabolism in Escherichia coli and the part played by genes in the
condition of phenylketonuria.’
Mark
The Jacob-Monod Hypothesis
Operon composed of structural and operator genes
Structural gene codes for B-galactosidase
To switch structural gene off:
Regulator gene produces repressor molecule/protein
Repressor molecule combines with operator and so switches structural/Bgalactosidase gene off
To switch structural gene on:
Repressor molecule combines with lactose
Repressor-lactose unable to fit into operator gene
Operator gene switches on structural/B galactosidase gene and Bgalactosidase produced
When substrate/lactose used up repressor switches structural/Bgalactosidase gene off again
Phenylketonuria
Phenylalanine normally broken down by a series of reactions/in a metabolic
pathway
Phenylketonuria Is caused by a genetic mutation/abnormal gene
Normal allele for gene required to make enzyme for reactions is missing.
As a result normal/correct enzyme is not produced OR abnormal/incorrect
enzyme is produced OR cannot code for normal/correct enzyme.
Phenylalanine cannot be metabolised as normal/converted to tyrosine/broken
down OR phenylalanine conc. increases OR metabolic pathway is blocked
Phenylalanine converted to other compounds/phenylpyruvic acid/toxic
substances
1
1
1
1
1
1
1
1
Maximum 4
1
1
1
1
1
1
Maximum 4
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’ headings
above.
- There must be a minimum of 5 points with at least 2 points given for each
group.
All must apply correctly to gain the coherence mark.
Relevance
- Must not give details of any other example in either section
- Must give a minimum of 5 relevant points with at least 2 points from each of
the two headings.
Both must apply correctly to gain the relevance mark.
1
1
Maximum
Total
10
Higher Biology
Control & Regulation
Core Essay
‘Give an account of the principal of negative feedback with reference to
the maintenance of blood sugar’
Mark
Principal of Negative Feedback
Negative feedback maintains constant internal conditions in the
body/homeostasis
A change from the normal level/set point is detected
A corrective mechanism is switched on/activated
When conditions return to normal level/set point, corrective mechanism
switched off.
Maintenance of Blood Sugar Level
Blood sugar/glucose level (BSL) detected by pancreas/Islets of Langerhans
If BSL increases (more) insulin is made
Insulin increases permeability of cells to glucose OR insulin increases uptake
of glucose by cells
Liver/muscle cells convert glucose to glycogen OR glucose converted to
glycogen and stored in liver/muscle
BSL returns to normal/set point*
If BSL decreases (more) glucagon is made
Glucagon causes conversion of glycogen to glucose
Glucose released into the blood
BSL returns to normal/setpoint*
1
1
1
1
Maximum 2
1
1
1
1
1
1
1
* Mark awarded once only
Maximum 6
Coherence
- The writing must be in sub-headings or divided into paragraphs
There should be sub-heading/paragraph for each of the ‘bolded’ headings
above.
- There must be a minimum of 1 point for Principle of Negative Feedback and
at least 4 points for Maintenance of Blood Sugar Levels.
Both must apply correctly to gain the coherence mark.
Relevance
- Must not give details of control of water balance or temperature regulation.
- Must give a a minimum of 1 point for Principle of Negative Feedback and at
least 4 points for Maintenance of Blood Sugar Levels.
1
1
Both must apply correctly to gain the relevance mark.
Maximum
Total
10
Higher Biology
Control & Regulation
Core Essay
‘Give an account of populations under the following headings:
i) the importance of monitoring wild populations
ii) the influence of density dependent factors on population changes.
Note: Marks may be awarded for information in a diagram. The relevant piece of
information must be clearly shown in a carefully drawn and labelled diagram
Mark
The Importance of Monitoring Wild Populations
Food species plus a strategy for management, eg prevent over-fishing/set
quotas
Raw material species OR species used in medicine plus strategy for
management, eg avoid over-harvesting
Pest species plus reason for monitoring, eg control of pest
Indicator species plus reason for monitoring, eg to assess levels of pollution
Endangered species plus reason for monitoring, eg to prevent extinction OR a
consequential strategy, eg protection/conservation (or named example)
One named example from any of points above
One different named example from another of points above
Influence of Density Dependent Factors on Population Changes
Effect of density dependent factor increases as density increases (or
converse)
Two density dependent factors named from list below
A third density dependent factor named from list:
- Disease/parasites/infection
- Food supply/availability
- Predation
- Competition for food/space/territory
- Toxic waste made by organisms
Relate population change to effect (listed below) of two factors
Relate population change to effect of third factors:
- if population increases then increase in disease/in spread of
disease/parasites/infection.
- if population increases then decrease in food available to individuals
- if population increases then increase in predation
- if population increases then increase in competition for food
- if population increases then increase in competition for space/territory
- if population increases then increase in production of toxic waste
(converses of the above also acceptable)
(linked to last two points)
Relate any of the above effects to a subsequent decrease in population OR
(if converses given in last two points) relate any of the above effects to
subsequent increase in population.
Population returns to a size that the environment can sustain/to a stable level.
1
1
1
1
1
1
1
Maximum 5
1
1
1
1
1
1
1
Maximum 5
Maximum
Total
10